Implantable Inductive Devices

Abstract

A surgical guide hub for implantation in an opening formed in a skull along a trajectory to a brain target, the guide hub comprising a through hole for delivering a device along the trajectory, at least one first structure on an exterior surface for securing the hub within the opening in the skull, and at least one second structure on a surface of the through hole for securing a guide device, an implantable device, or a cap to the hub. A jig for setting an insertion depth of a surgical instrument into a patient during surgery and a method for preparing a surgical length of a surgical instrument are also provided.

Description

[Technical field]

[0001] The present invention relates to an implantable guide hub for use in neurosurgery, neurotherapy and neurodiagnosis. The present invention also relates to a jig for setting the insertion depth of surgical instruments into a patient during surgery. The device and jig are particularly useful for image-guided stereotactic neurosurgery where precise and reproducible targeting is required. [Background technology]

[0002] Targets in the brain and trajectories to the targets in image-guided neurosurgery are identified on radiographic images and their image-based 3D coordinates are co-registered with the 3D coordinate system of the surgical targeting device or stereotactic guidance. This registration is traditionally done with reference to fiducials visible on the radiographic images attached to a base frame fixed to the patient's head. The resulting target and trajectory coordinates are set in the stereotactic guidance and fixed to the base frame and the target-guided instruments. Alternatively, so-called frameless registration can be achieved by mechanical means, using position sensor-equipped arms and optically or electromagnetically tracked instruments to identify the location of radiopaque markers fixed to the patient's head during image acquisition or to trace the contours of the patient's face with the head fixed to the operating table. The stereotactic guidance may include movable and lockable arcs or arms, or it may be a surgical robot. Targets in the brain include anatomical structures and pathological structures such as tumors.

[0003] Image-guided stereotactic neurosurgery can face many challenges. These include inaccuracies in targeting, leading to insufficient therapeutic efficacy and off-target side effects. Inaccuracies can also lead to high morbidity and mortality rates due to damage to the vasculature with bleeding and / or damage to critical brain structures. Achieving sufficient fixation of stereotactically inserted devices to the skull can be difficult, with the risk of device dislodgement or migration into the brain.

[0004] Current stereotactic systems are complex, requiring surgeons to make multiple measurements and adjustments to deliver devices to the brain. The risk of human error is high, which increases when multiple trajectories and targets are required. The complexity of current stereotactic systems increases surgical times and introduces additional risks, such as increased infection rates.

[0005] Current stereotactic systems do not fully meet the demands of precise reproducibility in repeat surgeries, which are particularly beneficial for optimizing gene therapy, chemotherapy drug delivery, lesioning procedures, etc.

[0006] If an implantable device is misplaced or dislodged, reinsertion requires repeating the entire surgical workflow, including preoperative imaging, surgical planning, and application of the stereotactic system.

[0007] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to address at least some of the above-mentioned problems by providing improved apparatus and methods for targeted neurosurgical procedures. Summary of the Invention [Means for solving the problem]

[0008] According to a first aspect of the present invention, there is provided a surgical guide hub for implantation into an opening formed in a skull and along a trajectory to a brain target, The induction hub is a through hole for trajectory delivery through the device; at least one first structure on the exterior surface for securing the hub within an opening in the skull; and at least one second structure on a surface of the through hole for securing a guide device, an implantable device, or a cap to the hub. Equipped with.

[0009] The guide hub may have a cylindrical or generally cylindrical body, and the through hole may be along the axis of the cylindrical or generally cylindrical body.

[0010] The through-holes may be aligned to deliver an implantable device along a trajectory, for example into the brain, by the methods described herein. Thus, the through-holes in the guide hub may provide trajectory guidance for the device. Thus, the guide hub is utilized in neurosurgery, but may also be used in other surgical applications where it is desirable to fix the guide hub to bone.

[0011] The guide hub can be configured to provide guidance along a trajectory to a brain target. The guide hub typically provides a guide element to the skull as close as possible to the target in the brain, thereby aiding in the accuracy of the guided delivery along a trajectory. The opening formed in the skull penetrates the entire thickness of the skull. Thus, the guide hub can typically be configured to provide access between the exterior of the skull and the interior of the skull. The through-hole of the guide hub is suitable for delivering devices through the skull into the cranial cavity and / or brain. In particular, fluid transport tubes such as catheters and cannulas can be delivered into the cranial cavity and / or brain via the guide hub.

[0012] The guide hub does not include a guide tube as in the prior art device shown in Figure 1 and described in U.S. Patent Application Publication No. 2001 / 0003156, but may have a guide tube attached as described below, so that the forces used to insert the guide hub through the opening in the skull are not transmitted to the brain by the attached guide tube.

[0013] The guide hub can be sized so that when attached to the patient's skull, it does not protrude above the surface of the skull. Thus, the guide hub can be for implantation at or below the surface of the skull within an opening formed in the skull. The guide hub is particularly useful when repeat surgeries are envisioned. The guide hub can be closed with a cap that fits over the second structure, and the scalp can be closed over it when not in use. When delivery of the device is required, the scalp can be reopened, the cap removed, and the device delivered through the guide hub.

[0014] Using the guidance hubs and systems described herein, a wide range of devices can be delivered through the skull to the cranial cavity and brain, including cannulas or catheters for delivering or removing fluids for diagnosis or treatment, electrodes for recording, stimulating, or blocking neural activity, including radiofrequency lesions, brachytherapy devices for delivering therapeutic radioisotopes, glass fibers for transmitting light, including lasers, for lesioning or optical stimulation, probes for monitoring pressure, temperature, fluid flow, or concentrations of metabolites, drugs, or gases, biopsy devices, and stylets for providing markers into the brain or for maintaining a pathway to later reaccess the brain target with another device.

[0015] More specifically, catheters and cannulas can be delivered through the guide hub to any intracranial cavity, including to the ventricles, subdural or subarachnoid spaces, as well as to abscesses, cysts, cavities and tumors, as well as within the brain parenchyma. Fluids delivered for diagnostic purposes can include contrast agents, diagnostic radioisotopes and dyes visible on x-ray images such as x-ray computed tomography (CT) and magnetic resonance imaging (MRI). Fluids delivered for therapeutic purposes include, but are not limited to, chemotherapy, antibiotics, enzymes, neurotrophins, gene therapy, small interfering RNA (SiRNA) and antisense oligonucleotides, enzymes, immunomodulatory therapies (such as monoclonal antibodies and chimeric antigen receptor T cell (CAR-T) therapy), Auger electron emitters, immunotoxins, molecular targeted therapies, monoclonal antibodies, oncolytic viruses, nanoparticles and botulinum toxin. Inert fluids (such as artificial cerebrospinal fluid, saline, Hartmann's solution, or lactated Ringer's solution) may be injected for therapeutic purposes.

[0016] The device can be delivered through the directing hub using a guide tube secured to the through hole.

[0017] Thus, the guidance hub and associated systems and methods described herein may be applied in a wide range of surgical procedures and treatments, including, but not limited to, the surgical treatment of abnormalities in brain function, including the treatment of neurodegenerative and movement disorders such as Parkinson's disease, Alzheimer's disease, Huntington's disease, tremors, and cerebral palsy, neuro-oncological diseases such as glioblastoma, brain metastases, and diffuse pontine glioma, neuro-inflammatory diseases such as multiple sclerosis, psychiatric disorders such as depression and obsessive-compulsive disorder, metabolic diseases such as lysosomal storage diseases, hydrocephalus, intracranial hypertension, and epilepsy.

[0018] The guide hub may be generally cylindrical in shape. The hub may have an outer diameter of 3 mm to 12 mm, advantageously 3 mm to 6 mm. The height of the hub may be 3 mm to 10 mm, advantageously 4 mm to 6 mm. The guide hub may thus fit compactly within the patient's skull.

[0019] The through-hole may be of reduced diameter at its distal end (the end distal to the outer surface of the skull in use), for example, 0.5 mm to 5 mm in diameter, or even 1 mm to 3 mm in diameter. The reduced diameter may be selected to provide a snug fit for the device to be delivered or the associated guide tube.

[0020] The guide hub can further include a seal disposed within the through hole and configured to provide a sealing engagement with a device passing therethrough or with a cap attached to the through hole and engaging the second structure. The seal can be an O-ring seal or washer with a central opening sized to pass the device, guide tube, or cap. The O-ring seal or washer can be configured to compress axially and expand radially to provide a sealing engagement of the guide device, implantable device, or cap to the hub within the central opening.

[0021] The guide hub may have a conical distal end, and the through-hole can have a conical distal end configured to engage a corresponding cone on the guide device, implantable device, or cap to the hub to provide a sealing engagement therebetween.

[0022] The guide hub may include a proximal rim that extends outwardly from the hub to provide an edge for mounting to a surface surrounding the opening in the skull. For example, the proximal rim may extend from the hub by 0.5 mm to 2 mm. Guide hubs in which the proximal rim does not extend from the hub are also contemplated.

[0023] The guide hub has a first structure on its exterior surface that allows the hub to engage and be secured within an opening in the skull. The guide hub can be attached to the opening in the skull without the use of small screws or other separate fasteners that are often used to attach surgical devices to bone. The guide hub can be press-fit into the skull opening, and thus the first structure can be in the form of one or more protrusions that allow for the press-fit action and / or prevent rotation of the guide hub once attached.

[0024] Thus, the first structure on the exterior surface of the hub may comprise at least one broach tooth for securing the hub to the skull. There may be a gap between the broach tooth and the proximal rim to allow for bone ingrowth in use. The at least one broach tooth may be triangular in cross section and configured to bite into the surrounding bone to lock the hub in use.

[0025] Additionally or alternatively, the first structure on the outer surface of the hub can include at least one rib for securing the hub relative to the skull. The one or more ribs can extend generally axially along a surface of the guide hub from the proximal end to the distal end.

[0026] Other patterned surfaces may be used to provide a grip between the guide hub and the bone, for example a pattern of protrusions may be distributed around the outer surface of the guide hub.

[0027] Alternatively, the first structure on the exterior surface of the hub may include threads for securing the guide hub to the skull.

[0028] The second structure on the surface of the through hole is for securing the guide device, the implantable device, or the cap to the hub. The second structure allows the guide device, the implantable device, or the cap to be releasably secured to the hub.

[0029] Conveniently, the second structure may also be used to secure the hub insertion instrument to the hub. The hub insertion instrument may comprise a rod with a structure at its distal end for engaging the second structure of the hub. The hub insertion instrument thus constitutes a guidance device that may be used with a stereotactic guidance system to insert the hub into the skull along a trajectory, as described further below and with reference to specific examples.

[0030] Advantageously, the hub insertion instrument may be hollow along its length, allowing a surgical instrument or implantable device to be inserted through the hub insertion instrument, through the attached hub in the skull, and into the patient's brain. In this manner, the combination of the guide hub and hollow hub insertion instrument (or another hollow elongated instrument that fits into the second structure) can be used in combination as an elongated guide fixed to the patient's skull for inserting an instrument or device into the patient along a trajectory. For example, as further described below with reference to specific examples, a surgical instrument, such as a pathway forming probe for forming a pathway in the brain to enable and guide the insertion of an implantable device, can be delivered into the patient's brain along a selected trajectory via the combination of the hub and hub insertion instrument.

[0031] An elongate guide comprising a directing hub and a hollow hub insertion instrument (or another hollow elongate instrument that fits into the second structure), and methods of using the elongate guide, constitute further aspects of the invention. The hollow hub insertion instrument (or another hollow elongate instrument) can be provided with a hole at its distal end to allow air to escape as an instrument or device is delivered therethrough.

[0032] The second structure on the guide hub can include threads configured to engage corresponding threads on an insertion tool or to engage a guide device, implantable device, or cap that is loaded into the through hole, or a bayonet-style fixation can be used between the device or cap and the second structure.

[0033] If the second structure and the guide device, implantable device, or cap have threads, the corresponding threads can be formed to allow for quick attachment of the device or cap, for example with only half a turn of the device or cap. Thus, the threads can be dual entry threads with a first thread portion and a second thread portion, each of which sweeps approximately half a turn of the hub so that the device or cap can be fully inserted into the thread and locked therein with half a turn.

[0034] The corresponding threads may be locking screw threads. For example, they may comprise a Spiralock®-type locking screw arrangement utilizing relatively free-floating threads that lock when the male threads engage a wedge ramp at the base of the female threads. Further, for example, at least one of the first and second threads may comprise a notch configured to temporarily lock the device or cap within the first or second threads by engagement of the notch with a corresponding rib on the device or cap. Each of the first and second threads may comprise a notch configured to temporarily lock the device, cap within the first and second threads by engagement of the notch with a corresponding rib on the device or cap.

[0035] Thus, the second structure can be used to quickly screw the guide device, implantable device, or cap onto the guide hub (e.g., in a half turn), which can be done with a simple driver instrument with an end formed for attachment to an appropriate structure on the device or cap. Advantageously, the engagement between the end of the driver and the structure on the guide device, implantable device, or cap provides a releasable attachment. For example, the end of the driver may be an interference fit with a structure on the device or cap such that the device or cap remains attached to the driver until attachment to the guide hub is complete. If the device being attached is elongated and extends beyond the guide hub after attachment (e.g., a cannula for delivering infusate as a treatment), the driver instrument may be hollow along its length to allow the device to pass through. If the driver is hollow along its length, a vent can be provided at or near the distal end to allow air to escape as the device or surgical instrument passes through the body of the instrument and into the patient. This helps to prevent air from entering the patient, such as into the patient's brain. Alternatively, as described in more detail below, the driver instrument may have a distal (head) end that allows an elongate device to be received in a side slot and passed through the distal-most end of the instrument. The side slot also functions as a vent. The side slot may extend to the distal-most end of the driver instrument. This allows for easy attachment and removal of elongate devices such as cannulas, as described further below. Driver instruments constitute another aspect of the present invention.

[0036] The guide hub of the present invention is for delivering a device along a trajectory through the through hole. The second structure on the surface of the through hole is for securing a device or a cap to the hub. A cap secured to the second structure can secure a device to the hub. Thus, the present invention also provides a system comprising a surgical guide hub according to the present invention as described herein, and a device or cap configured to engage and preferably lock within the through hole of the hub.

[0037] The device or cap may include a seal to provide a sealing engagement with the through hole in the hub. Alternatively, or additionally, a seal may be provided in the through hole.

[0038] The device or cap of the system may include a cone configured to engage a corresponding cone on the hub to provide a seal therebetween.

[0039] The device or cap can include threads configured to engage corresponding threads of a second structure on the through hole of the hub.

[0040] Thus, the device may include a structure for fastening within a second structure within the guide hub (eg, a structure having external threads may be fastened around the body of the device).

[0041] The cap of the system may be for sealing the through-hole when entry into the cranial cavity is not required.

[0042] Alternatively, the cap may have a cap through-hole extending therethrough, which may be for securing the implantable device to a guide hub. For example, a cannula may pass freely through the cap through-hole. As the cap is secured to the through-hole, for example by a screw, the cannula may be gripped by an O-ring seal within the through-hole, which is axially compressed by the cap and radially expanded inward.

[0043] In use, the guide hub of the present invention is implanted into an opening in the skull. The guide hub functions as a guide for inserting a device along a trajectory to a target within the cranial cavity, and particularly within the brain. After imaging and using a stereotactic system to determine the trajectory, the general procedure utilized to insert the hub is: The scalp is incised to expose the skull, A facing tool is used to cut a flat surface into the skull. Drill pilot holes into the skull along the trajectory, providing a profiled opening and enlarging the pilot hole to accept the guide hub; and The step includes attaching the guide hub to the profiled opening by press fitting or threading.

[0044] The flat surface formed by the cutting instrument provides a surface that is generally perpendicular to the trajectory, thereby allowing the drilling of the pilot hole while avoiding slippage of the pilot hole drill, which can occur if the pilot drill is applied directly against the curvature of the skull surface.

[0045] The guide hub is then used for insertion of the device. The profiled holes, attachment of the guide hub, and preparation of the device for delivery, particularly into the brain, require careful guidance and precision throughout the surgery, including the use of stereotactic tools such as a stereotactic frame or robotic arm.

[0046] Using conventional methods of drilling into the skull surface to create profiled holes and attach devices within the brain typically requires many measurements to be taken, especially when multiple different devices are used to create holes for the introduction of hubs or other devices.

[0047] When using conventional stereotactic guidance, the brain image is registered using a stereotactic reference system and the stereotactic guidance is set to the target coordinates along the desired trajectory. The stereotactic guidance has its own reference point and the target is at a measured distance from the reference point along the selected trajectory. Currently available stereotactic guidance has a distance between the reference and the target of, for example, 190 mm or 160 mm. Robotic stereotactic guidance allows the desired distance between the reference and the target of the robotic stereotactic guidance to be preset.

[0048] The imaging of the brain provides the thickness of the skull along the desired trajectory and the distance from the skull surface to the target. In the conventional method, this information is used by the surgeon to calculate the length of each piece of equipment to be introduced into the patient's head along the trajectory. For example, the surgeon calculates that a certain depth into the brain must be reached by a first device, and therefore cuts or adjusts the length of the first piece of equipment to allow the depth to be reached when utilizing stereotactic guidance methods. The next device introduced may be required to reach a different depth, often deeper, in the brain. The surgeon would again use the imaging data to calculate the length that the second device needs to be adjusted or cut to match to reach the desired depth when using stereotactic guidance. This process can be cumbersome and require many calculations with attendant risks of human error, especially in the stressful and tiring environment of brain surgery.

[0049] According to a further aspect, the present invention provides a jig for setting an insertion depth of a surgical instrument into a patient during surgery, the jig comprising: an instrument alignment device; a representative fiducial representing a stereotactic guidance fiducial; a reference guide movable relative to the representative reference, the reference guide being for setting a length of a reference line from the representative reference to a reference surface on the reference guide; the reference guide having at least one offset from a reference surface configured to receive a surgical instrument extending from the instrument alignment device; The depth of insertion of a surgical instrument when used in surgery on a patient is set on the jig by the distance from the representative datum to the offset.

[0050] The jig may also be used to set the insertion depth of a device into a patient, such as any of the devices (cannulas, catheters, DBS electrodes, etc.) discussed herein with respect to use of the guide hub of the present invention. Thus, the jig may be utilized in the insertion procedure and use of the guide hub of the present invention as described herein, but may also find more general application in neurosurgery and other surgical procedures. The reference surface on the fiducial guide represents a reference based on the patient's skull, or any other surface or reference used in surgery, such as the position of the guide hub of the present invention on the patient's skull.

[0051] The jigs and associated instruments described herein have the advantage that only a limited number of length measurements or calculations are required. For example, only one baseline measurement may be required to prepare a jig for setting the length or depth of all instruments and devices required for a complete surgical procedure. Furthermore, the instruments and devices required for a procedure may be ready for transfer to a patient one after the other with minimal handling, thereby reducing the risk of infection.

[0052] The jig may also include a target fiducial representing the target location relative to the stereotactic guided fiducial as used in the selected stereotactic system or device. Thus, the distance from the representative fiducial to the target fiducial on the jig corresponds to the stereotactic guided fiducial to target distance when performing surgery on the patient. In a commercially available Cosman Roberts Wells (CRW) stereotactic frame, the distance is set at 160 mm from the target, while the corresponding distance for the Leksell frame is 190 mm. Thus, the reference plane on the fiducial guide may represent the skull surface that is between the representative fiducial and the target fiducial on the jig.

[0053] The jig may be generally rectangular. The jig may take the form of an open frame upon which surgical instruments are placed. The jig may include a backboard. The jig may include a stand that supports the jig at an angle (e.g., 45 degrees) to the horizontal.

[0054] The instrument alignment device may comprise a representation fiducial.

[0055] The instrument alignment device may comprise a groove in the back plate. The instrument alignment device may comprise a bar including a slot or groove for receiving a generally elongated instrument and orienting its distal end towards the reference guide. The reference guide may be in the form of a bar parallel to the bar of the instrument alignment device. The reference guide may be movable relative to the instrument alignment device while maintaining the parallel relationship.

[0056] In the jig, the reference guide is moveable relative to the representative datum. Conveniently, this is achieved by the reference guide being moveable and the representative datum being fixed. For example, the representative datum may be provided as part of an instrument alignment device that is in a fixed position within the jig. However, other arrangements are envisaged, for example where the reference guide and its associated reference surface are fixed and the representative datum is moveable to set the reference line length. For example, the representative datum may be provided on a moveable instrument alignment device. As yet another example, both the representative datum and the reference guide may be moved when setting the reference line length.

[0057] In a preferred form of the jig, the instrument alignment device comprises a bar including a slot or groove for receiving a generally elongated surgical instrument and orienting its distal end to the reference guide; The reference points are formed on the bar of the instrument alignment device; the reference guide comprises a bar parallel to a bar of the instrument alignment device and is movable relative to the instrument alignment device while maintaining the parallel relationship; The bar of the instrument alignment device and the reference guide are connected by at least two rails, which are located at each end of the bar of the instrument alignment device and connected to corresponding ends of the bar of the reference guide.

[0058] This configuration is particularly preferred since the instrument alignment device (and associated reference points) are fixed and the reference guide is movable.

[0059] The jig may also include one or more cross members to provide bracing, for example extending between at least two of the rails at each end.

[0060] The bar of the datum guide may be slidably engageable with at least two of the rails and may be securable to one or more of the rails to set the datum length. There may be at least three rails connecting the instrument alignment device and the datum guide, and a third rail may be located at a midpoint of the bar of the instrument alignment device and extend at least to a corresponding midpoint of the bar of the datum guide.

[0061] As an alternative to slidable engagement between the rails and the movable reference guide, at least two rails may be threaded and operate as lead screws through corresponding threads on the bars of the movable reference guide, or At least two of the rails may be provided with rack gears and the bar of the movable reference guide may be provided with a corresponding pinion.

[0062] The jig may be motor driven and computer controlled to set the baseline distance. Setting of the jig may be direct from the surgical planning software. The planning scan provides information such as target location relative to the skull, thickness, skull, and trajectory from the skull to the target. Thus, prior to surgery, the jig may be set by computer control using the scan data as input, for example by a servo motor driving a spindle shaft controlled by the computer.

[0063] In the jig of the present invention, the reference guide may include at least one guide channel extending therethrough for passage of a surgical instrument or device, the guide channel extending from said reference surface and continuing in a direction set by said instrument alignment device, so that the length of the device from the reference surface can be measured and adjusted or cut to the required length, for example the required length of a cannula to be used is the length that extends below the guide hub into the patient's brain.

[0064] The jig allows for setting the tools to create the profiled holes in the skull and the length of the device to be inserted into the skull, all determined from the scan data which is used to set the baseline length and determine the trajectory and distance to the target when planning the surgery.

[0065] For use in inserting a guide hub according to the present invention, or in similar surgical procedures in which holes are made in bone, an instrument alignment device may include: a cutting tool for forming a flat work surface on the bone; a pilot drill for forming a pilot hole in the bone; A core drill for forming a profiled hole in the bone; The device may be configured to receive one or more of the following:

[0066] The datum guide may further comprise a bore for receiving a surgical guide hub of the present invention, which may be used to set up instruments and devices on the jig prior to their transfer to a patient. Thus, the datum guide may include a guide channel for passing a surgical instrument through the movable datum guide, and a surgical hub disposed within the bore.

[0067] The jig may further comprise a movable cutting or depth measuring guide, which is positioned further from the instrument alignment device than the reference guide. This guide is configured to adjust the instrument or device to a selected length or to cut the instrument or device to a selected length (extending from the reference surface through the movable reference guide). The movable cutting or depth measuring guide may comprise a bar parallel to both the alignment device and the reference guide. The movable cutting or depth measuring guide may have a guide surface that engages with the distal end of the device or device portion. The device entering the skull from the guide hub can be set at a suitable distance from the reference surface on the reference guide to measure or cut to adjust the length. The movable cutting or depth measuring guide may comprise a slot transverse to the direction of the device positioned in the jig to allow for the insertion of a knife to cut the device to the selected length.

[0068] According to another aspect, the present invention comprises a jig according to the present invention, further comprising: a cutting tool for forming a flat work surface on the bone; a pilot drill for forming a pilot hole in the bone; a core drill for forming a profiled hole in the bone; A guide hub for insertion into a profiled hole as described herein; The present invention provides a system comprising at least one surgical instrument selected from the group consisting of:

[0069] According to another aspect, the present invention provides a method for producing a method for manufacturing a pharmaceutical composition comprising: i) providing a system comprising the jig of the present invention and at least one surgical instrument; ii) determining a reference line length from the representative datum to a reference surface on the reference guide by moving the reference guide relative to the representative datum; iii) moving the surgical instrument in the instrument alignment device to a predetermined offset in the fiducial guide to obtain a surgical length of the surgical instrument; A method for preparing a operative length of a surgical instrument is provided having steps.

[0070] The step of setting the reference line length includes: iv) holding a reference measuring instrument within an instrument alignment device; v) moving the reference guide relative to the instrument alignment device to contact the distal end of the reference measuring instrument; vi) fixing the reference guide stationary at a length from the representative reference determined by the reference measuring instrument; It may have steps.

[0071] The jig and associated methods may find use in implanting other devices into a patient's skull, such as in deep brain stimulation (DBS) surgery, particularly for mounting a skull-mounted deep brain stimulation (DBS) battery power source ("generator").

[0072] A DBS generator is used to power the DBS electrodes attached to the patient's brain. Traditionally, the DBS generator is attached to the patient's chest wall, with wires running subcutaneously to power the DBS electrodes on the skull via the neck. The DBS generator may include a removable battery. Alternatively, the DBS generator may be rechargeable, for example wirelessly charged by inductive charging.

[0073] When DBS generators are mounted near the DBS electrodes, such as in the patient's skull, they are typically rectangular or square. To mount such DBS generators, the surgeon must create a correspondingly shaped hole in the patient's skull, which is time-consuming. The jig of the present invention can be used to help prepare the hole in the patient's skull and to aid in mounting the tubular DBS generator, as described in more detail below and with reference to specific embodiments.

[0074] According to another aspect, the present invention provides a system for implanting a tubular DBS generator in a skull, said system comprising: a) a jig of the present invention as described herein; b) a cutting tool for forming a flat work surface on the bone; c) a pilot drill for forming a pilot hole in the bone; d) a core drill for creating a hole in the bone that is larger than the pilot hole; e) at least one milling tool for forming a profiled hole of a larger diameter than the core drill hole to accommodate a tubular DBS generator within the skull; Equipped with.

[0075] The milling instrument can include a distal cutting surface for cutting a DBS generator mounting hole through the skull of a larger diameter than the core drill hole, and a proximal cutting surface for forming a ledge in the skull around the DBS generator mounting hole to accommodate a corresponding edge of the tubular DBS generator. Alternatively, two milling instruments with different diameters can be utilized to cut a designed hole that includes a ledge to accommodate a corresponding edge of the tubular DBS generator.

[0076] The system may further include a blunt hook that is used to release the dura from beneath the inner plate of the skull following completion of the core drill hole. A hemostatic gel, such as DuraSeal® gel, may be provided and injected into the epidural space to provide a protective barrier to prevent tearing of the dura when the milling instruments are used.

[0077] The present invention also provides methods of surgery that involve the use of one or more of the guide hubs, jigs, and associated instruments and devices as described herein. [Brief description of the drawings]

[0078] Hereinafter, embodiments of the present invention will be described with reference to the following drawings. [Figure 1] 1a and 1b show a prior art inductive device. [Diagram 2] 2a-2f show features of an inductive device according to the present invention. [Diagram 3] 3a and 3b show a cap for use with the present invention. [Figure 4] Show alternative caps [Figure 5a] Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 5b] Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 5c] Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 5d] Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 5e] Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 5f] Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 5g] Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 5h] Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 5i] Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 5j]Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 5k] Shows the instruments and methods used to place the hub in the patient's skull and to provide a guide tube and catheter through the hub. [Figure 6] Figure 6a shows the profiled hole, and Figure 6b shows the core drill. [Figure 7] Demonstrates how to place the cap into the hub inside the patient's skull and then place the cannula or DBS electrode leads into the patient's brain [Figure 8] FIG. 1 shows a driver with an axially extending slot at its distal (head) end. [Figure 9] 1 shows a jig according to the present invention [Figure 10a] 1 shows an alternative jig according to the present invention; [Figure 10b] 1 shows an alternative jig according to the present invention; [Figure 11] FIG. 1 is a schematic diagram of the components of a jig; [Figure 12] FIG. 1 is a schematic diagram of the components of a jig; [Figure 13] FIG. 1 is a schematic diagram of the components of a jig; [Figure 14] Figures 14a-c show the jig combined with a sterilization tray. [Figure 15] Figure 15a shows a method of preparing the skull surface for delivery of a deep brain stimulation generator, Figure 15b shows the DBS generator being delivered into a hole in the skull, and Figure 15c shows the DBS generator of Figure 6b being secured to the skull by a screw. [Figure 16] Figure 16a shows a perspective view from below of the distal end of the driver, and Figure 16b shows an enlarged view of a portion of Figure 16a. [Figure 17] 17a-17c show an induction device with an external self-tapping thread and hub engagement mechanism. [Figure 18] 18a-18d show a cap for use with the present invention. [Figure 19]19a and 19b show an insertion tool having a tool engagement feature configured to engage a hub engagement feature on a guide device. [Figure 20] 20a and 20b show enlarged views of the distal end of the insertion tool of FIG. [Figure 21] FIG. 21 is an isometric view of the distal end of the insertion tool of FIGS. 19 and 20; [Figure 22] 22a and 22b show a shortening tool for removing the guide device from the patient's skull. [Diagram 23] 23a and 23b show a driver with a slot extending axially along its length. [Figure 24] Shows a driver with devices positioned along a hollow central axis [Diagram 25] 25a-25c show a fiducial marker having an indicator to show whether the fiducial marker is locked to an instrument. [Figure 26] 1 illustrates a cutting instrument having a stepped distal profile. [Figure 27] 27a-27d show preparation of a highly curved skull surface for insertion of a guide hub using the cutting instrument of FIG. 26. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0079] 1a and 1b show isometric and cross-sectional views, respectively, of a prior art guide device 100 comprising a tube 110 having a hub 120 attached to its proximal end. Hub 120 has a passageway that communicates with the bore of tube 110 and has threads on its exterior surface.

[0080] The guide device 100 is first placed for use on the patient's skull by drilling holes along a desired trajectory in the skull guided by stereotactic guidance. The guide device tube 110 is cut to an appropriate length to provide access to a brain target, for example, for a cannula delivered through the tube 110. The tube 110 is delivered over the stereotactic guided probe through a hole preformed in the skull such that the guide device hub 120 is secured in the preformed hole in the skull when the distal end of the tube is in the pre-determined position. The securement may be a press fit if there is a drill hole of appropriate size, a screw fit if there is a pre-formed female thread, or may be glued in the drill hole using acrylic cement. The probe is removed and the guide device 100 can remain attached, at least temporarily, to the patient's head to guide other neurosurgical devices, such as a cannula, to reach a target in the brain.

[0081] In some circumstances, the guide device 100 may be placed in the patient's skull and brain for an extended period of time. The guide device 100, fixed to the skull, does not move with the brain as it moves within the skull. Thus, relative movement of the brain with respect to the tube 110 of the guide device 100 occurs, potentially causing trauma to brain tissue in the vicinity of the tube 110. The guide device 100 does not provide a seal between the hole in the guide device and the surgical device passing therethrough. Thus, there is a space between the guide device 100 and the surgical device through which infection can potentially enter the brain. The guide device 100 does not provide a means to secure the surgical device delivered through its hole. For example, when the guide device 100 is used to deliver deep brain stimulation (DBS) leads, the leads are bent 90 degrees as they exit the hub 120 of the guide device 100 and are secured to the skull by compression under a bone plate secured to the skull with small screws. This fixation process is cumbersome to perform and poses the risk of inadvertently displacing the DBS lead from its target location.

[0082] Figures 2a and 2b show a guide device 200 according to the present invention. Figure 2c shows a guide device 200 similar to Figures 2a and 2b in cross-section. The example of Figure 2c differs by having a smaller broach tooth 225, as will be discussed further below. The guide device 200 is configured to be implanted in the skull of a patient. The guide device 200 provides a low profile access point for introducing a device into the brain along a selected trajectory. The device 200 also provides a means for fixing a device to the guide device 200.

[0083] The guide device 200 includes a guide hub 220, but does not include a guide tube 110 as in the device of Figures 1a and 1b.

[0084] The guidance hubs 220 can be made from titanium or PEEK (polyetheretherketone) or other biocompatible materials. PEEK hubs have the advantage of being long-term implantable devices that do not cause MRI artefacts and do not heat up in high magnetic fields. Each hub 220 has a conical portion 222 at its distal end with a through hole 221 and a central hole 223 forming the most distal end of the through hole 221. The hub 220 further comprises a proximal rim 224 at its proximal end. As described below, the rim 224 provides a hub fiducial HD and allows for the calculation of the distance between the hub fiducial HD and the brain target.

[0085] The body of the hub 220 has a diameter (D) and a length (L). The diameter of the hub 220 through the through hole 221 and the distal central hole 223 can be sized to guide and secure a variety of surgical devices, and can range from 0.5 mm to 5 mm in diameter, for example. By way of example, the dimensions of the guide hub 200 for use in delivering and securing a device having a cross-sectional diameter of 1.2 mm may have a diameter (D) of the body of the hub 220 of about 4 to 5 mm. The hub 220 may have a length (L) such that it is fully implanted within the thickness of the skull of most adults and children. Thus, the length (L) may be on the order of 4 to 5 mm. The through hole 221 may be on the order of 3 mm in diameter at the proximal end of the hub 220. The central hole 223 at the most distal end of the through hole 221 may typically be about 1.2 mm in diameter. The rim 224 may be about 0.5 mm in length (l1), 0.5 mm thick, with an outer diameter of about 5 mm and an inner diameter of about 4 mm. A variety of optional sized guide hubs 220 are envisioned for use in delivering devices of different diameters to the brains of humans and other animals, or for employment in other locations in the human body.

[0086] 2b and 2c, in these embodiments, conical section 222 tapers at an angle of about 45 degrees over a length (L) of about 1 mm. This provides a sloped surface of about 45 degrees on the exterior of hub 220 and a similar sloped interior surface that provides a surface for mounting a device within hub 220.

[0087] 2a, 2b and 2c, the hub 220 includes a number of broach teeth 225 to prevent rotation of the hub 220 when secured to the skull. The broach teeth 225 may begin at a distance (d1) from the rim 224, allowing bone to regrow in the gap when placed within the skull, thereby providing a stable long-term implant. The distance (d1) may provide a gap between the rim 224 and the broach teeth 225 of, for example, 0.5 mm. In some embodiments, the broach teeth 225 may extend to a width similar to the outer diameter of the rim 224, as seen in FIG. 2b. In FIG. 2c, a smaller broach tooth is shown.

[0088] In the example shown in Figures 2a, 2b and 2c, the hub 220 is provided with six broach teeth 225 evenly spaced around the hub 220. The shape and angle of the broach teeth 225 may be adjusted from those shown in the example figures to allow for insertion into bones of different bone density or strength. In an embodiment, the broach teeth 225 each have a triangular cross section and are configured to bite into the surrounding bone and secure the hub 220 as the hub 220 is driven into the bone. Other means for preventing rotation of the hub in the skull may be provided, such as ribs, such as axially extending ribs, located around the hub.

[0089] Instead of broach teeth 225, guide hub 220 may include external threads arranged to bite into the skull, or the hub may have an interference pattern (not shown). The interference pattern, such as an array of protrusions, may provide an interference fit to provide locking of hub 220 to the surrounding bone as hub 220 is driven into the bone.

[0090] 17a, 17b, and 17c show an example where the guide hub 220 includes male threads 1702. The male threads 1702 are self-tapping screws that are arranged to bite or cut into the skull. This allows the hub to be rigidly fixed to the skull. Additionally, the threads cut by the male threads 1702 in the skull can later be used to hold other threaded components following removal of the guide hub 220. For example, a threaded bone plug can be inserted to seal the hole in the skull using the same hole. The male threads 1702 preferably have relatively deep grooves between the threads. This allows the male threads 1702 to be configured to accommodate bone chips that are generated as the male threads 1702 cut into the skull. The minor diameter of the male threads 1702 may be smaller than the diameter of the drill hole into which the guide hub 220 is inserted by at least 0.2 mm, preferably at least 0.4 mm. This allows the guide hub 220 to be more easily inserted and may help encourage bone regrowth around the guide hub 220 with bone chips in the male threads 1702. As shown in Figures 17a, 17b, and 17c, the guide hub 220 may also have areas above and / or below the male threads 1702 where the outer diameter of the guide hub 220 matches the minor diameter of the male threads 1702 but is unthreaded. This provides additional space to accommodate bone chips that may be created as the male threads 1702 cut into the skull.

[0091] The proximal rim of the guide hub 220 may include a hub engagement feature for engaging with a hub insertion instrument, which will be described in more detail below. The hub engagement feature may include any suitable feature, such as a groove, a protrusion, or a notch. In the example of FIGS. 17a-17c, the hub engagement feature includes notches 1704 in the rim of the guide hub 220. Other example possible shapes include slots, holes, or castellations in the top (proximal) surface of the guide hub. The hub engagement feature allows a higher torque to be more easily and reliably applied to the guide hub 220 during insertion. This is particularly advantageous when the guide hub 220 has a self-tapping screw, as the guide hub 220 allows for easy application of sufficient force to the screw to cut into the bone.

[0092] Further embodiments of the guide hub 220 may have male threads that are not self-tapping but are inserted into the threaded hole. This is a preferred solution when the guide hub 220 is made from a material that is not suitable for forming self-tapping threads, such as PEEK. In this case, the jig has an additional tool to tap the hole to the desired depth.

[0093] 2d-2f, the internal configuration of the hub 220 is as follows: The through hole 221 of the hub 220 includes dual entry internal threads 226 extending from the proximal end of the cone 222. The threads 226 used in the example described here are M4 threads, have a 2mm pitch and a half turn sweep. The pitch may be adjusted for other threads used with different sized hubs 220.

[0094] As shown in Figure 2d, each half turn of the threads 226 includes a notch 227. A detailed view of one of the notches 227 is shown in Figure 2e. Each notch 227 is positioned to engage a rib (not shown) on a device that is inserted and locked into the hub 220. The notches 227 are spaced apart from each other by a 0.08 mm slit for a length (l3) of 0.2 mm that extends radially into the through hole 221 of the hub 220. 22e, the notch 227 includes a fillet 229 that is provided to allow a rib on the device to be inserted to slide past the notch 227 and provide compression of the notch 227 and / or the rib on the device. Once the rib passes the fillet 229, it securely engages into the threads 226, thereby locking the device into the hub 220. FIG. 2f shows a cross-sectional view of the hub 220 of FIG. 2b, showing the broach teeth 225 and the notch 227. Another locking thread arrangement, such as Spiralock®, may be employed in the through hole 221 of the hub 220.

[0095] In an exemplary use of the hub 220, an exemplary cap 300 is described with reference to Figures 3a and 3b. The cap 300 is overmolded onto a catheter or (in this example) a cannula 393, which may be made from or include PEEK. A PEEK cannula has the advantage of being strong, rigid, and biocompatible compared to many other plastic materials, and can be delivered into brain tissue over several centimeters without deviation, even with an outer diameter of around 0.5 mm. An additional advantage of PEEK is that it is easily cut and not brittle, unlike fused silica, which is used in some CED cannulas. PEEK can be made radiopaque so that its location in brain tissue can be established using x-ray and CT images. The overmolding serves as both a depth stop and a means of securing the catheter or cannula 393 to the guide hub. In this example, the cannula 393 includes a protective sleeve 393a extending proximally from the cap 300. Prior to inserting the cannula 393 through the guide hub 220, the cannula is cut to the desired length (length from the cap to the cannula tip) in a jig. The cap 300 has a number of recesses (in the form of grooves) 324 extending radially outward on its upper surface. In this example, six recesses 324 are provided. The radial recesses 324 allow engagement of a complementarily shaped end of a hollow driver to rotate the cap 300 within the hub 220. The cap 300 is thereby locked within the hub 220 by threading the cap 300 onto the threads of the hub 220 and engaging the ribs 327 with the notches 227 of the hub 220. It is not essential that the guide hub 220 includes the notches 227, and if the guide hub 220 does not include the notches 227, the cap 300 does not need to include the ribs 327. An example of a cap 300 without ribs is shown in Figures 18a-18d. The hollow driver may have typical conventional hexalobular or "star drive" ends to engage the recesses 324. The hollow driver ends may be attached to the radial recesses 324 with an interference fit.This interference fit (or "clip" attachment) is convenient because it allows the cap 300 to be held in place on the driver while it is threaded onto the guide hub.

[0096] As also shown in Figures 18c and 18d, the radial recess 324 also provides a means for holding a flexible cylindrical or tubular device, such as the cannula 393, after implantation in a patient, when it is bent up to 90 degrees to provide a low profile, for example, when chronically implanted under the scalp. The radial recess follows a 90 degree radius of curvature (324a) from the central axis of the cap. This radius defines and controls the bend radius of the attached device. Thus, for devices with larger diameters, the radial groove diameter is larger. Typically, larger diameter devices require a larger radius of curvature to avoid kinking or collapsing of the tube wall. Thus, these dimensions determine the size of the cap and guide hub in which the device curvature is utilized. In the example shown in Figures 3a and 3b, the sleeve 393a is made of polyurethane and the cannula 393 is made of PEEK tubing, both overmolded onto the cap 300. Sleeve 393a protects the delicate PEEK cannula 393 and facilitates retention of it in recess 324 with a tight fit, since it is made of a more compliant material than the cannula.

[0097] Cap 300 includes corresponding dual external threads 326 for engaging with dual entry internal threads 226 (FIG. 2c) of hub 220. Cap 300 includes a cap cone 322 at its distal end that is shaped and configured for sealing engagement with hub cone 222 when cap 300 and hub 220 are locked together. The engagement and locking in sealing engagement of cap 300 within hub 220 is described below.

[0098] In a second example of the hub 220, a second example of the cap 400 is used, as shown in Figures 4a and 4b. The cap 400 comprises a central through hole 421 for the passage of a device such as a probe, electrode, catheter, cannula or other device. The cap comprises a number of radial recesses 424, typically in the form of a hexalobular, on the upper surface. The radial recesses 424 allow for the engagement of a hollow driver, as described above with reference to the example of Figures 3a and 3b. The cap 400 differs from the cap 300 in that the cap 400 is not overmolded on the device and does not comprise a cap cone at its distal end. Instead, the cap 400 comprises a cap through hole 421 and a cap flat 422 at the distal end of the cap 400, configured to engage a seal in the alternative hub 220, as described below. The cap 400 also comprises a 90 degree radius of curvature (424a) for the radially extending recesses (grooves) 424.

[0099] 5a-5f, a method of inserting the hub 220 into the patient's skull 500 is shown. First, as shown in schematic diagram 5a, brain imaging is performed to determine the location of the target 501 and trajectory 502 relative to the stereotactic guidance reference 503. A stereotactic guidance system (not shown) is aligned with its target 501 and trajectory 502. Aligning the stereotactic guidance system involves setting the stereotactic guidance reference 503 of the stereotactic guidance system at a predetermined distance from the target 501. Commercially available stereotactic guidance systems typically set their stereotactic guidance reference 503 at around either 140 mm or 160 mm from the target 501. However, it will be appreciated that the selected distance between the stereotactic guidance reference 503 and the target 501 can be varied, provided the distance to be used is known, for example when using a robotic arm to guide the surgery.

[0100] The image scan provides the surgeon with information regarding the thickness of the skull and the location and arrangement of regions of interest within the brain. With the known distance between the stereotactic fiducials 503 and the target 501, the surgeon can accurately plan the procedure to be performed using instruments delivered using the stereotactic system.

[0101] (Data measurement and instrument settings) Advantageously, the setup of instruments and devices for surgery when utilizing the guide hub of the present invention uses the jig of the present invention, as described in further detail and discussed further below with respect to Figures 5-14.

[0102] More generally, as illustrated in FIG. 5b, a fiducial measuring instrument 535 with a cone-shaped distal end is passed through the stereotactic guide set to the target trajectory. The distance from the fiducial on the stereotactic guide 503 to the surface of the skull 500 is measured, from which the penetration depth of the instrument required to implant the guide hub into the skull is determined. To prepare the skull 500 for delivery of the hub 220, a cutting instrument 540 is attached to the stereotactic guide system and brought into contact with the surface of the skull 500 along the trajectory 502 to form a flat surface 541 on the surface of the skull 500, as shown in FIG. 5c. This is to prevent deviations, as may occur if a fine pilot drill 550 subsequently delivered along the trajectory engages the curved surface of the skull 500. The flat surface 541 provides a recess approximately 1 mm deep from the original skull outer surface.

[0103] As shown in FIG. 26, the cutting instrument 540 may have a stepped profile with the distal cylindrical cutter 1530 having a smaller diameter than the more proximal cylindrical cutter 1540. This configuration has particular advantages when forming holes in skulls 500 that are sharply curved and thin, such as those of children. The small distal cylindrical cutter 1530 forms a flat surface in the bone so that the pilot drill 550 can orthogonally engage the bone surface to ensure that it drills concentrically, as described above. For example, the distal cylindrical cutter 1530 may be between 0.5-1.5 mm deep, e.g., 1 mm deep, and 2-4 mm in diameter, e.g., 3 mm. This increases to a larger diameter proximal cylindrical cutter 1540, preferably larger than the diameter of the rim of the guide hub 220. For example, if the diameter of the rim of the guide hub is 5 mm, the diameter of the proximal cutting surface may be 6 mm. The larger diameter plane created by the stepped cutting tool ensures that the core drill creating the profiled hole engages the bone perpendicular to the current plane and does not deviate from its trajectory.

[0104] After forming the flat surface 541, a pilot drill 550 is used to drill completely through the thickness of the skull 500 to form a pilot hole 551 as shown in FIG. 5d. A core drill 560 having a nib at its distal end is then inserted into the pilot hole 551 and guided to form a profiled hole 561 in the skull 500 so that the implantable hub 220 can be press-fit therein as shown in FIG. 5e. The core drill 560 opens the pilot hole 551 and provides an internal profile that allows for the subsequent engagement of the hub 220 into the profiled hole 561 in a secure, low-profile manner.

[0105] A detailed view of the profiled hole 561 is shown in FIG. 6a, and a detailed view of the core drill 560 is shown in FIG. 6b. From the proximal end side, the core drill 560 has a step 562. The step is configured to engage with the skull and form a recess of 1 mm depth and 5 mm diameter in which the 0.5 mm high rim of the guide hub will be located. The core drill 560 further has a body 563 that opens a preformed pilot hole to a diameter of about 4 mm to receive the hub 220 (FIG. 5f described below). Furthermore, the core drill 560 has a conical surface 564 towards the distal end that forms a shoulder 565 in the skull. The core drill 560 also comprises a nib 566 at its distal end to guide the core drill 560 into the pilot hole. The profiled hole 561 formed as shown in FIG. 6a provides a press-fit of the implantable hub 220.

[0106] Profiled hole 561 is formed along the desired trajectory 502 (FIG. 5a) so that when hub 220 is inserted into the hole, the passage through hub 221 and central hole 223 will be aligned along the trajectory.

[0107] 27a-27d show a comparable process of preparing the skull for insertion of the guide hub 220 using a stepped profile cutting tool 540 in a highly curved skull surface. FIG. 27a is similar to FIG. 5c and shows the cutting tool 540 being used to form a flat surface 541. FIG. 27b is similar to FIG. 5d and shows a pilot drill 550 being used to form a pilot hole 551. FIG. 27c is similar to FIG. 5e and shows a core drill 560 engaging pilot hole 541 to form a profiled hole 561. The guide hub 220 can then be inserted as shown in FIG. 27d. As can be seen particularly in FIGS. 27c and 27d, the stepped profile created by the cutting tool 540 allows the core drill 560 and the guide hub 220 to be guided into position on the skull surface without compromising the highly curved skull surface in a manner that could cause the core drill 560 to dislodge or improperly insert the guide hub 220.

[0108] Referring now to Figures 5f and 5g, the insertion of the hub 220 into the profiled hole 561 of the skull 500 will be described. To insert the hub 220 into the profiled hole 561, the hub 220 is attached to an insertion tool 570, shown in Figures 5f and more specifically in Figure 5g. The insertion tool 570 includes a shaft 571 and a threaded distal end 572. The threaded distal end 572 includes a dual-entry male thread that engages with the female threads 226 of the hub 220 by means of the thread engagement of the hub 220. In this embodiment, the insertion tool 570 does not include a locking screw. Therefore, after the insertion tool 570 feeds the hub 220 into the profiled hole 561, the insertion tool 570 can be easily removed from the hub 220.

[0109] The hub 220 can be aligned and precisely positioned into the profiled hole 561 in the skull 500 using the insertion tool 570. The shaft 571 is dimensioned to be maneuverable with stereotactic guidance. For example, the insertion tool 570 includes a shaft that is 150 mm long and 10 mm in diameter. This allows the insertion tool 570 to be used with existing stereotactic guidance and provides the insertion tool 570 with a sufficient length to deliver the hub 220 into the profiled hole 561 using stereotactic guidance. The insertion tool 570 also includes a chamfer 573 between the threaded distal end 572 and the shaft 571. The chamfer 573 ensures a line of sight between the hub 220 and the medical professional as the hub 220 is introduced into the profiled hole 561. The insertion instrument 570 can be used to drive the hub 220 into the skull 500 with sufficient force to allow the broach teeth or other external profile to bite or cut into the skull 500, thereby securing the hub 220 to the skull 500 with the through holes 221 coaxial with the trajectory 502 to the target 501. If male threads or an interference pattern are used instead of the broach teeth 225, the insertion instrument 570 can have an additional feature used to secure the instrument against the hub inner threads to allow for an unscrewing action between the hub outer threads and the bone.

[0110] The insertion tool 570 can then be removed from within the hub 220 , and the hub 220 can be implanted into the profiled hole 561 in the skull 500 .

[0111] 19a and 19b show another example of an insertion instrument 570. A close-up view of the distal end of the insertion instrument 570 is shown in FIGS. 20a and 20b. As described above, the hub insertion instrument 570 comprises a rod 1804 having a configuration at its distal end for engaging a second structure in the surgical guide hub 220. In this example, the insertion instrument 570 is further configured to engage the guide hub 220 via an instrument engagement feature 1802. The instrument engagement feature 1802 may be configured to engage a hub engagement feature 1704 on the guide hub 220. The insertion instrument 570 may comprise a corresponding number of instrument engagement features 1802 to match the number of hub engagement features 1704 on the guide hub 220. Preferably, a plurality of instrument engagement features 1802 are provided spaced around the circumference of the insertion instrument 570. For example, at least three, and optionally at least four, instrument engagement features 1802 may be provided. The instrument engagement feature 1802 can have any suitable shape. The shape of the instrument engagement feature 1802 can be selected to correspond to the shape of the hub engagement feature 1704. For example, the instrument engagement feature 1802 shown in FIG. 21 has a castellation shape that engages with a notch forming the hub engagement feature 1704. If the hub engagement feature 1802 has a hole as described above, the instrument engagement feature 1802 may include a pin sized to fit into the hole. Preferably, the shapes of the instrument engagement feature 1802 and the hub engagement feature 1704 are selected so that the features can be easily engaged together and do not slip or become easily disengaged during use.

[0112] The structure at the distal end of the rod 1804, in this example a threaded distal end 572, may be configured to be movable relative to the axis 571 of the insertion tool 570. Preferably, the structure at the distal end of the rod 1804 is rotatable relative to the axis 571. The instrument engagement mechanism 1802 may be provided on the axis 571 of the insertion tool 570 such that the axis 571 of the insertion tool 570 engages with the guide hub 220 via the instrument engagement mechanism 1802. This means that after insertion of the guide hub 220 into the opening, the insertion tool 570 can be easily disengaged from the guide hub 220 by moving (e.g., rotating) the structure at the distal end of the rod 1804 relative to the axis 571 without interfering with the placement of the guide hub 220 into the opening. Additionally, the engagement of the insertion tool 570 and the guide hub 220 via the instrument engagement mechanism 1802 can be used to apply a force to the guide hub 220 to insert the guide hub 220 into the opening formed in the skull. This is particularly advantageous when the guide hub 220 includes self-tapping screws, which require greater rotational force to cut into the skull as the guide hub 220 is inserted into the opening.

[0113] 21 is another view of the distal end of the insertion instrument 570, illustrating the instrument engagement feature 1802 engaging with the hub engagement feature 1704 on the guide hub 220. As shown, engagement of the instrument engagement feature 1802 with the hub engagement feature 1704 effectively applies a rotational torque to the guide hub 220 for insertion of the guide hub 220 into the opening.

[0114] The insertion tool 570 may include a depth stop 1806, as shown in FIGS. 19a and 19b. The depth stop 1806 is similar to the fiducial markers 537, 538, 539, described below in connection with other tools used in implanting the guide hub 220. The depth stop 1806 helps prevent overinsertion of the guide hub 220 into the opening. The depth stop 1806 may engage the stereotactic guide datum 503 to provide a visual and / or tactile indication that the guide hub 220 has been inserted to the correct depth. The depth stop 1806 may be movable relative to the rod 1804 and / or shaft 571 of the insertion tool 570. Prior to inserting the guide hub 220, the depth stop 1806 is attached in the correct position along the insertion tool 570 such that when the guide hub 220 is inserted to the correct depth into the opening, the depth stop engages the stereotactic guide datum 503. Setting the location of the depth stop 1806 can be accomplished using a jig of the present invention.

[0115] The system including the guide hub 220 may include a shortening instrument 1850, as shown in FIGS. 22a and 22b. The distal end of the shortening instrument 1850 is substantially similar to the distal end of the insertion instrument 570, and includes a threaded distal end 572 and / or an instrument engagement mechanism 1802. The shortening instrument 1850 may include a shaft 571 and a rod 1804 that are movable relative to one another, similar to the insertion instrument 570. However, the length of the shortening instrument 1850 is shorter than the length of the insertion instrument 570. This allows for easier handling of the shortening instrument 1850. The shortening instrument 1850 may not include a depth stop 1806. This also allows for easier handling of the shortening instrument 1850. The shortening instrument 1850 may be particularly suitable for removal of the guide hub 220 when the axial position of the instrument does not need to be controlled as precisely as during insertion of the guide hub 220. The short length of the shortening instrument 1850 and / or the absence of a depth stop also eliminates the need to manipulate the shortening instrument 1850 using stereotactic guidance, further simplifying use of the shortening instrument 1850. The shortening instrument 1850 may have a narrower diameter than the insertion instrument 570. This provides the user with greater sensitivity to the force required to remove the guide hub 220, thereby improving control during the process of removing the guide hub 220.

[0116] The hub 220 can be placed entirely within the recess 561 previously formed by the core drill in the skull. If necessary, the through hole in the hub 220 can be sealed off by inserting a grub screw into the proximal end of the hub if it is not used to deliver the device through the skull. When fully inserted, for example with an Allen key, the grub screw will be flush with the proximal face of the guide hub.

[0117] 5h-5k show an example of the use of the hub 220 when placed on the skull 500. As shown in FIG. 5h, the hub 220 is aligned along a track 502 so that devices or instruments such as cannulas, probes, electrodes or other neurosurgical devices delivered through the hub 220 are also directed along the track 502 toward the target 501. In one example of delivery of such devices, a pathway can be formed through brain tissue between the hub 220 and the target 501 by using a pathway forming device 580 shown in FIG. 5i. In some procedures, a guide tube 581 can be inserted along the pathway formed by the pathway forming device 580. The guide tube 581 can include a cone-shaped enlarged diameter proximal end that can be fed through a through hole in the hub 220 and seated and sealed against the cone 222 of the hub 220. As shown in FIG. 5k, a cannula 582 can then be inserted through the guide tube 581 to reach the target 501.

[0118] In some embodiments, the device can be delivered through the hub 220 without the use of a guide tube 581. The device can be locked into the guide hub 220 in a manner similar to the cannula 393 described above by providing the device with its own threads to engage with threads in the hub 220 (FIGS. 2-4). The threads can act as a stop indicating the intended location (depth into the brain) where the device should be inserted and prevent the device from being inserted beyond the intended depth. To avoid wrapping the wires / tubes of the device as the threads are threaded into place, the threads can be configured to rotate independently of the rest of the device. This can be accomplished, for example, using one or more circumferential grooves that engage corresponding protrusions on the threads.

[0119] FIG. 7 shows an example of the insertion of a device through the hub 220 in a series of schematic views from left to right. In this example, the device 593 is a deep brain stimulation (DBS) electrode. The hub 220 is first inserted into a profiled hole in the skull as described above, and then a pathway forming tool 580 attached to the insertion tool is passed through the hub 220 to form a pathway along a desired trajectory in the brain. The insertion tool for the pathway forming tool may be a hub insertion tool 570 as described herein. In this example, the hub 220 includes a seal 230, which is in a free, uncompressed, unsealed state as the pathway forming tool 580 passes through the hub 220. The pathway forming tool 580 is then removed and the cap 400 is introduced into the hub 220. Because the example hub 220 described herein includes a seal 230 in the form of an O-ring seal, the cap 400 has a cap flat 422 as in the example shown in Figures 4a and 4b, rather than a cap cone 322 as shown in Figures 3a and 3b.

[0120] The use of hollow driver 590 and through holes in cap 400 allows device 593 to be delivered through both hollow driver 590 and cap 400. Rotation of cap 400 with hollow driver 590 moves cap 400 downward and engages seal 230, thereby compressing seal 230 axially and thereby expanding seal 230 radially. Seal 230 provides a fluid, gas and bacteria seal between hub 220 and cap 400 and provides a secure grip of device 593 passing through hub 220.

[0121] In the example of FIG. 7, the hollow driver 590 is configured such that the device 593 enters at its proximal end and exits the driver 590 at its distal end. Advantageously, such a driver is provided with an air vent at its distal end to facilitate air escape when the DBS electrode is inserted into the brain. Another arrangement is shown in FIG. 8. Another driver 591 has a hexalobular structure 592 at its distal end, but one of the six lobes is absent (see also FIGS. 16a and 16b below). The hexalobular structure engages with a snug fit in a recess in the cap 400 to temporarily attach the driver to the cap. A cannula 593 extends through the cap 400. The driver 591 includes an axially extending slot 594 at its distal (head) end to allow the cannula 593 to exit from the side of the driver 591. This arrangement allows devices to be delivered into the guide hub that have a portion at the proximal end that does not pass through the hollow driver bore. For example, the end of the cannula 593 can have a fluid connector for joining to a fluid supply line that has a larger diameter than the driver bore. The slot 594 in the driver 591 also provides a convenient air bleed. In some embodiments, the driver 591 can be hollow along its length and can be used to deliver devices such as those shown in FIG. 7 or FIG. 8.

[0122] As shown in Figures 23a and 23b, the axially extending slot 594 may extend all the way to the proximal end of the driver instrument such that it extends along the entire length of the driver 591 from the distal end to the proximal end. As explained in connection with Figure 8 above, this allows the hollow driver 591 to be used to deliver a device 593 into the guide hub 220, with a portion at the proximal end not passing through the bore of the hollow driver 591. However, by having the slot 594 extend along the entire length of the driver 591, the device 593 can be positioned approximately along the axis of the driver 591 through the bore of the driver 591. This is shown in Figure 24, which shows the driver with the device positioned along its axis ready for delivery. This allows the hollow driver 591 to rotate around the device 593, thereby preventing the device 593 from tangling or wrapping around the driver 591 as the driver 591 is rotated to deliver the device 593.

[0123] The driver 590 or 591 may further comprise a latch 1902, for example in the form of a rotating collar or disk as shown in FIGS. 23a and 23b. The latch 1902 may be configured to reversibly seal the slot 594 along at least a portion of the length of the slot 594 (e.g., by sealing off entry to the slot 594 from a radial direction). The latch 1902 is preferably provided at or near the proximal end of the driver 591. The latch 1902 may function to retain the device 593 within the hollow bore of the driver 590 and prevent it from falling out of the driver 591 again via the slot 594. This may reduce the chance of the device 593 wrapping or becoming tangled around the driver 591 as it is delivered or removed from the guide hub 220.

[0124] Referring to Figure 7, after the cap 400 is locked into the hub 220, the device 593 can be folded into one of the radially extending recesses 424 in the cap 400 to provide a low profile and secure attachment. At the end of the process shown in Figure 7, the inserted device is locked into the hub 220 and a gas, fluid and bacteria seal is formed. Although the device shown in Figure 7 is a DBS electrode, such methods can be utilized with other devices, such as catheters and cannulas.

[0125] Removal of the device from the patient is easy. Referring again to the sequence of Fig. 7, but starting from the right hand side, the device can be removed from the recess 424 and a hollow driver of either type 590 or 591 can be inserted onto the device to engage the recess 424. Advantageously, the driver is of type 591 with a side slot 594. The driver 591 can then be placed on the cap, with the device 593 received in the slot 594. The driver then unscrews the cap 400, releasing the seal, and thus the cap 400 and the device can be easily removed after use.

[0126] The implanted guide hub 220 can facilitate repeated access to intracranial targets without the need for further stereotactic surgery. For example, to replace a defective electrode or ventricular catheter, the device is removed as described above and the cap 400 is screwed back onto the hub 220 without compressing the O-ring. This aligns the hollow driver 590 with the target 501 along the axis of the track 502. The distance from the hub datum HD to the target 501 is known and should have been recorded in the surgical record (FIGS. 2b and 5a). The distance from the hub datum HD to the target 501 is added to the length of the distance from the proximal end of the driver 590 to the hub datum HD, and a depth stop is fixed to the exchange device at this same distance from the distal end of the exchange device. The exchange device is delivered through the hollow driver 590, the cap 400, the guide hub 220, to the target 501, which is reached when the depth stop engages the proximal end of the driver 590. The driver 590 is rotated to lock the device into the guide hub 220, after which the depth stop is removed and the driver 590 is removed, leaving the exchange device in place with its distal end at the target.

[0127] Approximately one-third of intraventricular catheters implanted to treat hydrocephalus eventually become clogged and require replacement every 10 years. Re-accessing the ventricles for catheter exchange can be technically challenging. Advantageously, a guide hub can be utilized to precisely position and secure the ventricular catheter, facilitating precise replacement if the catheter becomes clogged. In such instances, removal of the clogged catheter is accomplished by attaching the driver 591 to the cap 400 and unscrewing it. This releases the catheter, which can then be withdrawn through a side slot at the distal end of the driver 591. A new catheter is then advanced through the hollow driver 591, the cap 400, and the hub 220 to the same depth as the original catheter. The new catheter is secured by relocking the cap 400 to the hub 220.

[0128] Further, re-access to the same target 501 for repeated treatments without the need for stereotactic surgery can also be achieved using the guide hub 220 to replace devices such as lesion electrodes, catheters, cannulas, etc., with a plastic stylet of the same length. This stylet is secured to the hub 220 by a proximally threaded cap to keep the pathway open and facilitate re-access to the target 501 after days, months, or years. Alternatively, after removal of the device, a blind cap (not shown, but caps 300, 400 without a central through hole) can be placed within the hub 220 and secured and sealed in the same manner as previously described with reference to Figures 3a, 3b or Figures 4a, 4b to provide a secure seal of the hub 220 and prevent infection or loss of fluids from within the head. Alternatively, a grub screw cap with the same male threads as caps 300, 400 can be screwed onto the hub 220 with an Allen key so that its proximal face is flush with the proximal face of the hub. It is sealed to the hub 220 and provides a low profile, re-accessible alternative to other somewhat bulkier caps.

[0129] Referring again to Figures 5 and 7, re-access to the intracranial target 501 can be achieved by removing the blind cap and threading the guiding hub inserter 570 into the hub 220, thereby aligning and locking it coaxially with the trajectory 502 to the target 501. A probe is then inserted through the hollow guide tube inserter 570 to the target at a known distance from the hub reference point HD (Figure 2b). The probe is removed leaving a path to the target 501, and the guiding hub inserter 570 is removed. The cap 400 is attached to the driver 590 and threaded into the hub 220 without compressing the O-ring. As described above, the device is inserted through the hollow driver 590 or 591 to the target and locked in place.

[0130] Traditional methods of drilling holes in the skull surface, creating profiled holes, and delivering devices typically require many measurements to be taken, especially when multiple different instruments are used to create the holes for introducing the hubs. When repeat surgeries are required, the calculations for each step must be performed again between repeated surgeries, increasing the risk of human error throughout the surgical procedure.

[0131] Here we describe a jig that aids in setting up instruments for brain surgery and cutting implantable devices to length, reducing calculations and required adjustments.

[0132] 9 illustrates a jig 600 for setting the insertion depth of multiple neurosurgical instruments and devices into a patient's skull or brain during neurosurgery. Jig 600 can be used to set the instruments and devices used in surgical procedures, such as those shown in Figures 5a through 5k and described above.

[0133] The jig 600 has an open rectangular frame, provides an instrument alignment device 610, and has an upper crossbar providing a representative fiducial 503' representing the stereotactic guidance fiducial 503 of FIG. 5a. The jig 600 has a lower crossbar 640 with a target fiducial 641 in the shape of a surface corresponding to the target 501 of the patient's brain shown in FIG. 5a. The instrument alignment device 610 can be moved parallel to the lower crossbar 640 and its position can be fixed with reference to the scale 624 so that the distance between the representative fiducial 503' and the target fiducial 641 corresponds to the distance from the stereotactic guidance fiducial to the target 501 of the stereotactic guidance system in use. In the commercially available Cosman-Roberts-Wells stereotactic guide, the distance between the stereotactic guidance fiducial and the target is set at 160 mm. In the Leksell® stereotactic guide, the distance is set at 190 mm. If the jig 600 is to be used exclusively with a stereotactic guidance system with a fixed distance from the stereotactic guidance reference to the target, the jig 600 may be provided with a fixed relationship between the upper crossbar and the lower crossbar 640, but otherwise, it is desirable that the upper crossbar is adjustable relative to the lower crossbar 640. For example, the distance from the stereotactic guidance reference to the target can be varied by the operator for a particular target. This can be changed when the stereotactic guidance is a surgical robot. It can also be changed when the stereotactic guidance system is an instrument guide on an arm that can be moved and locked, and the spatial relationship of the instrument guide to the target in the patient's head is registered to volumetric images and tracked using optical, ultrasonic or electromagnetic sensors. In the latter case, the distance from the stereotactic guidance reference to the target defined in the surgical planning software is set in the jig 600 for each individual target.

[0134] The instrument alignment device 610 comprises a number of slots or grooves for receiving and aligning generally elongated instruments and instrument stops and orienting their distal ends in a direction parallel to the instrument alignment device 610 and perpendicular to the movable reference guide 620. The reference guide 620 is in the form of a bar parallel to the instrument alignment device 610 and is movable relative to the instrument alignment device 610 while maintaining a parallel relationship. Means for maintaining the parallel relationship are described below with reference to Figures 11 to 13. The reference beam 620 has an upper reference surface 621 that represents the skull surface 500 when performing the procedure as shown in Figures 5a to 5k. The reference guide 620 can be moved to set a reference line length from the reference line 503' of the instrument alignment device 610 to the reference surface 621.

[0135] The jig 600 may further include a movable cutting or depth measurement guide 630 having a surface 631 located at a selected distance from a target datum 641, as will be described in more detail below. The movable surface 630 is in the form of a bar and is parallel to and located below the datum guide 620 and above a lower cross bar 640 which provides the target datum 641. A further device cutting surface 635 may be provided at the target datum 641.

[0136] As shown in other embodiments, the jig 600 can be set at an angle, such as 45 degrees to the horizontal, which can be convenient to allow an instrument placed on the jig 600 (e.g., placed on the alignment device 610) to move into position under the force of gravity.

[0137] We now describe the use of a jig 600 to prepare an implement for forming a profiled hole 561 in the skull, as shown in Figures 5a to 5d.

[0138] The stereotactic guide is aligned to a planned trajectory 502 directed to a target 501 in the patient's brain. After incision to expose the surface of the skull 500, a rod-shaped fiducial measuring instrument 535 is held in the stereotactic guide and guided into contact with the patient's skull (FIG. 5b). A reference line length from the stereotactic guide fiducial 503 to the skull 500 can be marked on the instrument or measured. Conveniently, a fiducial marker 536 is fixed with a stop to the instrument at the position of the stereotactic guide to fix the starting point of the reference line length. The fiducial marker 536 is in the form of a collar that fits the instrument 535 and is fixed to the instrument 535 by a grub screw. The fiducial measuring instrument 535 is then transferred to the jig 600 and held in the instrument alignment device 610 with the first instrument fiducial marker 536 located in a slot in the alignment device 610, as shown in FIG. 9. The bottom of the slot is part of the representative point 503'.

[0139] The reference guide 620 is then moved upward and locked or held in place such that the reference surface 621 of the reference guide 620 contacts the distal end of the reference measuring instrument 535. The distance from the stereotactic guidance fiducial 503 to the surface of the patient's skull 500 is then established on the jig 600 as the reference distance from the representative fiducial 503′ to the reference surface 621.

[0140] Alternatively, the baseline length of jig 600 from 503' to 621 can be established using reference measuring tool 535, or using measured distances obtained by some other means such as a laser range finder, other measuring tool, imaging technique, etc. employed on a robotic arm or stereotactic frame.

[0141] Datum guide 620 has multiple offsets or channels from datum surface 621 that allow for setting different lengths for surgical instruments and devices with different capabilities, as will be described below.

[0142] To drill the skull and insert the guide hub 220, the sequence is as follows: A first offset 650 in the form of a recess in the reference surface 621 is for setting the cutting tool 540. A second offset 651 including a channel through the reference guide 620 is for setting the pilot drill 550. A third offset 652 is for setting the core drill 560. Each offset 650, 651, 652 provides a distance from the reference surface 621 that corresponds to the distance beyond the patient's skull surface that each instrument should extend as it performs its task during surgery. Thus, the offsets 650, 651, 652 in the reference guide 620 allow for the setting of different instruments following only one initial measurement, i.e. establishing the reference line length.

[0143] To set the length of the cutting instrument 540 from the representative datum 503', the cutting instrument 540 is placed in the instrument alignment device 610 and its distal end is guided to the first offset 650. The length of the cutting instrument 540 from the representative datum 503' to the distal end is set by fastening the instrument fiducial marker 537 to the instrument 540. The instrument 540 can then be used with stereotactic guidance to cut a plane into the skull and precisely bore to the desired depth, as shown in FIG. 5c.

[0144] In a similar manner, the required length (to penetrate the skull but avoid entering the brain - FIG. 5d) is set by guiding the pilot drill 550 to the second offset 651 and advancing the pilot drill to the required depth to penetrate the skull, followed by fixing the third instrument fiducial marker 538 to the pilot drill 550. This length is determined from a brain imaging scan and can be precisely set using the scale 622 on the movable fiducial guide 620. A similar approach is taken to set the core drill 560 to form a hole shaped to accommodate the guide hub 220 (FIG. 5e). In this manner, the required instrument length can be set based solely on the fiducial line length measured by the user.

[0145] In this example, a first offset 650 of 1 mm and a reference line length of 100 mm would result in the cutting instrument 540 being prepared 101 mm from the datum 503 (or representative datum 503') to prepare a plane on the skull during surgery. In other examples, the offset may be negative, i.e., the offset may be a protrusion on the reference plane 621 extending towards the instrument alignment device 610. In such an example, if the first offset 650 is -2 mm (i.e., a protrusion of 2 mm towards the instrument alignment device 610) and the reference line length is 100 mm, the instrument would be set 98 mm from the datum 503 for surgery.

[0146] In the above embodiment, each instrument 540, 550, 560 is attached to an instrument fiducial marker 537, 538, 539 that can be used in conjunction with stereotactic guidance to advance the instrument to a carefully measured depth into the skull. The fiducial markers 537, 538, 539 may be equipped with an indicator 2301 that indicates whether the fiducial marker 537, 538, 539 is locked to the instrument or in an unlocked state that allows it to move up or down the instrument. An example of such an indicator 2301 is shown in Figures 25a to 25c. In Figures 25a to 25c, the fiducial markers 537, 538, 539 use screws that are tightened to attach the fiducial markers 537, 538, 539 to the instrument. Figure 25a shows the indicator 2301 in an unlocked position, and Figure 25b shows the indicator 2301 in a locked position. The indicator 2301 allows a user to quickly determine if the fiducial markers 537, 538, 539 are locked and reduces the chance of accidentally moving the fiducial markers 537, 538, 539 if the instrument is removed from the jig without the fiducial markers 537, 538, 539 being locked to the instrument. The depth stop 1806 of the insertion instrument 570 can be provided with a similar indicator 2301 to indicate when it is locked to the insertion instrument.

[0147] As shown in Figures 5e and 5f, a jig 600 can also be used in a similar manner to aid in the insertion of the guide hub 220. The hub insertion tool 570 can be set at the appropriate length in the jig 600 utilizing the tool fiducial markers to avoid over-inserting the hub 220 into the skull.

[0148] The use of the jig 600 to prepare a surgical instrument or device for delivery through the guide hub 220 and into the brain is described.

[0149] Devices that may be delivered through guide hub 220 include guide tubes, electrodes and cannulas, although it will be understood that other types of devices may be delivered through hub 220.

[0150] 9 , the fiducial guide 620 includes a through channel 653 to allow passage of a device or instrument such that the device can extend down to the surface 631 of the cutting or measuring guide 630. In this example, the fiducial guide 620 includes a guiding hub 220 mounted in an appropriately shaped offset in the fiducial surface 621. This allows a hollow hub introduction instrument 570 to be inserted into the hub 220 of the jig 600. An instrument such as a pathway making probe 596 can be passed through the hub introduction instrument 570, the hub 220 in the jig 600, and the fiducial guide 620.

[0151] In this manner, the length of the device or instrument required to extend from the hub 220 can be set in the jig 600. In this example, if the pathway creating probe 596 is to create a pathway in the brain, the length of the probe 596 from the hub 220 to the desired location in the brain can be set as follows: The combination of the insertion instrument 570, hub 220 and probe 596 is positioned as shown in FIG. 9. A first grub screw 595, operated by finger grip, is positioned in the instrument 570 to lock in a stop over the (thicker) proximal end 596a of the probe 596 that passes through it. A second grub screw 595a (with an Allen key socket) is provided to lock in a fiducial marker in the form of a collar 536a to the proximal end 596a of the probe 596. The collar 536a provides a depth stop against the upper surface of the insertion instrument 570. The use of different screw types, finger operated grub screw 595 and Allen key operated grub screw 595a, assists the worker in using the correct screw when working with the tool.

[0152] As shown in FIG. 9, the pathway creation probe 596 extends to the cutting or measuring guide 630. The fiducial marker 536a is then secured to the proximal end 596a of the pathway creation probe 596 by tightening the grub screw 595a. The probe is then retracted into the body of the insertion tool 570 as shown by arrow A and held in place by hand tightening the first grub screw 595. The insertion tool, hub, and probe assembly (570, 220, 596) can then be removed from the jig and transferred to the patient. The guide hub 220 is inserted into place (FIG. 5f) and the pathway creation probe 596 is inserted through the hub 220 to the depth set by the jig, where the fiducial marker 536a rests against the top surface of the insertion tool 570. In this way, the attachment of the guide hub 220 to the patient's skull and the creation of the pathway along the trajectory can be combined into one operation with a single use of the insertion tool 570.

[0153] In this example jig, the fiducial guide 620 includes a first indicator 623 in the form of a first pointer indicating a point on a scale 624. The scale 624 provides a measurement along one side of the jig 600. The scale 624 indicates the distance of the lower cross member 640 from a target fiducial 641. Using this scale 624, the surgeon can set the position of the fiducial guide 620 if a fiducial length is not provided by the fiducial measuring instrument 535. If, as in this example, a fiducial measuring instrument 535 is used, the set fiducial length can be confirmed using the scale 624. The cutting or depth measuring guide 630 also has an indicator 633 in the form of a pointer that moves along the scale 624. This second indicator 633 can be used to set the position of the measuring guide 630 based on measurements provided by imaging of the patient.

[0154] The surgeon can use the jig 600 to set up all the instruments and devices before starting the operation on the patient. This can be done manually or using computer controlled motorized jig with scan data and surgical planning software. Alternatively, the surgeon can set the fiducial guide 620 and measurement guide 630 and then set the instruments or devices on the jig 600 as needed throughout the surgery. The hub insertion instrument 570 or another instrument of the same type can be used to deliver a pathway creation probe 596 into the brain of the patient and can be set again on the jig 600 with the next device to be inserted into the brain. In FIG. 9, an additional insertion instrument, the guide tube insertion instrument 570a, is used to deliver a second probe 597. The second probe in this example is used to deliver a guide tube 598 and create a pathway in the brain to the target 501. In the example shown in FIG. 9, the second probe 597 is set to enter the brain to the maximum depth allowed by the jig. The distal end of the second probe 597 is set on the upper surface of the lower cross member 640 (target datum 641 ).

[0155] Jig 600 can also be used to set guide tubes and cannulas. Reference guide 620 has a profiled hole 561 that can match a depth within the through hole of guide hub 220. Guide tube 598 is placed within profiled hole 561 and extends downward. The guide tube can then be cut to the desired length for insertion into the brain. The position for cutting guide tube 598 can be determined using scale 624 to set the position of guide 630, and the cut can be made using a knife through cutting slot 634.

[0156] Also shown is a jig 600 for loading the cannula 599. The cap 300 carrying the cannula 599 fits into a fiducial guide 620 in a profiled hole that corresponds to the internal through hole of the guide hub. The cannula 599 can then be cut to length by a knife inserted through a cutting slot 635. As shown in FIG. 9, when loaded into the jig 600, the cannula can be attached to a driver 591. The driver and cannula combination can then be removed from the jig for insertion into the patient.

[0157] Another jig 700 will now be described with reference to Figures 10a and 10b. As seen in perspective view 10b, jig 700 includes side plates 797 that support a rectangular frame at a 45 degree angle to the horizontal. This allows for easy attachment of instruments or devices to the jig and allows gravity to assist in correctly positioning the instruments or devices. In this example, the jig includes a back plate 798 on which the instruments or devices rest. Similar parts to jig 600 of Figure 9 are designated with similar reference numerals, increased by 100. For example, fiducial guide 720 is generally similar in function to fiducial guide 620 of Figure 9.

[0158] The jig 700 comprises a lower cross member 740, where a datum 741 corresponding to the position of the target (501 in FIG. 5a) is provided as the lower end of a scale 724, as a slot 743 in a cutting device 742 and as a platform 755. Thus, the distance from the stereotactic guidance datum 503 to the target 501 (FIG. 5a) is represented on the jig 700 by the scale 724, i.e. by the vertical distance from the representative datum 503′ to the datum 741.

[0159] The jig 700 further includes a second cutting device 744 having a corresponding second cutting slot 745 .

[0160] A convenient use of hollow insertion tool 770 will now be described with reference to Figures 10a and 10b. Insertion tool 770 is similar to tool 570 shown in the previous figure. Like the corresponding arrangement shown in Figure 9, tool 770 features a dual grub screw arrangement. A first grub screw 795 is disposed on tool 770 for securing a device to be passed therethrough. A second grub screw 796 is provided for securing a fiducial marker 799 to the device, thereby providing a stop against the upper surface of driver 790.

[0161] As shown in Figure 10a, the probe 756 is extended onto the platform 755. A fiducial marker 799 is then secured to the distal end of the probe 757 by tightening the grub screw 796. The probe is then retracted into the body of the instrument 770 as shown by arrow A and held in place by tightening the first grub screw 795. The instrument and probe assembly can then be attached to the guide hub of the patient's skull and the grub screw 595 released, allowing the probe 756 to be driven into the patient's brain to the depth preset by the jig (platform 755).

[0162] In jig 700, reference guide 720 and cutting or depth measurement guide 730 are movable and lockable.

[0163] As shown in Figure 10a, the jig 700 comprises two parallel outer guide rails 701 and 702 and a central guide rail 703 parallel to the two outer guide rails 701, 702. The central guide rail 703 connects a lower cross member 740 to the reference guide 720. The lower cross member 740 and a back plate 798 provide stability and rigidity to the jig 700. In this example, the back plate also includes a number of grooves 746 for receiving the body of the instrument to be mounted.

[0164] The outer guide rails 701, 702 provide a means to allow the reference guide 720 and the cutting or measuring guide 730 to move parallel to each other and to the instrument alignment device 710. The reference guide 720 has a first locking screw 747 that can be rotated to secure the reference guide 720 to the central guide rail 703, so that the reference guide 720 can be fixed in a selected position. The measuring guide 730 includes a similar second locking screw 748 that screws into locking engagement with the backplate 798.

[0165] Figures 11 and 12 show schematic mechanisms that can be used to move and lock the reference or measurement guides into position. Similar mechanisms can be employed in the jig of Figure 9 and the jig of Figure 10.

[0166] In the partially exploded view of FIG. 11, a first example of a tracking system is shown. The fiducial guide 720 and screw 747 are shown removed from their appropriate positions for clarity. The jig 700 is equipped with a rack and pinion arrangement so that the fiducial guide 720 can move up and down while remaining parallel to the instrument alignment device. First and second rack and pinion sets 749, 750 are provided at the outer guide rails 701, 702. As shown in FIG. 11, the fiducial guide 720 is attached to a cross member 751 that connects the pinions of the racks of the rack and pinion sets 749, 750.

[0167] The cutting measurement guide can be arranged to move in a similar manner.

[0168] As shown, the reference guide 720 is also attached to the central guide rail 703 so that it can slide up and down the central guide rail 703 when unlocked, and is locked to the central guide rail 703 using a first locking screw 747.

[0169] Alternatively, as shown in partially exploded view in FIG. 12, the reference guide 720 may be slidably engaged and moveable with first and second outer guide rails 701, 702. The outer guide rails 701, 702 pass through holes in the reference guide 720, allowing the reference guide to slide up and down within the jig until locked and held in place by screws 747.

[0170] FIG. 13 is an exemplary locking mechanism for the first locking screw 747. The same mechanism may be used for the second locking screw 748. FIG. 13 is a cross-sectional view through the first locking screw 747 and through the width of the reference guide 720 in a position within the jig 700. The first locking screw 747 is received in a threaded hole in the reference guide 720 and a threaded hole in the first locking screw block 752. Engagement with the first locking screw block 752 lifts the first locking screw block 752 into engagement with the central guide rail 703. When the first locking screw 747 is threaded to its full extent, the first locking screw 747 itself engages the central guide rail 703, thereby additionally securing the movable reference guide 720 to the central guide rail 703. Alternatively, a simpler arrangement may be provided in which the first locking screw 747 directly engages the central guide rail 703 to lock the movable reference guide 720 to the central guide rail 703. For example, nylon threads or locking screws with nylon ends have been found to provide good grip.

[0171] In some arrangements, it may be desirable to make particularly fine adjustments to the positioning of the reference guides or cutting and measuring guides, in which case the central guide rail 703 may be threaded where it attaches to the lower cross member 740 (not shown). Rotation of the guide rail 703 can be used to provide fine movement of the reference guides or cutting and measuring guides within the jig frame.

[0172] Figures 14a to 14c show a sterilization tray and case for the jig 700. The jig 700 is preferably placed at an angle when in use, allowing the instruments to be moved under gravity to the desired position. When not in use, the jig can be stored, preferably sterile and ready for use. Figure 14a shows the sterilization tray 800 comprising a lower tray 801 and an upper tray 802. The upper and lower trays 801, 802 together form a protective housing for the jig 700 and associated instruments or devices held therein. The upper and lower trays 801, 802 are held together by a fastener 803. The tray 800 protects the jig 700 and the instruments therein during transport and storage. When the jig 700 is to be used, the upper tray 802 can be removed as shown in Figure 14b. The lower tray 801 forms the base support for the jig 700 and is attached by a hinge at its distal end. In use, the proximal end of the jig is raised so that the distal end rotates about the hinge to form a 45 degree angle with respect to the base. As shown in FIG. 4c, one or more support bars folded behind the jig 700 are adapted to engage features on the inner base of the tray 801 to stably secure the jig at a 45 degree angle during surgery. Conveniently, after use, the instruments are repositioned in the jig 700 so that they can be flattened for resterilization, and the support bars folded behind the jig, leaving the instruments ready for use in a subsequent procedure. FIGS. 15a, 15b and 15c show instruments set using the jig of the present invention during attachment of a skull-mounted deep brain stimulation (DBS) battery power unit ("generator").

[0173] Figure 15a shows from left to right the sequence of preparing a hole in the patient's skull. The skull 900 and the dura layer 901 underneath the skull are shown in cross section. A stereotactic frame or robot is placed around the patient's head to place the DBS generator 980 (shown in Figure 15b) in the skull 900. The baseline length setting for the jig 700 is obtained as previously described. This baseline length sets the jig 700 so that the required tools can be set in much the same way as previously described.

[0174] Beginning with the left view of FIG. 15a, a cutting tool 910 is used to create a flat surface 911 in the skull 900. A pilot drill 920 then drills a pilot hole 921, which is reamed by a core drill 930 with a nib 931 to keep the core drill 930 pointed into the pilot hole 921 as it advances through the skull 900. A blunt hook 940 is manually inserted to separate the dura 901 from the skull 900 adjacent the reamed hole 932. A gel dispensing container 950 is then brought to the reamed hole 932 and butted against the reamed hole 932 with the aid of a stop 951. A hemostatic gel 952 is then delivered through the reamed hole 932 to provide a protective barrier separating the dura 901 from the skull 900 and prevent excessive bleeding.

[0175] A milling tool 960 then mills around the reamed hole 932 previously formed by the core drill 930. The milling tool 960 in this example comprises a first mill body 961 and a second mill body 962. The first mill body 961 has a cutting surface that opens the reamed hole 932 to a first diameter, and the second mill body 962 has a cutting surface that opens the reamed hole to a second diameter that is smaller than the first diameter. In this way, a ledge 963 is formed in the hole. The milling tool 960 further comprises a blunt nib 964 sized and dimensioned to be located in the reamed hole 932 during milling, thereby stabilizing the milling tool 960 and ensuring that it stays on the desired trajectory. The milling tool 960 is attached to a threaded shaft 970, allowing a larger diameter milling tool to be attached under a smaller diameter orientation guide. Two other milling tools of different diameters can also be used to form the hole containing the ledge.

[0176] After the above steps, the hole prepared in the skull is prepared to receive a DBS generator 980, as described with reference to Figures 15b and 15c.

[0177] In FIG. 15b, the hole 932 formed by the milling tool 960 is shown. The dura 901 beneath the skull is visible through the hole 932. The circular DBS generator 980 is inserted into the hole 932 by pushing the DBS generator 980 into the hole 932, either by hand, robotically, or with the guidance of a stereotactic frame and a suitable installation tool (not shown). In the illustrated method, the surgeon simply inserts the DBS generator 980 by hand until it is seated within the hole 932. As seen in FIG. 15c, the DBS generator 980 includes a circumferential stop 981 configured to engage with the ledge 963 to prevent over-insertion of the DBS generator 980. The surgeon can then attach the DBS generator 980 to the skull 900 using a set of screws 982 located within corresponding holes 983.

[0178] The cables 984, 985 can then be attached to the DBS generator 980 by inserting the cables 984, 985 through correspondingly sized holes in the DBS generator 980. The cables 984, 985 are secured to the DBS generator 980 by a second set of grub screws (not shown) placed in corresponding second grub screw holes 986, or by manipulating a capture cam lock that engages the outer surface of the inserted DBS electrode leads 984, 985 that are implanted through the patient's skull to a brain target.

[0179] The DBS generator 980 may be on the order of 2-6 cm in diameter. Alternatively, the DBS generator 980 may be on the order of 3-4 cm in diameter.

[0180] Figure 16a shows a perspective view from below of the distal end of a driver 1091 having similar features to that of Figure 8. Figure 16b shows a close-up of the distal end. As can be seen in these figures, the hexalobular structure 1092 is missing one lobe to allow the side slot 1094 to extend to the most distal end 1093 of the instrument. The side slot thus allows the driver 1091 to be mounted on a cap during installation and / or removal of a device such as a cannula, as described above and with reference to Figures 7 and 8.

Claims

1. A jig for setting the depth at which a surgical instrument is inserted into a patient during surgery, comprising: an instrument alignment device; a representative reference indicating a positioning guidance reference; a reference guide movable relative to the representative reference, the reference guide setting a reference line length from the representative reference to a reference plane of the reference guide; the reference guide is configured to receive a surgical instrument extending from the instrument alignment device, has at least one offset from the reference plane, and the depth of insertion of the surgical instrument when used in surgery on a patient is set in the jig by the distance from the representative reference to the offset; the instrument alignment device is a jig configured to receive one or more of: i) a cutting instrument for forming a flat work surface on bone, ii) a pilot drill for forming a pilot hole in bone, and iii) a core drill for forming a profiled hole in bone.

2. i) the instrument alignment device comprises the representative reference; ii) comprises a target reference indicating a target position relative to the positioning guidance reference in a selected positioning guidance system or device; iii) the reference guide is movable and the representative reference is fixed; iv) further comprises a stand for supporting the jig at an angle relative to the horizontal; The jig according to claim 1, satisfying at least any one of the above.

3. The jig according to claim 1, wherein the instrument alignment device comprises a bar including a plurality of slots or a plurality of grooves for receiving an elongate instrument and directing a distal end thereof in the direction of the reference guide.

4. The movable reference guide has a bar shape parallel to the bar of the instrument alignment device and is movable relative to the instrument alignment device while maintaining a parallel relationship. The jig according to claim 3.

5. The instrument alignment device has a bar including a plurality of slots or a plurality of grooves for receiving elongate surgical instruments and directing distal ends of those instruments in the direction of the reference guide; the representative reference is provided on the bar of the instrument alignment device; the reference guide has a bar parallel to the bar of the instrument alignment device and is movable relative to the instrument alignment device while maintaining that parallel relationship; The bar of the device alignment device and the bar of the reference guide are connected by at least two rails, and the at least two rails are respectively arranged at each end of the bar of the device alignment device and are connected to the corresponding ends of the bar of the movable reference guide. The jig according to claim 1. **Claim 6**: i) The bar of the reference guide is slidably engaged with the at least two rails. ii) It includes at least three rails connecting the device alignment device and the reference guide. The third rail is arranged at the midpoint of the bar of the device alignment device and extends to the corresponding midpoint of the bar of the reference guide. The jig according to claim 5, which satisfies at least any one of the above. **Claim 7**: i) The at least two rails are formed with threads and operate as lead screws by passing through corresponding threads on the bar of the reference guide, or ii) The at least two rails have rack gears, and the bar of the reference guide has corresponding pinions. The jig according to claim 5. **Claim 8** The reference guide includes at least one guiding channel extending through the reference guide for passing a surgical instrument. The guiding channel extends from the reference plane and extends in a direction set by the device alignment device. The jig according to claim 1. **Claim 9** The reference guide is a surgical guiding hub for implantation into an opening formed in the skull and formed along a trajectory to a brain target, a through hole for delivering along the trajectory through the device, at least one first structure on the outer surface for fixing the hub within the opening of the skull, at least one second structure on the surface of the through hole for fixing an induction device, an implantable device, or a cap to the hub, The jig according to claim 1, further comprising a hole for receiving a surgical guiding hub comprising the above. **Claim 10** The reference guide includes a guiding channel passing through the reference guide for passing a surgical instrument and a surgical hub arranged in a profiled hole. The jig according to claim 9. **Claim 11** A jig according to claim 1, further comprising a movable cutting or depth measuring guide that is disposed further away from the instrument alignment device than the reference guide and that adjusts or cuts to a selected length a surgical instrument or a portion of an instrument that extends through the movable reference guide from the reference plane.

12. The jig according to claim 11, wherein the movable cutting or depth measuring guide comprises a bar that is parallel to both the alignment device and the reference guide and that has a guiding surface that engages the distal end of a surgical instrument or a portion of an instrument.

13. A system comprising the jig according to claim 1, a cutting instrument for forming a flat work surface on a bone, a pilot drill for forming a pilot hole in a bone, a core drill for forming a profiled hole in a bone, a milling instrument for forming a profiled hole with an enlarged diameter in a bone, a surgical guiding hub for insertion into the profiled hole, a through hole for delivery along a trajectory to a brain target through the device, at least one first structure on an outer surface for fixing the hub within an opening of the skull, a surgical guiding hub comprising at least one second structure on a surface of the through hole for fixing a guiding device, an implantable device, or a cap to the hub, and a system further comprising at least one surgical instrument selected from the group consisting of.

14. The system according to claim 13, wherein the cutting instrument comprises a distal cylindrical cutter and a proximal cylindrical cutter, and the distal cylindrical cutter has a smaller diameter than the proximal cylindrical cutter.

15. A method of preparing a surgical length of a surgical instrument, comprising: i) installing the system according to claim 13, ii) setting a reference line length from the representative reference to a reference plane by moving the reference guide relative to the representative reference, iii) moving the surgical instrument within the instrument alignment device to a predetermined offset within the reference guide to obtain a surgical length of the surgical instrument.

16. The step of setting the reference line length comprises: iv) holding a reference measuring instrument within the instrument alignment device, v) moving the reference guide relative to the instrument alignment device and bringing it into contact with the distal end of the reference measuring instrument; vi) The method according to claim 15, further comprising the step of stationary fixing the reference guide at a length from the instrument alignment device determined by the reference measuring instrument. **Claim 17** A system for implanting a cylindrical DBS generator into the skull, comprising: a) the jig according to claim 1; b) a cutting tool for forming a flat work surface on the bone; c) a pilot drill for forming a pilot hole in the bone; d) a core drill for forming a hole in the bone that is larger than the pilot hole; e) at least one milling tool for forming a profiled hole for receiving the cylindrical DBS generator in the skull. A system comprising. **Claim 18** The at least one milling tool comprises: a distal cutting surface for cutting a DBS generator mounting hole having a diameter larger than the hole of the core drill through the skull; a proximal cutting surface for forming a ledge for receiving a corresponding edge of the cylindrical DBS generator in the skull around the DBS generator mounting hole. The system according to claim 17, comprising.

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