Reference device

Abstract

This invention provides a reference device that can be applied to patients before or during hip joint surgery. [Solution] A reference device for application on a patient comprises a support plate, a first positioning element extending from the support plate, a second positioning element extending from an upper support plate, a third positioning element extending from an upper support plate, an electronic direction monitor housing adapted to receive an electronic direction monitor, and a docking station adapted to receive the housing, thereby defining a reference point outside the patient's anatomical structure, relative to the patient's anatomical structure, wherein the first, second, and third positioning elements are positioned to be pressed down on the patient to provide a reference direction for the electronic direction monitor with respect to a given anatomical site.

Description

Technical Field

[0001] The present invention relates to surgical instruments and surgical methods, and more particularly to a referencing apparatus that can be applied to a patient before or during a surgical procedure, such as a hip surgery that requires artificial joint components.

Background Art

[0002] The discussion of the prior art in this specification is not an admission of the level of common general knowledge in the field of the present invention, nor should it be so received. Rather, the discussion of the prior art is provided solely to assist the reader in understanding the present invention and is included without prejudice.

[0003] The following discussion relates to hip replacement surgery, but those skilled in the art will understand that the present invention is not limited to this particular field of use and can be adapted for use in any bone structure or various types of surgery.

[0004] Hip replacement surgery involves restoring the function of the ball and cup joint of the hip using an artificial cup (acetabular cup) or an artificial ball (femoral stem) or both. The ball and cup joint allows the hip joint to rotate in various directions and to various degrees (in contrast to the relatively limited rotation of the knee joint).

[0005] Historically, hip replacement (arthroplasty) surgery required a curved incision up to 40 cm (7 to 12 inches) to provide sufficient access for the surgeon to manually access and handle the hip joint and femur. The artificial cup was attached to the hip socket, the head of the femur was removed and replaced with an artificial ball, or both were done.

[0006] After the incision is made, the ligaments and muscles are separated to allow the surgeon to access the hip bone. It is generally this part of the surgery that weakens the ligaments and muscles somewhat after the operation. Until they heal, which often takes about one to six weeks, the patient must follow special hip care instructions to prevent new hip dislocations.

[0007] A typical procedure for total hip replacement surgery includes the following: • Removal of the femoral head: Upon entering the hip joint, the femoral head dislocates from the acetabulum. Next, the femoral head is removed by cutting open the femoral neck with a power saw. • Reaming of the acetabulum: After removing the femoral head, cartilage is removed from the acetabulum using an electric drill and a special reamer. The reamer reshapes the bone into a hemispherical form to precisely fit into the metal shell of the acetabular component. • Insertion of the acetabular component: A trial component, which is an exact replica of the patient's artificial hip joint, is used to confirm that the received joint is the correct size 5 and fits properly. Once the correct size and shape of the acetabulum are determined, the acetabular component is inserted into place. In the uncemented type of artificial hip replacement, the metal shell is held in place simply by the tightness of the fit, or the metal shell is held in place with screws. In the cemented type, a special epoxy cement is used to "bond" the acetabular component to the bone. • Preparation of the femoral canal: To begin the femoral head replacement, a special file is used to shape the femur and hollow it out to the precise shape of the metal stein for the femoral component. A trial component is used again to confirm the correct size and shape. The surgeon also tests the movement of the hip joint. • Insertion of the femoral stem: Once the size and shape of the canal are precisely fitted to the femoral 15 components, the stem is inserted into the femoral canal. Again, in the case of the uncemented type of femoral component, the stem is held in place by the tightness of its fit to the bone (similar to the friction that holds a nail driven into a hole drilled in a wooden board with a diameter slightly smaller than the nail). In the cemented type, the femoral canal is machined to a size slightly larger than the femoral stem. Then, epoxy 20-type cement is used to bond the metal stem to the bone. • Femoral head placement: A metal ball that replaces the femoral head is attached to the femoral stem. • Completion of artificial hip replacement: Before closing the incision, an X-ray is taken to confirm that the new artificial joint is in the correct position.

[0008] Such surgeries had many problems, including the following: • Hospitalization for more than 3 days, postoperative pain, and several weeks of rehabilitation. Each centimeter of incision increases the risk of postoperative blood clotting and infection tenfold. To ensure accurate placement of the cup into the three-dimensional hip socket and to verify the alignment of the ball / femur and cup to achieve proper joint function, surgeons relied on their experience and eyes. Misalignment can lead to postoperative complications such as misalignment of the foot, incorrect leg length, and / or incorrect soft tissue tension. The long-term effects of misaligned prosthesis components can also include premature wear of the components, sterile loosening of the components, and potentially early re-operation.

[0009] Attempts to overcome these problems include the following: WO2003 / 037192 discloses a jib (impaction tool) for use in bone surgery, thus enabling the use of smaller incisions. In total hip replacement surgery, the jib allows the use of a 4 to 7 cm (2 to 3 inch) incision, i.e., keyhole surgery. Other advantages include shorter hospital stays, less bleeding, less pain, fewer postoperative dislocations, and faster recovery. WO2005 / 046475 discloses a gauge to assist in the precise placement of a prosthesis when using a fixture in keyhole surgery, since surgeons can no longer see the fit of the cup into the hip socket or the fit between the ball and the cup. WO2010 / 031111 discloses a brace designed to define a reference point for the patient during use in order to define the position for the placement of an artificial joint.

[0010] The gauge provided in WO2005 / 046475 enabled the efficient use of the impaction tool in WO2003 / 037192. A commercial example is the NivNav Hip System available from MAC Surgical. However, the gauge works only in two dimensions, and the optimal placement of the cup in the hip joint still largely depends on the surgeon's eye and experience.

[0011] Further attempts to overcome these problems are provided by WO2010 / 031111, the contents of which are incorporated herein in their entirety by cross-reference. This prior art document discloses a brace (3) in the form of a clamp that can be attached to a patient to define reference points to the patient's anatomical structures. The clamp of this prior art has a number of pads (14, 16, 17, 18) that are positioned to various points on the patient's anatomical structures. However, it has been understood by the inventors that this clamp may interfere with at least some surgical procedures and does not readily accommodate surgical drapes that are typically used in many surgical settings. [Overview of the project]

[0012] The object of the present invention is to overcome or improve upon at least one of the drawbacks of the prior art, or to provide a useful alternative.

[0013] According to a first aspect of the present invention, a reference device for application on a patient is provided. The reference device may include a support plate. The reference device may further include a first positioning element extending from the support plate. The reference device may further include a second positioning element extending from an upper support plate. The reference device may further include a third positioning element extending from an upper support plate. The reference device may further include an electronic direction monitor housing adapted to receive an electronic direction monitor. The reference device may further include a docking station adapted to receive the housing, thereby defining a reference point outside the patient's anatomical structure and relative to the patient's anatomical structure. The first, second, and third positioning elements may be positioned to be pressed down on the patient to provide a reference direction for the electronic direction monitor with respect to a given anatomical site.

[0014] According to a particular arrangement of the first embodiment, a reference device for application on a patient is provided, the reference device comprising: a support plate; a first positioning element extending from the support plate; a second positioning element extending from an upper support plate; a third positioning element extending from an upper support plate; an electronic direction monitor housing adapted to receive an electronic direction monitor; and a docking station adapted to receive the housing, thereby defining a reference point outside and relative to the patient's anatomical structure, wherein the first, second, and third positioning elements are positioned to be pressed down on the patient to provide a reference direction for the electronic direction monitor with respect to a given anatomical site.

[0015] The housing may be a sterile housing. The housing may include a body having an opening adapted to receive a direction monitor; a load funnel having an angled leading wall and an insertion wall for inserting a sterile direction monitor into the sterile housing while preventing contamination of the sterile housing; and a locking means having a sealed frame adapted to engage with a docking station, the frame being pivotably attached to the body of the housing. The housing may be a clamshell housing.

[0016] The load funnel may be a transport shield adapted to be placed over the opening of the housing to protect the sterile components of the housing in use while the monitor is inserted into the housing through the shield.

[0017] The locking mechanism may have a central opening shaped to receive a docking station, thereby securing the orientation monitor to a reference device in order to orient the electronic orientation monitor toward the patient.

[0018] The first and second positioning elements may be first and second anterior superior iliac spine positioning elements. The third positioning element may be a pubic bone positioning element. The first and second positioning elements may include a patient connection plate. The patient connection plate may be positioned to be fixed to the patient above the anterior superior iliac spine.

[0019] The electronic orientation monitor may be dockable with a docking station in either a first or second docking configuration. The electronic orientation monitor may be housed in an electronic orientation monitor housing. The electronic orientation monitor housing may be arranged to engage with a support plate to provide a reference orientation for the electronic orientation monitor.

[0020] The first docking configuration may define a first orientation of the electronic orientation monitor relative to the reference device. The second docking configuration may define a second orientation of the electronic orientation monitor relative to the reference device.

[0021] A second aspect of the present invention provides a method for calibrating an electronic orientation monitor using a reference device as defined in the first aspect. The method may include the step of positioning a patient connection plate on the left anterior superior iliac spine. The method may further include the step of positioning a patient connection plate on the right anterior superior iliac spine. The method may further include the step of connecting first and second positioning elements to their respective patient connection plates. The method may further include the step of positioning a third positioning element relative to the pubic bone. The method may further include the step of placing the electronic orientation monitor in a sterile housing equipped with means for receiving a non-sterile monitor while preventing contamination of the sterile housing. The method may further include the step of engaging the housing, which contains the monitor housed therein, with a docking station positioned on the reference device, thereby assuming a reference orientation outside the patient and relative to the patient. The method may further include the step of calibrating the electronic orientation monitor.

[0022] According to a specific arrangement of the second embodiment, a method is provided for calibrating an electronic orientation monitor using a reference device as defined in the first embodiment, the method comprising: positioning a patient connection plate on the left anterior superior iliac spine; positioning a patient connection plate on the right anterior superior iliac spine; connecting first and second positioning elements to the respective patient connection plates; positioning a third positioning element relative to the pubic bone; placing the electronic orientation monitor in a sterile housing having means for receiving a non-sterile monitor while preventing contamination of the sterile housing; engaging the housing, which contains the monitor housed therein, with a docking station positioned on the reference device, and assuming a reference orientation external to the patient and relative to the patient; and calibrating the electronic orientation monitor.

[0023] During the step of engaging the reference device with the surgical drape and during the calibration of the electronic direction monitor, the reference device may be positioned in front of the patient. A front approach may be used for surgical access to the patient's acetabulum.

[0024] During the above plurality of steps, the patient may be positioned to lie in a face up position.

[0025] According to a third aspect of the present invention, there is provided a method of calibrating an electronic direction monitor using a reference device as defined in the first aspect. The method may include positioning a surgical drape over the patient. The method may further include engaging a plurality of positioning elements with the surgical drape such that the surgical drape is disposed between each of the plurality of positioning elements and a plurality of predefined anatomical sites on the patient, and assuming a reference direction for the plurality of predefined anatomical sites at a docking station disposed on the reference device. The method may further include placing the electronic direction monitor in a sterile housing having means for receiving a non-sterile monitor while preventing contamination of the sterile housing, and docking the housing with the docking station so as to orient the electronic direction monitor in the reference direction. The method may further include calibrating the electronic direction monitor.

[0026] According to a specific arrangement of the third aspect, a method for calibrating an electronic direction monitor is provided using a reference device as defined in the first aspect. The method includes positioning a surgical drape over a patient, engaging a plurality of positioning elements with the surgical drape such that the surgical drape is disposed between each of the plurality of positioning elements and a plurality of predefined anatomical sites on the patient, causing a docking station disposed on the reference device to assume a reference direction with respect to the plurality of predefined anatomical sites, disposing the electronic direction monitor within a sterile housing having means for receiving a non-sterile monitor while preventing contamination of the sterile housing, and docking the housing with the docking station so as to orient the electronic direction monitor in the reference direction, and calibrating the electronic direction monitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings. [Figure 1] FIG. 1 is a perspective view of a reference device according to a first embodiment of the present invention. <00,00104> [Figure 2] FIG. 2 is a perspective view of the reference device of the embodiment of FIG. 1. [Figure 2A] FIG. 2A is a perspective view of a further embodiment of the reference device. [Figure 2B] FIG. 2B is a perspective view of a further embodiment of the reference device. [Figure 3] FIG. 3 is a partial perspective view of a first or second positioning element used with the reference device of FIG. 1. [Figure 4] FIG. 4 is a cross-sectional view of the first or second positioning element of FIG. 3. <0,000114> [Figure 5] FIG. 5 is an exploded view of an electronic direction monitor used with the reference device of FIG. 1. [Figure 5A] FIGS. 5A and 5B show alternative embodiments of an electronic direction monitor housing including a clam shell case and a transfer shield. [Figure 5B]Figures 5A and 5B show alternative embodiments of the electronic orientation monitor housing, including a clamshell case and a transport shield. [Figure 5C] Figure 5C is an exploded view of the alternative electronic orientation monitor shown in Figure 5A. [Figure 6] Figure 6 is a perspective view of the clamshell case for the electronic orientation monitor shown in Figure 5. [Figure 7] Figure 7 is a side view of the clamshell case shown in Figure 6. [Figure 8A] Figures 8A and 8B show a clamshell housing engaged with the embodiment of the reference device in Figure 1. [Figure 8B] Figures 8A and 8B show a clamshell housing engaged with the embodiment of the reference device in Figure 1. [Figure 9] Figure 9 is a perspective view of the electronic orientation monitor shown in Figure 5, attached to a surgical impactor. [Modes for carrying out the invention]

[0028] In a broad sense, the present invention relates to a reference device 100 for patient application for hip surgery, such as hip replacement, but is not limited thereto. Referring to the drawings, the reference device 100 of the present invention is used to assist a surgeon in orienting an artificial component relative to the patient's anatomical structure during surgery. The reference device 100 can be placed on the patient by the surgeon and allows for easy and reliable orientation of an electronic orientation monitor 46 in a housing 12. Once oriented, the electronic orientation monitor can be detached from the reference device 100 and attached to the artificial component, providing positional details of the artificial component for reliable and accurate insertion of the artificial component into the patient. The artificial component may be, for example, a surgical impactor used to position the artificial component within the patient. The orientation monitor provides positional details of the impactor corresponding to the position of the artificial component to ensure accurate placement of the artificial component within the patient. The orientation monitor 46 comprises an inertial measurement unit (IMU) including a 3-axis digital gyroscope and a 3-axis digital accelerometer. In certain embodiments, the IMU is an integrated digital gyroscope and accelerometer sensor specifically designed for inertial measurement, offering increased dynamic range, improved sensitivity, higher accuracy, lower bias, and lower drift compared to conventional gyroscope / accelerometer implementations. In certain embodiments, the selected IMU enables accurate position recognition and determination without requiring additional navigation components such as a magnetometer or compass component, which may experience interference from local magnetic fields (e.g., from medical imaging equipment) that could negatively affect the accuracy of critical directional parameters that must be determined by the direction monitor 46. In certain embodiments, the surgeon may be provided with the ability to select or input the angles and associated data of a particular prosthesis into the direction monitor 46, assisting and fine-tuning the orientation calibration with respect to the patient's unique anatomical structure.

[0029] A preferred embodiment is particularly suited to assisting a surgeon in properly positioning the acetabular cup within the reamed acetabulum during hip surgery, such as total, partial, or corrective hip replacement. When used in this context, the reference device 100 is pressed down from above onto the patient's pelvis to assume a reference position for orienting the electronic orientation monitor 46 and assist in positioning the surgical impactor and artificial components.

[0030] This detailed description illustrates the use of a reference device 100 and an electronic orientation monitor 46 as an aid in the insertion of an acetabular cup-shaped prosthesis component into a reamed acetabulum of a patient's pelvis where an anterior approach is used for surgical access to the patient's acetabulum. A key part of this process is the use of the reference device 100 for calibrating the electronic orientation monitor 46, which may be similar to a monitor disclosed in the applicant's earlier application no. WO2010 / 031111, the contents of which are incorporated herein in their entirety by cross-reference. However, it will be understood by those skilled in the art that the present invention may be used in other surgical contexts.

[0031] Referring to the drawing, the reference device 100 comprises the following components. • Frame 10 for positioning the electronic orientation monitor at a reference position relative to the patient. • First and second anterior superior iliac spine (ASIS) positioning elements 14, • Third, pubic bone positioning element 16, • Electronic orientation monitor 46, and • Electronic direction monitor housing 12.

[0032] The frame 10 includes an upper support plate in the form of a channel portion 11 and a T-channel portion 15 extending perpendicularly from the channel portion 11. A first ASIS positioning element 14 extends outward from the base of one longitudinal end of the channel portion 11, and a second ASIS positioning element 14 extends from the opposite longitudinal end of the channel portion 11. A third pubic bone positioning element 16 extends outward from the base of the T-channel portion 15.

[0033] The force application plate 13 forms part of the channel portion 11 and provides an interface for downward forces applied to the reference device 100 on the patient via positioning elements 14, 16, and directs the electronic direction monitor 46.

[0034] The first and second ASIS positioning elements 14 connect to the channel portion 11 and extend outward substantially perpendicular to the channel portion 11. In one embodiment, to provide the ability to use a single-size reference device 100 for patients of different sizes and hip profiles, the first and second ASIS positioning elements 14 are mounted on the channel portion 11 so that they can be fixed in different positions. In one embodiment, the connecting surface of the channel portion 11 has a number of fixing points from which the first and second ASIS positioning elements 14 can be selected for mounting. In an alternative embodiment, the lower surface of the channel portion 11 includes a rail having mounting points for the first and second ASIS positioning elements 14. The mounting points can be locked in place as desired.

[0035] A third pubic positioning element 16 connects to the T-channel portion 15 and extends outward, substantially perpendicular to the T-channel portion 15. In one embodiment, to provide the ability to use a single-size reference device 100 for patients of different sizes and hip profiles, the third pubic positioning element 16 is attached to the T-channel portion 15 so that it can be fixed in different positions. In one embodiment, the connecting surface of the T-channel portion 15 has a number of fixing points from which the third pubic positioning element 16 can be selected to be attached.

[0036] In an alternative embodiment, the lower side of the T-channel portion 15 includes a rail having a mounting point for a third pubic bone positioning element 16. The mounting point can be locked in place if desired.

[0037] Extending from the channel section 11 is a docking station 19 formed to receive an electronic orientation monitor 46 contained within the housing 12. The docking station 19 is designed to be highly tolerant so as not to impair the accuracy of the measurement system and to position the monitor 46 precisely in a defined location. Engaging one of the docking stations 19 with the electronic orientation monitor 46 contained within the housing 12 defines a reference point relative to the patient's anatomical structure. This reference point is outside the patient and is used to orient the electronic orientation monitor 46 in the reference direction. While in this direction, the electronic orientation monitor 46 acquires reference direction information used to calibrate the electronic orientation monitor 46 in the reference direction. In one embodiment, as shown in Figure 1, the docking station 19 of the frame 10 includes a central opening 17, and the docking station 19 has a contour to receive and secure the electronic orientation monitor 46 in a predetermined position. In a further embodiment of the frame, for example, the frame 70 in Figure 2B, the docking station 19 does not have an opening within it.

[0038] The first and second ASIS positioning elements 14 include a rod extension 20 extending from the base of the channel portion 11, a base 21, and a patient connection plate 18. The patient connection plate 18 is positioned to be fixed to the patient's body on the patient's ASIS. The position of the patient connection plate 18 determines where the first and second ASIS positioning elements 14 are positioned on the patient.

[0039] The pubic positioning element 16 extends as a bar from the channel portion 11 and terminates with a pubic probe 23. The pubic probe 23 is formed to be positioned within the pubic ridge of the patient when in use. With the pubic probe 23 positioned between the pubic ridges of the patient and the first and second ASIS positioning elements 14 in place on the connecting plate 18, a known reference position for the channel portion 11 and the reference device 100 as a whole, relative to the patient, is then known.

[0040] In this known position, the electronic orientation monitor 46 can be positioned on a docking station 19 within the electronic orientation monitor housing 12 appropriate to the hip joint side they are operating on, according to the surgeon's personal preference; that is, regardless of which hip joint the surgeon is operating on, the surgeon can position the orientation monitor 46 within the housing 12 and mount the housing to one of the two docking stations 19 (on the left or right side of the frame 10,70) of the reference device 100. In practice, the range of desired positions selectable by the surgeon for the orientation monitor 46 is limited by the patient's anatomical structure and clinical effectiveness. The position selected by the surgeon is determined by the combination of the type of implant and the patient's anatomical structure, adjusted by the surgeon's clinical judgment. The reference device 100 can be thought of as establishing commonly used / acceptable predefined orientations with respect to the patient's anatomical structure. The addition of the orientation monitor 46 to the device 100 provides the surgeon with live positional feedback, which allows the surgeon to position the implant in a desired position that may differ from the predefined position if the surgeon deems it appropriate.

[0041] Figure 2A shows an alternative embodiment 50 of the frame 10, in which the channel section 11 and T-channel section 15 of the previous embodiment are replaced by rigid non-channel arms 51 and 52, respectively, and replaced by a non-channel frame 50. Adjustment slots 52 and 53 are provided in at least one of the arms 51 and in the T-section 54 for adjusting the spacing between the first and second ASIS positioning elements 14 having feet 22, and for adjusting the pubic positioning element 16 with respect to the patient's specific anatomical structure. The particular embodiment shown in Figure 2A is described in more detail in Australian Patent No. AU2013204941, the contents of which are fully incorporated herein by cross-reference.

[0042] Figure 2B shows an alternative embodiment 70 of frames 10 and 50, where the channel frame is not used, and slots 71 and 72 on the arm 74 of frame 70 and slot 75 on the T-section 76 (similar in nature to slots 52 and 53 in Figure 2A) are provided. In this embodiment, the ASIS positioning element 14 terminates with a lever lock system that engages with slots 71 and 72 of frame 70, respectively. Similarly, the pubic positioning element 16 terminates with a lever lock system that engages with slot 75 so that the ASIS positioning element 14 and the pubic positioning element 16 can be adjusted to position the anatomical features of a patient and then locked in place. As shown in Figure 2A, slots 71 and 72 on the arm 74 and slot 75 on the T-section 76 may optionally be provided with a series of regularly spaced detents to assist in the correct positioning of the positioning elements 14 and 16 and to assist in the lock clamps for fixing the positioning elements 14 and 16 in place.

[0043] The docking station 19 in the embodiment shown in Figure 2B also includes a magnetic positioning feature 77. The positioning feature 77 is sensed by the direction monitor 46 when it engages with any of the docking stations 19. The positioning feature 77 senses the arrangement of the direction monitor housing 12, including the direction monitor 46, and helps ensure that the reference device 100 is used as intended and to avoid errors that may occur if, for example, the monitor 46 or frames 10, 50, 70 are used before they are properly calibrated.

[0044] As best illustrated in Figures 3 and 4, the patient connection plate 18 includes a central ring projection 29 defined by the perimeter 22 of the first and second ASIS positioning elements 14, a central opening 30 defined by the central ring projection 29, a base 27, and a base projection 28. The central ring projection 29 acts to receive into a recess 32 defined by the perimeter 22 of the first and second ASIS positioning elements 14. With the patient connection plate 18 fixed in place on both the left and right second ASIS, the recess 32 on the first and second ASIS positioning elements 14 can be placed on the central ring projection to position the reference device 100 in the reference direction, when the pubic positioning element 16 is also in place. The ring structure of the patient connection plate 18 also allows the surgeon to easily place the patient connection plate 18 directly on the patient's ASIS when the patient is covered by a surgical drape.

[0045] Figure 4 shows the fixation of the patient connection plate 18 to the patient. The adhesive sterile film 35 is attached to the patient's skin 36. The connection plate adhesive 34 is attached to the adhesive film 35 on the anterior superior iliac spine and is used to fix the patient's outer side and to orient the electronic orientation monitor 46 in the reference direction. During this orientation, the electronic orientation monitor 46 acquires reference direction information used to calibrate the electronic orientation monitor 46 in the reference direction. The patient cover sheet 33 can be accommodated between the patient connection plate 18 and the first and second anterior superior iliac spine positioning elements 14.

[0046] Figures 5 to 8 show the electronic orientation monitor 46 and the electronic orientation monitor housing 12. The electronic orientation monitor housing 12 is a sterile housing so that the electronic orientation monitor 46 does not need to be sterile for patient use. In one embodiment, the electronic orientation monitor housing 12 is a clamshell housing. The electronic orientation monitor housing 12 includes a body 24 for receiving the electronic orientation monitor 46, a lid 41, a load funnel 37, and a locking mechanism 80.

[0047] The clamshell housing 12 performs three main functions. 1. It provides a physical barrier against biological contamination of the direction monitor. 2. It provides physical vibration isolation from the high levels of shocks experienced when the direction monitor is in use. 3. It maintains the proper alignment of the direction monitor. Because the accuracy of the direction monitor is highly sensitive to any misalignment, the clamshell has a built-in alignment function to maintain proper alignment during use.

[0048] The clamshell housing 12 is preferably designed to be supplied as a sterile, single-use part. Reusing the clamshell housing 12 may pose safety risks to the patient through one or more of the following: • Wear and tear from reuse, and displacement due to tears. • Misalignment caused by deformation due to washing or handling. • Contamination leading to infection due to inaccurate or insufficient resterilization.

[0049] The load funnel 37 includes an angled leading wall 38 and an insertion wall 39. The load funnel is sterile and prevents non-sterile components from coming into contact with the sterile components of the electronic direction monitor housing 12. The load funnel is inserted into the electronic direction monitor housing 12 to allow the insertion of a non-sterile electronic direction monitor 46 into the electronic direction monitor housing 12. While inside the electronic direction monitor housing 12, the non-sterile electronic direction monitor 46 can be used in a sterile environment and can withstand forces applied to the electronic direction monitor housing 12, as will be further described later. The housing 12 also preferably includes one or more internal positioning features adapted to ensure the correct alignment of the monitor 46 within the housing 12 and thus ensure repeatable and accurate direction measurements.

[0050] In the alternative embodiment shown in Figure 5A, the load funnel 37 is replaced by a transfer shield 60. The shield 60 is placed over the opening of the housing 12 to protect the sterile components of the housing 12 while the monitor 46 is inserted into the housing 12 through the shield 60. The shield 60 provides improved protection to the sterile components of the housing 12 during insertion of the monitor 46 compared to the load funnel 37 in Figure 5. The housing 12 protects the navigation unit during use and provides shock isolation and a physical barrier against biological contamination.

[0051] The electronic direction monitor housing 12 includes a body 24, a cap 41, a clip 42, and a clip lock 47 positioned to receive the clip 42 and the cap 41 and lock them in place to seal the body 24. The cap 41, clip 42, and clip lock 47 are part of the lid 43 of the electronic direction monitor housing 12. The cap 41 rotates around its connection point with the lid 43 to seal the body 24.

[0052] The locking means 80 extends from the base of the electronic direction monitor housing 12 to engage with the docking station 19 and secures the electronic direction monitor 46 to the reference device 100 to obtain a reference direction.

[0053] The locking mechanism 80 includes vertical extension members 25 extending perpendicularly from the main body 24. There are front and rear pairs of vertical extension members 25 that form a square profile. A support frame member 26 extends between the front and rear vertical extension members 25 to form an enclosed frame. The vertical extension members 25 are attached to the main body at an upper pivot point 45. This allows the vertical extension members 25 to rotate about the upper pivot point 45. The support frame member 26 is attached to the vertical extension members 25 using a lower pivot point 44. This allows the ends of the vertical extension members 25 to pivot around the support frame member 26. The mounting mechanism is further adapted to engage with a mounting frame 90 that includes vibration isolation (vibration damping) features for absorbing forces applied longitudinally to the electronic orientation monitor housing 12, as will be described later. The isolation features in a particular embodiment are described below and include, for example, a spring feature 91 as shown in Figure 5B.

[0054] The enclosed frame of the locking mechanism 80 includes a central opening 48 shaped to receive the docking station 19, securing the electronic orientation monitor 46 to the reference device 100 and orienting the electronic orientation monitor 46 toward the patient for further surgical use.

[0055] Further embodiments of the electronic monitor housing 12 are shown in Figures 5A to 5C. In this further embodiment, the angle of the housing 24 is set to an inclined angle by a mounting frame 90 to make it more visible to surgeons and surgical staff. The mounting frame 90 is configured to engage precisely with the docking station 19 of the reference device 100. Spring features 91 of the mounting frame 90 act to isolate the direction monitor housing 12 and the installed direction monitor 46 from ambient vibrations during operation, thereby improving the positional accuracy that can be provided by the direction monitor 46.

[0056] Figures 6 and 7 show further illustrations of the clamshell housing 12 disclosed above. Figures 8A and 8B depict the clamshell housing 12 engaged with the frame 70 of the reference device 100.

[0057] Referring to Figure 9, in the direction assumed by the electronic direction monitor 46, the electronic direction monitor housing 12 into which the electronic direction monitor 46 is inserted is attached to an insertion instrument 52 having an acetabular cup 54. The surgeon manipulates the insertion instrument 52 so that the cup is adjacent to the patient's pelvis, and a display on the electronic direction monitor 46 (not shown) guides the surgeon to orient the insertion instrument so that the current direction of the electronic direction monitor 46 is equal to the reference direction (or so that the current direction has some other desirable relationship with the reference direction). The display provides the surgeon with positional and directional information, including yaw / tilt axis direction and anterior / pitch axis direction, enabling the surgeon to precisely orient the prosthetic tool in the patient's unique anatomical structure. The direction monitor 46 may provide directional information to the surgeon in many different ways, depending on the preference of the particular surgeon. For example, the orientation of the insertion instrument 52 relative to the patient's pelvis may be communicated to the surgeon through a simple target display, and the degree to which the instrument 56 is off target may be communicated visually. Further examples of directional indicators may include, depending on the surgeon's personal preference, "bubble level" visual indicators or numerical indicators.

[0058] Once the desired orientation is achieved, the electronic orientation monitor 46 provides the surgeon with instructions such as visual and / or audible indications on the display, prompting the surgeon to evaluate the trial cup or to strike the impactor plate 55 to transmit force through the shaft 53 to strike the acetabular cup 54 into the patient's reamed acetabulum.

[0059] When placed on the insertion device 52, the electronic direction monitor housing 12 is positioned to isolate impacts from the electronic direction monitor 46. The vertical extension members 25 pivot around pivot points 44 and 45, moving the support frame members 26 forward or backward to isolate the force applied to the impactor plate 55 from the electronic direction monitor 46. The spring formation 91 in the embodiment of the housing 12 shown in Figure 5B is particularly adapted for shock isolation from the insertion device in use.

[0060] From the above description, it will be understood that the reference device 100 is configured to engage exclusively forward with the patient and the patient connection plate 18 on the patient during the step of pushing the reference device into engagement with the surgical drape and during the calibration of the electronic orientation monitor. This is favorably compared to the clamp disclosed in WO2010 / 031111, which requires both forward and backward engagement with the patient. This is because the inventors have understood that the clamp of WO2010 / 031111 can, in practice, cause undesirable injuries to the surgeon.

[0061] Although the present invention has been described with reference to specific embodiments, those skilled in the art will understand that it can be embodied in many other forms.

Claims

1. A reference device for application to a patient, Support plate and A first positioning element extending from the support plate, A second positioning element extending from the upper support plate, A third positioning element extending from the upper support plate, An electronic orientation monitor housing adapted to accept an electronic orientation monitor, Includes a docking station adapted to receive the housing, thereby defining a reference point outside the patient's anatomical structure and relative to the patient's anatomical structure, The first positioning element, the second positioning element, and the third positioning element are positioned to be pressed down on the patient to provide a reference direction for the electronic orientation monitor with respect to a predetermined anatomical site. Reference device.

2. The reference apparatus according to claim 1, wherein the housing is a sterile housing.

3. The aforementioned housing is A body having an opening adapted to receive the aforementioned direction monitor, A load funnel having an angled leading wall and an insertion wall for inserting a sterile direction monitor into the sterile housing while preventing contamination of the sterile housing, A locking means comprising a sealed frame adapted to engage with the docking station, wherein the frame is pivotably mounted to the body of the housing, A reference device according to claim 2, comprising:

4. The reference apparatus according to claim 3, wherein the load funnel is a transport shield adapted to be placed over the opening of the housing to protect the sterile components of the housing in use while the monitor is inserted into the housing through the shield.

5. The reference device according to claim 3 or 4, wherein the locking means comprises a central opening shaped to receive the docking station, thereby fixing the direction monitor to the reference device in order to orient the electronic direction monitor toward the patient.

6. The reference device according to any one of claims 1 to 5, wherein the housing is a clamshell housing.

7. The reference device according to any one of claims 1 to 6, wherein the first and second positioning elements are first and second anterior superior iliac spine positioning elements.

8. The reference device according to any one of claims 1 to 7, wherein the third positioning element is a pubic bone positioning element.

9. The reference device according to any one of claims 1 to 8, wherein the first and second positioning elements include a patient connection plate.

10. The reference device according to any one of claims 1 to 9, wherein the patient connection plate is positioned to be fixed to the patient above the anterior superior iliac spine.

11. The reference device according to any one of claims 1 to 10, wherein the electronic orientation monitor is housed in an electronic orientation monitor housing.

12. The reference device according to claim 10 or claim 11, wherein the electronic orientation monitor housing is arranged to engage with the support plate to provide a reference orientation for the electronic orientation monitor.

13. The reference device according to any one of claims 1 to 12, wherein the electronic orientation monitor is dockable with the docking station in either a first docking configuration or a second docking configuration.

14. The first docking configuration defines the first direction of the electronic orientation monitor relative to the reference device, The second docking configuration defines the second direction of the electronic orientation monitor relative to the reference device. The reference device according to claim 13.

15. A method for calibrating an electronic orientation monitor using the reference device described in claim 1, The steps include positioning the patient connection plate on the left anterior superior iliac spine, A step of positioning the patient connection plate on the right anterior superior iliac spine, The steps include connecting the first and second positioning elements to their respective patient connection plates, A step of positioning the third positioning element relative to the pubic bone, The steps include: placing the electronic orientation monitor within a sterile housing that has means for receiving a non-sterile monitor while preventing contamination of the sterile housing; The steps include engaging a housing containing a monitor with a docking station positioned on the reference device, and assuming a reference direction outside the patient and relative to the patient, The steps include: calibrating the electronic orientation monitor, A method that includes this.

16. The method according to claim 14, wherein the reference device is positioned in front of the patient during the step of engaging the reference device with the surgical drape and during the calibration of the electronic orientation monitor.

17. The method according to claim 14 or claim 15, wherein an anterior approach is used for surgical access to the acetabulum of the patient.

18. The method according to any one of claims 14 to 16, wherein the patient lies in a supine position during the aforementioned steps.

19. A method for calibrating an electronic orientation monitor using the reference device described in claim 1, The steps include positioning the surgical drape over the patient, The steps include engaging the positioning elements with the surgical drape so that the surgical drape is positioned between the positioning elements and each of the predefined anatomical sites on the patient, thereby causing the docking station positioned on the reference device to assume a reference direction for the predefined anatomical sites, The steps include: placing an electronic orientation monitor in a sterile housing equipped with means for receiving a non-sterile monitor while preventing contamination of the sterile housing, and docking the housing with the docking station so that the electronic orientation monitor is oriented in a reference direction; The steps include: calibrating the electronic orientation monitor, A method that includes this.

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