Surgical screw guides

Abstract

A surgical screw guide configured to guide at least one surgical screw into a target bone structure. The surgical screw guide may be a pedicle screw guide (1). The pedicle screw guide (1) may comprise a first guide tube (11a) and a second guide tube (11b) arranged to be positioned either side of the spinous process, St, of a target vertebra, Vt. Each of the first and second guide tubes (11a, 11b) may comprise an internal bore configured to guide a pedicle screw (115a, 115b) into the target vertebra, Vt. The pedicle screw guide (1) may comprise first and second support legs (15a, 15b) arranged to be positioned either side of the spinous process, St, of the target vertebra, Vt and comprising a distal end (17a, 17b) adapted to mate with a lamina of an adjacent vertebra, Va. The pedicle screw guide (1) may be removable after the pedicle screws (115a, 115b) are inserted into the target vertebra, Vt, using the pedicle screw guide (1).

Description

[0001] SURGICAL SCREW GUIDES

[0002] TECHNICAL FIELD

[0003] The present invention relates to surgical screw guides and methods of producing surgical screw guides, in particular pedicle screw guides and methods of producing pedicle screw guides.

[0004] BACKGROUND

[0005] Spinal correction surgery typically requires the insertion of surgical screws into two or more vertebrae of the spine. Screws are typically inserted into the pedicles of a vertebra. These screws are commonly referred to as pedicle screws. Pedicle screws in adjacent vertebrae are then fixed together using metal rods or other suitable means. Misalignment of pedicle screws in adjacent vertebra can result in damage to the vertebrae or the spinal cord or associated nerves, blood vessels, or ligaments. There is therefore a need to maximise the accuracy of pedicle screw insertion. There is also a need to maximise the accuracy of insertion of surgical screws in other applications, such as in orthopaedic or maxillofacial surgery.

[0006] SUMMARY

[0007] A first aspect provides a surgical screw guide configured to guide at least one surgical screw into a target bone structure. The surgical screw guide comprises at least one guide tube. The or each guide tube comprises an internal bore configured to guide a surgical screw into the target bone structure. The surgical screw may be a pedicle screw and the target bone structure may be a target vertebra.

[0008] The or each guide tube may comprise a first end. The or each guide tube may comprise a second end opposite the first end. The internal bore may extend continuously in a longitudinal direction from the first end to the second end. The internal bore may comprise a constant diameter or a variable diameter. The internal bore may be open and the first end and the second end.

[0009] The first end of the or each guide tube may be arranged to mate with a target vertebra. The first end of the or each guide tube may comprise one or more features arranged to mate with the target vertebra. The one or more features may comprise one or more projections or any other suitable feature. The first end of the or each guide tube may be adapted to mate with a target vertebra. The first end may comprise a surface adapted to mate with the target vertebra. The surface may be adapted to mate with a surface contour of the target vertebra. The surface may be a patient specific surface. The patient specific surface may be adapted to mate with a surface contour of a target vertebra of a particular patient. The patient specific surface may be adapted based on a three-dimensional model of the target vertebra of the particular patient. In use, the three-dimensional model may be generated using low-dose CT scanning, 3D x-ray scanning, black bone MRI scanning, or any other suitable technique.

[0010] The pedicle screw guide may comprise at least one support leg. The or each support leg may comprise a proximal end fixed to a guide tube of the at least one guide tube. The or each support leg may comprise a distal end adapted to mate with the target vertebra or an adjacent vertebra. The distal end may be adapted to mate with a lamina of the target vertebra or the adjacent vertebra. Alternatively, or additionally, the distal end may be adapted to mate with a process extending from a lamina of the target vertebra or the adjacent vertebra. The process may be a transverse process or a superior articular process. The adjacent vertebra may be adjacent the target vertebra. The adjacent vertebra may be immediately adjacent the target vertebra or the adjacent vertebra may be separated from the target vertebra by one or more intermediate vertebra.

[0011] The or each support leg may be configured to extend diagonally from the guide tube to which the support leg is fixed to the adjacent vertebra. In this context, ‘diagonal’ may mean straight and sloping relative to a vertical plane and a horizontal plane. In use, the horizontal plane may be in the coronal plane and the vertical plane may be the axial plane (also known as the transverse plane).

[0012] The proximal end of the or each support leg may be fixed to a central region of the guide tube to which the support leg is fixed. The central region may be the middle half of the length of the respective guide tube. The central region of the or each guide tube may be located between the first and second ends of the guide tube. The central region may extend between a first location and a second location. The first location may be at a distance from the first end of the guide tube of 10-40%, 15-35%, or 20-30% of the length of the guide tube. The first location may be at a distance from the first end of the guide tube of 25% of the length of the guide tube. The second location may be at a distance from the second end of the guide tube of 10-40%, 15-35%, or 20-30% of the length of the guide tube. The second location may be at a distance from the second end of the guide tube of 25% of the length of the guide tube.

[0013] The distal end of the or each support leg may comprise a surface adapted to mate with the target vertebra or the adjacent vertebra. The surface may be adapted to mate with a surface contour of the target vertebra or the adjacent vertebra. The surface may be adapted to mate with a lamina of the target vertebra or the adjacent vertebra. The surface may be adapted to mate with a surface contour of the lamina. The surface may be a patient specific surface. The patient specific surface may be adapted in the same manner as described above with reference to the patient specific surface of the first end of the or each guide tube.

[0014] The at least one support leg may comprise a first support leg and a second support leg. The distal end of the first support leg and the distal end of the second support leg may be arranged to be positioned either side of the spinous process of the respective target vertebra or adjacent vertebra.

[0015] The at least one guide tube may comprise a single guide tube. The proximal end of each of the first support leg and the second support leg may be fixed to the single guide tube. The at least one guide tube may comprise a first guide tube and a second guide tube. The proximal end of the first support leg may be fixed to the first guide tube. The proximal end of the second support leg may be fixed to the second guide tube. The first end of the first guide tube and the first end of the second guide tube may be arranged to be positioned either side of the spinous process of the target vertebra.

[0016] The at least one support leg may comprise a first support leg and a second support leg and the at least one guide tube may comprise a first guide tube and a second guide tube. This arrangement may be particularly advantageous as it provides four points of contact on the target vertebra and / or adjacent vertebra via the distal end of each of the first support leg and the second support leg and the first end of each of the first guide tube and the second guide tube. The at least one guide tube and the at least one support leg may be formed integrally. The at least one guide tube and the at least one support leg may be formed integrally using an additive manufacturing process, such as 3D printing, or a moulding process, or any other suitable process. In other examples, the at least one guide tube and the at least one support leg may be formed separately before being fastened together. The at least one guide tube and the at least one support leg may be fastened together using one or more mechanical fastenings, by adhesion, by fusion, or by any other suitable means.

[0017] The pedicle screw guide may comprise a polymer. The pedicle screw guide may consist essentially of a polymer. The polymer may be any suitable medical grade polymer. The polymer may be Acrylonitrile Butadiene Styrene (ABS), Polylactic Acid (PLA), or Acrylic Styrene Acrylonitrile (ASA), or any other suitable polymer, such as an acrylate- based polymer.

[0018] The pedicle screw guide may comprise a bridging element joining the first guide tube and the second guide tube together. The bridging element may be configured to space apart the first and second guide tubes. The bridging element may be configured to space apart the second end of the first guide tube and the second end of the second guide tube. This may allow for simultaneous insertion of a pedicle screw into the internal bore of each of the first and second guide tubes and / or simultaneous guiding of a pedicle screw in the internal bore of each of the first and second guide tubes into a target vertebra as the pedicle screws are sufficiently spaced apart so as not to interfere with each other.

[0019] The bridging element may be configured to contact a spinous process of the target vertebra. The bridging element may comprise a bore configured to receive a screw for fixing the bridging element to the spinous process of the target vertebra. The bore may be configured to extend diagonally through the bridging element. In this context, ‘diagonal’ may mean straight and sloping relative to a vertical plane and a horizontal plane. The horizontal plane may be in the coronal plane and the vertical plane may be the transverse plane.

[0020] The bridging element may be fixed to a central region of the first guide tube and a central region of the second guide tube. This may provide optimum rigidity of the pedicle screw guide. The bridging element may comprise a first end fixed to a central region of the first guide tube and a second end fixed to a central region of the second guide tube. The central region may be the middle half of the length of the respective guide tube. The central region of the or each guide tube may be located between the first and second ends of the guide tube. The central region may extend between a first location and a second location. The first location may be at a distance from the first end of the guide tube of 10-40%, 15-35%, or 20-30% of the length of the guide tube. The first location may be at a distance from the first end of the guide tube of 25% of the length of the guide tube. The second location may be at a distance from the second end of the guide tube of 10- 40%, 15-35%, or 20-30% of the length of the guide tube. The second location may be at a distance from the second end of the guide tube of 25% of the length of the guide tube.

[0021] The bridging element may be configured to avoid interference with a supraspinous ligament. The bridging element may be configured to avoid interference with a portion of a supraspinous ligament extending between the target vertebra and an adjacent vertebra. The bridging element may be curved to avoid interference with the supraspinous ligament or portion of the supraspinous ligament. The bridging element may be curved in the posterior direction. The bridging element may be configured such that the supraspinous ligament is arranged between the bridging element and the target vertebra.

[0022] The bridging element and the or each guide tube may be formed integrally. The bridging element, the or each guide tube, and the or each support leg may be formed integrally as a single part.

[0023] The pedicle screw guide may be removable after the pedicle screw is inserted into the target vertebra using the pedicle screw guide. This may allow a connecting rod or other structure to be fixed to the pedicle screw without having to leave the pedicle screw guide in situ. In use, the pedicle screw guide is held in contact with the target vertebra by means of downward pressure on the pedicle screw. The interaction between the or each guide tube and the target vertebra and the interaction between the or each support leg with the target vertebra or adjacent vertebra inhibits lateral movement of the pedicle screw guide during insertion of the pedicle screw. The pedicle screw guide may be configured to guide the pedicle screw into the target vertebra at a specific location and / or orientation. A position of the first end of the or each guide tube relative to the distal end of the or each support leg may be selected in dependence on the specific location and / or orientation. An angle of a longitudinal axis of the or each guide tube relative to a surface of the target vertebra may be selected in dependence on the specific location and / or orientation. The specific location and / or orientation may be selected based on an intended alignment of the respective pedicle screw with a pedicle screw inserted, or intended to be inserted, into an adjacent vertebra.

[0024] The internal bore of the or each guide tube may be configured to guide a head of the pedicle screw. The internal bore of the or each guide tube may be configured to restrict radial movement of the head of the pedicle screw within the internal bore. The internal bore of the or each guide tube may be configured to allow axial movement of the head of the pedicle screw though the internal bore. The skilled person will appreciate that pedicle screws may vary in size and so a diameter of the internal bore of the or each guide tube may be dependent on a particular pedicle screw intended for a particular application. Whether or not an internal bore of a guide tube is configured to guide a head of a pedicle screw may be directly and positively verified by trial and error by inserting different sized pedicle screws into the internal bore of the guide tube.

[0025] The pedicle screw guide may comprise at least one screw adaptor. At least a portion of the or each screw adaptor may be configured to be removably received within the internal bore of a guide tube of the at least one guide tube. The pedicle screw guide may comprise a screw adaptor for each guide tube. At least a portion of each screw adaptor may be configured to be removably received within the internal bore of a different one of the at least one guide tube. Where the pedicle screw guide comprises a first guide tube and second guide tube, the pedicle screw guide may comprise a first screw guide and a second screw guide. The or each screw adaptor may be configured to narrow the internal bore of the guide tube to guide a threaded portion of the pedicle screw. In use, the or each screw adaptor may eliminate the need for a Kirschner wire (K-wire) or other additional means to guide the threaded portion of the pedicle screw.

[0026] The or each screw adaptor may comprise a guide portion. The guide portion may be configured to be removably received within the internal bore of a guide tube of the at least one guide tube. The guide portion may be configured to narrow the internal bore of the guide tube. The guide portion may comprise a bore configured to narrow the internal bore of the guide tube to guide a threaded portion of the pedicle screw. The or each guide tube may comprise at least one slot configured to receive a guide portion of a screw adaptor of the at least one screw adaptor. The at least one slot configured to receive the guide portion may be arranged in a central region of the guide tube as defined above.

[0027] The or each screw adaptor may comprise a securing portion configured to secure the screw adaptor to a guide tube of the at least one guide tube. The or each screw adaptor may comprise a first end and a second end. The first end may comprise the guide portion and the second end may comprise the securing portion. The second end of the or each guide tube may comprise an edge defined by the internal bore of the guide tube. The securing portion of the screw adaptor may comprise a lip configured to hook over the edge to secure the screw adaptor to the guide tube. The securing portion may comprise a tab to facilitate hooking of the lip over the edge and / or to facilitate removal of the lip from the edge. The securing portion may comprise a bore configured to receive a head of the pedicle screw.

[0028] The or each screw adaptor may comprise two halves. Each half of the or each screw adaptor may comprise one half of the securing portion. Each half of the securing portion may comprise a lip and / or a tab as described above. Each half of the or each screw adaptor may comprise one half of the guide portion. The two halves of the guide portion may be configured to co-operate to narrow the internal bore of the guide tube. The two halves of the guide portion may be configured to define the bore configured to narrow the internal bore of the guide tube. The or each guide tube may comprise a first slot configured to receive a first half of the guide portion and a second slot configured to receive a second half of the guide portion. The first and second slots may be arranged at opposite sides of the respective guide tube. The first and second slots may be arranged in a central region of the respective guide tube as defined above.

[0029] The pedicle screw guide may comprise two or more of the screw adaptor, wherein each screw adaptor is configured to narrow the internal bore of the guide tube to a different diameter. This advantageously facilitates the use of different sized pedicle screws with the pedicle screw guide. For example, the screw adaptors may be configured to narrow the internal bore of the guide tube to 4.5mm, 5.5mm, or 6.5mm. The pedicle screw guide may comprise at least one drilling insert. The or each drilling insert may be configured to be removably received within the internal bore of a guide tube of the at least one guide tube. The pedicle screw guide may comprise a drilling insert for each guide tube. Where the pedicle screw guide comprises a first guide tube and second guide tube, the pedicle screw guide may comprise a first drilling insert and a second drilling insert. The or each drilling insert may be configured to narrow the internal bore of the guide tube to guide a drill bit for drilling a hole in the target vertebra for receiving the pedicle screw. Alternatively, or additionally, the or each drilling insert may be configured to narrow the internal bore of the guide tube to guide a pedicle finder. The or each drilling insert may comprise an internal bore configured to guide the drill bit and / or the pedicle finder.

[0030] The pedicle screw guide may comprise at least one wire guide. The or each wire guide may be configured to be removably received within the internal bore of a guide tube of the at least one guide tube. The pedicle screw guide may comprise a wire guide for each guide tube. Where the pedicle screw guide comprises a first guide tube and second guide tube, the pedicle screw guide may comprise a first wire guide and a second wire guide. The or each wire guide may be configured to narrow the internal bore of the guide tube to guide a K-wire for insertion of the K-wire into the target vertebra. The or each wire guide may comprise an internal bore configured to guide the wire. The internal bore of the or each drilling insert may be configured to removably receive a wire guide of the at least one wire guide.

[0031] The or each guide tube may comprise a longitudinal slot for observing a pedicle screw within the guide tube. The longitudinal slot enables a user to monitor the progress of a pedicle screw as it is inserted into the target vertebra. The longitudinal slot may extend longitudinally in a direction parallel to a longitudinal axis of the respective guide tube. The length of the longitudinal slot may be greater than 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80% the length of the respective guide tube. The length of the longitudinal slot may be within a range defined by any two of the following values: 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80% of the length of the respective guide tube. The length of the longitudinal slot may be within the range of 55-80%, 60-75%, or 65-70% of the length of the respective guide tube. The longitudinal slot may be closed at both ends. This may minimise the impact of the longitudinal slot on the structural integrity and / or stiffness of the respective tube guide. The longitudinal slot may comprise a first end distanced from the first end of the respective guide tube and a second end distanced from the second end of the respective guide tube. The longitudinal slot may extend longitudinally between the first and second ends of the longitudinal slot. The longitudinal slot may be closed at both the first and second ends of the longitudinal slot. The longitudinal slot may be arranged centrally between the first and second ends of the respective guide tube. The distance between the first end of the guide tube and the first end of the longitudinal slot may be substantially equal to the distance between the second end of the guide tube and the second end of the longitudinal slot.

[0032] The pedicle screw guide may be labelled with an identifier of the target vertebra. For example, where the target vertebra is vertebra LI, the pedicle screw guide may be labelled with ‘LI ’ .

[0033] For the avoidance of doubt, the pedicle screw guide of the first aspect is configured to guide at least one pedicle screw into a pedicle of the target vertebra. In another aspect, the pedicle screw guide may be an alternative screw guide configured to guide at least one screw into another part of the target vertebra, or another part of the body.

[0034] A second aspect provides a multi-level pedicle screw guide comprising a plurality of pedicle screw guides according to the first aspect. Each pedicle screw guide of the plurality of pedicle screw guides may be configured to guide at least one pedicle screw into a different target vertebra. The different target vertebrae may comprise two or more successive vertebrae of a portion of a spine, such as the cervical spine, the thoracic spine, or the lumbar spine. The pedicle screw guides of the plurality of pedicle screw guides may be joined together. The pedicle screw guides of the plurality of pedicle screw guides may be integrally formed.

[0035] A third aspect provides a method of producing a pedicle screw guide or a multi-level pedicle screw guide. The pedicle screw guide may be the pedicle screw guide of the first aspect. The multi-level pedicle screw guide may be the multi-level pedicle screw guide of the second aspect. The method may comprise generating a three-dimensional model of at least one target vertebra and / or at least one adjacent vertebra. The method may comprise producing the pedicle screw guide or the multi-level pedicle screw guide based on the three-dimensional model.

[0036] Generating the three-dimensional model may comprise using low -dose CT scanning, 3D x-ray scanning, or black bone MRI scanning to generate the three-dimensional model. Use of these scanning methods is advantageous as they may minimise the exposure of a patient to harmful radiation. In other examples, alternative scanning methods may be used.

[0037] Producing the pedicle screw guide or the multi-level pedicle screw guide may comprise using additive manufacturing to produce the pedicle screw guide or the multi-level pedicle screw guide. Using additive manufacturing may comprise using a 3D printing method, such as stereolithography (SLA), selective laser sintering (SLS), or fused deposition modelling (FDM). SLA may be preferred. In other examples, an alternative method such as moulding may be used to produce the pedicle screw guide or the multilevel pedicle screw guide.

[0038] A fourth aspect provides a method of inserting at least one pedicle screw into at least one target vertebra using the pedicle screw guide of the first aspect or the multi -level pedicle screw guide of the second aspect. The method may comprise positioning the pedicle screw guide or the multi-level pedicle screw guide on a target vertebra. The method may comprise inserting the or each pedicle screw using the pedicle screw guide or the multi-level pedicle screw guide after positioning the pedicle screw guide or the multi-level pedicle screw guide on a target vertebra. The method may comprise removing the pedicle screw guide or the multi-level pedicle screw guide after the or each pedicle screw is inserted. The method may comprise using additional equipment, such as a navigation system, alongside the pedicle screw guide or the multi-level pedicle screw guide to insert at least one pedicle screw into at least one target vertebra.

[0039] A fifth aspect provides a pedicle screw -insertion kit comprising the pedicle screw guide of the first aspect or the multi-level pedicle screw guide of the second aspect and at least one pedicle screw, wherein the pedicle screw guide or the multi-level pedicle screw guide is configured to guide the or each pedicle screw into a target vertebra as described herein. Although the above examples relate to pedicle screw insertion into a target vertebra, the features described above may be equally applicable to an alternative surgical screw guide, such as an orthopaedic screw guide or a maxillofacial screw guide. In such cases, references to a ‘target vertebra’ and an ‘adjacent vertebra’ above may be replaced with a ‘target bone structure’ and an ‘adjacent bone structure’ respectively.

[0040] Any of the aspects described above may comprise any feature of any of the other aspects described above.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Implementations will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0043] Figure la shows a schematic rear view of a pedicle screw guide according to a first example;

[0044] Figure lb shows a close-up view of a first end of a first guide tube and a distal end of a first support leg of the pedicle screw guide of Figure la;

[0045] Figure 1c shows a schematic plan view of the pedicle screw guide of Figure la;

[0046] Figure Id shows a schematic side view of the pedicle screw guide of Figure la;

[0047] Figure le shows a schematic side view of the pedicle screw guide of Figure la in situ relative to a target vertebra and an adjacent vertebra of a patient;

[0048] Figure If shows a schematic plan view of the arrangement of Figure le;

[0049] Figure 1g shows a schematic rear view of the arrangement of Figure le;

[0050] Figure Ih shows a schematic rear isometric view of the arrangement of Figure le;

[0051] Figure 2a shows a schematic plan view of a pedicle screw guide according to another example;

[0052] Figure 2b shows a schematic isometric front view of the pedicle screw guide of Figure 2a in situ relative to a target vertebra of a patient ;

[0053] Figure 2c shows a further schematic isometric front view of the arrangement of Figure 2b;

[0054] Figure 2d shows a schematic plan view of the arrangement of Figure 2b;

[0055] Figure 3a shows a schematic isometric view of a pedicle screw guide according to another example; Figure 3b shows a schematic isometric view of a screw adaptor of the pedicle screw guide of Figure 3a;

[0056] Figure 3c shows a further schematic isometric view of the screw adaptor of Figure 3b ;

[0057] Figure 3c shows a schematic representation of a threaded portion of a pedicle screw received within a bore of a guide portion of the screw adaptor of Figure 3b;

[0058] Figured 3d shows a schematic close-up front view of a second guide tube of the pedicle screw guide of Figure 3a;

[0059] Figure 3e shows a close-up view of a first guide tube of the pedicle screw guide of Figure 3a;

[0060] Figure 3f shows a cross-section of the view of Figure 3e with the first guide tube removed;

[0061] Figure 3g shows a cross-sectional view of a first screw adaptor of the pedicle screw guide of Figure 3a in use;

[0062] Figure 3h shows a schematic close-up plan view of the pedicle screw guide of Figure 3a in use;

[0063] Figure 3i shows a schematic cross-sectional front view of the pedicle screw guide of Figure 3a in use;

[0064] Figure 4a shows a schematic plan view of a multi-level pedicle screw guide according to one example in use;

[0065] Figure 4b shows a schematic side view of the view of Figure 4a with pedicle screws inserted into a target vertebrae; and

[0066] Figure 5 shows a method of producing a pedicle screw guide or a multi-level pedicle screw guide.

[0067] DETAILED DESCRIPTION

[0068] Figure la shows a schematic rear view of a pedicle screw guide 1 according to a first example. The pedicle screw guide 1 comprises a first guide tube I la and a second guide tube 11b. The first guide tube I la comprises a first end 12a and a second end 13a, opposite the first end 12a. The first end 12a comprises a patient specific surface 14a adapted to mate with a surface contour of a target vertebra of a particular patient. The first guide tube I la comprises an internal bore extending continuously in a longitudinal direction from the first end 12a to the second end 13a. The longitudinal direction is parallel to a longitudinal axis a a of the first guide tube I la. The internal bore is open at the first end 12a and the second end 13a. In use, a pedicle screw will extend through the internal bore of the first guide tube I la in parallel with the longitudinal axis a La of the first guide tube I la. The internal bore comprises a constant diameter configured to guide a head of a pedicle screw, as described further below. The second guide tube 11b comprises the same features as the first guide tube I la, labelled in Figure la with the suffix ‘b’ in place of ‘a’ .

[0069] The pedicle screw guide 1 further comprises a first support leg 15a and a second support leg 15b. The first support leg 15a comprises a proximal end 16a fixed to a central region of the first guide tube 12a. The second support leg 15b comprises a proximal end 16b fixed to a central region of the second guide tube 12b. The first support leg 15a comprises a distal end 17a comprising a patient specific surface 18a adapted to mate with a surface contour of a lamina of an adjacent vertebra, where the adjacent vertebra is adjacent the target vertebra. In this example, the adjacent vertebra is immediately adjacent the target vertebra. In other examples, the adjacent vertebra may be sep arated from the target vertebra by one or more intermediate vertebra. The second support leg 15b comprises a distal end 17b comprising a patient specific surface 18b adapted to mate with a surface contour of the lamina of the adjacent vertebra.

[0070] The pedicle screw guide 1 further comprises a bridging element 19 joining the first guide tube I la and the second guide tube 11b together and spacing apart the first and second guide tubes I la, 11b. The bridging element 19 is configured to space apart the second end 13a of the first guide tube I la and the second end 13b of the second guide tube 11b. The bridging element 19 comprises a first end 110 fixed to a central region of the first guide tube I la and a second end 111 fixed to a central region of the second guide tube 11b.

[0071] In the example of Figure la, the first and second guide tubes I la, 11b, the first and second support legs 15a, 15b, and the bridging element 19 are formed integrally as a single polymer part by means of a 3D printing process. The pedicle screw guide 1 is produced by generating a three-dimensional model of the target vertebra and the adjacent vertebra and 3D printing the pedicle screw guide 1 based on the three - dimensional model.

[0072] Figure lb shows a close-up view of the first end 12a of the first guide tube I la and the distal end 17a of the first support leg 15a of the pedicle screw guide 1 of Figure la. Figure lb shows further detail of the patient specific surface 14a of the first end 12a of the first guide tube I la and the patient specific surface 18a of the distal end 17a of the first support leg 15a. The patient specific surface 14a of the first end 12a of the first guide tube I la is highlighted in Figure lb for reference.

[0073] Figure 1c shows a schematic plan view of the pedicle screw guide 1 of Figure la. As shown in Figure 1c, the first guide tube I la comprises a longitudinal slot 112a for observing a pedicle screw within the first guide tube I la. The second guide tube 11b comprises a longitudinal slot 112b for observing a pedicle screw within the second guide tube 11b. Figure 1c shows the internal bore 113a of the first guide tube I la and the internal bore 113b of the second guide tube 11b.

[0074] Figure Id shows a schematic side view of the pedicle screw guide 1 of Figure la. As shown in Figure Id, the longitudinal slot 112a of the first guide tube I l a is closed at both ends. The longitudinal slot 112a comprises a first end 1121a and a second end 1122a. The first end 1121a is distanced from the first end 12a of the first guide tube I l a and the second end 1122a is distanced from the second end 13b of the first guide tube I la. The longitudinal slot 112a extends longitudinally between the first end 1121a and the second end 1122a in a direction parallel to the longitudinal axis a a of the first guide tube I la. The longitudinal slot 112a is arranged centrally between the first end 12a of the first guide tube I la and the second end 13a of the first guide tube I l a. In this example, the length of the longitudinal slot 112a is greater than 50% of the length of the first guide tube I l a. The longitudinal slot of the second guide tube 11b is arranged in the same way with respect to the second guide tube 11b as the longitudinal slot of the 112a of the first guide tube I la is arranged with respect to the first guide tube I l a.

[0075] Figure le shows a schematic side view of the pedicle screw guide 1 of Figure la. The pedicle screw guide 1 is shown in situ relative to a target vertebra Vtand an adjacent vertebra Vaof a patient. In Figure le, the plane of the page lies in the sagittal plane. The view of target vertebra Vtand the adjacent vertebra Vaas shown in Figure le corresponds to a view of the patient from the side with the patient lying on their front. Figure If shows a schematic plan view of the arrangement of Figure le. Figure 1g shows a schematic rear view of the arrangement of Figure le. Figure Ih shows a schematic rear isometric view of the arrangement of Figure le. Figures 1g and Ih show transparent views of the pedicle screw guide 1. Figures le-h show a first pedicle screw 115a received within the internal bore 113a of the first guide tube I la and a second pedicle screw 115b received within the internal bore 113b of the second guide tube 11b. As shown in Figure le, a threaded portion 116b of the second pedicle screw 115b is visible through the longitudinal slot 112b of the second guide tube 11b.

[0076] As shown in Figures le-h, the second support leg 15b extends diagonally from the second guide tube 11b to the adjacent vertebra Va- The second support leg 15b extends in a straight and sloping manner relative to the coronal plane and the transverse plane. The first support leg 15a extends form the first guide tube I l a in the same manner. The distal end 17a of the first support leg 15a and the distal end 17b of the second support leg 15b are positioned either side of the spinous process St of the target vertebra Vt. The first end 12a of the first guide tube I la and the first end 12b of the second guide tube 11b are also positioned either side of the spinous process St of the target vertebra Vt.

[0077] Although not show in Figures le-h, the skilled person will appreciate that in practice a supraspinous ligament extends between the target vertebra Vtand the adjacent vertebra Va. The bridging element 19 is configured to avoid interference with the supraspinous ligament, i.e., the height of the bridging element 19 above the target vertebra Vtand the adjacent vertebra Vais sufficient to avoid contact between the bridging element and the supraspinous ligament.

[0078] As also shown in Figures le-h, the internal bore 113a of the first guide tube I l a is configured to guide a head 117a of the first pedicle screw 115a. The internal bore 113a of the first guide tube I la is configured to restrict radial movement of the head 117a of the first pedicle screw 115a within the internal bore 113a, while allowing axial movement of the head 117a of the first pedicle screw 115a through the internal bore 113a, to guide the head 117a of the first pedicle screw 115a. The internal bore 113b of the second guide tube 11b is configured in the same manner with respect to a head 117b of the second pedicle screw 115b.

[0079] In use, the second pedicle screw 115b is inserted into the internal bore 113b of the second guide tube 11b until the head 117b is received within t3he internal bore 113b. The second pedicle screw 115b is then rotated about its central longitudinal axis in order to insert the pedicle screw 115b into the target vertebra Vt. The first pedicle screw 115a is operated in the same manner with respect to the internal bore 113a of the first guide tube I la. After the first and second pedicle screws 115a, 115b have been inserted into the target vertebra Vt, the pedicle screw guide 1 is removed. This is enabled by the clearance between the heads 117a, 117b of the first and second pedicle screws 115a, 115b and the internal bores 113a, 113b of the respective first and second guide tubes I la, 11b.

[0080] The pedicle screw guide 1 is configured to guide each of the first pedicle screw 115a and the second pedicle screw 115b into the target vertebra Vtat a specific location and orientation. In use, the first pedicle screw 115a and the second pedicle screw 115b will form part of an array of pedicle screws inserted into adjacent vertebrae. The intended location and orientation of the first pedicle screw 115a and the second pedicle screw 115b, once inserted into the target vertebra Vt, will be selected based on the intended location and orientation of the other pedicle screws in the array in order to align the pedicle screws of the array.

[0081] Figure 2a shows a schematic plan view of a pedicle screw guide 2 according to another example. The pedicle screw guide 2 of Figure 2a has features in common with the pedicle guide 1 of Figure la. Common features are indicated with like reference numerals prefixed with ‘2’ in place of ‘ 1 ’ in Figure 2a. In the example of Figure 2a, the pedicle screw guide 2 does not comprise support legs; however, in other examples, the pedicle screw guide 2 may comprise at least one support leg which may have the same features as each of the support legs of the pedicle guide 1 of Figure la. The bridging element 29 of the pedicle screw guide 2 of Figure 2a comprises a bore 218 configured to receive a screw for fixing the bridging element 29 to a spinous process of a target vertebra, as described further below.

[0082] Figure 2b shows a schematic isometric front view of the pedicle screw guide 2 of Figure 2a. The pedicle screw guide 2 is shown in situ relative to a target vertebra Vtof a patient. Figure 2c shows a further schematic isometric front view of the arrangement of Figure 2b. Figure 2c shows a transparent view of the pedicle screw guide 2. Figure 2d shows a schematic plan view of the arrangement of Figure 2b.

[0083] Although not show in Figures 2b-d, the skilled person will appreciate that in practice a supraspinous ligament extends between the target vertebra Vtand the adjacent vertebra Va. The bridging element 29 is configured to avoid interference with the supraspinous ligament. In this example, the bridging element 29 is curved in the posterior direction dpto avoid interference with the supraspinous ligament. As shown in Figure 2c, the bore 218 of the bridging element 29 extends through the bridging element 29 to receive a screw for fixing the bridging element 29 to the spinous process St of the target vertebra Vt. In this example, the bore 218 extends diagonally through the bridging element 29, i.e. the bore 218 extends in a straight and sloping manner relative to the coronal plane and the transverse plane.

[0084] Figure 3a shows a schematic isometric view of a pedicle screw guide 3 according to another example. The pedicle screw guide 3 of Figure 3a has features in common with the pedicle screw guide 2 of Figure 2a. Common features are indicated with like reference numerals prefixed with ‘3 ’ in place of ‘2’ in Figure 3a.

[0085] The pedicle screw guide 3 of Figure 3a differs from the pedicle screw guide 2 of Figure 2a in that neither of the first end 32a of the first guide tube 31a nor the first end 32b of the second guide tube 31b comprise a patient specific surface as described above. Instead, each of the first end 32a of the first guide tube 31a and the first end 32b of the second guide tube 31b comprises an arrangement of projections 341a, 341b arranged to mate with a target vertebra. In other examples, one or both of the first end 32a of the first guide tube 31a and the first end 32b of the second guide tube 31b may comprise a patient specific surface as described above.

[0086] In the example of Figure 3a, the pedicle screw guide 3 further comprises a first screw adaptor 319a and a second screw adaptor 319b. Each of the first and second screw adaptor 319a, 319b comprises a guide portion 320a, 320b, a securing portion 321a, 321b, and an intermediate portion 322a, 322b, described in further detail below.

[0087] Figure 3b shows a schematic isometric view of one of the first and second screw adaptors 319 of the pedicle screw guide 3 of Figure 3a. It will be appreciated that the first and second screw adaptors are substantially identical. The screw adaptor 319 comprises a first end comprising the guide portion 320 and a second end comprising the securing portion 321. The intermediate portion 322 connects the guide portion 320 and the securing portion 321. The guide portion 320 comprises a bore 323 and the securing portion 321 comprises a bore 324. As shown in Figure 3b, the screw adaptor 319 comprises two substantially identical halves. Each half comprises one half of the guide portion 320, one half of the securing portion 321 , and one half of the intermediate portion 322. The two halves of the guide portion 320 are configured to define the bore 323 of the guide portion 320 and the bore 324 of the securing portion 321. A first half of the securing portion 321 comprises a first lip 325a and a first tab 326a and a second half of the securing portion 321 comprises a second lip 325b and a second tab 326b.

[0088] Figure 3c shows a further schematic isometric view of the screw adaptor 3 19 of Figure 3b. Figure 3c shows a schematic representation of a threaded portion of a pedicle screw 315 received within the bore 323 of the guide portion 320 of the screw adaptor 319.

[0089] Figured 3d shows a schematic close-up front view of the second guide tube 31b of the pedicle screw guide of Figure 3a. The second guide tube 31b comprises a first slot 327a configured to receive the first half of the securing portion of the second screw adaptor and a second slot 327b configured to receive the second half of the securing portion of the second screw adaptor. The first and second slots 327a, 327b are arranged on opposite sides of the second guide tube 31b, in a central region of the second guide tube 31b, so that, when installed, the two halves of the securing portion of the second screw adaptor align to define the bore of the securing portion of the second screw adaptor. The first guide tube of the pedicle screw guide of Figure 3a also comprises corresponding slots to receive the two halves of the securing portion of the first screw adaptor in the same manner.

[0090] Referring back to Figure 3a, when installed on the respective first and second guide tubes 31a, 31b, the two halves of the intermediate portion 322a, 322b of each of the first and second screw adaptors 319a, 319b are arranged outside of the internal bore of the respective first and second guide tubes 31a, 31b and the two halves of the guide portion 320a, 320b of each of the first and second screw adaptors 319a, 319b are received within the internal bore of the respective first and second guide tubes 31a, 31b through the first and second slots respectively, of the respective first and second guide tubes 31a, 31b.

[0091] Each of the first and second lips of the first and second screw adaptors 319a, 319b is configured to hook over an edge of the second end 33a, 33b of the first and second guide tubes 31a, 31b, respectively, the edge being defined by the internal bore of the respective guide tube 31a, 31b. The first and second tabs of the first and second screw adaptors 319a, 319b are configured to facilitate hooking of the first and second lips, respectively, over the respective edge and to facilitate removal of the first and second lips, respectively, from the respective edge. In use, after insertion of a pedicle screw, the first and second screw adaptors 319a, 319b will be removed from the first and second guide tubes 31a, 31b, respectively, to allow for removal of the pedicle screw guide.

[0092] Figure 3e shows a close-up view of the first guide tube 31a of the pedicle screw guide of Figure 3a. Figure 3f shows a cross-section of the view of Figure 3e with the first guide tube 31a removed. The pedicle screw guide further comprises a first drilling insert 328a. The first drilling insert 328a is configured to be removably received within the internal bore of the first guide tube 31a via the bore of the securing portion 321 of the first screw adaptor 319a. The first drilling insert 328a comprises an internal bore 330a configured to narrow the internal bore of the first guide tube 31a to guide a drill bit, for drilling a hole in the target vertebra for receiving a pedicle screw, or a pedicle finder. The first drilling insert 328a further comprises first and second slots configured to be aligned with the first and second slots of the first guide tube 31a and configured to receive the first and second halves, respectively, of the guide portion 320a of the first screw adaptor 319a.

[0093] The pedicle screw guide further comprises a first wire guide 329a. The first wire guide 329a is configured to be removably received within the internal bore 330a of the first drilling insert 328a and within the bore of the guide portion 320a of the first screw adaptor 319a. The first wire guide 329a comprises an internal bore 331a configured to narrow the internal bore of the first guide tube 31a to guide a K-wire for insertion of the K-wire into the target vertebra.

[0094] In an example use case, a user will insert the first drilling insert 328a into the internal bore of the first guide tube 31a via the bore of the securing portion 321 of the first screw adaptor 319a. The user will then insert a drill bit into the internal bore of the first drilling insert 328a and use the drill bit to drill a hole in the target vertebra. The user may then remove the drill bit from the internal bore of the first drilling insert 328a and insert the first wire guide 329a into the internal bore of the first drilling insert 328a. The user will then insert a K-wire into the internal bore of the first wire guide 329a and guide the K-wire into the hole in the target vertebra. The user will then remove the first wire guide 329a and the first drilling insert 328a from the internal bore of the first guide tube 31a. The user will then insert a pedicle screw into the hole in the target vertebra, using the K-wire in a known manner, via the internal bore of the first guide tube 31a as described above.

[0095] The pedicle screw guide of Figure 3a further comprises a second drilling insert, substantially identical to the first drilling insert, and configured to be removably received within the internal bore of the second guide tube. The pedicle screw guide also comprises a second wire guide configured to be removably received within the internal bore the internal bore of the second drilling insert and within the bore of the securing portion of the second screw adaptor. The second drilling insert and second wire guide function in the same way as described above with respect to the first drilling insert and the first wire guide.

[0096] Figure 3g shows a cross-sectional view of the first screw adaptor 319a of the pedicle screw guide of Figure 3a in use. Figure 3g shows a first pedicle screw 315a inserted into a target vertebra Vt. A threaded portion 316a of the first pedicle screw 315a extends through the bore of the guide portion 320a of the first screw adaptor 319a and into the target vertebra Vt. A head 317a of the first pedicle screw 315a is received within the internal bore of the first guide tube of the pedicle screw guide (not shown) between the two halves of the intermediate portion 322a of the first screw adaptor 319a.

[0097] Figure 3h shows a schematic close-up plan view of the pedicle screw guide of Figure 3a in use.

[0098] Figure 3i shows a schematic cross-sectional front view of the pedicle screw guide 3 of Figure 3a in use. Some features of the pedicle screw guide are omitted from Figure 3i for clarity. Figure 3i shows the first pedicle screw 315a and a second pedicle screw 315b after insertion into the target vertebra Vt.

[0099] In other examples, any of the first and second screw adaptor, the first and second drilling insert, and the first and second wire guide may not be present. Any of the first and second screw adaptor, the first and second drilling insert, and the first and second wire guide may be equally applicable for use with the pedicle screw guide of either Figure la or Figure 2a. Either of the pedicle screw guide of either Figure l a or Figure 2a may comprise any of the first and second screw adaptor, the first and second drilling insert, and the first and second wire guide, where the first and second screw adaptor, the first and second drilling insert, and the first and second wire guide function in the same way as described above with respect to the pedicle screw guide of Figure 3a.

[0100] Figure 4a shows a schematic plan view of a multi-level pedicle screw guide 4 according to one example in use. In this example, the multi-level pedicle screw guide 4 comprises five of the pedicle screw guide 3a-e of Figure 3a. In other examples, the multi-level pedicle screw guide 4 may comprise any number of the pedicle screw guide of Figure 3a. In other examples, the multi-level pedicle screw guide 4 may comprise any number of any other example pedicle screw guide described herein.

[0101] Each pedicle screw guide 3a-e is configured to guide pedicle screws into a different target vertebra Vti -5- The multi-level pedicle screw guide 4 comprises four first further bridging elements 432a-d and four second further bridging elements 433a-d joining the pedicle screw guides 3a-e together. The configuration of the first further bridging elements 432a-d and the second further bridging elements 433a-d is substantially the same. The pedicle screw guides 3a-e and the first and second further bridging elements 432a-d, 433a-d are formed integrally as a single polymer part by means of a 3D printing process. The multi-level pedicle screw guide 4 is produced by generating a three- dimensional model of the target vertebrae Vti -5 and 3D printing the multi-level pedicle screw guide 4 based on the three-dimensional model.

[0102] Figure 4b shows a schematic side view of the view of Figure 4a with first pedicle screws 415ai-as and second pedicle screws 415b i-b5 inserted into the target vertebrae Vti 5.

[0103] Figure 5 shows a method 5 of producing a pedicle screw guide or a multi-level pedicle screw guide. The pedicle screw guide or multi-level pedicle screw guide may be any of the pedicle screw guides or multi-level pedicle screw guides described above, or any other pedicle screw guide or multi-level pedicle screw guide falling within the scope of the appended claims. The method 5 comprises generating 501 a three-dimensional model of at least one target vertebra and / or at least one adjacent vertebra and producing 502 the pedicle screw guide or the multi-level pedicle screw guide based on the three-dimensional model. The examples described above are merely illustrative. Any other examples, and any combination of any of the features of the examples described above, are possible within the scope of the appended claims.

Claims

CLAIMS1. A pedicle screw guide, comprising: at least one guide tube, the or each guide tube comprising: a first end adapted to mate with a target vertebra; and an internal bore configured to guide a pedicle screw into the target vertebra; and at least one support leg, the or each support leg comprising: a proximal end fixed to a guide tube of the at least one guide tube ; and a distal end adapted to mate with a lamina of an adjacent vertebra, wherein the adjacent vertebra is adjacent the target vertebra; wherein the pedicle screw guide is removable after the pedicle screw is inserted into the target vertebra using the pedicle screw guide.

2. The pedicle screw guide of claim 1 , wherein the first end of the or each guide tube comprises a patient specific surface adapted to mate with a surface contour of the target vertebra.

3. The pedicle screw guide of claim 1 or claim 2, wherein the internal bore of the or each guide tube is configured to guide the pedicle screw into the target vertebra at a specific location and / or orientation.

4. The pedicle screw guide of any preceding claim, wherein the distal end of the or each support leg comprises a patient specific surface adapted to mate with the lamina of the adjacent vertebra.

5. The pedicle screw guide of any preceding claim, wherein the at least one guide tube comprises a first guide tube and a second guide tube and the at least one support leg comprises a first support leg and a second support leg , and wherein the proximal end of the first support leg is fixed to the first guide tube and the proximal end of the second support leg is fixed to the second guide tube.

6. The pedicle screw guide of claim 5, comprising a bridging element joining the first guide tube and the second guide tube together.

7. The pedicle screw guide of claim 6, wherein the bridging element is fixed to a central region of the first guide tube and a central region of the second guide tube.

8. The pedicle screw guide of claim 6 or claim 7, wherein the bridging element is configured to avoid interference with a supraspinous ligament, optionally wherein the bridging element is curved in a direction extending from the first guide tube to the second guide tube to avoid interference with the supraspinous ligament.

9. The pedicle screw guide of any preceding claim, wherein the internal bore of the or each guide tube is configured to guide a head of the pedicle screw.

10. The pedicle screw guide of any preceding claim, wherein the pedicle screw guide consists essentially of a polymer.

11. The pedicle screw guide of any preceding claim, wherein the at least one guide tube and the at least one support leg are formed integrally.

12. The pedicle screw guide of any preceding claim, wherein the or each support leg is configured to extend diagonally from the guide tube to which the support leg is fixed to the lamina of the adjacent vertebra.

13. The pedicle screw guide of any preceding claim, wherein the proximal end of the or each support leg is fixed to a central region of the guide tube to which the support leg is fixed.

14. The pedicle screw guide of any preceding claim, comprising at least one screw adaptor, wherein the or each screw adaptor comprises a guide portion configured to be removably received within the internal bore of a guide tube of the at least one guide tube, and wherein the guide portion is configured to narrow the internal bore the guide tube to guide a threaded portion of the pedicle screw.

15. The pedicle screw guide of claim 14, wherein the or each guide tube comprises at least one slot configured to receive a guide portion of a screw adaptor of the at least one screw adaptor.

16. The pedicle screw guide of any preceding claim, comprising at least one drilling insert, wherein the or each drilling insert is configured to be removably received within the internal bore of a guide tube of the at least one guide tube, and wherein the or each drilling insert is configured to narrow the internal bore of the guide tube to guide a drill bit for drilling a hole in the target vertebra for receiving the pedicle screw.

17. The pedicle screw guide of any preceding claim, comprising at least one wire guide, wherein the or each wire guide is configured to be removably received within the internal bore of a guide tube of the at least one guide tube, and wherein the or each wire guide is configured to narrow the internal bore of the guide tube to guide a K-wire for insertion of the K-wire into the target vertebra.

18. The pedicle screw guide of claim 17, when dependent on claim 16, wherein the or each drilling insert comprises an internal bore configured to guide the drill bit, and wherein the internal bore of the or each drilling insert is configured to removably receive a wire guide of the at least one wire guide.

19. The pedicle screw guide of any preceding claim, wherein the or each guide tube comprises a longitudinal slot for observing a pedicle screw within the guide tube.

20. The pedicle screw guide of claim 19, wherein the longitudinal slot is closed at both ends.

21. The pedicle screw guide of any preceding claim, wherein the pedicle screw guide is labelled with an identifier of the target vertebra.

22. A multi-level pedicle screw guide comprising a plurality of pedicle screw guides according to any preceding claim, wherein each pedicle screw guide of the plurality of pedicle screw guides is configured to guide at least one pedicle screw into a different target vertebra.

23. A method of producing the pedicle screw guide of any of claims 1 to 21 or the multi-level pedicle screw guide of claim 22, the method comprising: generating a three-dimensional model of the target vertebra and the adjacent vertebra; andproducing the pedicle screw guide or the multi-level pedicle screw guide based on the three-dimensional model.

24. The method of claim 23, wherein generating the three-dimensional model comprises using low-dose CT scanning, 3D x-ray scanning, or black bone MRI scanning to generate the three-dimensional model.

25. The method of claim 23 or 24, wherein producing the pedicle screw guide or the multi-level pedicle screw guide comprises using additive manufacturing to produce the pedicle screw guide or the multi-level pedicle screw guide.

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