Methods, instruments and implants for scapho-lunate reconstruction

A method for bone reconstruction includes aligning a first hone with a second bone using a plurality of guidewires to correct rotational deformity of the first and second bones. A first module of a targeting apparatus is positioned in proximity to the first bone. A tip of the first module is engaged with the first bone. A second module of the targeting apparatus is positioned in proximity to the second bone. A tip of the second module is engaged with the second bone. Alignment of the first module and the second module is secured. The alignment is verified using a guidewire, the guidewire wire is inserted through a passage extending through the second module. A length between the first bone and the second bone is determined using a depth gauge. An implant is selected based on the determined length for delivery along the passage extending through the second module.

BACKGROUND OF THE INVENTION

Field of the Invention

The subject disclosure relates to methods, surgical instruments and implants for reconstructing the scapho-lunate joint.

Background of the Related Art

Scapho-lunate dissociation is the most common carpal instability. Scapho-lunate dissociation can be characterized by diastases between the scaphoid and lunate bones and rotatory subluxation of the scaphoid. Scapho-lunate dissociation typically causes wrist pain, swelling, clicking, progressive radiocarpal arthritis, and decreased motion and grip strength.

There are currently many surgical treatment options that may be indicated depending on a variety of factors, including healing potential of the ligament, time elapsed since injury, alignment/reducibility of the carpal row and presence/extent of degenerative changes in the wrist. However, all of these treatments have some undesirable results (e.g., loss of range of motion, long periods of immobilization and/or high rates of failure).

One method used to treat scapho-lunate dissociation is dorsal capsulodesis. Dorsal capsulodesis can be performed with or without repair of the scapho-lunate interosseous ligament (SLIL). During either method, a physician temporarily pins Kirschner wires (“K-wires”) across the scapho-lunate and scapho-capitate intervals to restore proper carpal alignment during healing. Currently available results indicate that dorsal capsulodesis is associated with long term weakening and provides only limited motion recovery.

Bone-tissue-bone grafts are another treatment option for scapho-lunate dissociation. During the bone-tissue-bone graft procedure, the physician utilizes an autologous bone-tissue-bone graft to replace the scapho-lunate interval. Complications associated with bone-tissue-bone grafts include the problems associated with a second surgical site and selecting a graft that operates similarly to the SLIL being replaced.

As discussed briefly above, prior art methods and medical tools for treating scapho-lunate dissociation have drawbacks. They limit post-operative wrist motion and often prevent subsequent salvage procedures. More recently, the RASL procedure has been found to provide safe and effective treatment for chronic static scapho-lunate dissociation by re-aligning the scaphoid and lunate bones, restoring function, and reducing pain. Currently, surgeons performing the RASL procedure simultaneously use 1.6 millimeter (mm)-thick metal Kirschner wires (“K-wires”) to manipulate the bones, a headless cannulated screw to maintain the positioning of the bones post-operatively, and a guide wire to position the screw at the site.

A major difficulty in treating scapho-lunate dissociation using the RASL procedure is that there is very little clearance within the bones for the currently available medical tools used to perform in the procedure (e.g., K-wires, bone clamps, etc), a large number of bones at the site, and a compact area within which to perform the procedure. To wit, there is very little clearance and visibility between the K-wires for the guide wire and the screw, making it difficult and error-prone to properly manipulate the bones using K-wires while leaving enough room for the guide wire and screw to be introduced.

Moreover, the success of the procedure often depends on the surgeon's experience in making educated guesses based on anatomical and biomechanical landmarks and skill in positioning or repositioning the guide wire based on radiographic images. The success is further complicated by the K-wires employed to hold the bones in place getting in the way of the smaller guide wire used to locate the screw, sometimes causing deflection or inhibition.

Still further, identification of the proper position for the guide wire and drilling a pilot hole for the cannulated screw is also difficult and often requires a very skilled surgeon. Ideal placement of the screw is along the axis representing the instantaneous center of motion between the scaphoid and lunate bones in the wrist. Usually, the axis is parallel to the radial inclination and coincident with the mid-waist of the scaphoid and the apex of the lunate. Years of experience are typically required to find the correct axis for the screw.

Therefore, there still remains a need to solve the problems in the art pertaining to the accuracy of implant delivery and implant performance for repair of scapho-lunate tendon injury. More particularly there is a need to solve the challenges associated with bone de-rotation and alignment, and placement of the implant in the bone (trajectory). Further, there is a need to provide an implant that meets most or all of the design requirements of the surgeon, most particularly, one or both of torsional and longitudinal flexibility (bending) of the implant segment between the bones.

SUMMARY

Embodiments herein provide a method for bone reconstruction that includes aligning a first bone with a second bone using a plurality of guidewires to correct rotational deformity of the first and second bones. A first module of a targeting apparatus is positioned in proximity to the first bone. A tip of the first module is engaged with the first bone. A second module of the targeting apparatus is positioned in proximity to the second bone. A tip of the second module is engaged with the second bone. Alignment of the first module and the second module is secured. The alignment is verified using a guidewire, the guidewire wire is inserted through a passage extending through the second module. A length between the first bone and the second bone is determined using a depth gauge. An implant is selected based on the determined length for delivery along the passage extending through the second module.

The method can include inserting a guidewire tube into the passage before insertion of the guidewire. The guidewire and the guidewire tube can be removed from the passage. A path spanning a space between the first and second bone can be formed using a drill inserted through the passage. The implant can be delivered through the path. Securing alignment of the first and second modules can include using one or more knobs. The depth gauge can be a depth gauge on the targeting apparatus.

The implant can include a proximal threaded end and a distal threaded end configured and adapted for insertion into the first and second bones, the proximal threaded end and the distal threaded end can be configured to rotate independently after insertion of the implant into the first and second bones.

The first bone can be a lunate and the second bone can be a scaphoid. The plurality of guidewires can be positioned to rotate the lunate forward and rotate the scaphoid backwards. The plurality of guidewires can be K-wires. The first module can be a lunate engagement module operatively connected to a reduction frame of the targeting guide, the lunate engagement module comprising a lunate pin adapted to grip the lunate. The second module can be a scaphoid engagement module operatively connected to the reduction frame, the scaphoid engagement module having at least a drill tube, an adjustment knob and a fixation seat, the fixation seat can have a set of teeth adapted to grip the scaphoid.

Embodiments herein also provide for a medical apparatus for bone reconstruction including a reduction frame, a first module operatively connected to the reduction frame, the first module comprising a tip for engagement with a first bone, and a second module operatively connected to the reduction frame, the second module comprising a tip or engagement with a second bone and the second module can include a passage extending laterally through for delivery of at least one object.

The second module can include an arm operatively connected to a cannulated fixation seat comprising a set of teeth for engagement with the second bone, the cannulated fixation seat operatively connected to an adjustment knob and a drill tube. The drill tube can be configured to receive one or more additional removable sleeves. The one or more additional sleeves can include a guidewire tube for use in inserting a K-wire through. A drill can be passed through the drill tube to create a path from the first bone to the second bone. A medical implant can be delivered and inserted through the path.

The medical apparatus can also include a frame adjustment knob configured to move the second module towards the second bone for engagement with the second bone. The reduction frame can include a depth gauge for determining a distance spanning the space between the first and second bones. The first module can be a lunate engagement module for engagement with a lunate and the second module is a scaphoid engagement module for engagement with a scaphoid. Each of the lunate engagement module and the scaphoid engagement module can include an arm operatively connected to the reduction frame at one end and connected to the tip at another end.

Still further, embodiments herein provide for an implant assembly including a first threaded end section configured and adapted for insertion into a first bone, a second threaded end section configured and adapted for insertion into a second bone, and an intermediate section operatively connected to the first threaded end section and the second threaded end section. The first threaded end section and the second threaded section are configured to rotate independently after insertion into the first and second bones. The first and second threaded end sections can be configured with different diameters.

These and other features of the subject invention and the manner in which it is manufactured and employed will become more readily apparent to those having ordinary skill in the art from the following enabling description of the preferred embodiments of the subject invention taken in conjunction with the several drawings described below.

These and other aspects of the subject disclosure will become more readily apparent to those having ordinary skill in the art from the following detailed description of the invention taken in conjunction with the drawings.

DETAILED DESCRIPTION

Disclosed herein are detailed descriptions of specific embodiments of methods, instruments and implant for scapho-lunate reconstruction. It will be understood that the disclosed embodiments are merely examples of the way in which certain aspects of the invention can be implemented and do not represent an exhaustive list of all of the ways the invention may be embodied. Indeed, it will be understood that the systems, devices and methods described herein may be embodied in various and alternative forms. Moreover, the figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components.

Well-known components, materials or methods are not necessarily described in great detail in order to avoid obscuring the present disclosure. Any specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the invention. Moreover, the devices, instruments and implants are described herein as being used for scapho-lunate reconstruction, but those skilled in the art will appreciate that they can be used in other medical procedures.

Currently, most surgeries involving reconstruction of the scapho-lunate joint are performed free-handed, as there are limited options for tools to properly align the bones and the implant. Embodiments herein provide for a jig assembly/reduction apparatus that is a multi-function tool which allows the surgeon to align and implant a screw properly at the desired depth with the desired trajectory. Furthermore, the jig assembly/reduction apparatus provided herein can measure depth to be used as a guide for other ancillary tools (e.g., drills).

The present disclosure now will be described more fully, but not all embodiments of the disclosure are necessarily shown. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof.

Referring to the figures,FIGS. 1-5show an illustrative implant assembly150according to an embodiment herein. The implant assembly150includes three main components: a first threaded tubular end section160, (FIG. 2); a tubular intermediate section170(FIG. 3) and a second threaded tubular end section180(FIGS. 4 and 5). The first thread tubular section160has a series of threads164formed on its outer surface and has a drive socket162formed at one end and a smooth bore at the other for receiving the tubular intermediate section170. One end of the tubular intermediate section170also includes a drive socket172formed at one end and a series of threads174formed at the other for engaging with the second threaded tubular section180. Threads174allow the length of the implant assembly to be adjusted and also to allow for some relative rotation and translation between the two ends of the implant assembly150once installed.

The first end section160of implant assembly150can be a proximal threaded end section160and the second end section can be a distal threaded section180, proximal and distal being taken relative to the perspective of a user (e.g., a surgeon). The distal end section160is preferably smaller than the proximal end section160, as the difference in the core diameter and pitch diameter enables the implant assembly150to be used as a compression device. When the two threaded ends are of different diameters, after one set of threads crosses the scaphol-unate junction, which is the junction between the scaphoid and lunate bones, it then starts to act as a compressing tool.

Furthermore, implant assembly150is designed such that the threaded sections160and180can rotate freely independent of each other once inserted. The design allows for movement between the two threaded sections160and180in certain planes (translation), which can be helpful biologically and physiologically in the healing of the ligament being treated.

The implant assembly150is a three-piece construction that is welded together during the manufacturing process, the design of the implant assembly150allows for a freedom of rotation. Notably, the implant assembly150is not a monolithic implant. However, when the implant assembly150is inserted using a driver (e.g., driver bit1601ofFIG. 16), the driver1601can drive both thread sections160and180at the same time. The three-pieces160,170and180of the implant assembly150are in essence locked together when the implant assembly150is inserted (e.g., into the bones). That is, the implant assembly150is driven in with a monolithic screw, and once it is in place, the driver is removed and the two thread sections160and180can rotate in place independently of each other as the joint moves. Optionally, the driver can be used again subsequently to engage either the proximal or distal ends for adjustment or removal of the implant assembly150.

The implant assembly150is designed to be solid (not cannulated, e.g., without a hole in the center), so that it can be smaller and stronger in comparison to traditional bone screws/implant assemblies, and withstand the physiologic forces without breakage. The implant assembly150is pre-assembled during manufacture. Once inserted, the two ends of the implant assembly150can rotate freely from each other. The implant assembly150can be available in various sizes and/or lengths to accommodate differences in size of the spanned scaphoid and lunate.

Referring now toFIGS. 6-13, which illustrate a targeting guide100which has been constructed in accordance with an embodiment of the present disclosure. As will be described below, targeting guide100can be used in a RASL procedure.

Targeting guide100is a multi-function tool for scaphoid and lunate bone engagement and manipulation, and implant guidance. Targeting guide100includes a reduction frame30(FIG. 11) operatively connected to a cap32(FIG. 12) and an adjustment portion having a frame adjustment knob45operatively connected to a threaded drive rod34(FIG. 13). The reduction frame30includes an implant depth gauge70(FIG. 6). The reduction frame30includes a lunate engagement module20at an end opposite from the frame adjustment knob45. The lunate engagement module20includes a lunate jig25operatively connected to a lunate engagement pin22at one end.

The targeting guide100also includes a scaphoid engagement module40in operative engagement with the reduction frame30. The scaphoid engagement module40includes an arm35(FIG. 7), a threaded drill tube60that includes a fixation seat48and teeth50(FIG. 8), a knob55(FIG. 9), a lock nut65(FIG. 10). Threaded drill tube60is configured to receive drill guide tubes1801and1901shown inFIGS. 18 and 19. Notably, components60,55and48are each hollow, thereby forming a continuous path90(represented by dotted lines inFIG. 6) through which tools (e.g., guide wire, drill) and implants may pass through.

In embodiments herein, the targeting guide100aids in alignment of the bones, while the guidewire acts as an initial targeting guide before making the commitment to drill a hole. In many existing systems, a guide wire (e.g., K-wire) is placed, a hole is drilled and a screw (e.g., implant assembly150) is then placed over it, which means the screw has to be cannulated with a hole in the middle to accommodate the guide wire. Advantageously, in embodiments herein, the guidewire is only used as a last check prior to embarking on commitment to a screw path. The entire targeting guide100is used to realign the bones, and then a guide wire is placed and assessed on X-ray to see if the guidewire is headed where the screw is intended to go ultimately. The guide wire is subsequently removed and the screw path90is generated by a drill, the screw is then inserted through the screw path90. Notably, the guidewire is no longer present in the screw path90at the end of the operation, as it is in various existing methods.

In certain instances, the alignment can be manipulated (reduced) from a displaced posture by using additional wires (e.g., wires:2001, and2101ofFIGS. 20and.21) which are outside the plane of where the screw is heading. The additional wires can be used as “joysticks.” similar to manipulation tools to manipulate the bones into position. The targeting guide100can then be applied to the reduced alignment of the two bones and the device100holds them in that position by a squeezing/trapping mechanism. At this point the “joysticks” are no longer necessary and can be removed once the jig apparatus is in place.

Once the scaphoid and lunate bones are reduced/aligned, the targeting guide100can be applied to a specific geographic location of each of the two bones independently. The targeting guide100is designed with specific capturing points which are positioned at the lunate and scaphoid at specific locations, these point are visually documented and also checked by X-ray. The capturing points are shown as teeth50on fixation seat48on the scaphoid lunate engagement module40and as lunate engagement pin22on the lunate engagement module20. The capturing points are applied in specific positions anatomically according to visual and x-ray cues and landmarked, then these points are assessed by x-ray in two planes. At this point, the targeting guide100is tightened and secured using knob55, the bones are held in place to allow a surgeon to see the intended path of the screw. A K-wire2001is placed inside the targeting guide100through a sleeve (e.g., K-wire guide tube1701shown inFIG. 17), and then check by X-ray. The K-wire2001and the K-wire guide tube1701are removed, the implant assembly150is positioned first with a drill1601and then a tap (e.g., tap2201shown inFIG. 22) or no-tap based on bone quality and the implant assemble150is inserted.

Targeting guide100includes a path90for the tools to pass through.FIGS. 18 and 19show drill guide tubes1801and1901, which can be a 3.7 mm or 2.7 mm drill guide tube, respectively. The drill guide tubes shown inFIGS. 18 and 19can be used for two different drills. The drill guide tube1801or drill guide tube1901can be inserted into drill tube60, each of drill guide tube1801and drill guide tube1901can include a receptacle1802and receptacle1902, respectively, through which a drill (e.g., a 2.5 mm drill2301as shown inFIG. 23or a 3.5 mm drill2401shown inFIG. 24) can fit through. A removable sleeve can be fitted into the receptacle1802or1902, which is smaller and can be used for the guidewire (e.g., K-wire2001). The K-wire dimensions are much smaller than the drill so the K-wire guide tube (e.g., K-wire guide1701tube ofFIG. 17) is provided as a smaller insert that can be removed when the K-wire is removed. The drill itself can then go through the drill tube60and drill guide tube1801or1901(depending on the size of the drill), thereby forming the path90for delivery of the implant assembly150through the path90. The teeth50at the end of fixation seat48grips the bone so as to prevent the device from sliding and rotating, corresponding point22on the lunate side also grips the lunate, thereby gripping the two bones together. The rotating knob55aids in locking the targeting guide and bones together, and the distance between the scaphoid and lunate bones are determined using the scale of implant depth gauge70on the reduction frame30and/or a depth gauge1401as shown inFIGS. 14 and 15.

As described above, the sleeves/inserts are of different diameters to accommodate for the different diameter tools being used, i.e., a tube-within-a-tube configuration. The aperture at the end is pointed at the target where the implant assembly should ultimately be placed.

Advantageously, once the bones are reduced or aligned, the targeting guide100can hold them in place and everything being done after this point is done with the proper orientation of the two bones, thus avoiding rotational deformity of the bones. As such, the targeting guide100is critical not only to have a path for the tools and implants to pass through, but also for the final alignment placement of the implant.

A representative, method for operation of the targeting guide100is as follows:

1. Dissect on the dorsal surface of the hand to expose the scaphoid and lunate bones;

2. Drive guidewires (e.g., K-wires ofFIG. 20and/or wire2101ofFIG. 21) into both the scaphoid and lunate bones. Then manipulate the K-wires to align the scaphoid and lunate bones. The K-wires are placed in such a way that the scaphoid can be rotated backwards and the lunate forward to correct for any rotational deformity caused by the carpal instability;

3. Position the lunate engagement module20with the arm of the lunate jig25in proximity to the medial aspect of the lunate. Align the tip of the lunate engagement pin22with the apex of the lunate (central position) and insert the pin into the lunate;

4. With the reduction frame30fully extended, position the scaphoid engagement module40in proximity to the lateral aspect of the scaphoid and advance toward the scaphoid by rotating the frame adjustment knob45until the teeth50of cannulated conformal fixation seat48teeth rest on, but do not penetrate the lateral aspect of the scaphoid;

5. Articulate knob55to rotate the angulated face of fixation seat48. It has been found that adjusting the position of the angulated face of fixation seat48to better mate with the scaphoid curvature improves the reduction procedure. The angled surface mimics the scaphoid curvature and stabilizes the engagement of the fixation seat48to the bone;

6. Initiate the reduction process by further rotation of adjustment knob45to advance the conformal fixation seat48to engage the teeth50into the scaphoid to gain purchase into the bone;

7. Once the proper position of the fixation seat48has been established, adjust lock nut65so as to prevent further rotation of the seat48. Securing the lock nut also locks the alignment of the assembly in relation to the hand (e.g., the targeting guide100is laid against the patients forearm or hand) and out of the surgical field and x ray beam when utilized;

8. With the bones fully reduced and locked into place, read the implant depth gauge70provided on the frame30to determine the distance between the lateral surface of the scaphoid and the medial surface of the lunate;

9. A K-wire guide tube1701may be inserted into the drill tube if needed. Place the K-wire2001into the K-wire guide tube1701and check the alignment of the instrument. Then, slide the depth gauge1401over the K-wire2001to check the screw length. Then remove the depth gauge1401. K-wire guide tube and K-wire, and sequentially tap then drill the hole for the implant path90.FIGS. 18-24illustrate drill guide tubes, taps and drills that can be used for this procedure and inserted into the central bore formed in the drill tube60:

10. Select an implant length for use based on the reading from the implant depth gauge to determine the corresponding implant length and then the surgeon would subtract a length (e.g., 2 mm) to allow for the screw to be slightly recessed within the bone;

11. Load the implant assembly150shown inFIGS. 1-5onto the driver (FIG. 16) and engage both drive sockets162and172;

12. Use the implant guide in engagement with the drill guide to guide and deliver and install the implant assembly150along the path90through the scaphoid module.

It is believed that the present disclosure includes many other embodiments that may not be herein described in detail, but would nonetheless be appreciated by those skilled in the art from the disclosures made. Accordingly, this disclosure should not be read as being limited only to the foregoing examples or only to the designated embodiments.