System For Forming A Patient Specific Surgical Guide Mount

Abstract

A system for making a proximal resection of tibia having localized anatomical surface features prior to resection, comprising: a resection guide locator including a body, the body including opposing medial and lateral wings extending outwardly from the body, the body defining a recess being a socket defined by an annular wall, the annular wall including an upper wall, a lower wall, a resection guide having a body defining a resection slot, at least a portion of the resection guide body sized and configured to be received within the recess defined by the resection guide locator.

Claims

1. A resection system for making a proximal resection of a bone of a tibia, said bone having localized anatomical surface features prior to resection, comprising: a resection guide locator including a body having a bone engagement portion with a surface comprising localized features that are topographically complementary to said localized anatomical surface features of said bone of said tibia, the body including opposing medial and lateral wings, the wings extending outwardly from the body, the body defining a recess, the recess being a socket defined by an annular wall, the annular wall including an upper wall, a lower wall, and opposing medial and lateral side walls the medial and lateral side walls disposed between the upper and lower walls, the medial side wall disposed in the medial wing, the lateral side wall disposed in the lateral wing, the upper wall offset from the medial and lateral side walls such that a length of the upper wall is less than a distance between the medial and lateral side walls, and an elongate slot within the recess, a resection guide having a body defining a resection slot, at least a portion of the resection guide body sized and configured to be received within the recess defined by the resection guide locator, wherein the resection guide locator and the resection guide are formed from different materials, and wherein the resection slot defined by the resection guide aligns with the elongate slot defined by the resection guide locator when the resection guide is received within the recess defined by the resection guide locator, the resection slot positioned for making said proximal resection of said bone of said tibia when the resection guide is received within the recess of the resection guide locator.

2. The resection system of claim 1, wherein the resection guide locator includes a yoke including first and second arms that extend from the body in a direction that is different from the direction in which the pair of wings extend.

3. The resection system of claim 1, wherein the resection guide locator is formed from a resilient polymer material and the resection guide is formed from a metal.

4. The resection system of claim 1, wherein the localized features of the bone engagement portion are complementary to said localized anatomical surface features of an articular surface of said bone.

5. The resection system of claim 1, wherein the localized features of the bone engagement portion are complementary to said localized anatomical surface features of a condylar surface of said bone.

6. The resection system of claim 1, wherein the localized features of the bone engagement portion are complementary to said localized anatomical surface features of a cortical surface of said bone.

7. The resection system of claim 1 further comprising the recess having a back wall, the elongate slot formed through the back wall and extending between the opposing side walls.

8. The resection system of claim 1, wherein the upper wall of the annular wall adjoins the medial side wall via an L-shaped portion of the annular wall and further adjoins the lateral side wall via an opposing L-shaped portion of the annular wall.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] These and other features and advantages of the present invention will be more fully disclosed in, or rendered obvious by, the following detailed description of the preferred embodiment of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein:

[0013] FIG. 1 is a perspective view of femoral and tibial resection guides mounted within resection guide locators that have been formed in accordance with the present invention and located upon portions of a femur and a tibia, respectively;

[0014] FIG. 2 is a schematic representation of a scanned image of a human knee joint;

[0015] FIG. 3 is a schematic representation of the scanned image of the human knee joint shown in FIG. 2, after conversion to a computer model in accordance with the present invention;

[0016] FIG. 4 is a schematic representation similar to FIG. 7;

[0017] FIG. 5 is a schematic representation, similar to FIG. 3, showing proposed resection lines and local coordinates super positioned upon the computer model of FIG. 3, in accordance with the present invention;

[0018] FIG. 6 is a schematic representation similar to FIGS. 4 and 5, but showing a femoral and a tibial resection guide locator represented within the computer model of FIG. 3 in accordance with the present invention;

[0019] FIG. 7 is a schematic representation similar to FIGS. 4, 5, and 6, showing a digital representation of the femoral and tibial prostheses (in cross section) superimposed within the model in accordance with the present invention;

[0020] FIG. 8 is a perspective view of a femoral resection guide locator formed in accordance with the present invention;

[0021] FIG. 9 is a rear perspective view of the femoral resection guide locator shown in FIG. 8;

[0022] FIG. 10 is an elevational view of the front side of the femoral resection guide locator shown in FIG. 9;

[0023] FIG. 11 is an elevational view of the bottom of the femoral resection guide locator shown in FIGS. 8; 9 and 10;

[0024] FIG. 12 is a perspective view of a tibial resection guide locator formed in accordance with the present invention;

[0025] FIG. 13 is a perspective bottom view of the tibial resection guide locator shown in FIG. 12;

[0026] FIG. 14 is a top view of the tibial resection guide locator shown in FIG. 13;

[0027] FIG. 15 is a rear elevational view of the tibial resection guide locator shown in FIG. 14;

[0028] FIG. 16 is a perspective view of a typical tibial resection guide;

[0029] FIG. 17 is a front elevational view of the tibial resection guide shown in FIG. 16;

[0030] FIG. 18 is a side perspective view of the tibial resection guide shown in FIG. 17;

[0031] FIG. 19 is a perspective view of a femoral resection guide mounted within a femoral resection guide locator positioned upon the condyles of a femur; and

[0032] FIG. 20 is a perspective view of a tibial resection guide mounted within a tibial resection guide locator positioned upon the articular surfaces of a tibia.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033] This description of preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. The drawing figures are not necessarily to scale and certain features of the invention may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness. In the description, relative terms such as “horizontal,” “vertical,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms including “inwardly” versus “outwardly,” “longitudinal” versus “lateral” and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.

When only a single machine is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. The term “operatively connected” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. In the claims, means-plus-function clauses, if used, are intended to cover the structures described, suggested, or rendered obvious by the written description or drawings for performing the recited function, including not only structural equivalents but also equivalent structures.

[0034] The present invention provides custom manufactured surgical instruments, guides, and fixtures that are based upon a patients anatomy as determined by a computer tomography scanner (CT), magnetic resonance imaging machine (MRI), or the like medical imaging technology. For example, a CT or MRI scanned image 1 or series of images may be taken of a patient's knee 1, including portions of the limb from the pelvis or the foot (FIGS. 2 and 3). In the case of a total knee replacement, the CT or MRI scanned image data is then converted from, e.g., a DICOM image format, to a solid computer mod& 3 of the lower limb often including the pelvis, femur, patella, tibia, or foot to determine implant alignment, type and sizing using specialized modeling methods that are often embodied in computer software. Computer generated solid models 3 that are derived from CT or MRI scan image data 1 will often include precise and accurate information regarding the surface contours surrounding the structures that have been imaged, e.g., the surface topography of the bones or contour of fascia that have been imaged.

[0035] The methods disclosed in U.S. Pat. No. 5,768,134, issued to Swaelens et al., and incorporated herein by reference, have been found to yield adequate conversions of CT or MRI scanned image data 1 to solid computer model 3 usable with the present invention. In some embodiments, images are made of a lower limb, i.e., the pelvis, femur, patella, tibia, and/or foot of a patient using a CT or MRI machine, or other digital image capturing and processing unit (FIGS. 2 and 3). This scanning generates a scanned image of the diseased knee or ankle joint, including adjoining portions of the femur 5 and tibia 6. The image data 1 is first processed in a processing unit, after which a model is generated using the processed digitized image data.

[0036] With one embodiment of the invention scanned images of a diseased knee or ankle joint, including adjoining portions of the femur 5 and tibia 6, were generated using a Hitachi 0.3T Airis Elite open MRI. The Hitachi device comprises an asymmetric two-post open architecture, and provides a 0.3T magnetic field strength in a vertical orientation with high homogeneity. For example, scanned images of a diseased knee joint suitable for use in connection with the present invention incorporated sagittal slices of the knee using the patient's patella and tibial tubercle as anatomic landmarks. Two millimeter thickness slices, at zero millimeter slice spacing were gathered with the scan boundaries defining an approximate field of view of twelve centimeters proximal and nine centimeters distal of the joint line or the extent of the knee coil. A standard multiple array extremity coil was utilized with imaging set for bright cartilage and dark bone with crisp boundaries. The patient was placed with the leg to be scanned in the middle of the coil. It will be understood that in bilateral cases each leg would be scanned separately.

[0037] In addition to the forgoing parameters, when generating scanned images of a patients knee for use in connection with the present invention, it is often preferable to acquire a FATSEP 3D RSSG imaging sequence with the parameters listed in the Table 1 below. For preferred results, very clear boundaries should be determined between the cartilage and surrounding soft tissues, and the cartilage and bone. The cartilage will often present a bright signal and the bone a dark signal, allowing clear contrast between the two materials.

[0038] Scanned images (axial slices) of femur 5 and tibia 6 associated with a diseased knee may also be generated utilizing the rapid body coil of the Hitachi 0.3T Airis Elite open MRI. Anatomic landmarks found to be useful for these scans included the femoral head and distal femur as well as the distal tibia and proximal tibia. Five millimeter thick slices, at three millimeter spacing provided preferred results with the present invention. Preferred scan boundaries included the proximal femoral head through distal femur and the most proximal tibial point through most distal tibial point, e.g., the ankle joint. The patient may be placed with leg to be scanned in the middle of the coil, it again being understood that in bilateral cases each leg would be scanned separately.

[0039] The field of view available from the rapid body coil may not always cover the entire femur or tibia within one scan. In such instances, the femur or tibia may be scanned in two separate regions. Between the two scans the patient will have to move in order to reposition the coil to cover the most proximal or distal regions of interest. It is important in such instances to provide as much overlap as possible between the two scans. The patient's leg should be placed in the middle of the coil to ensure the largest field of view possible without distortion. The corners of the images at the field of view limits of the coil are susceptible distortion. The patient's legs should be scanned separately, as bilateral scans place the proximal and distal ends of the knee joint region within the field of view limitation and within areas of possible distortion. Additionally, a 2D T1 FSE (T1 weighted fast spin echo) imaging sequence may be acquired with the parameters listed in the Table 1. It should be noted that the boundaries of the bone, from the ball of the femoral head down to the distal condyles, should be clear for processing.

TABLE-US-00001 TABLE 1 Hitachi 0.3 T Airis Elite Sequence Overview Hip-Knee Knee Ankle-Tibia Coil Rapid Body Coil Multiple Array Rapid Body Coil Extremity Coil Study (Pulse 2D TI FSE FATSEP 3D 2D TI FSE Sequence) RSSG TR (ms) 2700 61 2700 TE (ms) 10 28.5 10 Plane Axial Sagittal Axial Slice Thickness 5 2 5 (mm) Slice Spacing 3 0 3 (mm) NEX 2 1 2 Flip Angle 90 90 90 Matrix 256*256 512*512 256*256 Acquisition Time 5:46 15:37 5:46 (min:sec)

[0040] In accordance with the present invention, interactive processing and preparation of the digitized image data is performed which includes the manipulation and introduction of additional extrinsic digital information 8, such as, predefined reference locations 9 for component positioning and alignment 10 so that adjustments to the surgical site, that will require resection during surgery, may be planned and mapped onto computer model 3 (FIGS. 4 and 5). After the interactive processing of the digitized image data, it is possible to go back to original CAD data to obtain a higher resolution digital representation of the patient specific surgical instrument, prostheses 7a, 7b (FIG. 7) guide, or fixture so as to add that digital representation to the patient's image data model.

[0041] For example, when the system of the present invention is used for knee replacement surgery, a digital representation of a femoral resection guide mount 20 may be added to the patient's image data mod& (FIGS. 1 and 6). In the context of a total knee replacement, femoral resection guide mount 20 may be formed for placement on the exposed condyles of a patient's femur to assure precise and accurate positioning of a femoral resection guide 26 which is used to direct and control bone resection of femur 5 during surgery. Although the femoral resection guide 26 can take various forms and configurations, the present invention be described with reference to a distal resection guide currently offered by applicant Wright Medical Technology, Inc, (Wright Medical Part No. K001-2659). Significantly, femoral resection guide mount 20 provides this precise and accurate positioning function without the need for other external fixtures or the use of an intramedullary stem inserted through the intercondylar notch and upwardly through femur 5 along the femoral shaft axis. A digital representation of a tibial resection guide mount 22 may also be added to the patient's image data model (FIG. 6). Tibial resection guide mount 22 is similarly formed for placement on the exposed superior articular surface of a patient's tibia 6 to assure precise and accurate positioning of a tibial resection guide 28 used to direct and control bone resection of the superior articular surface of the exposed tibia during surgery.

[0042] Referring to FIGS. 8-11, a femoral resection guide mount 20 according to one embodiment of the invention is formed from a resilient polymer material of the type that is suitable for use in connection with stereo lithography or the like manufacturing equipment. Resection guide mount 20 comprises a unitary block including a bifurcated condylar yolk 25 and a guide receptacle 29. Bifurcated yolk 25 includes a pair of spaced apart arms 30, 31 that project outwardly from a base 33. Arm 30 has a lower or bone engaging surface 36 and a through-bore 42, and arm 31 has a lower or bone engaging surface 40 and a through-bore 38. Through the previously discussed imaging operations, the bone engaging surfaces 36, 40 are configured for complimentary matching with anatomical surface features of a selected region of the patients natural bone. For the femoral resection guide mount 20 embodiment of FIGS. 8-11, the selected bone region comprises the condyles of the patient's femur.

[0043] Guide receptacle 29 includes a pair of wings 44,46 that project outwardly, in opposite directions from base 33 and in spaced relation to arms 30,31. Each wing 44, 46 includes a pylon 48 projecting upwardly to support guide housing 49 such that an elongate slot 52 is defined between base 33 and guide housing 49. Slot 52 is sized and shaped to allow a typical surgical saw, of the type often used for bone resection, to pass through from a correspondingly positioned and sized slot in resection guide 26 without contact, or with only incidental contact with resection guide locator 20. An annular wall 55, having a shape that is complementary to the outer profile of femoral resection guide 26, projects outwardly in substantially perpendicular relation to a back wall 61 and thereby defines a recess 58. In some preferred embodiments, recess 58 is sized so as to accept femoral resection guide 26 with a “press-fit”. By press-fit it should be understood that annular wall 55 is sufficiently resilient to deflect or compress elastically so as to store elastic energy when femoral resection guide 26 is pushed into recess 58. Of course, it will also be understood that femoral resection guide 26 will have an outer circumferential shape that is complementary to the circumferential shape of recess 58, but slightly larger in size, for press-fit embodiments. Also, femoral resection guide 26 may be retained within recess 58 by only frictional engagement with annular wall 55 or, in less preferred embodiments, resection guide 26 can simply slide into recess 58 without operative contact or only incidental engagement with annular wall 55. First through-bores 62, 64 are defined in back wall 61 in spaced relation to one another, with a second through-bore 67,69 being associated with each first through-bore 62,64. In the embodiment shown in FIGS. 8-11, the first through-bores 62, 64 are large square or rectangular openings, a configuration that eases manufacture, reduces material use, and provides sufficient space for driving pins, wires, screws or other appropriate fasteners through a plurality of adjacent bores provided on the femoral resection guide 26. A groove 70 is defined in the outer surface of base 33 and centrally located with respect to recess 58.

[0044] Referring to FIGS. 12-18, a tibial resection guide mount 22 according to one embodiment of the invention is formed from a resilient polymer material of the type that is suitable for use in connection with stereo lithography, selective laser sintering, or the like manufacturing equipment, e.g., a polyimide powder repaid prototype material is suitable for use in connection with selective laser sintering. Resection guide mount 22 comprises a unitary block including a bifurcated yolk 75 and a guide receptacle 79.

Bifurcated yolk 75 includes a pair of spaced apart arms 80, 81 that project outwardly from a base 83. Arm 80 has a lower surface 86 and arm 81 has a lower surface 90.

[0045] Guide receptacle 79 includes a pair of wings 84, 86 that project outwardly, in opposite directions from base 83 and in spaced relation to arms 80,81. Each wing 84,86 includes a pylon 88 projecting upwardly to support guide housing 89 such that an elongate slot 94 is defined between base 83 and guide housing 89. Slot 94 is sized and shaped to allow a typical surgical saw, of the type often used for bone resection, to pass through from a correspondingly positioned and sized slot in resection guide 28 without contact, or with only incidental contact with resection guide locator 22. An annular wall 95, having a shape that is complementary to the outer profile of tibial resection guide 28, projects outwardly in substantially perpendicular relation to a back wall 101 and thereby defines a recess 108. Recess 108 is sized so as to accept tibial resection guide 28 with a press-fit. First through-bores 112, 114 are defined in back wall 101 in spaced relation to one another, with a second through-bore 117, 119 being associated with each first through-bore 112, 114.

[0046] Returning to the digital image models 3 previously disclosed, and considering a generalized digital model of resection guide mount 20 added to the patient's femur image data, the anatomic surface features of the patient's femur, e.g., the condylar surface topography, may be complementarily mapped onto each of lower surface 36 and lower surface 40 of arms 30, 31. It will be understood that complementary mapping of the digital images results in localized prominences on the surface of a bone, e.g., a condyle or articular surface, becoming localized concavities on lower surface 36 or lower surface 40, while localized concavities on the surface of a bone become localized prominences on lower surface 36 or lower surface 40. In this way, each of lower surface 36 and lower surface 40 is redefined with a complementary, substantially mirror image of the anatomic surface features of a selected region of the patients femur. As a consequence of this complementary bone surface mapping, resection guide mount 20 releasably “locks” on to the complementary topography of the corresponding portion of the patient's natural femur, e.g., the condylar surfaces, without the need for other external or internal guidance fixtures. A substantially identical mapping is carried out in connection with the design of a patient specific tibial resection guide mount 22.

[0047] A visual presentation of the virtual alignment results between the patient's femur and resection guide mount 20 is created and forwarded to the surgeon to obtain approval of the results prior to manufacturing (FIGS. 1, 19, 20). Upon receipt of the surgeon's approval, resection guide mount 20, and in appropriate instances resection guide mount 22, is manufactured and returned to the surgeon for use in the surgery.

[0048] During a total knee replacement the present invention is used in the following manner. The surgeon first orients resection guide mount 20 on femur 5 until lower surfaces 36, 40 of resection guide mount 20 “lock” to the topography of the exposed surface 4 of femur 5. With resection guide mount 20 locked onto the patient's femur, a surgeon press-fits an appropriately configured Distal Resection Guide 26 (e.g. Wright Medical Technology, Inc. Part No. K001-2659) in recess 58 of resection guide mount 20. As indicated in FIGS. 19-20, this results in the resection guide mount 20, and particularly the guide receptacle portion 29 of the resection guide mount 20, being sandwiched between the resection guide 26 and the patient's bone. Pins are driven into through-bores of the resection guide 26, but advantageously the pins do not come into contact with the portions of resection guide mount 20 that define through-bores 62, 64 or 67, 69. These through-bores are often the most proximal on resection guide mount 20. With resection guide mount 20 held securely in place, a drill bit is advanced into through-bores 38 and 42, through-bores 62, 64 defined in back wall 61 and/or into second through-bores 67,69. It is often preferable for the drill to protrude about 15 mm into through-bores 38 and 42 into the femoral bone so the drill holes will be present after the distal resection. Increased hole depth may be necessary in the event of a larger distal resection to correct a flexion contracture. For additional stability, fixation pins (not shown) may be left in through-bores 38 and 42, but must be removed prior to resection. With the resection guide mount 20 thus accurately positioned with respect to the selected bone region and the resection guide 26-guide mount 20 construct appropriately secured to the patient's bone, the surgeon uses a conventional surgical blade and the resection slot of the resection guide 26 to resect the patient's bone.

[0049] It is to be understood that the present invention is by no means limited only to the particular constructions herein disclosed and shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims.