Source: https://patents.google.com/patent/US20060015109A1/en
Timestamp: 2019-04-20 13:45:03+00:00

Document:
A cutting tool is provided with an arcuate cutting blade that preferably engages a guide tool to create a curved resected surface during an arthorplasty procedure. In one embodiment, a depth of the cutting blade is sufficient to permit the simultaneous creation of resected surfaces on two bones that articulate, such as both the femor and the tibia for a given condyle, without the need to reposition the guide or the leg. In another embodiment, a cutting member has a generally rectangular cross-section along a longitudinal axis with a first and second surface having cutting teeth defined thereon and a third and fourth surface adapted to interface with a cutting guide positioned proximate the bone. In this embodiment, the cutting tool can resect the bone in two different directions without reorienting the cutting member.
The present invention claims priority to U.S. Provisional Application No. 60/551,307, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR IMPROVED CUTTING TOOLS FOR RESECTION,” and U.S. Provisional Application No. 60/551,080, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR PIVOTABLE GUIDE SURFACES FOR ARTHROPLASTY,” and U.S. Provisional Application No. 60/551,078, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR MINIMALLY INVASIVE RESECTION,” and U.S. Provisional Application No. 60/551,096, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR ENHANCED RETENTION OF PROSTHETIC IMPLANTS,” and U.S. Provisional Application No. 60/551,631, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR CONFORMABLE PROSTHETIC IMPLANTS,” and U.S. Provisional Application No. 60/551,262, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR IMPROVED DRILLING AND MILLING TOOLS FOR RESECTION,” and U.S. Provisional Application No. 60/551,160, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR IMPROVED PROFILE BASED RESECTION,” and U.S. patent application Ser. No. 11/036,584, filed Jan. 14, 2005, entitled, “METHODS AND APPARATUS FOR PINPLASTY BONE RESECTION,” which claims priority to U.S. Provisional Application No. 60/536,320, filed Jan. 14, 2004, and U.S. patent application Ser. No. 11/049,634, filed Feb. 3, 2005, entitled, “METHODS AND APPARATUS FOR WIREPLASTY BONE RESECTION,” which claims priority to U.S. Provisional Application No. 60/540,992, filed Feb. 2, 2004, entitled, “METHODS AND APPARATUS FOR WIREPLASTY BONE RESECTION,” the entire disclosures of which are hereby fully incorporated by reference.
This invention generally relates to methods and apparatus for bone resection to allow for the interconnection or attachment of various prosthetic devices with respect to the patient. More particularly, the present invention relates to methods and apparatus for improved cutting tools for resection and arthroplasty.
In total knee replacements, for example, a series of planar and/or curvilinear surfaces, or “resections,” are created to allow for the attachment of prosthetic or other devices to the femur, tibia and/or patella. In the case of the femur, it is common to use the central axis of the femur, the posterior and distal femoral condyles, and/or the anterior distal femoral cortex as guides to determine the location and orientation of distal femoral resections. The location and orientation of these resections are critical in that they dictate the final location and orientation of the distal femoral implant. It is commonly thought that the location and orientation of the distal femoral implant are critical factors in the success or failure of the artificial knee joint. Additionally, with any surgical procedure, time is critical, and methods and apparatus that can save operating room time, are valuable. Past efforts have not been successful in consistently and/or properly locating and orienting distal femoral resections in a quick and efficient manner.
The use of oscillating sawblade based resection systems has been the standard in total knee replacement and other forms of bone resection for over 30 years. Other forms of arcuate and curvilinear sawblades and chisels have been proposed in the past as shown, for example, in U.S. Pat. Nos. 4,069,824 and 4,349,058 and PCT Publ. Appl. WO 97/05827, but these non-planar sawblade arrangement have not been widely accepted or adopted. Unfortunately, present approaches to using existing planar or non-planar saw blade instrumentation systems all possess certain limitations and liabilities.
Perhaps the most critical factor in the clinical success of any bone resection for the purpose of creating an implant surface on the bone is the accuracy of the implant's placement. This can be described by the degrees of freedom associated with each implant. In the case of a total knee arthroplasty (TKA), for example, for the femoral component these include location and orientation that may be described as Varus-Valgus Alignment, Rotational Alignment, Flexion-Extension Alignment, A-P location, Distal Resection Depth Location, and Mediolateral Location. Conventional instrumentation very often relies on the placement of ⅛ or 3/16 inch diameter pin or drill placement in the anterior or distal faces of the femur for placement of cutting guides. In the case of posterior referencing systems for TKA, the distal resection cutting guide is positioned by drilling two long drill bits into the anterior cortex across the longitudinal axis of the bone. As these long drills contact the oblique surface of the femur they very often deflect, following the path of least resistance into the bone. As the alignment guides are disconnected from these cutting guides, the drill pins will “spring” to whatever position was dictated by their deflected course thus changing their designated, desired alignment to something less predictable and/or desirable. This kind of error is further compounded by the “tolerance stacking” inherent in the use of multiple alignment guides and cutting guides.
Another error inherent in these systems further adding to mal-alignment is deflection of the oscillating sawblade during the cutting process. The use of an oscillating sawblade is very skill intensive as the blade will also follow the path of least resistance through the bone and deflect in a manner creating variations in the cut surfaces which further contribute to prosthesis mal-alignment as well as poor fit between the prosthesis and the resection surfaces. Despite the fact that the oscillating saw has been used in TKA and other bone resection procedures for more than 30 years, there are still reports of incidences where poor cuts result in significant gaps in the fit between the implant and the bone.
Improvements in the alignment and operation of cutting tools for resecting bone surfaces are desired in order to increase the consistency and repeatability of bone resection procedures as is the improvement of prosthetic stability in attachment to bone.
The present invention provides for embodiments of cutting tools and soft tissue management techniques facilitating intraoperative and postoperative efficacy and ease of use. In one embodiment, the cutting tool is a side cutting tool that has only a portion of the arc of the cutting profile exposed for cutting and is preferably used in a dynamic cutting mode where the leg is moved in flexion to engage the exposed portion of the cutting profile. In another embodiment, a cutting tool having dual planar cutting profile, preferably orthogonal to each other, permits the cutting tool to be utilized to create multiple resected surfaces at different orientations without the need to disengage the cutting tool from the guide surfaces. In still another embodiment, the cutting tool is provided with an arcuate cutting blade that preferably engages a guide tool with spaced apart guide surfaces that permit the creation of resected surfaces on both the femor and the tibia for a given condyle without the need to reposition the guide or the leg.
The present invention utilizes a number of embodiments of cutting guide technologies loosely or directly based on Profile Based Resection (PBR). The overriding objects of PBR technologies are to provide for significantly improved reproducibility of implant fit and alignment in a manner largely independent of the individual surgeon's manual skills, while providing for outstanding ease of use, economic, safety, and work flow performance.
The present invention utilizes a number of embodiments of alignment or drill guides to precisely and accurately determine the desired cutting guide location/orientation, thus cut surface location(s)/orientation(s), thus prosthetic implant location and orientation. The overriding objects of the embodiments are to precisely and accurately dictate the aforementioned locations and orientations while optionally enabling ease of use in conjunction with manually or Computer Assisted techniques, and while optionally enabling ease of use in minimally invasive procedures where surgical exposure and trauma are minimized.
The present invention utilizes a number of methods and apparatus embodiments of soft tissue management techniques and the devices supporting said techniques. The overriding object of these embodiments is to take advantage of the anatomy, physiology, and kinematics of the human body in facilitating clinical efficacy of orthopedic procedures.
It should be clear that applications of the present invention is not limited to Total Knee Arthroplasty or the other specific applications cited herein, but are rather universally applicable to any form of surgical intervention where the resection of bone is required. These possible applications include, but are not limited to Unicondylar Knee Replacement, Hip Arthroplasty, Ankle Arthroplasty, Spinal Fusion, Osteotomy Procedures (such as High Tibial Osteotomy), ACL or PCL reconstruction, and many others. In essence, any application where an expense, accuracy, precision, soft tissue protection or preservation, minimal incision size or exposure are required or desired for a bone resection and/or prosthetic implantation is a potential application for this technology. In addition, many of the embodiments shown have unique applicability to minimally invasive surgical (MIS) procedures and/or for use in conjunction with Surgical Navigation, Image Guided Surgery, or Computer Aided Surgery systems.
FIG. 4 is a pictorial representation or approximation of one form of surgical exposure that is desired.
FIGS. 5-11, 29-30, 88-98, 119, 140-146 and 154-168 show various depictions of embodiments and methods in accordance with alternate embodiments of the present invention.
The embodiments of the present invention are shown for femoral resection. For the sake of clarity, it should be noted that any combination of the forms of the present invention disclosed herein may be modified or combined to form constructs not specifically disclosed herein, but still within the scope of the present invention. The embodiments represented in FIGS. 29 and 30 are outstanding examples of this, as one of ordinary skill in the art would clearly recognize the applicability and benefits of this embodiment for tibial and/or femoral resection in Unicondylar or Bicondylar procedures, for bone resection in ankle replacement or arthrodesis (fusion), mandibular advancement procedures, high tibial osteotomy procedures, proximal femoral and acetabular preparation in Hip Arthroplasty, and a list of other applications too long to list in detail where reproducible and safe removal of living tissue during surgical intervention is beneficial.
FIGS. 93 through 98 represent an implementation of the side cutting drill embodiment of the present invention for cutting tools. It is of interest to note that the milling handle shown could further be guided by the PBR guides of the present invention to further combine the accuracy and precision benefits of PBR with the soft tissue protection characteristics of tibially embedded femoral cutting tool. It should also be noted that the side cutting drill with a curved cutting profile, similar to that shown in FIG. 119, could also be used to attain cut geometries possessing simultaneously curved or curvilinear cutting profiles and cutting paths. In utilizing such, it would be critical that the side to side location of the cutting profile of the cutting tool be tightly controlled with respect to the desired side to side location of the implant as the side to side location of the implant would be dictated by the cut surfaces generated. Alternatively, a cutting tool with a linear cutting profile, as shown in FIG. 94, could be utilized to create cut surfaces with a linear cutting profile and a curved cutting path, and then a second cutter with a curved cutting profile could be used to create a second, contiguous or noncontiguous, cut with a curved cutting profile and/or path whose mediolateral location was closely controlled to result in proper fit and location of the prosthesis attached to said cut surfaces. It should be noted that the cutting path of the second cutter could be located within a single plane, such as for a bilateral femoral component design, or could be curvilinearly divergent from the plane containing the cutting path of the first cut surface. This would be useful for unilateral femoral component designs (ones which require separate left and right femoral implants) so as to allow for the implant design to reflect out of plane patellofemoral kinematics and/or out of plane tibiofemoral kinematics most accurately. Interestingly, this embodiment of kinematic resection style resection could be modified to allow the cutting tool to be directly or indirectly linked to the movement of the patella with respect to the femur, or directly connected to the patella, to enable cutting of patellofemoral articular surfaces on the femur while moving the tibia and patella through ranges of motion about the tibia. The embodiments of cutting tools for use in attaining this include curvilinear end cutting mills or face cutters, side cutting drills with linear or non-linear cutting profiles, and other cutting tools capable of cutting the femur while engaged, directly or indirectly, to the patella. The side-to-side location of such cutters could be determined by engagement or adjustment with respect to a PBR or other guide, or simply by the natural kinematic path of the patella about the femur during flexion-extension of the knee joint.
FIG. 130 represents a distal femur with the cuts shown for fixation to a conventional total condylar implant with the border of said cuts shown in black. FIGS. 131 through 146 show embodiments of the present invention for cutting the distal and posterior areas of the femur.
FIG. 131 shows an embodiment of the present invention constituting an improved oscillating saw design. As shown, this design possesses cutting teeth not only on the leading edge as is commonly known in the art, but also on an adjacent surface allowing the saw to cut both while plunging in a direction parallel its long axis and normal to its long axis. FIGS. 132 through 134 show this in use with a cutting guide in cutting the femur. It should be noted that the two smoother areas surrounding the cutting teeth of the saw are intended for bearing contact with a guide, but that bushings, or bearings could be added to facilitate ease of use and avoidance of debris generation.
FIGS. 136 through 146 show an alternative cutting means. The small cutting tool best shown in FIG. 136 is a small diameter (0.188 inches to 0.040 inches) side cutting drill, optionally for use in conjunction with a milling handle (not shown). As shown in these figures, a robustly guided cutting tool can be used to cut both condyles when guided by a guide either straddling only one condyle (as shown), or fixed to the medial side of the lateral condyle and the lateral side of the medial condyle. These embodiments may also be applied to cutting of only one condyle, and the cutting path of the guide shown modified to allow for standard or improved Unicondylar use. Also shown, the manipulation of the cutting tool while guided by a PBR guide can include plunging, sweeping and pivotally sweeping manipulations in completing the desired cuts. Once these cuts have been completed, or partially completed and finished by other means, as shown in FIGS. 145 and 146, alternate methods may be employed to complete the remaining cuts. It should be noted that methods allowing for the resection of the posterior femoral condyles and/or the distal femoral condyles in conjunction with the proximal tibia already having been cut, provide for a phenomenal amount of laxity of the soft tissues surrounding the joint allowing for a surgeon to more easily complete cutting of the anterior cut and anterior chamfer cut.
Looking at FIG. 132, it is of special interest to note that the cutting guide surfaces may be attached to a pliers like or milling handle like positioning device which is either guided manually or by a surgical navigation system to determine the ideal location of the rails with respect to the bone. Once the rails were properly positioned, the positioning device could be actuated to cause fixation features (perhaps small spikes, or a serrated or roughened surface capable gripping the bone to which it is in contact with) to grip the bone thus robustly fixing the guide in place. It is also of interest to note that this method and apparatus may be used to position the rails along the sides of a single condyle (as generally shown in FIG. 142), and/or between the condyles (where the gripping surfaces would expand mediolaterally to contact the lateral surface of the medial condyle and the medial surface of the lateral condyle), and/or to the medial side of the medial condyle and the medial side of the lateral condyle (and fixed in place using additional fixation features), and/or about the medial side of the medial condyle and the lateral side of the lateral condyle. In those applications where the rails of the embodiments of the present invention were to be located under soft tissues such as the extensor mechanism, the gripping handle would benefit from the addition of the soft tissue accommodating contours disclosed in the copending provisional patent applications.
FIGS. 154 to 161 show an embodiment of the present invention for performing femoral resection with an oscillating, radiofrequency, or ultrasonic driver. The cutting tool shown in FIGS. 154 and 155 is rotated about the centerline of the shaft within a limited arc of motion, similar to an oscillating saw driver, however the direction of cutting is parallel to the drive axis of the saw driver rather than normal to it as is conventionally known. In this manner, the cutting tool is capable of creating resected geometries closely mimicking natural anatomic bone shapes while enabling the resection of bone through minimal surgical exposures. As shown in comparing FIGS. 158 through 161, instead of creating a flat posterior cut, this invention allows for the creation of cuts with a curved cutting profile. FIG. 161 represents the ability of this concept to be used to simultaneously make all tibial and femoral cuts in a single plunging motion, and that this would be attained simply by modifying the thickness of the posterior femoral cutting portion of the cutter by the amount indicated in FIG. 159, perhaps making the difference between the radius responsible for femoral resection geometry and the radius responsible to tibial resection geometry of around 5 mm to 15 mm for a Unicondylar replacement or 5 mm to 20 mm for cortical to conventional tricompartmental replacement. It should be noted that all of the femoral cuts, and optionally the proximal tibial cut, could be made in this manner and the location and orientation of the cuts would be based off of the guide hole shown in the distal femur in FIG. 56 for making with the shaft of the cutter. Alternatively, a shaft or other guide feature could be inserted into the distal femur and the cutting tool possess a mating female feature for that shaft. This invention offers significant improvements in both minimizing soft tissue displacement and intraoperative time savings as compared to the Oxford Unicondylar Instrumentation.
FIGS. 162 through 168 show an alternate but similar approach to the aforementioned. Instead of basing the control of the cutting tool on a guide feature formed or positioned on the femur, this embodiment of the present invention shows tibial resection, and alternatively both tibial and femoral resection, guided by a tibially mounted cutting guide or feature. Again, the cutting tool would be driven by a driver similar to an oscillating saw driver, although an alternative power means would be ultrasonically based to transmit ultrasonic energy along the length of the cutting tool to its curved or curvilinear cutting edge (it should be noted that in an ultrasonic embodiment, the cutting profile of the cutting tool may be other than a single arc). As shown in FIGS. 164 and 165, this could work well with a Pinplasty style guide, or could be optionally stabilized by implementation of Cam Pin Features disclosed in copending provisional applications, and could as shown in FIGS. 167 and 168, be used to cut both the tibia and the femur.
It is of particular interest to note that what is described as the Inner cutting radius and the outer cutting radius in FIG. 163 could be ‘thickened’ as was described for the femoral mounted embodiment to allow for resection of both the tibia and a single cut on the femur in one plunging motion. Alternatively, the cutter could be extended into the femur until the cutting profile of the cutting tool became tangent to the intended cutting path of the cuts to be made and the tibia manipulated to traverse a range of motion about the femur while cutting the femur while maintaining the cutting profile of the cutting tool tangent to the cutting path of the intended resected surface. This method is very applicable to the methods and apparatus described in the copending applications referenced herein, especially, Wireplasty resection and Pinplasty resection. Alternatively, a guide like the one shown in FIG. 168 could be used to incrementally form a series of discrete femoral cuts with the femur at different positions with respect to the tibia.
FIGS. 5 through 11 concentrate on alignment guide and/or drill guide techniques. FIG. 5 shows a manually operated alignment guide suitable for use with surgical exposures similar to that shown in FIG. 2 (it should be noted that surgical navigation sensors could be used to assist in determining final drill guide location and orientation). FIGS. 6 and 7 show an improvement upon the embodiment shown in FIG. 5 for enabling manual alignment guide use in less invasive incisions by providing soft tissue accommodating contours or reliefs. In other words, for a medial parapatellar incision, the alignment guide is configured to allow for appropriate contact and referencing of the distal and posterior femoral condyles, the IM canal (when not relying on an extramedullary reference or inference of the mechanical axis) or IM Rod, the anterior cortex or anterior runout point of a given or proposed implant size (via a stylus not shown), and the epicondylar axis via palpitation or visual reference while the patellar tendon, patella, and/or quadriceps tendon is draped over the lateral side (right side as shown in the figures) of the alignment guide allowing insertion of the guide when the patella is neither everted not fully dislocated as in conventional techniques. It should be noted that initial alignment indicated by reference of the distal femur may be further adjusted in all six degrees of freedom as a fine tuning for final cut location and orientation. This simply calls for the inclusion of additional adjustment of the location and orientation of the crossbar mechanism and/or rotational alignment arm, with respect to the initial reference provide for by contact between the body of the guide and the bone (optionally including the IM Rod), in flexion-extension angulation, varus-valgus angulation (rotational angulation and Anterior-Posterior location are already shown), mediolateral location (represented in this embodiment of the current invention by the cross bar mechanism in FIG. 5 where drill guide mediolateral location is shown as being independently and infinitely adjustable), and proximal-distal location (as shown in FIGS. 5, 6, and 7—it should be noted that this adjustment might be best embodied in an infinitely adjustable slide as opposed to the incrementally adjustable slide shown, and that simple marking would be present indicating the relative movement of the slide with respect to the body). It may be desirable to only utilize only a medial drill guide plate with multiple drill guide bushings to create holes extending partially or completely across the femur depending upon the manner in which the guides are to be connected to the femur.
FIGS. 8, 9, and 10 show an alternative alignment/drill guide embodiment of the present invention wherein a cannulated surgically navigated handle/drill guide is used to create fixation apertures in the bone for direct or indirect fixation of a cutting guide. As shown in FIG. 8, it may be advantageous to include tines for penetrating the bone to obtain initial stabilization of the handle in the location and orientation indicated by the surgical navigation system (“Surg Nav”—this term shall be used interchangeably with Computer Aided Surgical System or Image Guided Surgical System throughout this disclosure) prior to extending the drill, represented in FIG. 10, into the bone to create the aperture. An alternate feature to the tines shown could be a smooth but thin walled cylindrical edge of sufficient thinness or sharpness allowing it to cut and penetrate the bone to achieve initial stabilization prior to drilling. It should be noted that the aperture, or hole, thus created could be blind or extended to a specific depth, or optionally extended entirely through the bone and out the furthest side of the bone. Importantly, this process could be utilized transcutaneously through a small stab wound (perhaps 4 mm in length) through the skin to the bone surface, or through a preformed incision through which other instrumentation of the present invention or other devices including the prosthetic implant may be introduced during a procedure. Further, although only one cannulation is shown, a single handle may desirably contain multiple cannulations, some or all of which could be adjustably extended into contact with the bone to reduce any wandering of the drill contacting oblique bone surfaces and improve the precision and accuracy of aperture creation (thus allowing for the creation of apertures in the medial side of the femur, represented in FIG. 11, with a single Surg Nav Handle—Also, the apertures of the drill guide may be configured such that the femoral and tibial apertures shown in FIG. 11 are all created using a single positioning step for the handle). As represented in FIG. 9, there is very little distance over which the drill is cantilevered between its guidance within the cannulation(s) and its point of initial contact with the outer surface of the bone. This aspect of this embodiment of the current invention is critical in preserving the potential accuracy of Surg Nav systems, ie; the navigation system (the computer and the sensors) may be capable of determining appropriate location and orientation to ±0.5 mm and ±0.5 degrees, but if the location and/orientation of the aperture created represents some path of least resistance in bone which is followed by the drill, the resultant location and orientation of cut surfaces, and thereby the location and orientation of the prosthesis attached thereto, will likely be seriously in error. At the end of the day, if the aperture creation step is not carefully controlled, you will have a very expensive alignment system whose stated purpose is to increase reproducibility, and whose method of implementation compromises this stated purpose.
It should also be noted that another embodiment of the present invention, represented in FIGS. 88-92, benefits from the apparatus and principles of operation outlined above. As shown in FIG. 88, an aperture and a plane are created in bone which actually act as the cutting guide in controlling the location and orientation of the cutting tool within a specific plane during the creation of a cut surface. In this embodiment of the present invention, the cannulated drill guide will, in either manual or Surg Nav techniques, be used to guide a forstner style drill bit (the ‘guide surface’ shown in FIG. 88 could have been created by a modified drill with a leading section 15 mm long by 4 mm in diameter, responsible for the pivot aperture, and a 10 mm diameter following section which was about 10 mm long, responsible for the pivot reference surface) to create a larger diameter cylindrical aperture the bottom of which would define a pivot reference surface parallel to the cut surface to be created, and a smaller diameter cylindrical aperture to form a pivot aperture for maintaining the body of the bushing shown in FIGS. 88-91 in the proper location and orientation while cutting. Importantly, the technique outlined above is beneficially applied to tibial resection or any other planar or curvilinear resection technique as well.
a cutting guide adapted to operably guide the cutting blade to create a curved resection surface on the bone.
2. The apparatus of claim 1, wherein the cutting guide includes at least one curved slot having a curve corresponding to a curve of the cutting profile of the cutting blade, the curved slot being wider than a width of the cutting blade in a direction normal to the longitudinal drive axis.
3. The apparatus of claim 2, wherein the cutting guide includes two curved slots, each slot corresponding to a desired curved resection surface to be created on one of two corresponding bones that articulate.
4. The apparatus of claim 3, wherein a depth of the curved slot of the cutting guide and a depth of the cutting profile of the cutting blade in a direction normal to the width of the cutting blade and normal to the longitudinal drive axis of the cutting tool are sufficient to simultaneously create a desired curved resection surface on each of two corresponding bones that articulate.
positioning the orthopedic prosthesis on the bone with the articulation surface of the orthopedic prosthesis aligned with the curved resected surface.
6. The method of claim 5, wherein the arthroplasty procedure involves a leg of a patient and the step of preparing the at least one bone comprises a dynamic cutting mode where the leg is moved in flexion to engage the cutting profile of the cutting blade.
7. The method of claim 5, wherein the step of preparing creates a desired curved resection surface on each of two corresponding bones that articulate.
8. The method of claim 7, wherein a first bone is the tibia and a second bone is the femor and at least one of the curved resection surfaces is to be made on the tibia and at a greater than 5 degree angle with respect to a mechanical axis of the femur when viewed in a mediolateral direction.
9. The method of claim 8, wherein the step of positioning the orthopedic prosthesis attaches the orthopedic prosthesis to the femur and to the tibia such that the orthopedic prosthesis on the femur and on the tibia coact to enable a degree of a contact area at a flexion deeper than 115 degrees that is no less than 35% of the contact area at a fiexion of 45 degrees.
10. The method of claim 7, wherein the step of preparing creates the desired curved resection surface on each of two corresponding bones that articulate simultaneously.
such that the cutting blade can resect the bone in two different directions without reorienting the cutting member.
12. The cutting member of claim 10, wherein the structure extends generally transverse to the longitudinal axis of the cutting guide from a position proximate one end of the longitudinal axis of the cutting member to define a generally L-shaped cutting member such that the cutting member can be snaked into an opening in tissue smaller in dimension than a length of the longitudinal axis of the cutting member so as to facilitate minimally invasive surgical techniques for the arthroplasty procedure.
13. The cutting member of claim 10, farther comprising bushings operably attached to the cutting member to facilitate interfacing with the cutting guide.

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