HK1222108B - Total knee arthroplasty methods, systems, and instruments - Google Patents

Abstract

A method of performing a total knee arthroplasty including the steps of inserting a first pin into the distal femur and through the knee center, locating the femoral mechanical axis, inserting at least one additional pin into the distal femur, locating the tibial mechanical axis, sizing the femur and applying a femoral cutting block having at least one cutting guide to an end of the femur, positioning a tibial cutting block having at least one cutting guide in a cutting position relative to the tibia, aligning the femoral cutting block relative to the tibial cutting block, aligning the femur relative to the tibia, cutting the femur using the at least one femoral cutting guide, cutting the tibia using the at least one tibial cutting guide, removing the femoral and tibial cutting blocks, and positioning permanent femoral and tibial components on the cut portions of the femur and tibia, respectively.

Description

Methods, systems and apparatus for total knee replacement

Cross Reference to Related Applications

The present application claims U.S. provisional patent application No.61/762,492, entitled "INSTRUMENT FOR LOCATING THE EFFECTAL MECHANICAL AXIS", filed on 8/2/2013, U.S. provisional patent application No.61/904,083, entitled "INSTRUMENT AND METHODS FOR LOCATING A FEMOREAL MECHANICAL AXIS", filed on 14/11/2013, U.S. provisional patent application No.61/904,086, filed on 14/11/2013, entitled "TOTAL KNEE WORK METHOD, SYSTEMS, AND INSTRUMENT", AND U.S. provisional patent application No.61/904,086, filed on 14/11/2013, entitled "TOTAL KNEE HROPLASTY METHOD, SYSTEMS, ANDISTRENTS", filed on 8/2/2013, the entire contents of which are hereby incorporated by reference.

Technical Field

The present invention relates to methods, systems and instruments for Total Knee Arthroplasty (TKA), including surgical techniques. In particular, the TKA technique of the present invention utilizes instrumentation that does not impinge on the intramedullary canal of the femur and tibia and multiple bone cuts to achieve minimal repositioning of the cutting guide.

Background

During a total knee replacement procedure, a number of instruments and techniques can be utilized. In many procedures, the procedure begins by exposing the ends of the bones making up the knee, including the femur, tibia, and patella. An elongated bore is then formed in the distal femur and an intramedullary rod is inserted into the bore. A first cutting guide is then inserted over the bar and positioned in the correct forward-backward and rotational orientation, and the anterior cortex is then cut by a saw. The first cutting guide is then removed and replaced with a second cutting guide for cutting the distal femur at the correct valgus angle. The second cutting guide is then removed with the intramedullary rod. The femur can then be measured to determine the size of the femoral component to be used.

After sizing the femoral component, another cutting guide (i.e., a third cutting guide) is positioned on the cutting surface and pinned or fixed in place. The front, back and chamfer cuts are made using a saw, as guided by the third cutting guide, and then the third cutting guide is removed. The fourth cutting guide is then positioned and pinned against the cutting surface to make a cut known as a "cut groove". After this cut is completed, the fourth cutting guide is removed. The trial femoral component is then positioned relative to the cutting surface to check for proper fit relative to the bone.

The tibia is then subluxated anteriorly so that the extramedullary guide can be positioned relative to the tibia. In particular, the extramedullary guide is positioned such that it can connect from the tibial plateau on its proximal portion to the ankle joint at its distal portion. At this point, the fifth cutting guide may be positioned relative to the tibia and stapled or fixed in place. Alternatively, a hole may be drilled in the tibia to enable another intramedullary rod to be inserted in a manner similar to the technique used to drill into the femur. A fifth cutting guide may then be positioned on the bar. In either case, once the fifth cutting guide is in its desired position, the tibia can be cut and the guide can be removed. The proximal tibia is typically prepared using a short tap that will form a tubular hole in the bone into which the stem of the trial tibial component can then be inserted.

Once the trial femoral and tibial components are placed in their desired positions, the relationship between the femur and tibia is tested and corrected so that they are balanced in the medial and lateral sides during extension and flexion. The entire lower limb axis is also checked to ensure that the axis is straight. A tight structure and/or a wrong bone cut may unbalance the system and/or mis-align the axis, where either one or all of these problems would require correction. In particular, if the structures are too compact, they can be released. If the bone cuts made are too small or too narrow, they may be re-cut using the cutting guide and the previous steps of the cut. If the bone cut is too large or too thick, suitable inserts may be added to the bone to transform the bone to the desired size and shape. All of these corrections and adjustments require additional steps that are inconvenient and may ultimately lead to less than successful surgical outcomes.

As noted above, successful results of total knee replacement include obtaining accurate bone cuts and adequate ligament balance. In particular, the bone cut must be made accurately with respect to the mechanical axis of the femur, which is difficult to determine because it extends from the center of the femoral head, which is not visible in total knee surgery, to the center of the knee joint. The most widely used method of locating the mechanical axis is to use a rod positioned in the femoral medullary canal. The mechanical axis is then positioned, presumably, at about 6 degrees from the inside of the axis of the rod. Although this method is easy to perform, it is not necessarily accurate due to variations in the anatomy of the femur and due to the gap between the stem and the medullary canal in which it is located. This method also does not allow the orientation of the mechanical axis to be determined when viewed in the sagittal plane. Furthermore, this approach also requires the medullary canal to be invaded, which can potentially lead to undesirable blood loss and possible complications. Invading the medullary canal can also potentially lead to activation of fat embolism or coagulation. Another method of locating the mechanical axis is by using a computerized navigation device to determine bone landmarks and correlate the bone landmarks with the motion of the femur to locate the mechanical axis. However, such devices are often expensive and cumbersome to use in surgery.

After the femur and tibia are balanced and their alignment is straight, the patella may be resurfaced and/or the knee may be moved through its range of motion to check for correct patellar tracking. Where the patella will re-emerge, the patella is everted when the knee is straight. The patella thickness may be measured, for example, by a caliper, and a patella cutting guide is then applied to the patella to cut the amount of patella that will subsequently be replaced with plastic. Once the patella is cut, the trial plastic component can be positioned relative to the cutting area and then examined for balance, alignment, and patellar movement or trajectory throughout the knee. After this process is complete, the trial components are removed, the bone ends are cleaned and dried, the bone-engaging agent is applied in place, and the final components are placed in their desired positions. The balance, alignment and patella track are again checked, the knee is closed and the procedure is considered complete.

While many of the described steps are quite effective, there remains a need to provide systems and methods for use in total knee replacement surgery that are less invasive, more accurate, and simpler for locating the femoral mechanical axis in the coronal and sagittal planes and for making accurate bone cuts using a more simplified cutting guide.

Disclosure of Invention

The invention described herein relates to a method of performing a total knee replacement that provides a number of components that contribute to a successful outcome. In embodiments of the present invention, methods, instruments and devices are provided for positioning the femoral head without the use of radiation or computer navigation, and in which the intramedullary canal of the femur and tibia is not affected. In an embodiment of the present invention, initial soft tissue balancing is done first to emphasize the soft tissue requirements of a total knee replacement (i.e., balancing the importance of the ligaments holding the bones together). That is, by associating the femur with the tibia prior to cutting any bone, less adjustment of the ligaments is required. In embodiments of the invention, all cuts of the femur and tibia are performed without changing the position of the knee and/or without removing, reorienting or replacing the cutting jig.

In one embodiment of the present invention, a method of performing a total knee replacement procedure is performed comprising the steps of: exposing a knee of a patient, centering the knee, inserting a first pin in front of and through the center of the knee, positioning a femoral mechanical axis with reference to the center of the knee, inserting at least one additional pin in front of the distal femur, the axis of the at least one additional pin intersecting the femoral mechanical axis and being perpendicular to the femoral mechanical axis, positioning a tibial mechanical axis, sizing the femur and applying a femoral cutting block to the distal end of the femur, wherein the femoral cutting block includes at least one femoral cutting guide, positioning a tibial cutting block in a cutting position relative to the proximal end of the tibia, wherein the tibial cutting block includes at least one tibial cutting guide, aligning the femoral cutting block relative to the tibial cutting block, aligning the femur relative to the tibia, cutting the femur through the at least one femoral cutting guide, cutting the tibia through the at least one tibial cutting guide, the method includes removing the femoral and tibial cutting blocks and positioning a permanent femoral knee implant component on the cut portion of the femur and a permanent tibial knee implant component on the cut portion of the tibia. Each of the femoral and tibial cutting guides may include slots through the femoral and tibial cutting blocks, respectively, wherein the cutting guides are positioned in positions that allow all of the femur and tibia in which both the tibia and femur are intended to receive their respective permanent knee implant components to be cut.

According to the method described above, the step of aligning the tibia relative to the femur may include positioning a jacking device between the tibial spine and the intercondylar notch and activating the jacking device to orient the femur in a desired external and internal rotation relative to the tibia. During positioning and activation of the jacking device, the femoral and tibial cutting blocks may be maintained in their respective positions relative to each other and relative to their respective femur and tibia. Further, the step of locating the mechanical axis of the femur may include using a mechanical axis probe that does not necessarily encroach on the intramedullary canal of the femur.

The method described above may further include the step of resurfacing the patient's patella after positioning the permanent femoral and tibial knee implant components relative to the femur and tibia, respectively. In addition, the method may further include positioning at least one trial femoral knee implant component and at least one tibial knee implant component on the cut portion of the femur and the cut portion of the tibia, respectively, and then removing the trial femoral knee implant component and the tibial knee implant component prior to the step of positioning the permanent femoral knee implant component and the tibial knee implant component. The method may further include the step of performing a soft tissue release procedure after the step of positioning the mechanical axis of the tibia and/or the step of aligning the tibia relative to the femur, and may include coupling a femoral cutting block to the tibial cutting block.

Drawings

The present invention is further explained with reference to the appended figures, wherein like reference numerals refer to like structures throughout the several views, and wherein:

FIG. 1 is a schematic view of a representative spherical surface associated with a femur in accordance with the present invention;

FIG. 2 is a perspective view of one embodiment of the mechanical axis detector of the present invention positioned relative to a femur;

FIG. 3 is a perspective view of a guide pin positioned in a representative location in a femur;

FIG. 4 is a perspective view of the alignment guide positioned relative to the femur;

FIG. 5 is a top view of a femur with an alignment rod positioned parallel to the mechanical axis when viewed in the coronal plane;

FIG. 6 is a side view of the femur with the alignment rod positioned collinear with the mechanical axis when viewed in the sagittal plane;

FIG. 7 is a perspective view of a tibial mechanical axis finder;

FIG. 8 is another perspective view of the tibial mechanical axis finder;

FIG. 9 is a perspective view of a tibial mechanical axis finder positioned relative to a representative tibia and femur;

FIG. 10 is a side view of an end portion of a tibial mechanical axis finder with an indicator at a distal end positioned relative to a representative tibia;

FIG. 11 is another side view of an end portion of a tibial mechanical axis finder with an indicator at a distal end positioned relative to a representative tibia;

FIG. 12 is a perspective view of a tibial mechanical axis finder with an indicator at the distal end positioned relative to a representative tibia;

FIG. 13 is a perspective view of a representative tibia and femur with a plurality of extension pegs;

FIG. 14 is a perspective view of a femoral sizer;

FIG. 15 is a perspective view of a femoral sizer having a plurality of extension pins positioned relative to a representative femur;

FIG. 16 is a perspective view of a femoral sizer positioned relative to a representative portion of a knee implant;

FIG. 17 is another perspective view of the femoral sizer positioned relative to a representative portion of a knee implant;

FIG. 18 is a perspective view of the alignment jig relative to a representative femur positioned cutting block;

FIG. 19 is a perspective view of the alignment jig and femoral cutting block relative to a representative femoral positioning cutting block;

FIG. 20 is a side view of a cutting end of a representative femur positioned relative to a cutting block;

FIG. 21 is a perspective view of one embodiment of a femoral cutting block in accordance with the present invention;

FIG. 22 is a perspective view of one embodiment of a femoral cutting block in accordance with the present invention;

FIG. 23 is a perspective view of a portion of a femoral cutting block, such as the type shown in FIG. 22;

FIG. 24 is a perspective view of a portion of a femoral cutting block, such as the type shown in FIG. 22;

FIG. 25 is a perspective view of a tibial cutting block according to an embodiment of the present invention;

FIG. 26 is a perspective view of a tibial cutting jig according to one embodiment of the present invention;

FIG. 27 is a perspective view of a tibial cutting jig positioned relative to an end of a representative tibia;

FIG. 28 is a perspective view of a C-clip according to one embodiment of the present invention;

FIG. 29 is a side view of a spreader according to one embodiment of the invention;

FIG. 30 is a perspective view of a tibial cutting block and a femoral cutting block;

FIG. 31 is a side view of a tibial cutting block and a femoral cutting block;

FIG. 32 is a perspective view of a femoral cutting block with the scorpion tail attachment of the present invention;

FIG. 33 is another perspective view of a femoral cutting block with the scorpion tail attachment of the present invention positioned relative to the knee;

FIG. 34 is a perspective view of various components including a spreader for a total knee arthroplasty device according to the present invention;

FIG. 35 is a side view of the femoral cut block and box reamer in a first position;

FIG. 36 is a side view of the femoral cut block and box reamer in a second position;

FIG. 37 is a perspective view of a femoral cut block and box reamer;

FIG. 38 is another perspective view of the femoral cut block and box reamer;

FIG. 39 is a perspective view of the chisel positioned relative to the femoral cutting block;

FIG. 40 is a perspective view of a tibial plate punch;

FIG. 41 is a perspective view of a tibial femoral component;

FIG. 42 is a perspective view of a trial tibial insert;

FIG. 43 is a perspective view of a patella clamp of the present invention;

FIG. 44 is a perspective view of a reamer shaft for use with the patella clamp of FIG. 43;

FIG. 45 is a perspective view of a reamer shaft with an attached measuring sleeve;

FIG. 46 is a perspective view of the reamer shaft positioned relative to the patella clamp;

FIG. 47 is a perspective view of a reamer shaft with attached collars;

FIG. 48 is a perspective view of a reamer shaft and attached ring of FIG. 47 positioned relative to a patella clamp;

FIG. 49 is a perspective view of a reamer shaft having a reamer at one end;

FIG. 50 is a perspective view of an adhesive clamp; and

FIG. 51 is a perspective view of an adhesive clamp positioned relative to a patella clamp.

Detailed Description

There are a number of fairly successful total knee arthroplasty systems that have been used, each of which includes a different set of instruments and a different technique accompanying each set of instruments. Several problems are encountered when using these systems which are not present when using the methods, systems and apparatus of the present invention which are first generally described below and then described with respect to specific embodiments of the present invention.

The primary goal of any total knee replacement surgery is to properly align the lower extremities. The alignment is guided by three points, which include (1) the center of the femoral head; (2) the center of the knee; and (3) the center of the ankle joint. Because the center of the knee and the center of the ankle joint are accessible during surgery, it is relatively simple to find these points. However, the femoral head is deep in the hip and outside the surgical field. Many systems have been developed that use guide rods inserted into the femoral canal and use these rods as a reference structure for achieving an average in the angle that will be assumed to be directed towards the femoral head. Some systems also use preoperative X-rays to locate the femoral head and place physical markers that the surgeon can palpate during surgery. Still other systems use expensive computerized navigation to position the femoral head. However, in accordance with the present invention, embodiments of the system described herein use a mechanical axis detector that requires neither radiation nor expensive instrumentation.

Successful total knee replacement also requires that the ligaments holding the bones together be balanced, which is performed prior to cutting any bone according to the present invention. That is, once the knee ligaments are first balanced, the bone cutting guides of the present invention are positioned on their respective planes, and the cuts are then performed. Further in accordance with embodiments of the present invention, all bone cuts are made to the bone at one location, unlike in other systems where the knee is at one location when cutting the femur and at another location when cutting the tibia. Ultimately, the cuts made using the devices and methods of the present invention will be more accurate, thus minimizing any possible complications caused by cutting more bone than necessary.

Referring now to the drawings, in which like numerals indicate like parts throughout the several views, a number of steps for a total knee replacement procedure in accordance with the present invention are shown and described. In preparation for the procedure, an appropriate surgical drape and foot/ankle positioner are used to position the knee in the desired configuration for use by the surgeon, and then the procedure may be performed.

To initiate the procedure, the patient's knee must be exposed. In this step, a medial paraspinal incision is used to expose the knee, enabling the Anterior Cruciate Ligament (ACL) and Medial Collateral Ligament (MCL) and meniscus to be removed. Any accessible osteophytes are also removed. The patella is moved to the side.

Next, the femoral mechanical axis is located, which can be performed using a variety of methods, wherein one method of the present invention includes using the mechanical axis detector of U.S. provisional application 61/762,492, filed 2013, 2, 8, the contents of which are incorporated herein by reference. Generally, locating the mechanical axis using this method includes determining certain points in space relative to the patient's femur, such as shown in fig. 1-6. Referring first to fig. 1, a schematic view of a femur 50 and a portion of a spherical surface 52 is shown. The spherical surface 52 and the femur 50 are positioned such that the center of the femoral head 54 coincides with the center 58 of the spherical surface 52. Further, the knee 56 is centered on the surface of the spherical surface 52. Thus, the spherical surface 52 has a radius equal to the distance from the center of the femoral head 54 to the center of the knee 56.

In accordance with the present invention, the problems typically encountered when attempting to locate the mechanical axis of a femur can be solved by finding a line through the center 58 of the spherical surface 52 using points on the spherical surface (e.g., first point 60, second point 62, and third point 64, as shown in FIG. 1). Locating the wire may be accomplished using the apparatus and/or methods of the present invention. Further in accordance with the present invention, the physical movement of the knee is assumed to be three-dimensionally rotational about the center of the femoral head. Thus, the center of the knee 56 will be tracked on the surface of the sphere 52 as the knee moves about, with the center of the knee 56 moving through the points 60, 62, and 64.

It can be shown that for any given spherical surface, a line passing through the center of the plane of the circle defined by at least three points on the spherical surface and perpendicular to that plane will pass through the center of the spherical surface. As applied to the present invention, the points 60, 62 and 64 are on the surface of the spherical surface 52 and serve to define a circle 66 having a center 68. To locate the mechanical axis 70 for a particular femur, the center of the knee 56 is moved to any point in space, which may correspond to the first point 60. The center of the knee 56 is then moved to a second point 62 and finally to a third point 64. These points 60, 62, 64 are used to define a circle 66, and a point 68 is determined as the center of this circle. After all of these points are determined and/or located, an axis 72 may be determined, the axis 72 being perpendicular to the plane containing the circle 66 and passing through the center 68 of the circle 66. By moving the center of the knee 56 into alignment with the axis 72, the mechanical axis 70 of the femur 50 becomes collinear with the axis 72, allowing the mechanical axis 70 to be positioned. The apparatus and method of the present invention are used to determine the points 60, 62, 64 and 68, and the axis 72, relative to the femur, and thus enable the positioning of the femoral mechanical axis, as described in the following paragraphs.

Referring now to fig. 2, there is shown one embodiment of the mechanical axis detector 1 of the present invention, the mechanical axis detector 1 generally comprising a base 2, an extension arm 3, a swivel arm 4 and a positioning arm 5. A representative or exemplary femur 50 of the patient is also shown adjacent to the mechanical axis detector 1. The base 2 may be attached to the table by clamping the base 2 to the side rails of the table or by using other attachment structures or structures that provide a fixed engagement between the machine axis detector and the table. In an exemplary method of using a mechanical axis probe of the type shown in fig. 2, after the knee joint is exposed, the center of the knee 56 is determined by the surgeon in the coronal and sagittal planes. If desired, a knee center locator device may be used to locate the knee center. It should be noted that the "sagittal plane" here and in the following refers to a plane parallel to the anatomical sagittal plane and passing through the center of the knee.

Once the center of the knee 56 is located, the peg 30 (which may optionally include a crimp, strap, or other locating feature) is inserted into the anterior portion of the distal femur along a sagittal plane generally perpendicular to the femoral anatomical axis and through the center of the knee 56, as shown in fig. 3. The peg 30 is inserted such that its locating feature is at a predetermined distance from the center of the knee 56. The location of the locating feature and the center of the femoral head 54 are two points that define an "approximate mechanical axis" of the femur that extends from the center of the femoral head 54 to the center of the locating feature.

The mechanical axis detector 1 comprises a plurality of parts and devices that are movable and/or lockable with respect to each other in order to position specific points as described above. Once these steps are performed, the positioning features of the nail 30 engage with the cradle and the femur is oriented so that the guide nail 37 can be drilled into the femur 50 at a predetermined distance/position relative to the nail 30, as shown in fig. 3, in such a way that it compensates for the angle between the true mechanical axis 70 and the approximate mechanical axis. Thus, when the nail 37 is drilled into the femur 50, the nail 37 is perpendicular to the axis 70 in fig. 1 and 2.

The mechanical axis probe 1 is then removed from the patient, leaving the guide pegs 30 and 37 in the femur 50 positioned in their respective positions, as shown in fig. 3. Rod alignment guide 39 is then placed over staples 30 and 37 as shown in fig. 4. Specifically, rod alignment guide 39 includes a guide hole slidable on peg 37 and a guide slot slidable on peg 30. Finally, the alignment rod 42 is placed in the guide hole of the rod alignment guide 39. The alignment rod 42 will be collinear with the mechanical axis 70 when viewed in the coronal plane, and the alignment rod 42 is parallel with the mechanical axis 70 when viewed in the sagittal plane, as shown in fig. 5 and 6. When viewed in the sagittal plane, the guide pegs 37 will be perpendicular to the mechanical axis 70. When viewed in the coronal plane, the line connecting the locating feature with the axis of the guide pin 37 will be collinear with the mechanical axis.

In the next step of the procedure, a soft tissue release procedure is performed and the tibial mechanical axis is positioned, wherein such procedures may be performed using an exemplary tibial mechanical axis finder 80 of the type shown in fig. 7 and 8. The steps of using such a tibial mechanical axis finder are shown in figures 9 to 13. Specifically, the tibial mechanical axis finder 80 is positioned on both anterior femoral pegs 30, 37 discussed above. In this way, this device will become an extension of the femoral mechanical axis which will form the correct mechanical axis for the entire lower limb from the centre of the femoral head through the centre of the knee and to the centre of the ankle joint. Appropriate soft tissue release procedures (e.g., lateral release, etc.) are then performed in the knee to cause the ankle joint to conform to the distal tip of the tibial mechanical axis probe, thus effectively realigning the limb with the correct coronal mechanical axis, which is a fundamental goal in a good total knee replacement.

The tibial mechanical axis finder 80 may comprise a telescoping member such that its length is adjustable to match the length of the tibia. Further, the tibial mechanical axis finder 80 is also adjustable along the sagittal plane. That is, the tibial mechanical axis probe 80 is then aligned along the sagittal plane by having it parallel to the palpable fibula or by having it oriented at a suitable angle relative to the anterior portion of the tibia. The pivotable pointer 82 is rotated downward so that its tip can be used to align the tibial mechanical axis finder 80 with the center of the ankle joint. Once this is done, the two threaded pegs 84, 86 are placed by means of suitable guiding means (see fig. 12) so that at the end of the procedure the two pegs 84, 86 are correctly positioned on the tibia and the two pegs 30, 37 on the femur. Furthermore, all of the staples are then correctly aligned in their respective coronal and sagittal planes as desired.

Referring now to fig. 14-24, the next step in the procedure involves sizing the femur and applying a femoral cutting block to the distal end of the femur. To accomplish this, the knee is placed in approximately a 90 degree flexion and then the femoral sizer is placed by the femoral nail. An exemplary embodiment of a femoral sizer 90 is shown in fig. 14, 16, and 17, the placement of the sizer 90 relative to the femur being shown in fig. 15. The femoral sizer 90 includes a top member 92 having a distal tip 94 and a bottom member 96 that is slidable relative to a post 98 to adjust the size of the femur. The members 92, 96 are used like calipers, wherein the distal tip 94 of the member 92 is engageable with the peg 37, e.g., to provide a desired reference point for the measurement. Alternatively, the sizing steps described above may be performed after the femur and tibia are spread apart in flexion to tension the collateral ligaments and for proper rotation and orientation of the femur relative to the tibia. A spreader or "jacking device" 160 (such as the device shown in fig. 29) may be used for this purpose. Femoral sizing is then performed in a direction parallel to the mechanical axis of the tibia.

Once the size of the femur is known, the sizer 90 is removed and replaced by a correspondingly sized femoral cutting block or jig that is connected to the two anterior femoral pegs 30, 37 by a cutting block alignment jig 100 as shown in fig. 18. The cutting block alignment fixture 100 allows the cutting block 110 to rotate and translate about a plane perpendicular to the femoral mechanical axis. The block 110 may be connected to the alignment fixture 100 by the extension flange 102, wherein the slot of the cutting block 110 may slide over the extension flange 102.

An embodiment of a femoral cutting block that may be used in this procedure is shown in its assembled and disassembled configuration in fig. 19-24. In particular, fig. 21 and 22 show the cutting block 110 in an assembled condition, while fig. 23 and 24 show separate pieces 112 and 114, respectively, of the block 110. The block 112 includes a plurality of slots 116 into which cutting blades may be inserted into the slots 116 to cut bone at a desired location when the block is in certain predetermined positions relative to the femur. Fig. 19 shows the position of the cutting block 110 when connected to the cutting block alignment jig 100. When the cutting block 110 is positioned in this manner, the block will be located in the correct varus-valgus angle (coronal plane) and the correct flexion-extension angle (sagittal plane) relative to the femur.

When the cutting block 110 is correctly positioned, the distal femur is cut using the cutting blade pressed through the predetermined groove 116 of the cutting block 110. Fig. 20 shows the femur with the distal end removed by the cutting step. The cutting block 110 is then proximally advanced or folded such that the cutting block 110 contacts the cut surface of the femur. This cut of the femur may be a separate distal cut that is made before the other cuts so that the femoral cut block 110 is folded for subsequent cuts. The distal cut may also be made with all other cuts (with corresponding modifications in the cutting block) without folding the cutting block 110; however, the cutting block 110 may be more secure if the cutting block 110 is aligned with the planar distal cutting surface of the femur and then pinned rather than abutting the generally rounded contour of the natural distal condylar bone.

Next, as shown in fig. 26 and 27, the tibial cutting jig 120 is slid onto the two pegs 84, 86 previously placed in the tibia. The tibial cutting block 130 is then positioned relative to the tibial cutting jig 120. This positions the block 130 in the correct varus-valgus angle (coronal plane) and the correct flexion-extension angle (sagittal plane) relative to the tibia.

As described herein, prior systems known in the art would involve cutting the tibia and femur separately, and then attempting to associate or match the tibia and femur after the bone cuts have been made. However, a total knee arthroplasty system and method according to the present invention will match the tibia and femur prior to making the osteotomy. A number of components are used in this process, including at least one anterior reference guide "scorpion tail" (shown in fig. 32 and 33), a C-clip (shown in fig. 28), and a spreader (shown in fig. 29), which are shown in further detail below.

In particular, fig. 32 and 33 show a connector, referred to herein as a "scorpion tail" 140, that may be connected to the femoral cutting block 110 for positioning the block in an anterior-posterior direction relative to the anterior femoral cortex. The scorpion tail connection 140 defines an anterior cut and also prevents cuts to the anterior femoral cortex. A C-clip 150 is then applied to connect the femoral and tibial cutting blocks (i.e., mate the femur and tibia so that they are parallel), as shown in fig. 30 and 31. Although one embodiment of a C-clip 150 is shown herein, it should be understood that a surgeon may be provided with multiple C-clips from which the surgeon can select for each particular patient. The C-clip defines the flexion gap and positions the tibial cutting block 130 so that only the desired amount of the tibial plateau is cut. Thus, the C-clip 150 also determines the thickness of the tibial implant component to be used. The C-clip 150 may achieve different gap sizes in response to different tibial implant component thicknesses.

A spreader or "jacking device" 160 (such as the device shown in fig. 29) is then positioned between the tibial spine and the intercondylar notch. The spreader 160 includes a first arm 162 and a second arm 164, the first arm 162 and the second arm 164 being pivotally connected to each other at a pivot point 166. The distal end 168 of the arm 162 includes an extending ratchet member 170, which extending ratchet member 170 is engageable with the distal end 172 of the arm 164 to provide the desired splaying function for the device. Notably, the cutting block does not need to be removed to place the spreader 160 in the desired location. The handles or proximal ends of the arms 162, 164 are squeezed toward each other to rotate the femur to the correct angle due to the tightening of the two lateral ligaments, for example, as shown in fig. 34. In this case, adjustment may be achieved using the spreader 160, which includes the ratchet member 170 locking the arms 162, 164 in position relative to each other and causing the femur to rotate, orienting the femoral cutting block in the correct rotation relative to the femur.

It can be noted that during this expansion step, the femoral cutting block is held parallel to the tibial cutting block by the C-clip 150. At the same time, the femoral cutting block is held perpendicular to the femoral mechanical axis by the cutting block alignment jig of fig. 18. This adjustment provides a more individualized adjustment for each patient rather than using a fixed amount of rotation (e.g., 3 to 5 degrees of rotation) as is assumed in other systems. Proper femoral rotation allows for more balanced flexion gap, better range of motion, and better tracking of the patella. Once the correct positioning of the femoral and tibial cutting blocks 110, 130 is achieved, the two are stabilized using staples. The scorpion tail connector 140, spreader 160 and C-clip 150 are then removed.

At this time, the cutting jigs or blocks will be in their desired positions relative to their respective bones. As described above, the distal femur is cut using an oscillating saw, and then the femoral cutting block is advanced onto the cutting surface. The guide (i.e., slot 116) of the cutting block 110 is then used to make the following cuts: an anterior femoral cut, an anterior chamfer, a posterior cut, and a posterior chamfer. In one embodiment, the "top" or proximal surface of the box and the distal femur are first cut, and then the cutting block is advanced or folded over the cut distal femur and pinned in place. A device referred to herein as a "box reamer" is then used to make a box cut, with one embodiment of the box reamer 180 shown in fig. 35-37, and the box reamer 180 shown relative to the femoral cut block in fig. 38. Alternatively, an oscillating saw may be used to cut the sides of the box. Another alternative is to use a box chisel or similar tool to cut the box. In an alternative sequence of cutting steps, the box is cut after the distal femur is cut. The front and rear chamfers may be cut before or after their respective front and rear cuts, as desired. The tibia is then cut using the tibial cutting block as a guide. A chisel 190 of the type shown in fig. 39 may then be used to cut "ridges" for the implant, with an exemplary positioning of the chisel 190 relative to the femoral cutting block 110 also shown. Alternatively, a rasp with an appropriate profile may be used to cut the "ridge".

Next, the cutting jig or block is removed and the tibial drill guide is positioned and pinned in place and the tibial reference pin is removed. The tibia is then drilled and the tibial drill guide is then removed. The trial tibial baseplate is then applied to the cut portion of bone.

The posterior osteophytes, if present, are removed and then a femoral trial component is placed on the distal femur, where the component has been selected to the correct size for the particular patient. An exemplary trial femoral component 200 is shown in fig. 41. A correspondingly correctly sized tibial trial insert is applied to the proximal tibia with the correct thickness setting for the insert, as determined by the C-clip dimensions used above. The trial component can be increased in thickness without removing it from the knee by using an adjustable trial tibial insert 210, for example of the type shown in fig. 42. The trial tibial insert 210 includes an upper component 212 that is adjustable along a post 216 relative to a lower component 214. The pieces 212, 214 are moved until they are positioned at a desired distance from each other, which will correspond to the desired thickness of the final tibial component. Alternatively, a trial tibial component having a fixed thickness may be used. The ability of the knee to achieve stable, fully extended and stable flexion with good patellar tracking is then evaluated. Alignment may be determined by applying a rod to the peg, where the rod would go from the center of the femoral head through the center of the knee to the center of the ankle joint. Additional disentangling and balancing may then be performed. In addition, tibial plate rotation may be indexed and a tibial plate punch 218 (see, e.g., fig. 40) may be used to punch the appropriate opening in the tibia. Finally, the tibial component may be removed and replaced by the final implant component, which is then cemented in place.

If it is desired to resurface the patella, the following procedure and corresponding instrumentation may be used in accordance with the present invention. First, the thickness of the patella is measured to establish a plane along which the patella is cut, wherein measuring the thickness of the patella may be accomplished by first everting the patella and then placing it in the patella clamp 220 (as shown in fig. 43). The thickness of the patella is then measured, for example by means such as a caliper. However, due to the irregular shape of the patella, a line connecting points on the surface of the patella corresponding to its thickness may not be perpendicular to the cut surface. In this case, it is difficult to correctly orient the caliper in order to make an accurate measurement. Thus, according to the present invention, the thickness of the patella can be measured using a measuring sleeve 222 (shown in FIG. 45) connected to a graduated reamer shaft 224 (shown in FIG. 44). The reamer shaft 224 and measuring sleeve assembly 230 (shown in fig. 45) are then inserted into the patella clamp. The indicator sleeve is used to measure the thickness of the patella using a scale on the reamer shaft, as shown in fig. 46.

After measuring the thickness of the patella, the collar 234 is placed on the reamer shaft 224, as shown in fig. 47. The collar 234 is pressed flush with the patella clamp 220 and locked in place, as shown in fig. 48. Collar 234 acts as a stop to prevent over drilling to ensure that the patella is drilled to the proper depth. The gauge sleeve 222 is then removed and replaced with a reamer 240 as shown in fig. 49. The patella is then drilled until the collar abuts the top surface of the patella clamp. The fit of the patella implant may be verified using a trial patella implant. The knee bone implant is then cemented into place. An adhesive clamp 250, such as the type shown in fig. 50, may be attached to the patella clamp 220 to hold the patella implant in place when the adhesive cures, as shown in fig. 51.

The present invention has now been described with reference to several embodiments thereof. The entire disclosure of any patent or patent application identified herein is incorporated by reference herein. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. It will be apparent to those skilled in the art that many changes can be made to the embodiments described without departing from the scope of the invention. Thus, the scope of the present invention should not be limited to the structures described herein, but only by the structures described herein and the equivalents of those structures.

Claims (12)

1. A system configured for performing a total knee arthroplasty for a patient, the system comprising:

a femoral mechanical axis detector configured to determine the position of the femur and to position the mechanical axes of the first and second pegs;

a mechanical axis of tibia finder configured to determine a position of a mechanical axis of the tibia and to locate the third peg and the fourth peg;

a femoral sizer;

a femoral cutting block alignment jig comprising at least two holes for engaging the first nail and the second nail;

a femoral cutting block engageable with the femoral cutting block alignment jig and configured to be associated with at least one measurement that can be provided by the femoral sizer, the femoral cutting block including at least one femoral cutting guide;

a tibial cutting jig including at least two holes for engaging the third peg and the fourth peg; and

a tibial cutting block comprising at least one tibial cutting guide, wherein the tibial cutting block is attachable to the femoral cutting block with a connection member to align the femoral cutting block relative to the tibial cutting block.

2. The system according to claim 1, wherein the tibial mechanical axis finder comprises at least one telescoping member including a pointer member pivotable relative to the telescoping member.

3. The system of claim 1, wherein the femoral sizer comprises:

a column;

a top member extending radially from the post and including a distal tip, wherein the distal tip is engageable with the second staple; and

a bottom member extending radially from the post and slidable relative to the post to vary a distance between the top member and the bottom member.

4. The system of claim 1, wherein the connecting member comprises a substantially C-shaped clip.

5. The system of claim 4, wherein the C-clip comprises:

a base member;

a first extension member extending from the base member in a first direction; and

a second extension member extending from the base member in the first direction and spaced apart from the first extension member.

6. The system of claim 5, wherein the first extension member is engageable with the femoral cutting block and the second extension member is engageable with the tibial cutting block for selective positioning of the femoral cutting block relative to the tibial cutting block.

7. The system of claim 1, further comprising a rod alignment guide comprising a guide slot slidable over the first peg and a guide hole slidable over the second peg.

8. The system of claim 1, wherein the tibial mechanical axis finder further comprises a first hole engageable with the first peg and a second hole engageable with the second peg.

9. The system of claim 1, wherein the at least one femoral cutting guide of the femoral cutting block comprises at least one slot.

10. The system of claim 1, further comprising a spreader means for orienting the femoral cutting block in a desired position relative to the patient's femur.

11. The system of claim 10, wherein the spreader device comprises first and second arms pivotally connected at a common pivot point, the pivot ends of the first and second arms being movable toward or away from each other.

12. The system of claim 11, wherein the spreader device further includes a ratchet member extending from a distal end of the first arm, the ratchet member being engageable with a distal end of the second arm for securing the first arm in a desired position relative to the second arm.