HK1127990B - Guide assembly for guiding cuts to a femur and tibia during a knee arthroplasty - Google Patents

Description

Guide assembly for guiding cuts of a femur and a tibia during knee arthroplasty

Technical Field

The present invention relates to the use of instruments for guiding the preparation of a knee joint to install implants during arthroplasty, and, in particular, to the use of ligaments and other anatomical features surrounding the knee joint for locating the guiding instruments and providing a reference for the cutting of the tibia and femur.

Background

During knee arthroplasty, the surgeon typically must gain access to the knee joint in order to perform resection of the existing bone and cartilage to shape the tibia and femur to fit the mating surfaces of the implant. Some arthroplasty methods attempt to minimize the intrusion into the proximity of the knee joint by minimizing the size of the incision in the soft tissue structures surrounding the knee joint and patella. Preserving the soft tissue structure also preserves some of the support provided by these tissues. However, it is sometimes difficult to retain the soft tissue surrounding the knee joint because the resection guide must be supported firmly relative to the tibia and femur.

Retaining ligaments and other soft tissue structures surrounding the knee joint can provide reference points for positioning the tibial and femoral components of the knee implant, particularly when the structures are under tension or other loading conditions. For example, ligament tension may be used to guide placement of the resection guide. Conversely, preservation of soft tissue structures requires balancing the forces exerted by the soft tissue to promote normal knee motion and normal patellar tracking. Therefore, ligament forces can play an important role in reconstructing the normal function of the knee joint. Thus, in general, the reduction in invasiveness of the knee arthroplasty procedure, coupled with improvements in positioning and installation of the knee components, enables a better overall surgical outcome for the patient.

Therefore, it would be advantageous to have a tool to guide resection of the femur, tibia and other structures within the knee during knee arthroplasty that functions well with minimally invasive access to the tibia and femur. It would be further advantageous if the tools assisted the balance of forces between the knee implant components and the remaining ligaments and soft tissue structures to improve the function of the knee implant. Furthermore, it would be advantageous to guide resection with tools that use the ligamentous structure of the knee joint to guide placement of the tools and, consequently, placement of the knee joint components.

Disclosure of Invention

The present invention meets the above needs and achieves other advantages by providing an assembly for guiding resection of a femur and tibia of a knee joint in preparation for installation of femoral and tibial knee components. For example, the assembly may include tibial and femoral IM rods connected by a torque bolt that allows controlled adjustment of the distraction of the tibia and femur during cutting positioning in a range of flexion angles. Further, by attaching relatively narrow, low profile components to the tibial and femoral IM rods, the assembly can be used in a relatively small, non-invasive approach to the knee joint. In addition, the assembly includes several quick disconnect components to allow for quick assembly and disassembly during surgical setup. Each of these aspects, along with the ability of the assembly to accurately guide initial reference cuts to the tibia and femur, facilitates improved surgical outcomes for the patient.

The assembly of one embodiment of the present invention includes a selection of femoral and tibial IM rods, a flexion cutting guide, an extension cutting guide, and a selective locking component. Each IM rod includes a shaft portion configured to extend within an IM canal of a femur or tibia. The femoral IM rod also includes a femoral mount at a shaft end thereof that is configured to extend outwardly from the femur when the shaft is within the femoral IM canal. Likewise, the tibial IM rod further includes a tibial mount at the shaft end thereof that is configured to extend outwardly from the tibia when the shaft is within the tibial IM canal. Each mount is configured to attach to one or more of the selectively lockable components. The flexion and extension cutting guides define one or more slots configured to guide the use of cutting and other instruments to prepare the femur and/or tibia for cutting during flexion and extension of the knee joint. Each cutting guide is configured to attach to one or more of the selectively lockable components so as to be supported by the femoral and tibial IM rods. A selectively lockable component is configured to attach to the femoral and tibial IM rods such that at least one portion has a relatively small cross-section that extends in an anterior or anterior-medial direction from the knee compartment to attach to the flexion and extension cutting guides and support and limit movement thereof.

In one aspect, the femoral mount has a cylindrical shape that extends in an anterior-posterior direction between the femoral condyles and includes a central opening and a plurality of scale markings extending along an outer surface thereof. The central opening may also include an anterior anti-rotation portion (e.g., a hexagonal portion) and a larger diameter cylindrical portion. The tibial mount may include or support a flex bolt (flexion bolt) having a threaded shaft at one end that is configured to extend into an opening in the tibial IM shaft, a bushing at the other end, and an outer hexagonal flange between the two ends. The bushing is configured to extend into the cylindrical portion and further includes an inner hexagonal bore. The hexagonal flange is configured to allow clamping by an external torque wrench or an internal torque wrench (driver) to urge the femoral mount away from the tibial mount (by rotation of the threaded shaft) and to distract the tibia and femur to a desired torque reading value. This allows the surgeon to apply the appropriate amount of tension to the ligamentous structure as he or she defines, and the amount applied can be recorded for later comparison in the method.

Included in an exemplary embodiment of the selective locking feature is a first locking mechanism having an arm, a plunger assembly, and an anti-rotation extension, in this case defined as a hexagon. The arm has an elongated portion extending from the head. Likewise, a hexagonal anti-rotation extension extends from the head. The head and the hexagonal extension define an opening configured to receive a shaft of the plunger assembly. The plunger assembly includes a snap on one end of the shaft and an anti-rotation feature similar to the anti-rotation extension on the other end of the shaft, in this case defined as a hexagonal tip that extends out of the hexagonal extension. Further, the shaft includes a pin that extends into a helical slot defined within the head. A spring extends between the head and the thumb press. Depressing the thumb press moves the shaft forward while the pin and helical slot rotate the shaft and align the flats of the hexagonal tip with the hexagonal extension. This causes the hexagonal tip and the hexagonal extension to become concentric and to be inserted into the anterior hexagonal portion of the central opening of the femoral mount. In addition, the hex end is configured to extend out of the hex portion of the opening and into the cylindrical portion and rotate (due to the helical slot and pin) into an eccentric position upon release of the thumb press, thereby locking the locking mechanism within the femoral mount. When attached, the head of the arm extends out of the knee joint compartment towards the outer end, and the elongate portion extends anteriorly (relative to the tibia) through the surgical incision.

The support member of the flexion guide of the assembly of the present invention includes a slider member and a ratchet bar. The slider member is configured to attach to and slide along the elongated portion of the arm of the first locking mechanism, for example, by having an opening defined therein that matches a cross-section of the elongated portion. The ratchet bar is configured to extend toward a plane defined by the tibial plateau. Preferably, when assembled, the femoral mount, the first locking mechanism and the support member of the flexion guide generally form a U-shape that is relatively narrow in the medial-lateral direction to allow use with narrow incisions.

Also included within the selective locking component is a quick release mechanism that is configured to slide along and lock onto the ratchet bar of the support member of the curved guide. For example, the quick release mechanism may define an opening configured to extend and slide along the ratchet bar and a locking pin spring-loaded to extend into a portion of the pawl to prevent sliding. The locking pin is spring biased but can be overcome with a manual pulling force, for example, to allow further sliding or resetting of the quick release mechanism. The quick-release mechanism may also include a spring-biased locking bar that may extend into the opening and lock to the curved cutting guide, along with an engagement member of the quick-release mechanism. After the flexion cutting guide is secured in place to the tibia or femur using a K-wire or other fastener, re-depression of the locking lever easily releases the flexion cutting guide. This allows the resection guide to move toward the proximal tibia and away from the tensioning assembly as the knee flexes.

Once the flexion resection guide is secured to the proximal tibia, the resection guide has a plurality of slots for resecting several components of the femur and tibia, most importantly, for resecting measured proximal tibial resection and posterior arthrodesis. Resection with the strained knee at 90 degrees will theoretically allow the user to perform strained flexion gap resection.

The selectively lockable components may also include components configured to attach to the femoral and tibial IM rods when the knee joint is in extension. For example, the components may include a cannulated extension bolt (cannulated extension bolt), a tibial angulation guide, an extension guide support member, and a second locking mechanism. The tibial angulation guide is configured to attach to the tibial IM rod via a cannulated extension bolt that is in turn coupled to the tibial IM rod and extends around the femoral mount, such as by having a block defining an arcuate channel configured to receive the cylindrical outer surface of the femoral mount. A plurality of graduated markings are included on the tibial angulation guide that, when associated with the graduated markings on the outer surface of the femoral mount, record valgus angulation values of the tibia relative to the femur. The tibial angulation guide may be configured to extend into the bushing of the bolt as described above, or alternatively, configured with its own threaded shaft and hexagonal flange, to allow it to be used to distract the tibia and femur in extension to a torque value corresponding to that previously measured when the knee is flexed.

The support member of the extension guide is configured to have a relatively narrow side and extend forward out of the joint compartment by providing an incision proximate thereto. For example, the extension guide support member may include a mounting portion that is cylindrical and defines a cylindrical opening, and a support arm disposed to extend proximally from the mounting portion. The second locking mechanism is substantially configured similarly to the first locking mechanism except that it has no fixed elongate portion of the arm. And, it includes a cylindrical head portion configured to extend through the cylindrical opening of the mount of the extension guide support member to connect the extension guide support member to the femoral mount while allowing the support member to rotate at a given position independent of the previously selected valgus angle.

The extension guide support member also includes a support arm configured to extend from the proximal end of the mount when the mount is attached to the femoral mount with the second locking component. The extension cutting guide is configured to be slidably attached to the support arm, such as by defining a channel in the body thereof. In addition, the extension cutting guide preferably includes a swivel arm that can be swung into abutment with the tibial plateau and plateau flange of the tibial mount to provide an additional reference point for performing a femoral resection with the knee in extension. The extension cutting guide, similar to the flexion cutting guide, may also define a plurality of fixation openings that allow fasteners to extend therethrough and attach the extension cutting guide to the tibia or femur. This allows for removal of the selectively lockable components to provide room for tibial and/or femoral cuts.

Once the proximal tibia is fiducially resected, the swivel arm will allow the extension cutting guide to make a predetermined resection of the distal femur. Resecting the knee in tension in the extended position will allow the user to perform a balanced extension gap resection when compared to performing a tension resection when the knee was previously positioned in flexion.

The assembly of the present invention has many advantages. For example, it provides a relatively narrow, low profile assembly of a locking component that securely attaches a cutting guide to a tibial and/or femoral IM rod. This provides a reliable guide for reference cuts to the tibia and femur, reducing the invasiveness of accessing the joint. In addition, many components, such as the first and second locking mechanisms and the quick release mechanism, facilitate quick assembly, easy adjustment, and quick disassembly, thereby improving efficiency. The use of flexion bolts in flexion and extension bolts and tibial angulation guides allows the tibia and femur to be distracted in flexion and extension at matched amounts of tension to ensure a better fit of the tibial and femoral knee replacement components throughout the range of flexion. In addition, the tibial angulation guide allows the surgeon to adjust the amount of valgus angulation of the tibia as desired to match the anatomy of the patient.

Drawings

The invention will now be described in general terms with reference to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

FIG. 1 is a plan view of a tibial Intramedullary (IM) rod and a femoral IM rod of an assembly in one embodiment of the present invention;

FIG. 2 is a perspective view of the femoral IM rod of FIG. 1 inserted into a femur;

FIG. 3 is a cross-sectional view of the femoral mount of the femoral IM rod shown in FIG. 2;

FIG. 4 is a perspective view of the femoral and tibial IM rods of FIG. 1 inserted into the femur and tibia, respectively, of the knee joint;

FIG. 5 is a perspective view of a bushing extending from a screw bolt of the assembly of the present invention, wherein the screw bolt is connected to the tibial IM rod of FIG. 1;

FIG. 6 is a plan view of the screw-on bolt of FIG. 5 and the tibial angulation guide and the curved knee cutting guide of the assembly of the present invention;

FIG. 7 is a perspective view of the bushing and IM rod of FIG. 5 with the bushing of the attachment bolt moved forward to connect the IM rod;

FIG. 8 is a side view of a first locking mechanism of the assembly of the present invention;

FIG. 9 is a perspective view of a first locking mechanism connected to the assembled IM rod and bolt of FIG. 7, which is subjected to the torque of the required load;

FIG. 10 is another perspective view of the first locking mechanism in an unlocked position assembled to the IM rod and bolt of FIG. 9, subject to the torque of the desired load;

FIG. 11 is another perspective view of the first locking mechanism assembled and locked to the IM rod and the extension bolt of FIG. 9, subject to the torque of the desired load;

FIG. 12 is a perspective view of a support member of the bending guide of the assembly of the present invention connected to the first locking mechanism of FIG. 11;

FIG. 13 is a perspective view of a curved knee cutting guide assembly of the present invention connected to the support member of the curved guide of FIG. 12;

FIG. 14 is a side view of the assembly of FIG. 13;

FIG. 15 is a rear view of the assembly of FIG. 13;

FIG. 16 is a bottom view of the quick release mechanism of the flexed knee cutting guide assembly of FIG. 13;

FIG. 17 is a perspective view of the quick release mechanism of FIG. 16 and the support member of the flexure guide of FIG. 12;

FIG. 18 is a perspective view of a flexed knee cutting guide of the flexed knee cutting guide assembly of FIG. 13;

FIG. 19 is an elevation view of a tibial angulation guide of the assembly of the present invention, extending between the femoral and tibial IM rods of FIG. 1, connected to a screw-on bolt;

FIG. 20 is an enlarged view of the IM rod and tibial angulation guide of FIG. 19;

FIG. 21 is another enlarged view of the IM rod and tibial angulation guide of FIG. 19;

FIG. 22 is a perspective view of the extension guide support member and secondary locking mechanism of the assembly of the present invention assembled to the femoral IM rod of FIG. 1;

fig. 23 is an enlarged perspective view of the extension guide support member of the present invention assembled to the second locking mechanism of fig. 22;

24-26 are perspective views of the extended knee cutting guide of the assembly of the present invention attached to an extended guide support member, the second locking mechanism of FIG. 22, and the femoral IM rod of FIG. 1;

FIG. 27 is a perspective view showing the second locking mechanism of FIG. 22 disengaged from the femoral IM rod of FIG. 1 when the extended knee cutting guide is secured in place to the distal femur;

FIG. 28 is a front view of the extended knee cutting guide of FIG. 24;

FIG. 29 is a side view of the extended knee cutting guide of FIG. 24;

FIG. 30 is a plan view of an L-shaped cutting module of the assembly of the present invention;

fig. 31 is a side view of the L-shaped cutting module of fig. 30 for cutting the anterior condyle of a femur.

FIGS. 32-40 illustrate various alternative modules of the present invention that facilitate quick assembly and that facilitate minimally invasive use during surgery;

FIG. 41 illustrates an articulating retractor for use in one embodiment of the invention; and

FIG. 42 shows an embodiment of the invention for use in a bench test.

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, and the embodiments are provided so that this disclosure will be compliant with the legal requirements. Like reference numerals refer to like parts throughout the drawings.

The drawings illustrate an assembly 10 of the present invention for facilitating preparation of a knee joint that includes guided positioning of cuts to the femur 11 and tibia 12 of the knee joint for subsequent mating of femoral and tibial knee replacement components. In general, the assembly 10 includes various components (such as one or more Intramedullary (IM) rods) selected and arranged to fit at a reference point located within the knee compartment, extend through a relatively narrow, small or non-invasive approach defined within the knee soft tissue, and attach outside the knee to select resection guides.

Here, anatomical directions as used herein are with reference to the knee joint during preparatory surgery and correspond to the illustrated embodiment of the assembly 10. However, these directions may vary depending on the handedness (handedness) of the knee joint, or changes in individual morphology and ligament structure, and typically, should not be considered limiting.

The assembly 10 can be configured to be applied to different knee flexion angles to facilitate positioning of the components throughout a range of flexion or extension. Shown here are the components of the assembly 10 that are used to guide the cutting and preparation of the knee at two different flexion angles, i.e., 90 and full extension. However, the components (or other components used within the spirit and scope of the present invention) may be adjusted or configured to extend through relatively non-invasive pathways to knee joints (30 °, 45 °, 60 °, etc., up to excessive flexion) at any range of flexion.

In the illustrated embodiment, the assembly 10 includes two IM rods, a femoral IM rod 13 and a tibial IM rod 14, which provide reference points for supporting the remainder of the assembly 10 in knee flexion, in this case 90 of flexion. The femoral IM rod 13 includes a femoral mount 15 and a main shaft 16, as shown in FIG. 1. The main shaft 16 of the femoral IM rod 13 is preferably an elongated, relatively rigid shaft, which main shaft 16 extends within the IM canal of the femur 11 in the proximal and distal directions when installed, as shown in FIG. 2. The main shaft 16 may include structure, such as a tapered end 17, to facilitate its insertion into the femur 11. Preferably, the main shaft 16 is made of a relatively rigid material, such as a hard plastic, stainless steel, titanium or other metal, or a material that can be inserted into bone without damage and that securely supports the femoral mount 15.

The femoral mount 15 is attached to the distal end of the main shaft 16, opposite the tapered end 17. Typically, the femoral mount is cylindrical with its axis extending perpendicular to the long axis of the main shaft 16. As shown in the cross-sectional view of the femoral mount in fig. 3, a central opening 18 is defined along the axis of the femoral mount 15. The central opening comprises two parts, namely: a rotation-preventing portion, in this case a hexagonal portion 19; and a cylindrical portion 20 that allows for locking of other components of the assembly 10 to the femoral mount 15, as will be described in more detail below. Regardless, once the femoral IM rod 13 is installed, the femoral mount 15 and its central opening 18 preferably extend in an anterior-posterior direction along the femoral notch between the femoral condyles. A plurality of longitudinally extending scale markings 21 are defined on the outer cylindrical surface of the femoral mount 15 which assist in the positioning of the tibial and femoral components, as will be described in more detail below.

As shown in fig. 1 and 4, the tibial IM rod 14 includes a main shaft 22 that supports a tibial mount 23. Similar to the main shaft 16 of the femoral IM rod 13, the main shaft 22 has an elongated configuration with a tapered distal end 24 to facilitate its insertion into the IM canal of the tibia. However, the main shaft 22 preferably includes one or more grooves 25, the grooves 25 extending along the length of the main shaft 22 to further facilitate insertion and prevent rotation within the IM canal of the tibia. Optionally, the spindle 16 may also include such grooves thereon. An opening 27 is defined in the proximal end of the main shaft 22 that extends into the recess 25. These openings further facilitate insertion into the IM canal of the tibia. Like the main shaft 16 of the femoral IM rod 13, the main shaft 22 can be made of a variety of materials that are relatively rigid to provide firm support for the tibial mount 23.

Included in the tibial mount 23 is a thickened cylindrical portion 26 and a plateau flange 28, as shown in fig. 4. Preferably, the cylindrical portion 26 is sized to fit the IM canal of the tibia 12. The cylindrical portion is connected at its distal end to the main shaft 22 and supports at its proximal end a platform flange 28. The platform flange extends outwardly perpendicular to the cylindrical portion 26 and has three flat sides and a crescent-shaped side. The crescent-shaped side is broken to provide space for the anterior cruciate ligament prior to resection of the proximal tibia. The flat sides may further assist in guiding positioning and cutting, such as during tibial compartmental resection in a unicondylar arthroplasty procedure, where only a single condyle and a portion of the tibial plateau are reconstructed.

A threaded opening 29 extends into the tibial mount 23 and provides a coupling connection for a bending bolt 30, the bending bolt 30 including a threaded shaft 31, a hexagonal flange 32 and a bushing 33, as shown in fig. 5 and 6. The threaded shaft 31 has a plurality of threads and extends away from the hexagonal flange 32, while the bushing 33 is a smooth cylindrical shaft that extends from the other side of the hexagonal flange 32 opposite the threaded shaft. The hexagonal flange 32 is shaped to allow tightening by a tightening device or other wrench to provide the motive force for advancing the threaded shaft 32.

The threaded shaft 31 is positioned to advance into the threaded opening 29 of the tibial mount 23 until it is flush with the plateau flange 28, thereby positioning the bushing 33 in its lowest profile position, as shown in fig. 5. These positions allow the femur 11 and the femoral mount 15 to extend therefrom and slide into position over the bushing 33. The torque wrench is then used to reverse the movement of the threaded shaft 31 until the bushing 33 engages the cylindrical portion 20 of the central opening 18 in the femoral mount 15, as shown in fig. 7. The reverse rotation is continued until a preselected torque measurement is obtained on the torque wrench or sufficient tension of the ligamentous structure is obtained. Once the appropriate ligament tension is achieved, this torque is recorded for comparison in the methods hereafter. The resulting assembly simulates the static connection of the femur and tibia when the knee is flexed (e.g., 30, 60, or 90, or more flexion), which the surgeon may use as a reference for subsequent resection instruments, as described below.

Also included in assembly 10 is a quick connect locking mechanism 34 that connects into hexagonal portion 19 of central opening 18, as shown in fig. 8 and 9. Included in this embodiment of the locking mechanism are a static bracket arm 35, a spring biased plunger 36 and a static locking extension 37, the static locking extension 37 emulating an anti-rotation feature 19 and, in this case, having a hexagonal shape. The arm 35 has an elongated portion 38 and a rounded portion 39. The elongate portion 38 of the arm 35 has a square cross-section and extends from a rounded head portion 39, said rounded head portion 39 having a partially cylindrical shape with two opposite flat faces at its ends. Extending from one plane of the head portion is a hexagonal extension 37. The hexagonal extension 37 has a hexagonal cross-section that is configured to closely mate with the hexagonal portion 19 of the central opening 18 defined in the femoral mount 15. Defined within one of the circular surfaces of head 39, as shown in fig. 8, is a helically extending slot 43 which guides the movement of plunger 36, as described below.

Defined by the rounded head portion 39 and the hexagonal extension 37 is a cylindrical opening 40 through which the plunger 36 extends. In particular, the plunger 36 comprises a snap 41, a shaft 42, a spring 45 and a rotation extension 44, the rotation extension 44 emulating an anti-rotation feature 37, in this case a hexagon, but which may be non-cylindrical, such as square, triangular or oval capable of limiting rotation. The thumb press 41 is located at one end of the plunger 36 and is disc-shaped with a protuberance to facilitate pressing with a thumb. Located beneath the thumb press 41 is a spring 45, preferably a coil spring, which extends around the shaft 42 and is located between the thumb press and the head portion 39 so as to bias them apart.

The shaft 42 includes a pin 46 that extends perpendicular to the shaft and into a helical slot 43 defined in the head 39, as shown in fig. 8. Thus, depression of the thumb press 41 moves the shaft 42 forwardly within the opening 40 of the head 39 and also causes rotation of the shaft because the pin 46 mounted thereon moves helically within the helical slot 43. The hexagonal end 44 of the plunger 36 is fixed to the end of the shaft 42 opposite the thumb press 41, extends along the free end of the hexagonal extension 37, and has a hexagonal shape sized to mate with the hexagonal extension 37.

Due to the connection to the shaft 42, depression of the thumb press 41 also causes rotation of the hexagonal end 44 of the plunger 36 until the flats of the hexagonal end match the orientation of the flats of the hexagonal extension 37, as shown in FIG. 10. Matching this orientation allows the hexagonal extension 37 and the hexagonal end 44 to be inserted into the hexagonal portion 19 of the central opening 18 of the femoral mount 15, as shown in fig. 11. Once the thumb press 41 is released, the spring 45 biases the thumb press, shaft 42 and hexagonal end 44 upwardly so that the plane of the hexagonal end returns to its unmated, staggered position relative to the plane of the hexagonal extension 37 (as shown in FIG. 9).

At this point, the hexagonal end 44 of the plunger 36 is located within the cylindrical portion 20 of the central opening 18 and, because it is in the unmated position, it cannot be retracted through the hexagonal portion 19 of the central opening. Thus, the locking mechanism 34 becomes rotationally and movably locked relative to the femoral mount 15 and the femoral IM rod 13. Once locked in place, the arms 35 of the locking mechanism 34 extend anteriorly outward from the condyles of the femur 11 and the femoral mount 15. In particular, the combination of the relatively narrow femoral mount 15 and the narrow elongated structure of the arms 35 allows for a relatively small surgical access opening, facilitating use of the assembly 10 in less invasive procedures. For example, a small 8-10 cm incision can be made with an altered medial, or inferior femoral approach, which avoids quadriceps laxity from the anterior tibia.

Also included in the assembly 10 of the illustrated embodiment of the invention is a curved guide support member 47 that is supported by the locking mechanism 34. The flexion guide support member includes a slider member 48 and a ratchet bar 49. The slider member defines a rectangular opening 50 sized and shaped to allow the slider member to be supported by and slide along the rectangular cross-section of the arm 35 of the locking mechanism 34. These movements allow the ratchet bar 49 attached to the slider member 48 to move towards and away from the knee joint. Preferably, the slider member 48 is shaped with a gripping portion (e.g., the tapered portion of the slider member shown) and may also include some sort of pin or locking assembly to prevent, but not inhibit, it from sliding relative to the arm 35. The ratchet bar 49 itself is also rectangular in cross-section and when assembled extends distally from the arm 35 of the locking mechanism 34 as shown in fig. 12. The ratchet bar 49 also includes a pair of chamfers that support a plurality of adjacent pawl grooves 51, the pawl grooves 51 extending along the length of the ratchet bar.

The assembly 10 also includes a flexed knee cutting guide assembly 52 attached to the flexion guide support member 47, as shown in fig. 13, 14 and 15. The flexed knee cutting guide assembly 52 includes a quick release mechanism 53 and a cutting guide 54. The quick release mechanism 53 includes a body 55, a pull pin 56, first and second springs 57, 58, a locking lever 59, and a locking pin 60. As shown in FIG. 16, the main body 55 defines a rectangular opening 61 that allows the main body to slide over the rectangular cross-section of the ratchet bar 49. In addition, the body 55 includes a side opening through which a draw pin 56 extends so that its end engages the pawl recess 51. Specifically, the first spring 57 biases the draw pin to a position normally engaging the pawl recess to lock the draw pin, and the body 55 into a particular position on the slider member 48. A locking pin 60 extends through the body and through the draw pin 56 to secure the draw pin 56 and prevent its removal.

In addition, the body 55 includes a clevis 62 that extends outwardly from the side of the body opposite the kingpin 56 and supports rotation of the locking lever 59 near an intermediate portion thereof. Also, as shown in fig. 17, the lock lever has a curved gripping portion that is biased outwardly from the body 55 by a second spring 58, and the opposite end of the lock lever includes a tapered wedge 63 that engages the cutting guide 54 to lock the quick release mechanism 53, as described below. Extending away from the clevis 62 is an engagement member 64 of the body 55 opposite the locking lever. The engagement member 64 has a rectangular cross-section and, in the assembled condition shown in fig. 13, extends into engagement with the cutting guide 54.

As shown in fig. 13, the cutting guide 54 extends posteriorly (when assembled) from the quick release mechanism 53 and includes a mounting member 65, a K-wire guide or fixation pin portion 66, a cross pin portion 71, a proximal tibial cut guide portion 67, and a posterior articular femoral cut guide portion 68. The mounting member 65 defines a rectangular opening 69 sized and shaped to slidably receive the engagement member 64 of the body 55 of the quick release mechanism 53. The mounting member 65 also defines a recess 70 in one side wall of the rectangular opening 69, as shown in FIG. 18. The notch 70 is sized, shaped and positioned to receive the tapered key 63 of the locking lever 59 when the locking lever is under the bias of the second spring 58, as shown in fig. 15. Release of the cutting guide 54 can be easily accomplished by depressing the free end of the locking lever 59, overcoming the bias of the second spring 58, and disengaging the notch 70 of the mounting member 65 from the tapered wedge.

The fixation pin (or K-wire) guide portion 66, tibial cut guide portion 67 and femoral cut guide portion 68 all have a crescent shape that extends in a medial-lateral direction around the physiologic curvature of the anterior medial or lateral tibia (depending on which cut is desired), as shown in fig. 13. The fixation pin guide portion 66 is adjacent the mounting member 65 and defines a plurality of fixation pin holes 72, the fixation pin holes 72 extending rearwardly at an angle to guide fixation pins (for securing the cutting guide 54 prior to release of the other components of the assembly 10) into the thickest anterior portion of cortical bone on the tibia 12. Although not most preferred, the number and orientation of the fixation pin holes may vary depending on the desired degree of security of the connection, the size and configuration of the tibia 12, and the like.

The tibial cutting guide portion 67 is positioned adjacent to the fixation pin guide portion 66 and defines a slot for guiding a tibial cut. The slot extends along the length of the crescent shape of the guide portion 67 and is oriented generally parallel relative to the tibial plateau. However, the resection plane defined by the guide portion 67 may vary in posterior slope (sagittal plane angle) and varus/valgus (coronal plane angle), depending on the desired position and preference of the surgeon for the cutting guide 54. An example of such a cut is shown in fig. 19, where the tibia has a flat planar cut that extends in the anterior-posterior and medial-lateral sides of the proximal end of the tibia 12. The femoral cut guide portion 68 is proximally spaced from the tibial cut guide portion 67 by a pair of connecting flanges 73 so as to bridge the knee joint compartment. Similar to the tibial cutting guide portion 67, the femoral cutting guide portion 68 defines a slot that extends along the length of the crescent. However, because the knee is flexed, the cut is directed through the posterior aspect of the condyles of the femur 11.

An advantage of the components of the assembly 10 for positioning cuts during flexion of the knee, including the femoral mount 15, tibial mount 23, flexion bolt 30, locking mechanism 34, flexion guide bearing member 47 and the flexed knee cutting guide assembly 52, is that they are relatively capable of non-invasive, narrow cuts of the anterior soft tissue of the knee (with the patella retracted). In general, as can be seen in fig. 14 and 15, the assembled components for cutting when the knee is flexed are relatively narrow because they extend in a U-shape out of the joint space while providing a strong connection for supporting the cutting guide 54 and providing for quick assembly and disassembly of the components and precise positioning of the flexed knee cutting guide. Considering only the cutting guide 54 (which may be positioned inside the capsular incision), the width of this component is smaller than conventional cutting guides, e.g., in the range of approximately 4 to 5 centimeters, thus allowing them to approach the knee joint in a minimally invasive manner.

The assembly 10 also includes a tool configured to guide cuts when the knee joint is in extension (i.e., the tibia and femur are generally aligned, or the angle of flexion is 0 °), as shown in fig. 19-29. For extension of the knee joint, both the femoral IM rod 13 and the tibial IM rod 14 remain in place, as shown in FIG. 19. However, rather than the tibial mount 23 being connected to the tibial IM rod 14, the tibial angulation guide 74 is attached to the tibial IM rod. Tibial angulation guide 74 includes gauge block 76 and post 97, which post 97 fits into extension bolt 96 (similar to flexion bolt 30, but without bushing 33). The extension bolt 96 also has a hexagonal flange 75. Alternatively, a separate gauge block 76 may be used with a shaft (as shown in FIG. 6) that extends into an opening in bushing 33 to avoid release of bolt 30.

In any event, when the threaded shaft of the attachment bolt 96 extends into the threaded opening 29 and defines the arcuate surface 77 and the plurality of scale markings 78, the gauge block 76 extends upwardly from the plateau flange 28 of the tibial mount 23, wherein the scale markings 78 are defined on the front surface of the threaded shaft, as shown in fig. 19-21. The arcuate surface 77 is shaped and dimensioned to receive the outer surface of the cylindrical femoral mount 15 and allow the femoral mount 15 to rotate in the varus and valgus directions and slide in the anterior and posterior directions. These movements are free so as not to over-constrain the femur 11 and tibia 12, but still facilitate the anterior and posterior alignment of the instrument and the choice of rotational position to obtain better positioning of the tibial and femoral cuts. Other variations and combinations of the shapes of the femoral mount 15 and tibial angulation guide 74 may be used to allow these ranges of articulation, such as by interchanging the shapes of the gauge block 76 (which is cylindrical) and the femoral mount 15 (which is arcuate), by providing a circle between the two planes, extending the flexion reading device away from the instrument assembly, etc., and still be within the scope of the present invention.

Similar to the technique employed in the flexion position, the relative proximal-distal positioning of the femur 11 and tibia 12 is accomplished by adjusting the rotation of the hexagonal flange 75 of the extension bolt 96 with a torque wrench. This movement causes the threaded shaft of the tibial attachment bolt 96 to enter or exit the threaded opening 29 in the tibial mount 23 and the tibial angulation guide 74 to move anteriorly toward the femoral mount 15. Preferably, the femur 11 and tibia 12 are separated until the torque wrench has a reading similar to that of the knee in flexion to ensure that the joint is not too tight in knee extension. With respect to the torque wrench and the size of the joint gap, the torque wrench may be equipped with an extender that extends the length of the wrench, has a hexagonal slot (jaw) at its end, and has a relatively thin low profile. If so, the torque measurement may be adjusted to compensate for the additional length of the extender. In both cases the aim is to match the torque values obtained when the instrument structure forces the knee joint to bend to some extent, in this case 90 ° of bending or more, and to rotate the bolt to similar torque measurements that were achieved on the torque wrench at an early stage, or until sufficient tension of the ligamentous structure was obtained.

Referring again to fig. 20 and 21, the gauge marks 78 of the gauge block 76 radiate outward from the center of rotation of the femoral mount 15, starting at the outer surface of the femoral mount and located on the anterior surface of the gauge block. The gauge marks 78 of the gauge block 76 are configured to match the gauge marks 21 of the femoral mount 15 (shown by the arrow) to indicate the valgus angle of the tibia 12 relative to the femur 11. Typically, the valgus angle should be in the range of 3 to 7 degrees, or even 2 to 9 degrees, depending on the anatomy of the knee joint, surgeon preference, etc.

Once the angle and proximal-distal positioning of the tibia 12 is adjusted relative to the femur 11, the extension guide support member 79 is attached to the femoral mount 15 using the second locking mechanism 84, as shown in fig. 22 and 23. Generally, the second locking mechanism 84 includes the plunger 36 (components of which include the hexagonal end 44), the hexagonal extension 37, and the helical slot 43, which are generally the same in number because they serve the same function as the same components of the first locking mechanism 34. The second locking mechanism 84 differs in that its head 39 is longer, cylindrical, and lacks the elongate portion 38 of the arm 35. In addition, the second locking mechanism 84 includes a gripping flange 86 positioned adjacent the plunger 36 that facilitates gripping when the plunger is depressed. Regardless, the hexagonal end 44 has the same rotational movement that facilitates quick connection of the end of the second locking mechanism 84 to the femoral mount 15.

The extension guide support member 79 includes a mounting portion 80, a support arm 81, and a fixing flange 82. The mounting member 80 has a cylindrical shape and has a cylindrical opening 83 extending therethrough that is configured to slidably receive the second locking mechanism 84, but is not rotationally constrained by the second locking mechanism 84. Extending from one side of the mounting member 80 is a support arm 81 which is an elongate structure having a T-shaped cross-section. Extending from the other side of the mounting 80 is an auxiliary flange 82 which serves as a housing for the mechanism, in this case a ball and spring 85, to provide some resistance to rotation of the extension guide support member 79 relative to the second locking mechanism 84.

Also included in the illustrated embodiment of the assembly 10 is an extended knee cutting guide 87 which is supported by the extended guide support member 79 during positioning, as shown in fig. 24-29. The extended knee cutting guide 87 includes a mounting member 88, a fixation pin (or K-wire) guide portion 89, a femoral cut guide portion 90, and a reference rod 91. The mounting member 88 is generally centered in the body portion of the extended knee cutting guide 87 and defines a channel 92 having a cross-sectional shape that matches the T-shaped cross-section of the support arm 81. The matching shape allows the extended knee cutting guide 87 to slide along the support arm 81 in the proximal-distal direction.

The fixed pin guide portion 89 defines a plurality of K-wire holes 93 (or other types of fasteners, e.g., bolts, nails, etc.), which holes 93 allow for fixation with fixed pins after the extended knee cutting guide 87 is positioned. When positioned, the holes 93 are located on the medial and lateral sides of the anterior femur to allow fixation to relatively thick cortical bone, as shown in fig. 25. With the K-wire hole 72, the K-wire hole 93 can be oriented at various angles, or selectively positioned to guide a fastener into and through a longer length of compact bone on the femur 11.

The femoral resection guide 90 extends either outward or inward for reconstructing a consistent compartment (as in the illustrated embodiment) or in both directions for a total resection of the femoral condyle. In particular, when the extended knee cutting guide 87 is in place (as shown in fig. 29), the guide portion 90 extends distally in a U-shape that encircles the second locking mechanism 84. Regardless, the guide portion 90 extends distally from the K-wire guide portion 89 and then outwardly or inwardly to define the guide slot 94. The guide slots 94 are of sufficient width to allow the passage of a cutting tool or blade, but still promote relatively straight or flat resection. In particular, the inward extension allows for avoiding the patella from moving outward by accessing the knee joint compartment with an inward orientation.

Extending further distally from the femoral cut guide portion 90 is a portion of the extended knee cutting guide 87 that defines a clevis 95 that rotatably supports the reference bar 91. The reference rod extends outward or inward and rotates in an anterior-posterior direction to allow positioning within the joint compartment, as shown in fig. 24 and 25. The reference bar 91 has a wide, flat distal face that is positioned to rest on the flat tibial cut and a flat lateral face that is positioned to abut the side of the plateau flange 28. These surfaces prevent distal movement of the extended knee cutting guide 87 along the support arm 81 of the extended guide support member 79. With the reference rod 91 and the second locking mechanism 84 in place, fixation pins may be inserted through the pin holes 93 into the guide portion 89 to secure the femoral cut guide portion 90 to the femur 11. This allows for removal of the extension guide support member 79 as shown in fig. 27, 28 and 29.

Advantageously, the components for positioning the cuts with the knee in extension include the extension bolt 96, the tibial angulation guide 74, the extension guide support member 79 and the extended knee cutting guide 87, which are configured to pass through by approaching the knee compartment anteriorly and medially due to the narrow width and sides of the components. For example, as shown in FIG. 25, the rear portion of the second locking mechanism 84 and the reference bar 91 will pass through the cutout and have the narrowness and low profile described above. Preferably, the width of this component is smaller than conventional cutting guides, for example, in the range of approximately 4 to 5 centimeters, thus allowing them to approach the knee joint in a minimally invasive manner.

After this initial cutting, further cutting is performed using the initial cutting as a reference. As shown in fig. 30 and 31, an L-shaped plate 99 is used to abut the posterior distal plane of the femur 11 to guide the anterior cut. Chamfer cuts (front and rear) may be made with the chamfer module and other finish cuts may be made with reference to the initial cut made with the assembly 10 of the present invention. Additional descriptions of these finishing cuts may be found in U.S. patent application 10/794,188 filed 3/5/2004, entitled "Reference Mark Adjustment device for Femoral clamping and Method of using the Same," which is incorporated herein by Reference.

In another embodiment of the present invention, as shown in fig. 32-40, the assembly 10 includes additional module options to facilitate faster assembly. As shown in fig. 32, the femoral IM rod 13 includes a second femoral mount 100. The secondary femoral mount 100 is saddle or crescent shaped and extends outwardly and distally from the central link to the distal end of the main shaft 16 of the femoral IM rod 13. An opening 101 is defined in the medial side of the saddle (convexly curved surface) that is configured to receive a femoral mount post 102 that supports the femoral mount 15, as shown in fig. 33.

Referring again to fig. 32, the tibial IM rod 14 includes a modification of the tibial mount 23 supported by the shaft 22. Specifically, the plateau flange 28 of the tibial mount 23 has a widened rectangular shape that extends laterally outward from the threaded opening 29. A pair of pilot mounting openings 103 are defined in the forward side of the platform flange 28, the pilot mounting openings 103 extending rearwardly into the platform flange. As shown in fig. 34, the bent bolt 30 may also be further modular by providing a post 104 for mounting a bushing 33 and a hexagonal flange 32 located within a central opening defined within a hex bolt 105, the hex head bolt 105 including a threaded shaft 31 extending from a top 105 thereof. Fig. 35 and 36 illustrate assembly of the femoral mount 15 and the tibial mount 32, and tension adjustment by raising the hex head bolt 105.

As shown in fig. 37, the assembly 10 also includes a flexed knee cutting guide assembly 52 that includes a flexed knee cutting guide 54 and a direct mount 106. The direct mount includes two posts 107 that are spaced apart and extend from a mounting block 108. The posts 107 are spaced and sized to extend into the guide mounting openings 103, the guide mounting openings 103 being defined within the platform flange 28. The mounting block 108 may be coupled to the tibial mount 32, such as by a sealed magnet 111. The flexed knee cutting guide 54 is attached to and extends distally from the mounting block 108. The flexed knee cutting guide defines a selection of slots 109 for guiding the cutting of the tibia and femur.

The posterior femoral cut may be accomplished by moving the flexed knee cutting guide assembly 52 up and down, or by using another module which may be a variation of the up and down motion cutting guide assembly 52 wherein the selection of cutting guides 54 and slots 109 are moved toward the post 107, thus closer to the posterior femoral condyle of the knee. The slot 109 of the cutting guide assembly 52 may be selected such that the slot is attached centrally as shown, or may be open centrally and attached along both sides of the cutting guide 54.

As shown in fig. 38 and 39, the tibial IM rod 14 includes a valgus adapter member 110 or a modification of the femoral mount 15 that itself has a post configured to be inserted into the central opening of the hex head bolt 105. As shown in fig. 40, the valgus adapter member 110 is convex in shape and is configured to extend into the concave second femoral mount 100. This match allows for positioning of the cuts at a varus-valgus (varus-valgus) angle when the knee is extended, similar to the first embodiment described above. An extended knee cutting guide may be mounted via a strut 107, similar to a flexed knee cutting guide.

The assembly 10 of the present invention has a number of advantages. It provides a relatively narrow, low profile combination of locking components that securely attach the cutting guide to the tibial and/or femoral IM rods. This provides a reliable guide for reference cuts to the tibia and femur, with reduced invasiveness of access to the joint. Further, many of the components, such as the first and second locking mechanisms 34, 84 and the quick release mechanism 53, facilitate quick assembly, easy adjustment, and quick disassembly, thereby improving efficiency. The use of the bolts 30 and 96 or 105 and the tibial angulation guide 74 or valgus adapter component 110 allows the tibia and femur to distract under a matching amount of torque during flexion and extension, thereby ensuring a better fit of the tibial and femoral knee replacement components throughout the range of flexion. In addition, the tibial angulation guide allows the surgeon to adjust the amount of valgus angulation of the tibia as desired to match the anatomy of the patient.

In another embodiment of the invention, as shown in fig. 41, the improved femoral mounting stem 102 and femoral mount 15 can be used with a retractor stem, the femoral mount 15 having a hinge mechanism that attaches the mount 15 to the femoral mounting stem 102, the retractor stem being placed through a hole 18 in the femoral mount 15 and guided posteriorly to the tibia, thus providing a fulcrum and lever arm for the retractor to move the tibia anteriorly or anteriorly to allow it to be exposed for placement of the entire knee arthroplasty tibial component after a bone cut is made. Since the IM rods are rigidly mounted to the bone, additional retractors may also be attached to the guide assembly to facilitate knee exposure during knee surgery.

In another embodiment of the invention, as shown in fig. 42, a small trial component, or a trial component that is smaller but shaped to have the same thickness and radius as the actual knee arthroplasty graft in order to fit in the hole 101 of the femoral IM rod 13 and the hole 29 of the tibial IM rod 14 and articulate in the central portion of the knee, can be used to check alignment and ligament stability prior to placement of the actual final knee arthroplasty graft. The system of small knee arthroplasty implants positioned in this pair can be independent total knee arthroplasty. One advantage of this embodiment of the invention is that smaller appliances occupy less space. The mini-trial femoral component may be designed with cutting surfaces or slots for chamfer cuts and other finishing cuts, thus eliminating the need for the chamfer cut module and L-plate 99 shown in fig. 30 and 31.

In another embodiment, because the guide assembly is rigidly mounted to the bone and left in place during the main step of knee preparation, a computer-assisted guide is attached to the guide assembly instrument, thus facilitating computer-assisted total knee replacement.

In some embodiments, the guide assembly instruments can be varied to be used with short IM rods or tibial platforms instead of IM rods for extramedullary knee preparation.

In some embodiments, the guide assembly holds the patient's leg in place. This reduces the need for medical assistance for holding the patient's leg.

Those skilled in the art will appreciate that the invention disclosed herein is capable of many modifications and other embodiments, which have the advantages of the technology disclosed in the foregoing description and the accompanying drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (34)

1. An assembly for guiding resection of a femur and a tibia of a knee joint in preparation for installation of femoral and tibial knee components, the knee joint having a tissue structure connecting the femur and the tibia, the assembly comprising:

a femoral component configured for fixation to a femur;

a tibial component having a tibial mount coupled to a tibial intramedullary rod, the tibial mount further including a threaded opening extending into a portion of the tibial intramedullary rod, the tibial component configured for fixation to a tibia;

a tension assembly configured to adjust the positioning of the femoral and tibial components relative to one another to achieve a desired amount of tension in the anatomy of the knee joint; and

a cutting guide configured to attach to at least one of the femoral component, the tibial component, or the tension assembly and guide a cut of at least one of a tibia or a femur.

2. The assembly of claim 1, wherein the tension assembly includes a torque mechanism configured to separate the femoral component and the tibial component in response to application of a controlled torque.

3. The assembly of claim 1, wherein the tensioning assembly includes a tensioning mechanism configured to separate the femoral component and the tibial component in response to application of a controlled or tensioning force.

4. The assembly of claim 2, wherein the torque mechanism includes a threaded shaft configured to threadably couple with the threaded opening in the tibial mount.

5. The assembly of claim 2, wherein the torque mechanism defines the threaded opening.

6. The assembly of claim 4, wherein the torque mechanism is a detent mechanism.

7. The assembly of claim 2, wherein the femoral component comprises a femoral mount having an opening, and wherein the torque mechanism comprises a threaded shaft configured to couple with the opening of the femoral mount.

8. The assembly of claim 7, wherein the opening of the femoral mount is a threaded opening.

9. The assembly of claim 7, wherein the torque mechanism further comprises a first end configured to extend into the unthreaded opening of the femoral mount and a second end configured to extend into the threaded opening of the tibial mount.

10. The assembly of claim 7, further comprising a hinged femoral mount that allows a retractor to be inserted into a hole in the femoral mount to act as a fulcrum and lever arm to displace the tibia from the femur to facilitate placement of a total knee arthroplasty implant.

11. The assembly of claim 10, wherein the retractor facilitates exposure of a knee joint.

12. The assembly of claim 7, further comprising a trial component shaped to have the same thickness and radius as an actual knee arthroplasty implant to fit in a hole in a femoral intramedullary rod and a hole in a tibial intramedullary rod and hinged in a central portion of the knee joint to allow pre-trial alignment, ligament balancing, and stability of knee joint preparation, wherein the femoral component comprises a femoral intramedullary rod extending from the femoral mount and configured for insertion into a medullary canal of a femur.

13. The assembly of claim 12, wherein the trial component is a standalone total knee arthroplasty prosthesis.

14. The assembly of claim 9, wherein the torque mechanism includes at least one torque-wrench attachment surface that allows a threaded portion of the torque mechanism to rotate to threadably couple with the threaded opening to separate the tibial mount from the femoral mount.

15. The assembly of claim 14, wherein the femoral component comprises an intramedullary rod extending from the femoral mount and configured for insertion into a medullary canal of a femur, and wherein the tibial intramedullary rod extends from the tibial mount for insertion into a medullary canal of a tibia.

16. The assembly of claim 15, wherein the opening defined in the femoral mount extends in an anterior-posterior direction relative to the femur, and wherein the opening defined in the tibial mount extends in a proximal-distal direction relative to the tibia.

17. The assembly of claim 16, wherein the opening in the tibial mount is threaded and the opening in the femoral mount is unthreaded.

18. The assembly of claim 16, wherein the femoral mount has a curved surface, and wherein the tibial mount further comprises a block having a curved surface configured to receive the curved surface of the femoral mount and allow varus-valgus rotation of the tibial component relative to the femoral component.

19. The assembly of claim 18, wherein the femoral mount is cylindrical and has an axis extending in an anterior-posterior direction relative to the femur, and wherein the module curves and has an axis extending in an anterior-posterior direction relative to the tibia.

20. The assembly of claim 19, wherein the opening in the femoral mount extends along an axis of the femoral mount and includes an anterior end and a posterior end, wherein the posterior end of the femoral mount is configured to receive one end of the torque mechanism, and wherein the anterior end of the femoral mount is configured to receive a portion of the cutting guide.

21. The assembly of claim 20, further comprising a scale indicating a varus-valgus angle, wherein the scale is located on at least one of the tibial and femoral components.

22. The assembly of claim 1, wherein the tension assembly is configured to adjust the relative positioning of the tibia and the femur at a plurality of knee flexion angles.

23. The assembly of claim 22, wherein the plurality of knee flexion angles includes a knee range of motion including a fully extended angle and a flexion angle greater than 60 degrees.

24. The assembly of claim 23, wherein the bend angle greater than 60 degrees is about 90 degrees.

25. The assembly of claim 1, wherein the femoral component comprises a femoral stem configured to be inserted into a medullary canal of a femur and the tibial stem is configured to be inserted into a medullary canal of a tibia.

26. An assembly for guiding resection of a femur and tibia of a knee joint in preparation for installation of a femoral and tibial knee prosthesis, the assembly comprising:

a femoral intramedullary rod configured to extend within a medullary canal of a femur;

a tibial intramedullary rod configured to extend within a medullary canal of a tibia;

a first mount secured to a first end of the tibial intramedullary rod, the first mount including a threaded opening extending into an interior of the tibial intramedullary rod;

a second mount secured to a first end of the femoral stem, the second mount including an opening extending into an interior of the femoral stem;

a cutting guide configured to guide resection of at least one of a tibia or a femur in preparation for attachment of the knee joint prosthesis; and

an outrigger having a first arm with a first end and a second end, the first end of the first arm configured to be coupled to the second mount and extend outwardly and anteriorly from the second mount to an opening defined in soft tissue surrounding a knee joint, the second end of the first arm configured to support the cutting guide.

27. The assembly of claim 26, wherein the opening of the second mount is configured to fittingly receive the first end of the first arm in a fore-aft direction.

28. The assembly of claim 27, wherein the first end of the first arm includes a locking mechanism configured to secure the first end of the first arm within an opening defined in the second mount.

29. The assembly of claim 28, wherein the outrigger further comprises a second arm having a first end supported by the first arm and a second end attached to the cutting guide.

30. The assembly of claim 26, wherein the cutting guide is selected from the group consisting of a flexion cutting guide, an extension cutting guide, a tibial cutting guide, and a femoral cutting guide.

31. The assembly of claim 26, wherein the first arm and the cutting guide have a width in the medial-lateral direction of less than 5 centimeters when secured to a knee joint.

32. The assembly of claim 26, wherein the first arm and the cutting guide have a width of less than 4 centimeters in a medial-lateral direction when secured to a knee joint.

33. The assembly of claim 26, further comprising a tibial angulation guide coupled to a proximal end of the tibial intramedullary rod, wherein the tibial angulation guide extends around a portion of the first mount to register a physiological angle between the tibia and the femur.

34. An assembly for guiding resection of a femur and tibia of a knee joint in preparation for installation of femoral and tibial components of a knee joint prosthesis, the assembly comprising:

a femoral intramedullary rod configured to extend within a medullary canal of a femur;

a tibial intramedullary rod configured to extend within a medullary canal of a tibia;

a femoral mount fixedly coupled to a distal end of the intramedullary rod and defining an opening extending anteroposteriorly through the femoral mount;

a tibial mount fixedly coupled to a distal end of the tibial intramedullary rod and defining a threaded opening extending into an interior of the tibial intramedullary rod;

a tibial angulation guide fixedly coupled to a proximal end of the tibial intramedullary rod, the tibial angulation guide occupying a portion of the femoral mount to register an angle between the tibia and the femur;

a first cutting guide configured to guide resection of at least one of a tibia or a femur with a knee joint in flexion to provide for attachment of a femoral and tibial component of the knee joint prosthesis, the first cutting guide defining an attachment opening;

an outrigger having a first arm and a second arm interconnected via a base member, wherein the first arm of the outrigger includes a first locking mechanism configured to extend through an anteroposterior opening defined in the femoral mount when the knee is flexed to lock the outrigger thereto, wherein the base member extends generally anteriorly out of the opening defined in soft tissue surrounding the knee, and wherein the second arm extends perpendicular to the base member and parallel to the first arm;

a second cutting guide configured to guide resection of at least one of the tibia or the femur when the knee joint is in the extended position to provide for attachment of a femoral and tibial component of the knee joint prosthesis, the second cutting guide defining an attachment opening for fittingly receiving a portion of the first arm, and the second arm configured to extend through the attachment opening of the second cutting guide to provide support thereto; and

a second locking mechanism configured to extend posteriorly through the attachment opening of the first cutting guide and an anteroposterior opening defined in the femoral mount to interlock the first cutting guide and the femoral mount.