US20210228377A1

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Info

Publication number: US20210228377A1
Application number: US16/775,430
Authority: US
Inventors: Carlos E. Collazo
Original assignee: Howmedica Osteonics Corp
Current assignee: Howmedica Osteonics Corp
Priority date: 2020-01-29
Filing date: 2020-01-29
Publication date: 2021-07-29
Also published as: US12201534B2; US20250195241A1; US20230074908A1

Abstract

Disclosed herein are apparatuses and methods for performing joint balancing procedures. The apparatus may have femoral paddle and a tibial paddle attached to a housing. The housing may include a distraction mechanism to vary the space between the femoral paddle and the tibial paddle. The tibial paddle may lie entirely within the femoral paddle in a closed position. A load sensor may be placed in the femoral paddle to measure ligament tension. The apparatus may be inserted into a knee joint and positioned to remain within the knee joint during flexion and extension of the knee without everting a patella.

Description

FIELD OF INVENTION

The present disclosure relates to an apparatus and a method for performing orthopedic procedures, and in particular to an apparatus and a method for performing joint replacement procedures.

BACKGROUND OF THE INVENTION

Joint replacement procedures generally include replacing a subject's joint with prosthetic joint components. For example, a total knee arthroplasty (“TKA”) procedure includes replacement of the distal end of the femur and the proximal end of the tibia with a femoral prosthesis and a tibial prosthesis, respectively. Multiple bone resections on the distal femur and the proximal tibia are required prior to the implantations of these prostheses. Proper soft-tissue tension, joint alignment and balance are necessary for smooth and well-aligned joint movement.

Various surgical tools such as tensors, balancer, spacers, alignment guides, load indicators, etc. are generally used to perform a TKA. After the initial bone resections of the tibia and/or the femur, a surgeon determines the knee extension and flexion gaps using tools such as spacers, a tensor, or a balancer. Spacers typically consist of a set of one-piece blocks of varying thicknesses that can be inserted into the resected joint space to confirm the flexion and extension gaps. A tensor or balancer generally have multiple components including a set of paddles with telescoping means to allow for insertion into the joint space and distraction in situ. The tensor must be structurally strong enough to withstand substantial loading during flexion and extension of the knee. However, a tensor with large paddles cannot be easily located within the tight joint space, especially during the initial insertion prior to distracting the knee joint.

Knee joint balancing with the tensioner may be performed during the TKA without everting the patella. This generally requires a tensor with sufficiently long linking members and femoral/tibial paddles that are offset to the linking members for the placement of the tensioner in anterior-to-posterior direction without requiring the dislocation of the patella from the trochlear groove of the femur. However, long linking members have a tendency to induce cantilever loading and offset paddles cause torsion loading which reduces the load bearing capability of the tensor. Joint balancing may also be performed by everting the patella which may allow for the use of a tensioner without the attendant problems just mentioned. However, dislocating the patella in this manner can damage the soft tissue of the extensor mechanism. Moreover, a complete and accurate assessment of the joint's balance through a flexion-extension range of motion cannot be assessed.

Furthermore, load sensors which can be used with the tensors to provide real-time ligament tension during the TKA must be placed in contact with the paddles. These sensors further increase the size of the tensor paddles and increase the difficulty of locating the paddles in a tight joint space.

Therefore, there exists a need for an apparatus and a method that allow for soft tissue balancing and proper knee alignment during a knee replacement procedure.

BRIEF SUMMARY OF THE INVENTION

In certain embodiments, the present disclosure relates generally to a tensor with a tibial paddle that can lie within a femoral paddle and methods for performing a joint balancing using the tensor. In other embodiments, the present disclosure relates generally to a tibial spacer and balancer and methods for performing a joint balancing using the tibial spacer and balancer.

In an aspect of the present disclosure, an apparatus for performing an orthopedic procedure on a knee is provided. In accordance with this aspect, the apparatus may include a femoral paddle, a tibial paddle, a load sensor and a housing. The femoral paddle may define a thickness. The femoral paddle may have a proximal side and an opposite distal side. The proximal side may include at least one proximal femoral recess. The distal side may include a distal femoral recess. The tibial paddle may include a tibial proximal side and an opposite tibial distal side. The load sensor may be disposed in the femoral recess to indicate a load on the femoral paddle. The housing may be coupled to the tibial paddle and the femoral paddle. The housing may include a distractor to vary the distance between the tibial paddle and the femoral paddle. The tibial paddle may be disposed within the distal femoral recess in a closed position such that a combined thickness of the femoral paddle, the tibial paddle and the load sensor in the closed position may be substantially the same as the thickness.

Continuing in accordance with this aspect, the femoral paddle may include a plurality of tiered recesses within the distal femoral recess. The tibial paddle may include a plurality of tiered ribs on the tibial proximal side. Each of the plurality of tiered ribs may be disposed within a corresponding tiered recess in the closed position. At least one of the tiered ribs may contact a distal surface of the corresponding tiered recess in the closed position.

Continuing in accordance with this aspect, the femoral paddle may extend along a central femoral paddle axis. The femoral paddle axis may separate the femoral paddle into a femoral medial side and a femoral lateral side. The tibial paddle may extend along a central tibial paddle axis. The tibial paddle axis may separate the tibial paddle into a tibial medial side and a tibial lateral side. The femoral paddle axis and the tibial paddle axis may be parallel to each other and lie on a first plane. A femoral paddle shaft may couple the femoral paddle to the housing and a tibial paddle shaft may couple the tibial paddle to the housing. The femoral paddle shaft may extend along a femoral paddle shaft axis and the tibial paddle shaft may extend along a tibial paddle shaft axis. The femoral paddle shaft axis and the tibial paddle shaft axis may be parallel to each other and lie on a second plane. The first plane may be offset to the second plane.

In a further aspect of the present disclosure, an apparatus for performing an orthopedic procedure on a knee is provided. An apparatus according to this aspect may include a femoral paddle, a tibial paddle and a housing. The femoral paddle may define a thickness. The femoral paddle may have a proximal side and an opposite distal side. The proximal side may include at least one proximal femoral recess. The distal side may include a distal femoral recess. The tibial paddle may include a tibial proximal side and an opposite tibial distal side. The housing may be coupled to the tibial paddle and the femoral paddle. The housing may include a distractor to vary the distance between the tibial paddle and the femoral paddle. The tibial paddle may be disposed within the distal femoral recess in a closed position. A combined thickness of the femoral paddle and the tibial paddle in the closed position may be equal to the thickness.

Continuing in accordance with this aspect, a load sensor may be disposed in the femoral recess to indicate a load on the femoral paddle.

In a further aspect of the present disclosure, a method of performing an orthopedic procedure on a knee is provided. A method according to this aspect may include the steps of resecting a proximal tibia, placing a femoral paddle and a tibial paddle of a tensor in a closed position without everting a patella, distracting the knee joint using a housing coupled to the tibial paddle and the femoral paddle, and measuring knee loads using a load sensor disposed in a femoral recess of the femoral paddle to indicate a load on the femoral paddle. The femoral paddle may contact an unresected distal femur. The tibial paddle may contact the resected proximal tibia in the closed position. The femoral paddle may define a thickness. The femoral paddle may have a proximal side and an opposite distal side. The proximal side may include the at least one proximal femoral recess. The distal side may include a distal femoral recess. The tibial paddle may include a tibial proximal side and an opposite tibial distal side. The housing may include a distractor to vary the distance between the tibial paddle and the femoral paddle. The tibial paddle may be disposed within the distal femoral recess such that a combined thickness of the femoral paddle, the tibial paddle and the load sensor in the closed position may be substantially the same as the thickness.

Continuing in accordance with this aspect, the method may further include the step of taking the knee joint through flexion and extension to measure knee gap and knee tension while the patella remains everted.

In a further aspect of the present invention, a method of performing an orthopedic procedure on a knee is provided. A method according to this aspect may include the steps of placing a femoral paddle and a tibial paddle of a knee balancer in a closed position, distracting the knee joint using a housing coupled to the tibial paddle and the femoral paddle, and measuring knee loads using a load sensor disposed in a femoral recess to indicate a load on the femoral paddle. The femoral paddle may contacts a distal femur and the tibial paddle may contacts a proximal tibia in the closed position. The femoral paddle may define a thickness. The femoral paddle may have a proximal side and an opposite distal side. The proximal side may include the at least one proximal femoral recess. The distal side may include a distal femoral recess. The tibial paddle may include a tibial proximal side and an opposite tibial distal side. The housing may including a distractor to vary the distance between the tibial paddle and the femoral paddle. The tibial paddle may be disposed within the distal femoral recess such that a combined thickness of the femoral paddle, the tibial paddle and the load sensor in the closed position may be substantially the same as the thickness.

In a further aspect of the present invention, a method of trialing a knee joint for determining an appropriate size for a tibial insert is provided. A method according to this aspect may include the steps of inserting first and second members into a space between a tibia and a femur, engaging a first concave surface of the first member with a first condylar portion of a femoral component or femur, operating an adjustment mechanism to move the first and second members apart a first known distance corresponding to a first size tibial insert, and articulating the first condylar portion of the femoral component or femur with the first condylar portion of a tibial component or tibia through a range of flexion and extension motion to assess the knee joint at the first known distance. The first and second members may be connected to an adjustment mechanism. The first member may have the first condylar portion defining a first concave surface.

Continuing in accordance with this aspect, the second member may include a first plate and a first arm. The first plate may include the first condylar portion of the first member. The first arm may be connected to the adjustment mechanism. The method may further include the step of connecting the first arm to the first plate. The step of connecting the first arm to the first plate may include sliding the first arm in a lateral-medial direction into a recess defined in a bottom side of the first plate. The step of connecting the first arm to the first plate may include sliding the first arm in an anteroposterior direction into a recess defined in a bottom side of the first plate.

Continuing in accordance with this aspect, the method may include the step of operating the adjustment mechanism to move the first and second members apart a second known distance corresponding to a second size tibial insert, articulating the first condylar portions of the first member and femoral component to assess the knee joint at the second known distance.

Continuing in accordance with this aspect, the operating step may be performed by rotating a rack engaged to a pinion.

Continuing in accordance with this aspect, the engaging step may include engaging a second concave surface of a second condylar portion of the first member with a second condylar portion of a femoral component.

Continuing in accordance with this aspect, the method may further include engaging a bone contact surface of the second member with a resected proximal surface of the tibia. The second member may include a second plate and a second arm. The second plate may include the bone contact surface. The second arm may be connected to the adjustment mechanism. The method may further include connecting the second arm to the second plate.

In a further aspect of the present disclosure, a tibial trial system is provided. A tibial trial system according to this aspect may include an upper plate with an upper articular surface, an upper arm, a lower arm and an adjustment mechanism connected to the upper and lower arms. The upper articular surface may have condylar portions each defining a concave surface configured to articulate with a corresponding condylar portion of a femoral component. The adjustment mechanism may be configured to move the upper and lower arms relative to each other. The upper arm may be separately formed from the upper plate and may be connectable to the upper plate.

Continuing in accordance with this aspect, the adjustment mechanism may be connected to a respective outer end of each of the upper arm and lower arm and configured to adjust a spacing between the upper and lower arms in a proximal-distal direction when the upper and lower arms are disposed between a proximal tibia and distal femur.

Continuing in accordance with this aspect, the adjustment mechanism may be a rack and pinion mechanism. The adjustment mechanism may include a shaft extending in a transverse direction relative to a direction of the spacing and may include a series of teeth extending along the shaft. A gear may be disposed within a housing and operatively engaged with the series of teeth. The shaft may be connected to the upper arm. The housing may be connected to the lower arm.

Continuing in accordance with this aspect, the upper plate may have a lower side opposite the articular surface. The lower side may define a recess configured to receive the upper arm. The recess may extend in a lateral-medial direction such that the upper arm may be slidingly received by the recess from a lateral or medial side of the upper plate. The recess may extend in an anteroposterior direction such that the upper arm may be slidingly received by the recess from an anterior side of the upper plate. The recess may define a pair of opposing grooves which may be configured to receive opposing side edges of the upper arm.

Continuing in accordance with this aspect, the system may include a lower plate having a bone contact surface configured to engage a proximal resected surface of a tibia. The lower arm may be configured to connect to the lower plate.

Continuing in accordance with this aspect, the lower arm may have a planar bone contact surface configured to engage a proximal resected surface of a tibia.

In a further aspect of the present disclosure, an adjustable tibial trial insert assembly is provided. An adjustable tibial trial insert assembly according to this aspect may include an upper plate, an upper arm, a lower arm and an adjustment mechanism. The upper plate may include an upper articular surface configured to allow a femoral component to articulate through a range of motion in flexion and extension therewith. The upper arm may be releasably connected to the upper plate and extend in a transverse direction relative to an axis of the tibia when the upper arm is disposed between a proximal tibia and a distal femur. The lower arm may extend in the transverse direction. The adjustment mechanism may be connected to each of the upper arm and lower arm and configured to adjust a spacing between the upper plate and the lower plate.

Continuing in accordance with this aspect, the lower arm may have a planar surface configured to contact a proximal resected surface of a tibia.

Continuing in accordance with this aspect, the trial insert may further include a lower plate that may have a lower surface configured to engage a proximal resected surface of a tibia. The upper arm may be releasably connected to the lower plate.

Continuing with this aspect, the articular surface may include a pair of concave surfaces for engaging respective distal condyles of a femoral component. The concave surfaces may each extend in an anteroposterior direction. The upper arm and the lower arm may extend in a lateral-medial direction.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the subject matter of the present disclosure and the various advantages thereof can be realized by reference to the following detailed description, in which reference is made to the following accompanying drawings:

FIG. 1 is a perspective side view of a tensor of the present disclosure;

FIG. 2 is a perspective top view of a femoral paddle of the tensor ofFIG. 1;

FIG. 3 is a perspective bottom view of the femoral paddle ofFIG. 2;

FIG. 4 is a perspective side view of a tibial paddle of the tensor ofFIG. 1;

FIG. 5 is a perspective side view of a housing of the tensor ofFIG. 1;

FIG. 6 is a side cross-sectional view of an adjuster along line A-A of the housing ofFIG. 5;

FIG. 7 is a partial side cross-sectional view of the tensor ofFIG. 1 along line B-B;

FIG. 8 is a schematic top view of the tensor ofFIG. 1 placed in a knee joint;

FIG. 9 is a perspective view of a load sensor of the tensor ofFIG. 1;

FIG. 10 is a side view of the tensor ofFIG. 1 placed in a knee joint;

FIGS. 11A-C are top cross-sectional views of the femoral paddle and the tibial paddle of the tensor ofFIG. 1;

FIG. 12 is a side perspective view of a balancer according to another embodiment of the present disclosure;

FIG. 13 is a perspective view of a flat tibial trial used with the balancer ofFIG. 12;

FIG. 14 is a perspective view of a set of articular tibial trials used with the balancer ofFIG. 12;

FIG. 15 is a schematic view of an articular tibial trial ofFIG. 14 and the balancer ofFIG. 12;

FIG. 16 is a schematic view of the articular tibial trial ofFIG. 14 placed on the balancer ofFIG. 12, and

FIG. 17 is a front perspective view of a balancer according to another embodiment of the present disclosure.

DETAILED DESCRIPTION

In describing preferred embodiments of the disclosure, reference will be made to directional nomenclature used in describing the human body. It is noted that this nomenclature is used only for convenience and that it is not intended to be limiting with respect to the scope of the invention.

As used herein, when referring to bones or other parts of the body, the term “anterior” means toward the front part or the face, and the term “posterior” means toward the back of the body. The term “medial” means toward the midline of the body, and the term “lateral” means away from the midline of the body. The term “superior” means closer to the heart, and the term “inferior” means more distant from the heart.

Reference will now be made in detail to the various embodiments of the present disclosure illustrated in the accompanying drawings. Wherever possible, the same or like reference numbers will be used throughout the drawings to refer to the same or like features. It should be noted that the drawings are in simplified form and are not drawn to precise scale. Additionally, the term “a,” as used in the specification, means “at least one.” The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import. Although at least two variations are described herein, other variations may include aspects described herein combined in any suitable manner having combinations of all or some of the aspects described. As used herein, the terms “distractor” and “tensor” will be used interchangeably and as such, unless otherwise stated, the explicit use of either term is inclusive of the other term. Similarly, the terms “aperture,” “hole,” and “recess” will be used interchangeably and as such, unless otherwise stated, the explicit use of either term is inclusive of the other term.

Referring now toFIG. 1, there is shown a perspective view of atensor10 according to an embodiment of the present disclosure.Tensor10 includes afemoral paddle100 and atibial paddle200 attached to ahousing300.Tensor10 can be used to perform various functions during a TKA procedure to achieve the desired knee joint biomechanics as more fully described below. Whiletensor10 described herein is configured to be placed in a subject's left knee joint in an anterior-to-posterior direction, it should be understood that the features oftensor10 are similar for a tensor configured to be placed in a subject's right knee in an anterior-to-posterior direction. It is also envisioned thattensor10 can be placed in subject's knee joint from a posterior-to-anterior, medial-to-lateral, or lateral-to-medial direction. In such embodiments,housing300 connects to femoral and

tibial paddles

100,200 at different locations depending on the approach. For example, where the approach is lateral-to-medial,housing300 connects to a lateral side of

paddles

100,200.

FIG. 2 shows a top view offemoral paddle100 oftensor10.Femoral paddle100 includes afemoral plate102 having a thickness T1.Femoral plate102 extends along a femoral plate axis L4, which dividesfemoral plate102 into a femorallateral side107 and a femoralmedial side105. Arecess110 runs along the peripheral edge offemoral plate102 and serves as a receptacle to receive a load sensor. Ashaft106 extending fromfemoral plate102 along a shaft axis L1 couplesfemoral paddle100 tohousing300.Shaft106 can be rotated either manually or with a suitable tool around shaft axis L1. A groove or notch108 at the distal ofshaft106 allows for attachment of the tool that can be used to rotatefemoral plate102. As best shown inFIG. 2, shaft axis L1 is offset from femoral plate axis L4.Femoral paddle100 includes aslot104 to receive a corresponding post fromhousing300 as explained below.

Referring now toFIG. 3, there is shown a bottom view offemoral paddle100.

Tiered pockets

112,114,116,118 are located across femorallateral side107 and femoralmedial side105. The tiered pockets are sized and positioned to receive corresponding tiered ribs fromtibial paddle200 as more fully described below. In addition,

tiered pockets

112,114,116, and118 are located at different depths withinpaddle100.

FIG. 4 shows a top view oftibial paddle200. Tibial paddle includes atibial plate202 extending along a tibial plate axis L5. Atibial shaft207 extends fromtibial plate202 along a shaft axis L7. Tibial shaft axis L7 and shaft axis L1 lie on a first plane parallel to a second plane containing the femoral plate axis L4 and the tibial plate axis L5 (not shown). The tibial shaft includes structural reinforcements such asstructure209 to structurally strengthentensor10 and maximize load capacity of the tensor. Abore206 located ontibial shaft207 extends transverse to the tibial shaft and is configured to receive a corresponding shaft fromhousing200. A distraction mechanism—e.g., ascrew210 attached to bore206 in this embodiment, allows for translation offemoral paddle100 in reference totibial paddle200. Ananti-rotation post208 configured to be received in a corresponding recess ofhousing300 prevents rotation oftibial paddle300.Various holes204 located ontibial paddle200 serve as drill guides or alignment references during a balancing procedure. A set of

tiered ribs

212,214,216 and218 are provided on a proximal side oftibial plate202 as best shown inFIG. 4. Such

tiered ribs

212,214,216, and218 extend from the proximal side at differing heights which correspond to the depths of the respective

tiered pockets

112,114,116, and118. In this regard, each tiered rib is configured to lie within a corresponding tiered pocket offemoral plate102. Whentibial plate202 andfemoral plate102 are brought together by the distraction mechanism, the

tiered ribs

212,214,216,218 oftibial plate202 are designed to be positioned within the corresponding

pockets

112,114,116,118 offemoral plate102 such thattibial plate202 lies completely withinfemoral plate102.

FIGS. 11A-11C show cross-sectional views of the tiered rib and pocket interface oftensor10 in a collapsed state when thetibial plate202 lies entirely withinfemoral plate102. As shown inFIG. 11A,tiered rib212 oftibial plate202 is received withinpocket112 offemoral plate102. Similarly,tiered rib216 is received in pocket116 (FIG. 11B) andtiered rib218 is received in pocket118 (FIG. 11C) whentensor10 is in the collapsed state. The tiered rib and pocket interface allow for increased load bearing capacity oftensor10 while simultaneously ensuring a low paddle profile to allow the tensor to be placed in the narrow gap between a femur and a tibia. For example, the combined thickness T1 of the femoral paddle, sensor array and the tibial paddle is constructed to be 6.1 mm or less. Despite this low profile, the tiered pockets, tiered ribs and reinforcing gussets enable the tensor to be robust enough to withstand at least 200 pounds per condyle or a total of at least 400 pounds. While a femoral plate with tiered pockets and a tibial plate with tiered ribs is shown in the present embodiment, in another embodiment the femoral plate can have tiered ribs and the tibial plate can have corresponding tiered recesses.

Referring now toFIG. 5, a perspective view ofhousing300 is shown.Housing300 includes ashaft306 designed to be placed inbore206 to couple the housing withtibial paddle200. Abore304 extending transverse toshaft306 is configured to receiveshaft106 offemoral paddle100 to couple the housing with the femoral paddle. Abore308 is configured to receiveanti-rotation post208 fromtibial paddle200 in order to prevent rotation oftibial paddle200 with reference tohousing300. Anadjuster302 for varying varus-valgus of the joint is located onhousing300 allowing for linear translation offemoral plate102 as more fully explained below.

FIG. 6 shows a cross-sectional view ofadjuster302 along line A-A ofFIG. 5.Adjuster302 includes ascrew314 located betweenend washers310 and anend cap312. The adjuster has apost316 extending fromscrew314 that can be placed inslot104 offemoral paddle100. Screw threading318 ofscrew314 allow the adjuster to translate thefemoral plate102 viapost316. This translation allows for varus-valgus adjustment of the knee described below.End washers310 andend cap312 restrict movement of the femoral paddle confining translation of the femoral plate to rotation ofscrew314.

FIG. 7 shows a cross-sectional view along line B-B ofFIG. 1 depicting the various adjustment mechanisms oftensor10.Shaft106 offemoral paddle100 can be rotated about shaft axis L1 to movefemoral paddle102 to various positions to adjust varus/valgus rotation of the knee for a desired joint orientation. For example,shaft106 can be rotated counterclockwise to locate femoral plate to asecond position102′ to provide avalgus rotation angle322. Similarly,shaft106 can be rotated in an opposite clockwise direction to locate femoral plate to athird position102″ to provide avarus rotation angle324 as best shown inFIG. 7.Adjuster302 allows for linear translation offemoral plate102 along atranslation axis320 transverse to shaft axis L1. As indicated by the position ofpost316,adjuster302 can move the femoral plate from the first location to asecond location316′ or athird location316″ in the opposite direction. The linear translation alongtranslation axis320 allows a surgeon to control internal and external rotation of the joint. Arotation indicator326 onadjuster302 indicates the external or internal rotation offemoral plate102 as best shown inFIG. 5

Referring now toFIG. 8, there is shown a schematic top view oftensor10 placed over a resectedtibia14 withpatellar tendon12 being moved laterally away to accommodate the femoral and tibial paddles oftensor10. As shown here, the shaft lengths (femoral shaft106 and tibial shaft207) and the plate offsets from shaft axis L1 (femoral plate102 and tibial plate202), allowtensor10 to be located in the knee joint without everting the patella. Femoral load centers during extension and flexion of the knee joint are also shown inFIG. 8. Aload center122 on femoralmedial side105 offemoral plate102 is located on medial load axis L2 representing a femoral medial condyle load during extension and flexion of the knee joint.Load center122 is offset from shaft axis L1 by a distance D1. Femorallateral side107 includes afirst load center124 representing the lateral condyle load in extension of the knee, and asecond load center126 representing the lateral condyle load in flexion. Load centers124 and126 lie on lateral load axis L3 as shown inFIG. 8, which is offset from shaft axis L1 by a distance D2. As distance D2 is greater than D1,tensor10 will be subject torsional loads during balancing. However, the plate offsets allowtensor10 to be placed in anterior-to-posterior direction in a subjects left knee joint without requiring the eversion of the subject's patella. As best shown inFIG. 8,housing300 and

shaft

106,207 can lie medial topatellar tendon12, while the laterally extending femorallateral side107 offemoral plate102 can contact the lateral condyle of the subject.Tensor10 can be maintained in this position while the knee is being taken through its range of motion from flexion to extension during balancing.

FIG. 9 shows a perspective view of aload sensor134 that can be placed inrecess110 offemoral plate102.Load cells132 andsensor load plates134 are sized and shaped to fit withinfemoral plate102 and contact load centers122,124 and126 during flexion and extension to indicate femoral load values. Asensor housing130 can include a processor, a power source and other components necessary for load reading and transmission. The sensor housing is located on the femoral shaft away fromfemoral plate102 to ensure thatonly load cells132 andsensor load plates128 ofload sensor134 are located infemoral plate102 to minimize the thickness of the femoral plate.Tensor10 allows for convenient placement and removal ofload sensor134. Whiletensor10 described herein includes a load sensor, it should be understood thattensor10 can be used without the load sensor.

Referring now toFIG. 10, there is shown a side view oftensor10 placed in a subject's knee joint.Tibial plate202 lies entirely withfemoral plate102 when the femoral and tibial paddles are brought together as shown inFIG. 10. When the paddles are in this collapsed state, the combined thickness of the femoral plate includingload sensor134 and tibial plate is equal to thickness T1 of femoral plate. While a load sensor may lie completely withinrecess110 offemoral plate102 such that the load sensor does not extend past the thickness of femoral plate, in another embodiment the thickness ofload sensor134 may slightly extend past the femoral plate thickness.

Another aspect of the present disclosure is a method for performing a TKA with a tensor such astensor10. After resecting theproximal tibia14,tensor10 with its femoral paddle and tibial paddle fully retracted—i.e., in the collapsed state, is inserted into the knee joint as shown inFIG. 10. The low profile oftensor10 in the collapsed state allows the tensor to be inserted in an anterior-to-posterior direction without resecting aproximal femur16. Of course, the proximal femur can be resected prior to insertion if desired. Furthermore, as more fully described above, the shaft lengths (femoral shaft106 and tibial shaft207) and the plate offsets (femoral plate102 and tibial plate202) from shaft axis L1, allowtensor10 to be located in the knee joint without everting the patella. Once thetensor10 is firmly located in the knee joint, the tensor can be used to perform various functions to measure and achieve the desired knee joint biomechanics.Tensor10 can be maintained in this position while the knee is being taken through its range of motion from flexion to extension during balancing. For example, the femoral paddle and tibial paddle can be separated usingscrew210 to adjust the gap betweentibia14 andfemur16,adjuster302 can be used to translatefemoral plate102 to adjust varus/valgus and internal/external rotation of the knee joint, andshaft106 can be rotate to adjust varus/valgus rotation of knee joint. Furthermore, real-time load values of the lateral and medial condyles offemur16 are measured and communicated to an operator during flexion and extension of the knee joint.

Referring now toFIG. 12, there is shown abalancer400 according to another embodiment of the present disclosure.Balancer400 is an adjustable tibial spacer and balancer that allows for trialing of a tibial spacer during a TKA procedure.Balancer400 includes afemoral plate402 and atibial plate404 coupled to ahousing405.Housing405 includes a rack and pinion distraction mechanism which is used to vary the distance betweenfemoral plate402 andtibial plate404. Arotation indicator410 provided onhousing405 allows for varus/valgus rotation adjustments offemoral plate402. Alock pin412 allows an operator to lock the varus/valgus rotation of femoral plate. The lock pin can be released to rotate the femoral plate to achieve the desired varus/valgus alignment. Once the desired varus/valgus alignment is achieved the lock pin can be activated to secure femoral plate alignment.Thickness indicators416 indicate the tibial spacer size—i.e., distraction gap between the femoral and tibial plates, and can be locked into place once the desired tibial spacer size is achieved.

FIGS. 13 and 14 show various attachments that can be readily attached to adistal end406 offemoral plate402. Aflat tibial trial500 is shown inFIG. 13. Flattibial trial500 includes anopening502 shaped and sized to be removably connected to distal end offemoral plate402. Opening502 can have various features such as grooves, notches, tabs, etc. that can readily attached to mating features present ondistal end406 offemoral plate402. Aflat surface504 of flattibial trial500 contacts a proximal femur or a femoral component when the flat tibial trial is placed in a knee joint. While opening502 shown here extends in an anterior-to-posterior direction, another embodiment can have an opening extending in a medial-to-lateral direction. A flat tibial trial having anopening502 extending in a medial-to-lateral direction can be slidably engaged withbalancer400 and placed in a knee joint in a medial-to-lateral direction to prevent everting of the patella during a TKA. Flattibial trial500 can be attached tobalancer400 and inserted to a knee joint to determine the proper tibial spacer thickness for balanced extension and flexion gaps.Thickness indicator416 is used to lock in the desired thickness.

A set of articular

tibial trials

602,604,606,608 are shown inFIG. 14. The articular tibial trials are similar toflat tibial trial500 and include anopening610 for attachment tofemoral plate402. However, articular tibial trials include an articular surface with concave surfaces to contact medial and lateral condyles of a femur or femoral implant. The articular tibial trials allow the knee joint to be taken through a range of motion from flexion to extension by providing an articular surface for the femoral condyles to articulate during the range of motion. The articular tibial trials are provided in various sizes that can be readily attached and detached fromfemoral plate402. The tibial trial sizes can be limited to a small number, as the distraction mechanism ofbalancer400 can be used to adjust to trial for tibial spacers that are larger or smaller than the available tibial trials. As described above,openings610 of articular tibial trials can extend in a medial-to-lateral direction to allow placement of thebalancer400 in a knee joint in a medial-to-lateral or lateral-to-medial direction.

Another aspect of the present disclosure is a method of trialing a tibial spacer with a balancer such asbalancer400. Flattibial trial500 can be readily attached tofemoral plate402 by slidingopening502 of the flat tibial trial intodistal end406. Depending on the orientation of opening502—i.e., anterior-to-posterior or medial-to-lateral, the balancer with the attached flat tibial trial is inserted into the knee joint in the same direction. For example, if theopening502 extends in a lateral-to-medial direction,balancer400 can be inserted in lateral-to-medial direction into the knee joint with the attached flat tibial trial. The femoral and tibial plates can be distracted usingdistraction mechanism408 if necessary to determine the desired knee gap.

Once these desired gap is achieved, the flat tibial trial can be removed from balancer and an appropriate articular tibial trial can be attached tobalancer400. As shown inFIGS. 15, and 16

articular tibial trial

606 is slidably connected tofemoral plate402 ofbalancer400. The knee joint can now be taken through a range of motion from flexion to extension to determine the desired joint biomechanics and the tibial spacer size. As attachment tibial trials can be easily attached and removed frombalancer400,balancer400 can be removed from the attachment tibial trials once they are placed in the knee joint to facilitate convenient knee flexion and extension.

FIG. 17 shows abalancer700 according to another embodiment of the present disclosure.Balancer700 is a fully adjustable tibial spacer and balancer that allows for trialing of a tibial spacer during a TKA procedure.Balancer700 is similar tobalancer400 but is fully adjustable requiring no tibial trials or trial inserts for trialing of a tibial spacer.Balancer700 includes afirst post706 and asecond post708 that can be adjusted to vary the distance between them as indicated by adistance712 inFIG. 17. Adjusting the distance between the first and second posts allows for adjusting the spacing between medial and lateralfemoral plates702 and medial and lateraltibial plates704 by adistance714. An operator can adjust the size of the tibial insert by varyingdistance712, which will in turn change the distance betweenfemoral plates702 andtibial plates704 via alink710. Thus, femoral and tibial plate sizes can be increased or decreased by manipulatingfirst post706 andsecond post708 ofbalancer700. Whiledistance714 betweenfemoral plates702 andtibial plates704 are simultaneously varied by adjustingdistance712 in this embodiment, in another embodiment distance between the femoral plates and the tibial plates can be individually controlled and adjusted.

Adistance716 betweenfemoral plates702 andtibial plates704 ofbalancer700 is also adjustable. Depending on the required thickness of the tibial insert, an operator can increase or decreasedistance716 to increase or decrease the thickness of femoral and tibial plates of700. Thus,balancer700 provides a fully adjustable tibial inserter allowing an operator to increase the size and thickness of a tibial insert without requiring the need for any tibial inserts. While a typical surgical kit to perform a TKA may include as many as576 different tibial inserts with different sizes, thickness and procedure-specific configurations,balancer700 can be utilized without any tibial inserts asbalancer700 is fully adjustable to assume the shape, size and configuration of any required tibial insert.

While a TKA procedure is generally described in these embodiments, the apparatus and methods of the present disclosure can be used for various other knee and hip procedures or any part of these procedures. The various components oftensor10 andbalancer400 can be modular. For example, the housing oftensor10 can be configured to couple with femoral and tibial paddles of various sizes. Tensors and balancers disclosed herein can be made wholly, or in part, by polymers such as PEEK, carbon fiber reinforced PEEK, PAEK, UHMWPE, metals, ceramics, combinations of the foregoing, or other suitable materials that are biocompatible and possess sufficient strength and rigidity. Near net shape casting, subtractive manufacturing techniques, and additive manufacturing techniques such as 3D printing may be used to fabricate the tensor and balancers of the present disclosure.

Furthermore, although the invention disclosed herein has been described with reference to particular features, it is to be understood that these features are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications, including changes in the sizes of the various features described herein, may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention. In this regard, the present invention encompasses numerous additional features in addition to those specific features set forth in the claims below. Moreover, the foregoing disclosure should be taken by way of illustration rather than by way of limitation as the present invention is defined in the examples of the numbered paragraphs, which describe features in accordance with various embodiments of the invention, set forth in the claims below.

Claims

1. An apparatus for performing an orthopedic procedure on a knee, the apparatus comprising:

a femoral paddle defining a thickness, the femoral paddle having a proximal side and an opposite distal side, the proximal side including at least one proximal femoral recess, the distal side including a distal femoral recess;

a tibial paddle including a tibial proximal side and an opposite tibial distal side;

a load sensor disposed in the femoral recess to indicate a load on the femoral paddle; and

a housing coupled to the tibial paddle and the femoral paddle, the housing including a distractor to vary the distance between the tibial paddle and the femoral paddle,

wherein in a closed position the tibial paddle is disposed within the distal femoral recess such that a combined thickness of the femoral paddle, the tibial paddle and the load sensor in the closed position is substantially the same as the thickness.

2. The apparatus ofclaim 1, wherein the femoral paddle includes a plurality of tiered recesses within the distal femoral recess and the tibial paddle includes a plurality of tiered ribs on the tibial proximal side such that each of the plurality of tiered ribs is disposed within a corresponding tiered recess in the closed position.

3. The apparatus ofclaim 2, wherein at least one of the tiered ribs contact a distal surface of the corresponding tiered recess in the closed position.

4. The apparatus ofclaim 1, wherein the femoral paddle extends along a central femoral paddle axis, the femoral paddle axis separating the femoral paddle into a femoral medial side and a femoral lateral side, and the tibial paddle extends along a central tibial paddle axis, the tibial paddle axis separating the tibial paddle into a tibial medial side and a tibial lateral side.

5. The apparatus ofclaim 4, wherein the femoral paddle axis and the tibial paddle axis are parallel to each other and lie on a first plane.

6. The apparatus ofclaim 5, wherein a femoral paddle shaft couples the femoral paddle to the housing and a tibial paddle shaft couples the tibial paddle to the housing.

7. The apparatus ofclaim 6, wherein the femoral paddle shaft extends along a femoral paddle shaft axis and the tibial paddle shaft extends along a tibial paddle shaft axis.

8. The apparatus ofclaim 7, wherein the femoral paddle shaft axis and the tibial paddle shaft axis are parallel to each other and lie on a second plane.

9. The apparatus ofclaim 8, wherein the first plane is offset to the second plane.

10. The apparatus ofclaim 1, wherein the distractor includes a distraction screw to move the tibial paddle and/or the femoral paddle along a distraction axis transverse to the femoral paddle shaft axis and the tibial paddle shaft axis.

11. The apparatus ofclaim 10, wherein the tibial paddle includes an aperture for receiving an anti-rotation shaft extending from the housing to prevent rotation of tibial paddle about the tibial paddle shaft axis.

12. The apparatus ofclaim 11, wherein the housing includes an adjuster to translate the femoral paddle along an adjuster axis transverse to the distraction axis.

13. The apparatus ofclaim 12, wherein the femoral paddle shaft is rotatable about the femoral paddle shaft axis to rotate the femoral paddle with respect to the distraction axis.

14. The apparatus ofclaim 9, wherein a medial load center of a medial condyle in contact with the femoral medial side lies on a medial load center axis and a lateral load center of a later condyle in contact with the femoral lateral side lies on a lateral load center axis.

15. The apparatus ofclaim 14, wherein a medial offset distance measured between the medial load center axis and the femoral paddle shaft axis along the femoral paddle is less than a lateral offset distance measured between the lateral load center axis and the femoral paddle shaft axis along the femoral paddle.

16. The apparatus ofclaim 15, wherein the lateral offset distance allows the femoral paddle and tibial paddle to be placed between a femur and a tibia in posterior-anterior direction without everting a patella.

17. An apparatus for performing an orthopedic procedure on a knee, the apparatus comprising:

a tibial paddle including a tibial proximal side and an opposite tibial distal side; and

wherein in a closed position the tibial paddle is disposed within the distal femoral recess such that a combined thickness of the femoral paddle and the tibial paddle in the closed position is equal to the thickness.

18. The apparatus ofclaim 17, further including a load sensor disposed in the femoral recess to indicate a load on the femoral paddle.

19. A method of performing an orthopedic procedure on a knee, the method comprising the steps of:

resecting a proximal tibia;

placing a femoral paddle and a tibial paddle of a knee balancer in a closed position without everting a patella, the femoral paddle contacting an unresected distal femur and the tibial paddle contacting the resected proximal tibia in the closed position, the femoral paddle defining a thickness, the femoral paddle having a proximal side and an opposite distal side, the proximal side including at least one proximal femoral recess, the distal side including a distal femoral recess, the tibial paddle including a tibial proximal side and an opposite tibial distal side;

distracting the knee joint using a housing coupled to the tibial paddle and the femoral paddle, the housing including a distractor to vary the distance between the tibial paddle and the femoral paddle; and

measuring knee loads using a load sensor disposed in the femoral recess to indicate a load on the femoral paddle,

wherein the tibial paddle is disposed within the distal femoral recess such that a combined thickness of the femoral paddle, the tibial paddle and the load sensor in the closed position is substantially the same as the thickness.

20. The method ofclaim 19, further including the step of taking the knee joint through flexion and extension to measure knee gap and knee tension while the patella remains everted.