CA1230277A - Distal femoral condyles cutting jig - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A prosthetic knee is implanted after cutting the femor and tibia in the proper manner, implantation being aided by a distal femoral condyles a distal femoral condyles cutting jig comprising a bar, a downwardly extending tongue from said bar for reception securement to attaching means in a distal femoral cutting jig, femoral securing pins extending downwardly from said bar remote from said tongue, a generally vertical cutting guide surface on said bar between said tongue and said securing means, and pin holder guide attaching means on said bar.

Description

~3~'7~7 EYE

This application is divided from applicant's co-pending Canadian application Serial No. 421,712 which was filed on February 16, 1983.
Prosthetic knee components have long been known and used in the art. In order to prepare the lemon and tibia for the components, i-t is necessary to make a series of cuts from these bones to conform to the size and shape of the prosthetic components. Generally these cuts are made by visual reliance on where the cuts should be sometimes with the aid of simply-fled jigs and/or score lines. Such techniques are necessarily imprecise which limits the ability to provide the anatomically most desirable prosthetic knee.
Applicant's cop ending Canadian application No. 421,731, filed February 16, 1983 describes such an anatomically desirable prosthetic knee system.
The affronted prosthesis is designed to reproduce anatomic movement of the knee without compromising stability.
This prosthetic knee, as the natural knee, provides a "screw home mechanism which increases stability in extension. As flaxen proceeds, the femoral condoles initially roll poster-forty. Through asymmetric kindlier and tibia compartments, the natural and changing axes of rotation are preserved, there-by preventing the development of abnormal tension in retained ligaments. When abnormal ligaments tension develops, it either restricts flaxen and increases shear stress at fixation interfaces and/or leads to eventual progressive ligament alien-ration and joint instability. The design also allows natural internal and external rotation of the knee in flaxen.

Furthermore, contouring of the posterior margins of the tibia plateaus facilitates stability in flaxen and provides a broad contact surface. The combination of these factors, which bet-ante soft tissue elements in the joint, minimizes shear stress at the fixation interfaces, enhancing the potential for long term function of the replaced knee.
In order to make such prosthetic knee system lees-isle, the necessary bone cuts must be precisely accomplished.
This, in turn, requires a set of proper instruments including guides and jigs. Such instruments should assure reproducibly accurate bone cuts, prosthetic seating, and lower limb align-mint.
This invention involves a cutting jig which permits the above-noted knee prosthesis to be implanted.
In applicant's aforementioned parent application Serial No. 421,712, there is claimed a distal femoral cutting jig for the implantation of a prosthetic knee comprising a central section, lateral handle means extending laterally out-ward of said central section from at least one side thereof, a medial handle means extending outwardly from the front face of said central section, a positioning pin extending outwardly from the rear face of said central section, attaching means on the upper surface of said central section for selective attach mint of a pin holder alignment guide thereto, and securing means on said upper surface of said central section for select live attachment of a distal femoral condoles cutting jig.
According to the present invention, there is provided a distal femoral condoles cutting joy comprising a bar, a down-warmly extending -tongue from said bar for reception Sacramento to attaching means in a distal femoral cutting jig, femoral securing pins extending downwardly from said bar remote from said tongue, a generally vertical cutting guide surface on said icily bar between said tongue and said securing means, and pin holder guide attaching means on said bar.
Thus, in this invention and in those disclosed in applicant's parent and other divisional applications Serial No 421,712, ~3qSO, ~3~'1, , and go , a set of instruments is provided which allows for variations in the anatomical axis of the lemon. The instruments include cutting jigs which are selectively locked directly to -the bane. By use of these instruments, eight basis bone cuts are made to align and seat the femoral and tibia components of the prosthesis.
This invention, together with those in applicant's aforementioned parent and divisional applications, will now be further described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 illustrates the anatomical considerations of the legs which are taken into account in accordance with the invention;
Figures pa through of illustrate the eight basis bone cuts;
Figures 3-30 illustrate the various steps and incitory-mints used therein from incision to final tibia preparation;
Figures 31~35 are side, top, front, bottom and rear views, respectively, of the distal femoral cutting jig shown in Figures 7-13;
Figures 36-40 are side, front, rear, bottom and plan views, respectively, of the pin holder alignment guide shown in Figures 8-9;
Figures 41-44 are cross-sectional views taken through Figure 37 along the lines 41-41, 42-42, 43-43 and 44-44;
Figure 45 is a front elevation view partly in section ll23~

of the distal femoral cutting jig shown in Figures 10-13;
Figures 46-49 are top, bottom, side and rear views, respectively, of the femoral cutting jig shown in Figure 45;
Figure 50 is a cross-sectional view taken through Figure 48 along the line 50-50;
Figures 51-55 are bottom, front, rear, side and top views, respectively, of the femoral drill jig shown in Figures 13-14;
Figure 56 is a cross-sectional view taken through Figure 52 along the line 56-56, Figures 57-61 are top, front, rear, bottom and side views, respectively, of the transverse femoral cutting jig shown in Figures 15-16;

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, Figure 62 is a cross-sectional view taken through Jo Figure 57 along the line 62-62;
Figure 63-67 are side, top, front> rear and bottom ¦ views, respectively, of the femoral spacer/tensor jig shown in Figures 17-22;
Figure 68 is a cross-sectional view taken through Figure 66 along the line 68-68-Figures 69-72 are to, rear, front and bottom Elena-I lion views, respectively, of the transverse tibia cutting jig If shown in Figures 17-23;
Figures 73-74 are end elevation views of the trays . verse tibia cutting jig shown in Figures 29-72;
Figure 75 is a cross-sectional view taken through Figure 69 along the line 75-75;
it Figures 76-80 are bottom, front, rear, top and end I views, respectively, of the femoral chamfer cutting jig shown ,' in Figure 24;
Al Figure 81 is a cross-sectional view taken through , Figure 76 along the line 81-81;
,, Figures 82-86 are bottom, front, rear, top and end , views, respectively, of a modified form of femoral chamfer ,, cutting jig;
Figure 87 is a cross-sectional view taken through Al figure 82 along the line 87-87;
If Figures 88-92 are side, top, bottom, front and rear ,~, views, respectively, of the tibia positioning/fixation fig , shown in Figures 25-30;
Figure 93 is a cross-sectional view taken through Figure 89 along the line 93-93; and Figure 94 is a cross-sectional view taken through Figure 88 along the line 94-94.

-pa-~23(~;277 The instruments utilized for prosthetic knee prepare-lions consist of long axial alignment guides and cutting jigs.
The jigs may be subsequential numbered relative to their order of use to simplify the procedure. The alignment guides are designed to assist the surgeon in positioning all primary cutting jigs prior to making the bone cuts. All cutting jigs lock onto their respective bones to insure the accuracy of the cuts.
The instrument system is designed to seat the femoral and tibia components parallel to the anatomic transverse axis of the knee. Since this axis is parallel to the ground and perpendicular to the vertical in two-legged stance, this post-toning achieves: (1) uniform stress distribution at fixation interfaces, (2) optimal alignment; and (3) physiological lima-mentors balance of the knee. It is also important to recognize that the ankles remain closer to the midline vertical axis of the body that either the knees or hips throughout normal gait.
To achieve the goals of total knee arthropLasty, these align-mint features must be preserved or reconstituted.
The inventive instrument system uses the femoral shaft axis (S), the center of the knee (K), the center of the ankle joint (A), and the transverse axis of the knee (T) as its alignment references (Figure 1). The mechanical axis of the lower limb, which runs from the center of the hip (H) through the center of the knee (K) to the center of the ankle (A), generally forms an angle of 3 with the vertical (V), because the hips are wider apart than the ankles in both normal stance and gait (Figure 1).

Z3~Z~'7 Since the femoral head and neck overhang the shaft, the axis of the femoral shaft does not coincide with that of the leg, but forms with the leg a more acute valgus angle of 6 (SKY, Figure 1). In total, the femoral shaft axis averages 9 of valgus with the vertical. The valgus angle of the femur varies relative to body build. The specific femoral valgus for a given individual can be determined by measuring angle HIS
(Figure 1) on a long x-ray which includes both the hip and the knee, and adding 3 (the mechanical axis). This method is valid for reconstituting a mechanical axis of 3 regardless of the degree of preoperative axial deformity at the knee.
jig For tibia alignment, the center of the knee and the center of the ankle are used as reference points. Instruments which rely on the proximal tibia shaft as their key alignment reference tend to be inaccurate due to the frequent occurrence of tibia bowing. Recognizing that the center of the ankle is closer to the midline vertical axis than the center ox the knee in two-legged stance and throughout gait, this system uniquely requires a small angle at the proximal transverse libel cut (TEA, Figure 1). This angle keeps the transverse axis of the prosthesis parallel to the ground while the mechanical axis of the entire lower extremity remains in valgus (HA, Figure 1).
Figure illustrates the eight basic bone cuts required to align and seat the femoral and tibia co onents of the prosthesis. As later described in detail, the instrument soys-them consists of seven sequentially numbered cutting jigs and a femoral/tibial alignment guide. These are designed to insure the accuracy and alignment of all femoral and tibia bone cuts.

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123~Z~'7 In the practice of the invention, the knee is approached through a longitudinal skin incision, followed by a medical pane-, patellar consular incision. The quadriceps tendon is incised longitudinally, allowing version and dislocation of the ayatollah ' laterally (Figure 3).
Orientation , With the knee flexed to 90, a 5/16 inch drill hole is made by drill bit 10 in the distal femur. It is placed roughly in the center 12 of the intercondylar notch just anterior to the femoral attachment of the posterior crochet ligament (Figure 4). The position of this hole 13 (Figure 6) is not critical to toe orientation of any femoral bone cuts -- -it is simply a point of purchase for the distal femoral cutting jig IA. The laterally.
protruding handles 22 are used to rotate the jig so that the posterior rounded eminences parallel to the posterior femoral condoles and the anterior femur is seen as on a sunrise view (Figure 5). The jig is then hammered into place. Jig IA in-i! ' '' --'`
eludes a pair of locking panacean the side hidden from view in i! Figure 5. If there has been significant preoperative deformity, ' the short locking pin facing the most prominent condole is ham-I mired into place bringing the face of the jig IA flush to that condole only.
1, The Transverse Distal Femoral Cut: Varus-Val~us ,.
i And Flexion-Extension Alignment !
¦ The long axial alignment guide 16 is used to establish ¦, proper varus-~algus and flaxen extension alignment of the distal femoral cuts. The guide pin 18 is positioned into the pin holder in the appropriate right or left 7, 9 or 11 hole I (Figure I
. I This angle is chosen relative to the reparative x-ray measure-!

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mint technique previously described in the alignment rationale section Most often 9 will be appropriate. The guide 16 is then placed into the anterior holes of the distal femoral cutting jig IA. Correct axial alignment is achieved when the long alignment guide pin 18 is parallel to the femoral shaft axis in both the anterior and lateral views (Figures 7 and 8). An examining finger can be slipped proximally under the quadriceps to get a better idea of the direction of the femoral shaft during this alignment procedure. If the alignment yin 18 does not parallel the femoral shaft, a mallet is used to tax the medial handle 20 or lateral handle 22, advancing the jig IA
away from the deformed condole until the axial guide pin 18 parallels the femoral shaft (Figure 9). With the alignment completed, one can easily visualize how much bone is missing from the deformed condole. The IA jig is not stable a this point but must be manually held during insertion and removal of the alignment pin holder and also while placing the IT jig.
A short alignment pin is available to facilitate alignment in two special circumstances. The shorter pin avoids impingement with the tourniquet on an obese thigh or with the abdomen of a short patient.
Locking The Distal Femoral Cutting Jig In Position The axial alignment guide 16 is removed and the tongue of the distal femoral cutting jig IA and jig IT is slid into the first Hart of the distal femoral jig IA (Figure lo) With the teeth of the IT jig resting lightly on the anterior femur, recheck the alignment for both varus-valgus and flaxen-extension prior to hammering it in place. When proper align-'.

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Al , mint is assured, first gently tap the IT jig with a mallet so ! that the teeth engage the bone without sliding down an oblique If surface, thereby changing alignment. Then remove the alignment .11 guide and hammer the IT jig firmly in place. There are also ¦ drill holes in the cutting bar of the IT jig through whichl/8 inch drill pins can be passed into the condoles if add-tonal stability is necessary.
Final position of the distal femoral cutting jig IA
is rechecked with the alignment guide. Measure twice, cut once (Figure 12).
Cutting The Distal Femur Lyons the distal femoral cutting jig IA is locked on to the femur, the surgeon is free to direct his full alien-lion to the cutting of the distal condoles. Pistol grip, end-j cutting oscillating saws are most effective for these cuts. It is important that the surgeon pay strict attention to maintain-in the saw blade flat against the proximal cutting surface of the jig in order to achieve a precise cut (Figure 13). Care If should be taken to avoid the central intermeddler fixation - peg of the jig. Following the initial transverse cut, the saw Al blade is passed back and forth across the cutting bar to shave the kindlier cuts level with the plane of the cutting jig. This i step is important since the saw blade tends to salve away from the desired plane, particularly in more sclerotic bone and toward the deeper portions of the cut. The jigs are now no-l moved and the distal femoral cuts are completed. In completing ¦ these cuts, the anterior aspect of the distal femoral cut will I serve as the "cutting block" for the remaining posterior aspect.
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I 7'7 It is, therefore, important that the saw blade be inserted tote full depth of the initial cut before the oscillation is started. Otherwise, one runs the risk of starting a new plane.
Once the posterior part has been completed, the broadest blade should be passed over the surface to be sure that the cut is a single-flat plane. This can also be checked with a cutting block. , Femoral Component Rotational, Medial-Lateral And Anterior Posterior Alignment Rotational, medial-lateral and anterior-posterior orientation of the femoral prosthesis is determined by the femoral drill jig II. This jig has two posterior skids 24 which are slid between the posterior femoral condoles and tibia plateaus. These skids automatically position the instrument in of rotation relative to the coronal plane of the distal femur (ALA, Figure 14). The jig should first be centered in !
the medial-lateral position on the flat cut distal femoral sun-face, ignoring the initial keying hole for the IA jig. The jig II is now hammered flush with the flat surface of the disk tat femoral condoles. The jig's anterior projection contains two holes 26 marked respectively for right and left knees.
When a 1/8 inch drill pin 28, placed in the appropriate hole, is aligned with the center of the patello-femoral groove, eon-feat medial lateral and rotational positioning is assured (BOB, Figure 14). When correct positioning has been assured, a 5/16 inch drill 30 is used to make the holes for the femoral prosthesis fixation studs (C,C, Figure 14).
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Anterior And Posterior Femoral Cuts Following the removal of the drill jig II, the two 5/16 inch locking studs 32 of the anterior-posterior femoral cutting jig III, are inserted into the distal femaral fixation it holes. The jig III is hammered flush with the flat cut surface ¦ of the distal femoral condoles. The anterior plane of the cut-tying jig should intersect the anterior cortex of the femur at the proximal margin of the patellar facets (Figure 15). If this plane appears too deep or too anterior, the next most appear private size jig should be chosen. If there is any question of which size jig is to be used, always start with the larger jig.
The anterior and posterior femoral bone cuts are now completed (Figure 16). Once again, care must be taken to rest the saw blade flush against the flat surface of the jig. With the Jo posterior condoles removed, complete access to the posterior I compartment allows removal of the Munich and anterior crochet ligament. The tibia attachment of the posterior crochet is identifies and carefully avoided during the next step. Also, all remaining marginal osteophytes on the tibia and femur must be removed so they do not shorten or constrict ligaments or block full extension.
Tibia Alignment And Cuts , The femoral spacer/tensor jig IV and transverse tibia if cutting jig V are now assembled and positioned. The mortise I¦ cut out 34 in the transverse tibia cutting jig V is slipped over the tongue 36 of the moral spacer/tensor jig and slid as far proximally as it will go (Figure 17). Following insert , lion of the jigs studs into the femoral fixation holes, the If i l! I

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leg is brought into full extension. A folded towel or sheets placed behind the knee to prevent inadvertent hyperexten-soon at this stage of the procedure. Next the axial alignment wide 16 with both its femoral and tibia alignment Pins in place is positioned into the femoral s~acer/tensor jig IV
(Figure 18).
Axial And Rotational Alignment To achieve correct tibia axial alignment prior to making the transverse tibia cut, longitudinal traction and manipulation are applied from the foot. The goal is to bring the center of the ankle joint directly under the distal dip of the alignment pin. This alignment will produce a slight tibia angle of 2.5 (A, Figure lo). Anatomically, the centers of the ankle joints are closer together than the centers of the knee joints. Overall leg alignment will still be in valgus.-Correct extension alignment is achieved when the tibia shaft parallels the alignment pin when viewed from the side. Rota-tonal alignment is correct when the medial molehills is apt proximately 30 anterior to the lateral molehills in the coronal plane (B, Figure 19).
If correct axial alignment cannot be achieved at this point with the jig IV in place, then one of the special techniques for dealing with the severe deformity will have to be employed. The jig V cannot be locked onto the tibia until correct alignment is achieved.

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lZ3~Z77 If l ¦! , Soft Tissue/Joint Tension/Aliznment Soft tissue stability is established following initial l! manual tibia axial alignment. Each side of the furl spacer/
I tensor jig IV has expandable arms 38 which spread-when its apt propriety thumb screw 40 is tightened (Figure 20). The tensor arms are extended to stabilize the joint in the correct align-mint. Do not over tighten the femoral spacer/tensor jig IV. The transverse tibialcutt~ng jig V, pushed as far proximally as it will go ensures that only the minimal amount of the tibia plateaus it . :
will be removed. When one plateau is considerably more depressed, 1 than the other, the transverse cutting jig should be slid disk Al tally so that the plane of the tibia cut will remove enough bone from the depressed plateau to provide a sufficiently flat sun-face for seating the tibia prosthesis.
I, Check Of Overall Alignment !.
it Prior to locking the transverse tibia cutting jig V
i in place, overall lower limb alignment should be checked. For ! correct alignment, the femoral alignment pin 18 will parallel the femoral shaft in both the anterior and lateral planes. The ! tibia alignment pin 19 will extend from the center of the knee lo to the center of the ankle and be parallel to the tibia shaft, ¦, in the lateral plane. Rotation is correct when the medial molehills is approximately 30 anterior to the lateral molehills , ¦ (Figure 19).
If The Transverse Tibia Cut I While still under visual control of the axial align- 'I
mint guide pins 18, 19, the transverse tibia cutting jig V is locked in place by drilling two 1/8 inch pins through the appear-' -13-If l 30~7~ ' ;
private holes in the jig (Figure 21). The alignment guide If 16 is now removed and tension is removed from the jig IV by ¦, loosening the thumb screws 40. As the knee is flexed to 90, the femoral spacer/tensor jig IV will pull out omits anchor-I in holes in the femur. The jig IV is then slipped proximally, !! disengaging it from the tibia cutting jig V (Figure 22). The Al transverse tibia plateau cut is then made by resting, the saw ;! blade flush against the broad flat surface of the cutting jig !, v (Figure 23). The cut is made as deeply as the saw blade will Jo allow, while care is taken to protect collateral ligaments.
Jo Once again, following the initial cut of the oscillating saw 1 blade should be run back and forth across the flat surface of , I
' the transverse cutting jig to shave off any prominent bone ; that may be left posteriorly due to Savannah of the SOW blade in sclerotic bone. The jig V is then slipped off the locking pins and the cut is completed, making sure that the posterior rims of the plateaus are level with the plane of the transverse cut. Additional care should he taken to preserve the posterior crochet ligament. Since the transverse tibia cut is made parallel to the ground for optimal stress distribution as the prosthesis bone interface and because the normal tibia plateau slopes 7 to 10 posteriorly, more bone will be removed anterior-lye than posteriorly.
I Floral Chamfer Cuts ,¦ The femoral chamfer cutting jig VI is inserted then ,' into the femoral fixation holes. With the saw blade flush against the jig's cutting planes 42, the anterior and posterior cuts are made (Figure 24). As with other cutting jigs, it is !! - I

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I important to maintain the saw blade perfectly flush with the ! cutting surfaces 42 of the jig to assure precise cuts, other-wise the feral component will not fully seat.
l Tub -1 Component Rotational, ~ledial-Latêral And l Anterior-Posterior Alignment The knee is extended and traction is applied from ,, the foot to open the joint space. The posterior tabs of the ,1 appropriate sized tibia positioning/fixation jigs VII are hooked behind the cut proximal tibia (Figure 25). The two posterior tabs 44 of the jig position behind the posterior rims of the tibia plateau, assuring correct posterior position of the tibia prosthesis. The knee is then flexed and the jig VII is centrally positioned. Since the posterior margins ox the tibia plateaus are nearly parallel to the transverse axis of the tibia, the posterior tabs 44 will position the jig in , correct rotation. Rotational and medial-lateral positioning are .
,, checked by slipping an axial alignment guide pin 19 through the appropriate right or left alignment hole in the anterior flange of the jig. The two anterior thumb screws 46 of the jig are then lightly tightened, securing the jig in place. If I alignment is correct, the distal tip of the alignment pin should center over the ankle joint with the medial molehills Ii, 30 anterior to the lateral molehills (Figure 26). It this ! is not the case, the jig is manipulated into proper alignment,.
I Rotational malalignment tends to be toward external rotation of the tibia.
I An appropriate size tibia trial prosthesis 48 is If inserted onto the jig (Figure 27). The trial furl prosthesis Al it then positioned onto the femur.
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. I , Al Initial Trial Reduction Jo Range of motion and stability are now tested. If the joint is too lax, the next thickest tibia trial is slipped onto the tibia positioning/fixation jig VII. Once flaxen, rotation and stability are satisfactory, the overall alignment ¦ is checked in full extension (Figures 28 and 29~. The align-I mint guide is removed, and the knee is flexed to 9~. Next, ¦ the femoral trial and tibia spacer are removed. The thickness marked on the tibia trial spacer indicates the thickness of ! the prosthesis to be implanted.
! final Tibia Preparation If..................... I
When the stemmed tibia prosthesis is being used, the window 50 in the jig VII is used, as a cutting guide. A
it 1/2 inch osteotome 52 is used to prepare the fixation slot Jo while the jig is still locked onto the proximal tibia (Figure !,'30).
; For the affronted prosthesis resurfacing tibia prosthesis which uses medial and lateral fixation studs, a 5/16 inch drill 54 is used to make the stud holes through the I drill guides in the jig ELI (Figure 30). With fixation Peg ¦, or stud holes completed, the jig is removed. A final check of the joint is made for posterior loose bodies, and soft i tissue debridement is completed.
Instruments Figures 31-94 illustrate in full scale various in-struments used in accordance with this invention.
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Figures 31-35 illustrate the distal femoral cutting jig IA which is used for achieving Allah alignment ennui used it with the axial adjustment guide 16. Distal femoral cuts are I made when jig IA is used with cut jig IBM As indicated therein, the upper surface of the central portion 56 of jig IA has at-lacked thereto a pair of lateral handles 22, 22 while a medial handle 20 also extends from the front face of central section 56. A positioning pin 58 is disposed on the rear face of eon-trial section 56 as previously described. Attaching means are provided on the upper surface of the central section 56 for selective attachment of the pin holder alignment guide 16. me attaching means is in the form of a pair of holes 60, 62 which are of different diameter corresponding to the different diameter locking pins 64, 66 (Figure 37) of the pin holder 16. In this manner there is assurance that the pin holder can be mounted in , only the correct position.
j The rear surface of central section 56 also includes a pair of short alignment pins 68 as previously described.
, A vertical cut-out 70 extends com~letelv through ;, central section 56 for receiving the tongue I (Figure 45) of the distal femur cutting jig IBM An adjustable liken screw 74 is movable into cut-out 70 to lock tongue 72 in place.
If figures 36-44 illustrate the details of pin holder Al 16 which is used with guide pins 18, 19 (Figure 19) to assure I correct axial alignment throughout the surgical procedure.
if Pin holder 16 is in the form of an elongated bar and includes lo bifurcated pins 64, 66 to complement the holes 60, 62 in jig IA. The lower portion of pin holder 16 is provided with a pair '.

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I, of mirror image tibia holes 76, 76 for selectively receiving I tibia alignment pin 19. The holes are angled oppose r tell each other, as previously described, with one holder being for the right knee and the other being for the left knee. Similarly, three sets of holes 78, 80, 82 are provided for the femoral I alignment pin 18. The holes are disposed at the most likely angle required such as I 9 and 11 with one set being for the right knee and the other for the left knee.
Figures 45-50 illustrate the details of distal 1 femoral cutting jig IT which is in the form of a plate or it bar having a downwardly extending tongue 72 with non-sym-metric cross-section of complementary size and shape to fit if within the mortise cut-out 70 of jig IA. Jig IT is used for cutting the distal femoral condoles. Plate 84 includes a pair of femoral securing pins 86 for attachment to the femur-with two pairs of positioning pins 88 spaced inwardly i thereof. The upper surface of plate 84 is also provided with a pair of non-identical holes 90, 92 for receiving the locking pins 64, 66 of pin holder 16. Plate 84 is also provided with a generally vertical guide surface 94 on each wing portion thereof to act as a saw cutting guide (see Figure 13). A pair of vertical holes 96 are provided in plate 84.
I Figures 51-56 illustrate the femoral cutting jig II
I which is used to determine the rotational, medial-lateral and ' anterior-posterior orientation of the femoral component and if allows drilling of holes for prosthesis fixation stud.
I' As shown therein, jig II is in the form of a generally Yen-I tidal plate 98 having a flat inner surface 100. A pair of !

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I ~2~z~7 posterior skids 24 extend outwardly from inner surface 100 at the lower portion thereof. A pair of drill holes 26 extend through plate 98 as previously described. If the posterior condoles are intact, a hole may be drilled therein Thor the aid of one of the drill holes 102, 102 with holes 102, 102 being inclined for the right and left knee. Plate 98 also includes a pair of positioning pins ln4 on its inner surface Figures 57-62 illustrate the anterior-posterior cutting jig III. As indicated therein, jig III is in the for of a bar or plate 106 which has a flat vertical surface 108.
A pair of distal femoral fixation pins 32 extend from surface 108. A generally horizontal lower cutting guide surface 110 is also provided as well as an upwardly inclined cutting guide surface 112. A cut-out 114 is located centrally of bar 106.
Preferably jig III would come in small, medium and large sizes.
Figures 63-68 illustrate the details of femoral spacer/tensor jig IV which assembles and positions transverse tibia cutting jig V to determine correct soft tissue balance and tibia axial and rotational alignment prior to making the transverse tibia cut. Jig IV comprises a pair of spaced fixed legs 116 with each leg having a lower vertical section and ;
an inwardly inclined upper section. A transverse bridge member 118 joins the fixed legs at the junction of the upper and lower sections. A pair of spaced parallel movable legs 38 generally conform in size and shape to fixed legs 116 and are hingedly mounted at their ends thereof by hinge connection 102 to their respective movable legs. Adjusting means in the form of bolts or thump screws 40 are thread ably enjoyed with and extend through fixed legs 116 into contact with movable legs 38 for I ,1 .

if z3v2~7 Al If , controlling the spacing or relative positioning of the respect live sets of legs. A pair of studs 126 are provided at the lower portion of legs 116 while rounded contact surfaces 128 extend away from movable legs 38. Legs 38 may thus be moved so that surfaces 128 contact the tibia. Bridge member 118 in-Claudius outwardly extending tongue 36 which is of non-symmetrical cross section for complementary engagement with mortise cut-out 34 in jig V (Figure 17). Jig V could then slide in or out on ' tongue 36 to adjust for the length of cut.
Figures 69-75 illustrate transverse tibia cutting jig V which is in the form of a bar 130 having a flat upper cutting guide surface 132 and cut-out 34 for receiving tongue 36 of jig IV. A locking screw 134 is movable into cut-out 34 t to lock tongue 36 in place. A pair of vertical drill holes 136 also extend through bar 130.
Figures 76-81 show one form of femoral chamfer cutting jig VI which is in the form of a bar 138 having its front race formed in three sections which include a pair of inclined upper and lower cutting guide surfaces 42 extend-in to the upper edge and lower edge of bar 138. The inter-mediate surface 140 is generally vertical. A pair of post-toning studs 142 are provided to extend into the same medial alignment holes which are utilized by various other jigs.
Figures 82-87 show a modified form of jig Vote wherein a kindlier quote 144 is provided in the lower guide surface. Preferably jig VI would come in five different sizes varying in size of the cut-out 144 and/or being sized small, medium or large.
Figures 88-94 illustrate the tibia positioning/
fixation jig VII. Jig VII generally includes a plate 146 having a lower planar surface 148 from which extend a pair ' I

3~7 ilparallel tabs 44. An osteotome cut-out or window 50 is provided Olin the central portion thereof with an inclined drill hole 150 on ;
leach side of cut-out 50. A block 152 is connected to plate 146.
-Lowe pair of vertical alignment holes 154 which are inclined for the Wright and left knee extend through block 152. Additionally thumbscrews 46 are threadedly mounted into and extend through block I 152 while a pair of non-identical holes 156, 158 are provided in I block 152 for receiving the locking pins 64, 66 of holder 16.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A distal femoral condyles cutting jig comprising a bar, a tongue extending downwardly from said bar for receptive securement to attaching means in a distal femoral cutting jig, femoral securing pins extending downwardly from said bar remote from said tongue, a generally vertical cutting guide surface on said bar between said tongue and said securing pins, and pin holder alignment guide attaching means on said bar.