NEXGEN COMPLETE KNEE SOLUTION - Joint Replacement

1 NEXGEN COMPLETE knee SOLUTIONE picondylarInstrumentationSurgical TechniqueFor Legacy PosteriorStabilizedKnees1 INTRODUCTIONS uccessful total knee arthroplasty is directlydependent on reestablishment of normal lowerextremity alignment, proper implant design and orientation, secure implant fixation, andadequate soft tissue balancing and stability. TheNexGen Epicondylar Instruments are designed to help the surgeon accomplish these goals by combining optimal alignment accuracy with asimple, straightforward center of the hip, knee , and ankle arerestored to lie on a straight line, establishing aneutral mechanical axis. The femoral and tibialcomponents are oriented perpendicular to thisaxis. Femoral rotation is determined using thecollateral ligament attachment to the epicondyles,(the transepicondylar axis).

2 The A/P position of the femoral component is ascertained by acombination of anterior and posterior referenc-ing. Well-designed instruments allow accuratecuts to help ensure secure component component sizes allow soft tissue balancing with appropriate soft tissue surgical technique was developed in conjunction with:John N. Insall, , Insall/Scott/Kelly Institute for Orthopaedics and Sports Medicine Beth Israel Medical Center- North DivisionNew York, New YorkGiles R. Scuderi, Director, Insall/Scott/Kelly Institute for Orthopaedics and Sports MedicineAttending Surgeon Beth Israel Medical Center-North DivisionNew York, New York2 PREOPERATIVE PLANNINGUse the template overlay (available through yourZimmer representative) to determine the anglebetween the anatomic axis and the mechanicalaxis. This angle will be reproduced intraopera-tively.

3 This surgical technique ensures that thedistal femur will be cut perpendicular to themechanical axis and, after soft tissue balancing,will be parallel to the resected surface of theproximal APPROACHThe femur, tibia, and patella are prepared independently, and can be cut in any sequenceusing the principle of measured resection(removing enough bone to allow Replacement bythe prosthesis). Adjustment cuts may be neededlater (pg. 15).3 SIZE THE FEMURD rill a hole in the center of the patellar sulcus of the distal femur (Fig. 1), making sure that thehole is parallel to the shaft of the femur in boththe anteroposterior and lateral projections. Thehole should be approximately one-half to onecentimeter anterior to the origin of the posteriorcruciate ligament. Medial or lateral displacementof the hole may be needed according to preoper-ative templating of the the 8mm IM Drill with step to enlarge theentrance hole on the femur to 12mm in will reduce IM pressure during placement of subsequent IM guides.

4 Suction the canal toremove medullary the IM Femoral A/P Sizing guide into thehole until it contacts the distal femur. Compressthe guide until the anterior boom contacts the anterior cortex of the femur, and both feetrest on the cartilage of the posterior or extension of the guide can produceinaccurate readings. Check to ensure that theboom is not seated on a high spot, or an unusu-ally low spot on the anterior the femoral size directly from the guide (Fig. 2). If the indicator is between two sizes, thesmaller size is typically chosen which will require in between placement of the A/P Cutting guide .(See page 10) for more detail on in between place-ment.)The sizing can be confirmed when theanterior and posterior femoral condyles are cut,along with any adjustment to the A/P 1 Fig. 24 ESTABLISH FEMORAL ALIGNMENTIn this step, the valgus angle and depth of distalfemoral resection are , set the IM Alignment guide to the propervalgus angle as determined by preoperativeradiographs.

5 Check to ensure that the proper Right or Left indication is used and engagethe lock mechanism (Fig. 3).The Standard Cut Block must be attached tothe IM Alignment guide for a standard distalfemoral plate should be tight-ened on the guide prior to use, but the screwsshould be loosened for sterilization. Remove theStandard Cutting Block if a large flexion contrac-ture exists. This will allow for an additional 3mmof distal femoral bone resection (Fig. 4).Insert the guide into the IM hole on the Technique: An Extramedullary Alignment Arch and AlignmentRod can be used to confirm the alignment. If this isanticipated, identify the center of the femoral headbefore draping. If extramedullary alignment will bethe only mode of alignment, use a palpableradiopaque marker in combination with an A/P x-ray to ensure proper location of the femoraI the epicondylar axis as a guide in setting theorientation of the IM Alignment guide .

6 Positionthe handles of the guide relative to the epi-condyles. This does not set rotation of thefemoral component, but keeps the distal cut oriented to the final component the proper rotation is achieved, impact theIM guide until it seats on the most prominentcondyle. After impacting, check to ensure thatthe valgus setting has not changed. Ensure thatthe guide is contacting at least one distal condyleThis will set the proper distal femoral 3 Fig. 45 CUT THE DISTAL FEMURW hile the IM Alignment guide is being insertedby the surgeon, the scrub nurse should attach theDistal Femoral Cutting guide to the appropriateDistal Placement Distal Placement guide sets 3 of flexioninto the distal femoral cut to help protect againstnotching of the anterior femoral that the attachment screw is tightened(Fig.)

7 5). Verify that the anterior thumb screw isbacked out, away from the bone holding pins through two or three of thepin holes in the anterior surface of the DistalFemoral Cutting guide to secure it further to thefemur (Fig. 7).Insert the Distal Placement guide with theCutting guide into the IM Alignment guide untilthe Cutting guide rests on the anterior further stabilize the guide , turn the anteriorscrew by hand until it contacts the anteriorfemoral cortex (Fig. 6). Do not loosen the attachment screw (Fig. 8)in the Distal Placement 5 Fig. 6 Fig. 7 Fig. 86 Use the Slaphammer Extractor to remove the IMAlignment guide and the Distal Placement guide (Fig. 9).Cut the distal femur through the distal cuttingslot in the cutting guide using a .050 blade (Fig. 10). This slot removes the same amount ofbone that will be replaced by the femoral component.

8 (The correct thickness of boneresection is determined in the previous step byhaving the IM Alignment guide flush against the most prominent condyle.)Check the flatness of the distal femoral cut witha flat surface. (A/P Cutting Guides or the DistalFemoral Recutting Plate may be used for thispurpose.) If necessary, modify the distal femoralsurface so that it is completely flat. This isextremely important for the placement of subsequent guides and for proper fit of 9 Fig. 107 ESTABLISH FEMORAL ROTATION ldentify the epicondyles. To identify the lateralepicondyle it is necessary to dissect away thepatello-femoral ligament. The lateral epicondyleis a discrete point at the center of the lateral collateral ligament attachment. The medial epicondyle can be found by removing the synovium from the medial collateral ligamentattachment to the femur.

9 The medial collateralligament has a broad attachment to the medialepicondyle forming an approximate semicircle(Fig. 11). Choose the center of the diameter. Markthese two points with methylene blue (Fig. 12).Then, draw a line between the two epicondyleson the resected surface of the distal femur (Fig. 13). This line represents the epicondylar line can also be drawn along the deepest pointof the patellar sulcus to serve as an additionalreference the Epicondylar guide along the line drawnon the distal femur (Fig. 14). Ensure correct orientation by checking the handles of the guiderelative to the epicondyles. The handles shouldbe in line with the axis. Center the guide medio-laterally using the line along the patellar sulcusor the intramedullary 11 Fig. 12 Fig. 13 Fig. 148 SECONDARY LANDMARKS FOR FEMORALROTATIONA/P AxisThe A/P axis of the distal femur as defined by thedeepest point of the patellar sulcus, is approximatelyat right angles to the epicondylar line althoughthere is considerable variation, (90 7 ).

10 1 Posterior Condyles The epicondylar line is rotated externally 0-8 , (4 4 )1, relative to the posterior condylar line (Fig. 15).The Posterior Reference Rotation guide should readbetween 0 and 8 .Both of these secondary landmarks can be used toconfirm femoral the proper rotation is achieved, secure theEpicondylar guide with two an oscillating blade marked to a 30mmdepth, cut the distal femur through the slot in theEpicondylar guide (Fig. 16). The EpicondylarGuide provides a 30mm line in order to measure1) Poilvache PL, Insall JN, Scuderi GR, Font-Rodriguez Landmarks and Sizing of the Distal Femur in TKA. Presentedat the knee Society Speciality Day, Atlanta, GA, Feb 25, 15 Fig. 169 CUT THE ANTERIORAND POSTERIORFEMORAL CONDYLESS elect the correct size A/P Cutting guide usingthe measurement from the IM Femoral A/PSizing guide .