NexGen Femur Patela

8/11/2019 NexGen Femur Patela

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NEXGEN

COMPLETSOLUTIO

Multi-Refere4-in-1 Femor

InstrumentatZimmer MIS Mini-Surgical TechniqueTotal Knee Arthrop

For NexGen CruciateRetaining & NexGe Legacy PosteriorStabilized Knees


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ZIMMER MISMINI-INCISION SURGICAL

TECHNIQUE FOR TOTAL KNEEARTHROPLASTY

THIS SURGICAL TECHNIQUE WASDEVELOPED IN CONJUNCTION WITH:

Thomas M. Coon, M.D.Orthopedic Surgical Institute

Red Bluff, California

Mark Hartzband, M.D. Director, Total Joint Service

Hackensack University Medical Center Hackensack, New Jersey

Carl L. Highgenboten, M.D.Charles Rutherford, M.D.Ortho Neuro Consultants, PA

Dallas, Texas

John N. Insall, M.D.Giles R. Scuderi, M.D.

Insall Scott Kelly Institute Beth Israel Hospital - Singer Division

New York, New York

Aaron G. Rosenberg, M.D. Professor Orthopaedic Surgery Rush University Medical College

Chicago, Illinois

Alfred J. Tria, Jr., M.D.Clinical Professor of Orthopaedic Surgery

University of Medicine and Dentistry - New Jersey Robert Wood Johnson Medical School

New Brunswick, New Jersey

Luke M. Vaughan, M.D.Clinical Associate Professor of Orthopaedic Surgery

University California San Diego School of Medicine La Jolla, California

CONTENTS

MINI-INCISION ABBREVIATED SURGICALTECHNIQUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

PREOPERATIVE PLANNING . . . . . . . . . . . . . . . . . . . 5

SURGICAL APPROACH . . . . . . . . . . . . . . . . . . . . . . . . 5

PATIENT PREPARATION. . . . . . . . . . . . . . . . . . . . . . . 6

INCISION AND EXPOSURE . . . . . . . . . . . . . . . . . . . . 6Midvastus Approach . . . . . . . . . . . . . . . . . . . . . . 8Subvastus Approach . . . . . . . . . . . . . . . . . . . . . . 9

Mini Medial Arthrotomy. . . . . . . . . . . . . . . . . . . 11STEP ONE ESTABLISH FEMORAL ALIGNMENT . . . . . . . . . . . 12

STEP TWO CUT THE DISTAL FEMUR . . . . . . . . . . . . . . . . . . . . . 14

STEP THREE SIZE FEMUR & ESTABLISHEXTERNAL ROTATION. . . . . . . . . . . . . . . . . . . . . . . . 16

STEP FOUR

FINISH THE FEMURAnterior Referencing Technique . . . . . . . . . . . 18Posterior Referencing Technique. . . . . . . . . . . 22

STEP FIVECHECK FLEXION/EXTENSION GAPS . . . . . . . . . . 25

STEP SIX PREPARE THE PATELLA. . . . . . . . . . . . . . . . . . . . . . . 26

APPENDIX 1In-Between Sizing for PosteriorReferencing Technique. . . . . . . . . . . . . . . . . . . . . . . . 32

APPENDIX 2Crossover Technique. . . . . . . . . . . . . . . . . . . . . . . . . . 33


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1 Drill 8mm Pilot Hole.

MINI-INCISION ABBREVIATED SURGICAL TECHNIQUE

2

5a

Set External Rotation(Anterior Referencing).

5b

Set External Rotation

(Posterior Referencing).

Insert and Secure Mini Distal FemoralCutting Guide.


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3 Cut Distal Femur.

4 Size the Femur.

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Place Femoral Finishing Guide; Adjust

M/L & Pin (Anterior Referencing).

7Finish the Femur.1. Anterior condyles2. Posterior condyles3. Posterior chamfer4. Anterior chamfers

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3

2


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INTRODUCTIONSuccessful total knee arthroplasty depends in parton re-establishment of normal lower extremity

alignment, proper implant design and orientation,secure implant fixation, and adequate soft tissuebalancing and stability. The NexGen

CompleteKnee Solution and Multi-Reference

4-in-1Instruments are designed to help the surgeonaccomplish these goals by combining optimalalignment accuracy with a simple, straight-forward technique.

The instruments and technique assist the

surgeon in restoring the center of the hip, knee,and ankle to lie on a straight line, establishinga neutral mechanical axis. The femoral andtibial components are oriented perpendicular tothis axis. Femoral rotation is determined usingthe posterior condyles or epicondylar axis as areference. The instruments promote accurate cutsto help ensure secure component fixation. Amplecomponent sizes allow soft tissue balancing with

appropriate soft tissue release.

The femur, tibia, and patella are preparedindependently, and can be cut in any sequenceusing the principle of measured resection(removing enough bone to allow replacementby the prosthesis). Adjustment cuts may beneeded later.

The Multi-Reference 4-in-1 Instruments provide a

choice of either anterior or posterior referencingtechniques for making the femoral finishingcuts. The anterior referencing technique usesthe anterior cortex to set the A/P position of thefemoral component. The posterior condyle cut isvariable. The posterior referencing technique usesthe posterior condyles to set the A/P positionof the femoral component. The variable cut ismade anteriorly.

Smaller incisions and less disruption oftissue during surgery have been shown toreduce the risk of complications as well as todecrease hospital length of stay in some cases.Additionally, some patients may experience lesspain, may be able to return to their activities ofdaily living much sooner, and prefer the cosmetibenefit of the smaller scar.1-4

The Mini-Incision TKA technique has beendeveloped to combine the alignment goals oftotal knee arthroplasty with less disruption ofsoft tissue. To accommodate this technique,some of the original Multi-Reference 4-in-1

Instruments have been modified. However, ifpreferred, a standard incision can be used withthe instruments. Prior to using a smaller incisionthe surgeon should be familiar with implanting NexGen components through a standard incision.

Total knee arthroplasty using the Mini-Incisiontechnique is suggested for nonobese patientswith preoperative flexion greater than 90 .Patients with varus deformities greater than

17 or valgus deformities greater than 13 aretypically not candidates for the Mini-Incisiontechnique.

Please refer to the package inserts for completeproduct information, including contraindicationswarnings, precautions, and adverse effects.


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PREOPERATIVE PLANNINGUse the template overlay (available through your Zimmer Representative) to determine

the angle between the anatomic axis and themechanical axis. This angle will be reproducedintraoperatively. This surgical technique helpsthe surgeon ensure that the distal femur will becut perpendicular to the mechanical axis and,after soft tissue balancing, will be parallel to theresected surface of the proximal tibia.

SURGICAL APPROACHThe femur, tibia, and patella are preparedindependently, and can be cut in any sequenceusing the principle of measured resection(removing enough bone to allow replacementby the prosthesis). Adjustment cuts may beneeded later.

6

Transverse Axis

M e c

h a n

i c a

l A x i s

90


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PATIENT PREPARATIONTo prepare the limb for Mini-Incision total kneearthroplasty, adequate muscle relaxation is

required. This may be accomplished with a short-acting, nondepolarizing muscle relaxant. Theanesthesiologist should adjust the medicationbased on the patients habitus and weight,and administer to induce adequate muscleparalysis for a minimum of 30-40 minutes.This will facilitate the eversion of the patella, ifdesired, and minimize tension in the remainingquadriceps below the level of the tourniquet. It is

imperative that the muscle relaxant be injectedprior to inflation of the tourniquet. Alternatively,spinal or epidural anesthesia should produceadequate muscle relaxation.

Apply a proximal thigh tourniquet and inflateit with the knee in hyperflexion to maximizethat portion of the quadriceps that is belowthe level of the tourniquet. This will helpminimize restriction of the quadriceps and

ease patellar eversion.

Once the patient is draped and prepped on theoperating table, determine the landmarks for thesurgical incision with the leg in extension.

INCISION AND EXPOSThe incision may be made with the leg inextension or flexion depending on surgeon

preference. The surgeon can choose a mid-vastus approach, a subvastus approach, or amini medial arthrotomy. Also, depending onsurgeon preference, the patella can be eithereverted or subluxed.

The length of the incision is dependent on thesize of the femoral component needed. Althoughthe goal of a Mini-Incision technique is tocomplete the surgery with an approximately

10cm-14cm incision, it may be necessary toextend the incision if visualization is inadequateor if eversion of the patella is not possiblewithout risk of avulsion at the tibial tubercle.If the incision must be extended, it is advisableto extend it gradually and only to the degreenecessary. The advantage of a Mini-Incisiontechnique is dependent on maintaining theextensor mechanism insertion.


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Make a slightly oblique parapatellar skin incision,beginning approximately 2cm proximal andmedial to the superior pole of the patella, andextend it approximately 10cm to the level of thesuperior patellar tendon insertion at the centerof the tibial tubercle (Fig.1). Be careful to avoiddisruption of the tendon insertion. This willfacilitate access to the vastus medialis obliquis,and allow a minimal split of the muscle. It willalso improve visualization of the lateral aspect ofthe joint obliquely with the patella everted. Thelength of the incision should be about 50% aboveand 50% below the joint line. If the length of theincision is not distributed evenly relative to the joint line, it is preferable that the greater portionbe distal.

Divide the subcutaneous tissue to the level ofthe retinaculum.

Technique Tip: Using electrocautery to completethe exposure will help minimize bleeding afterdeflation of the tourniquet, as well as late muscle bleeding. Fig. 1


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Midvastus Approach Developed in conjunctionwith Luke M. Vaughan, M.D.Make a medial parapatellar incision into thecapsule, preserving approximately 1cm ofperitenon and capsule medial to the patellartendon. This is important to facilitate completecapsular closure.

Split the superficial enveloping fascia of thequadriceps muscle percutaneously in a proximaldirection over a length of approximately 6cm.This will mobilize the quadriceps and allow forsignificantly greater lateral translation of the

muscle while minimizing tension on the patellartendon insertion.

Split the vastus medialis obliquis approximately1.5cm-2cm (Fig. 2).

Use blunt dissection to undermine the skinincision approximately 1cm-2cm aroundthe patella.

Slightly flex the knee and remove the deep third

of the fat pad.The patella can be either everted or subluxed.If everting the patella, release the lateralpatellofemoral ligament to facilitate full eversionand lateral translation of the patella. Then usehand-held three-pronged or two-pronged hooksto begin to gently evert the patella. Be carefulto avoid disrupting the extensor insertion. Tohelp evert the patella, slowly flex the joint and

externally rotate the tibia while applying gentlepressure. Once the patella is everted, use astandard-size Hohmann retractor or two smallHohmann retractors along the lateral flare of thetibial metaphysis to maintain the eversion of thepatella and the extensor mechanism.

Fig. 2

Note: It is imperative to maintain close observatiof the patellar tendon throughout the procedureto ensure that tension on the tendon is minimizeespecially during eversion of the patella and

positioning of the patient.Remove any large patellar osteophytes.

Release the anterior cruciate ligament, if presentPerform a subperiosteal dissection along theproximal medial and lateral tibia to the levelof the tibial tendon insertion. Then perform alimited release of the lateral capsule (less than5mm) to help minimize tension on the extensormechanism.


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Subvastus Approach Developed in conjunction

with Mark W. Pagnano, M.D.The subvastus medial arthrotomy has been

slightly modified to optimize minimally invasivesurgery. It provides excellent exposure for TKAwhile preserving all four attachments of thequadriceps to the patella. This approach does notrequire patellar eversion, minimizes disruption ofthe suprapatellar pouch, and facilitates rapid andreliable closure of the knee joint.

Dissect the subcutaneous tissue down to butnot through the fascia that overlies the vastus

medialis muscle.Identify the inferior border of the vastus medialismuscle, and incise the fascia at approximately5cm to 8cm medial to the patellar border (Fig. 3)to allow a finger to slide under the muscle bellybut on top of the underlying synovial lining ofthe knee joint. Use the finger to pull the vastusmedialis obliquis muscle superiorly and maintainslight tension on the muscle.

Use electrocautery to free the vastus medialisfrom its confluence with the medial retinaculum,leaving a small cuff of myofascial tissue attachedto the inferior border of the vastus medialis.

The tendonous portion of the vastus medialisextends distally to insert at the midpole ofthe medial border of the patella. Be careful topreserve that portion of the tendon to protect the

vastus medialis muscle during subsequent steps.

Fig. 3


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An incision along the inferior border of the vastusmedialis to the superior pole of the patella willresult in a tear, split, or maceration of the muscleby retractors. Incise the underlying synovium ina slightly more proximal position than is typicalwith a standard subvastus approach. This willallow a two-layer closure of the joint. The deeplayer will be the synovium, while the superficiallayer will be the medial retinaculum andthe myofascial sleeve of tissue that has beenleft attached to the inferior border of thevastus medialis.

Carry the synovial incision to the medial border of

the patella. Then turn directly inferiorly to followthe medial border of the patellar tendon to theproximal portion of the tibia. Elevate the medialsoft tissue sleeve along the proximal tibia in astandard fashion.

Place a bent-Hohmann retractor in the lateralgutter and lever it against the robust edge of thetendon that has been preserved just medial andsuperior to the patella. Retract the patella andextensor mechanism into the lateral gutter. Ifnecessary, mobilize the vastus medialis eitherfrom its underlying attachment to the synoviumand adductor canal, or at its superior surfacewhen there are firm attachments of the overlyingfascia to the subcutaneous tissues and skin.Depending on surgeon preference, the fat padcan be excised or preserved.

Flex the knee. The patella will stay retracted

in the lateral gutter behind the bent-Hohmannretractor, and the quadriceps tendon and vastusmedialis will lie over the distal anterior portion othe femur. To improve visualization of the distalanterior portion of the femur, place a thin kneeretractor along the anterior femur and gently liftthe extensor mechanism during critical stepsof the procedure. Alternatively, bring the kneeinto varying degrees of extension to improve

visualization by decreasing the tension on theextensor mechanism.


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Mini Medial Arthrotomy Developed in conjunctionwith Giles R. Scuderi, M.D.

The mini medial parapatellar arthrotomy providesexcellent exposure for the Mini-Incision TKA.Extending the medial parapatellar arthrotomy isa simple solution that can be performed quicklyif more exposure is needed.

Divide the subcutaneous tissue to the level ofthe retinaculum. Develop medial and lateral flapsalong with proximal and distal dissection in orderto expose the extensor mechanism. This permitsmobilization of the skin and subcutaneous tissue

as needed in the procedure.The medial parapatellar arthrotomy is used toexpose the joint, but the proximal division of thequadriceps tendon should be limited to a lengthof 2cm-4cm to permit lateral subluxation ofthe patella (Fig. 4).

Partially release the deep portion of the medialcollateral ligament. Depending on surgeonpreference, the fat pad can be excised orpreserved distal to the patella. Remove anyosteophytes from the area of the femoral notch.Then remove the anterior cruciate ligament and,if using a posterior stabilized implant, remove theposterior cruciate ligament. Fig. 4


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STEP ONEESTABLISH FEMORAL ALIGNMENTUse the 8mm IM Drill w/Step to drill a hole in the

center of the patellar sulcus of the distal femur(Fig. 5), making sure that the drill is parallel tothe shaft of the femur in both the anteroposteriorand lateral projections. The hole should beapproximately one-half to one centimeteranterior to the origin of the posterior cruciateligament. Medial or lateral displacement of thehole may be needed according to preoperativetemplating of the A/P radiograph.

165mm (6.5 inches). Choose the length bestsuited to the length of the patients leg, which wprovide the most accurate reproduction of theanatomic axis. If the femoral anatomy has beenaltered, as in a femur with a long-stemmed hipprosthesis or a with a femoral fracture malunionuse the short Adjustable IM Alignment Guide anuse the extramedullary alignment technique.

Note: It is preferable to use the longest intramedullary rod to help achieve the mostaccurate replication of the anatomic axis.

Set the Adjustable IM Alignment Guide tothe proper valgus angle as determined by

preoperative radiographs. Check to ensure thatthe proper Right or Left indication (Fig. 6) iused and engage the lock mechanism (Fig. 7).

Fig. 5

Fig. 7

Fig. 6The step on the drill will enlarge the entrancehole on the femur to 12mm. This will help reduceintramedullary pressure during placement ofsubsequent IM guides. Suction the canal toremove medullary contents.

The Adjustable IM Alignment Guide is available

with two intramedullary rod lengths. The rod onthe standard instrument is 229mm (9 inches)long and the rod on the short instrument is


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The Standard Cut Plate must be attachedto the Adjustable IM Alignment Guide for astandard distal femoral resection.Use a hex-head screwdriver to tighten the plate on the guideprior to use (Figs. 8a & 8b). The screws must beloosened for sterilization.

If preferred, remove the Standard Cut Plate if asignificant flexion contracture exists.

Note: This will allow for an additional 3mm ofdistal femoral bone resection.

Insert the IM guide into the hole in the distalfemur. If the epicondyles are visible, theepicondylar axis may be used as a guidein setting the orientation of the AdjustableIM Alignment Guide. If desired, add theThreaded Handles to the guide and positionthe handles relative to the epicondyles. Thisdoes not set rotation of the femoral component,but keeps the distal cut oriented to the finalcomponent rotation.

Once the proper orientation is achieved, impactthe IM guide until it seats on the most prominentcondyle. After impacting, check to ensure that thevalgus setting has not changed. Ensure that theguide is contacting at least one distal condyle.This will set the proper distal femoral resection.

Optional Technique: An Extramedullary Alignment Arch and Alignment Rod can be used to confirm the alignment. If this is anticipated, identify the center of the femoral head before draping. If extramedullary alignmentwill be the only mode of alignment, use a palpable radiopaque marker in combination with an A/P

x-ray film to help ensure proper location of the femoral head.

Fig. 8a

Fig. 8b


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Using the 3.2mm drill bit, drill holes through thetwo standard pin holes marked 0 in the anteriosurface of the Mini Distal Femoral Cutting Guidand place Headless Holding Pins through theholes (Fig. 11).

STEP TWOCUT THE DISTAL FEMURWhile the Adjustable IM Alignment Guide is being

inserted by the surgeon, the scrub nurse shouldattach the Mini Distal Femoral Cutting Guide tothe 0 Distal Placement Guide (Fig. 9).

Ensure that the attachment screw is tight.

Insert the Distal Placement Guide with the cuttingguide into the Adjustable IM Alignment Guideuntil the cutting guide rests on the anteriorfemoral cortex (Fig. 10). The Mini Distal FemoralCutting Guide is designed to help avoid softtissue impingement.

Optional Technique:The 3 Distal Placement Guide can be used to placethe Mini Distal Femoral Cutting Guide in 3 of flexion to protect the anterior cortex from notching.

Fig. 9

Fig. 10

Fig. 12

Fig. 11

Additional 2mm adjustments may be made byusing the sets of holes marked -4, -2, +2, and +4The markings on the cutting guide indicate, inmillimeters, the amount of bone resection eachwill yield relative to the standard distal resectionset by the Adjustable IM Alignment Guide and

Standard Cut Plate.

If more fixation is needed, use two 3.2mmHeaded Screws or predrill and insert two Hex-head Holding Pins in the small oblique holes onthe Mini Distal Femoral Cutting Guide, or SilveSpring Pins may be used in the large obliqueholes (Fig. 12).


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The IM guide can be left in place during resectionof the distal condyle, taking care to avoid hittingthe IM rod when using the oscillating saw.

Completely loosen the attachment screw

(Fig. 13) in the Distal Placement Guide. Then usethe Slaphammer Extractor to remove the IMguide and the Distal Placement Guide (Fig. 14).

Cut the distal femur through the cutting slot inthe cutting guide using a 1.27mm (0.050-in.)oscillating saw blade (Fig. 15). Then removethe cutting guide.

Fig. 13

Fig. 14

Fig. 15

Check the flatness of the distal femoral cutwith a flat surface. If necessary, modify thedistal femoral surface so that it is completelyflat. This is extremely important for theplacement of subsequent guides and forproper fit of the implant.


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STEP THREESIZE FEMUR AND ESTABLISHEXTERNAL ROTATIONFlex the knee to 90 . Attach the MIS ThreadedHandle to the Mini A/P Sizing Guide, and placethe guide flat onto the smoothly cut distal femur(Fig. 16). Apply the guide so that the flat surfaceof the Mini A/P Sizing Guide is flush against theresected surface of the distal femur and the feetof the Mini A/P Sizing Guide are flush against theposterior condyles.

Slide the body of the Mini A/P Sizing Guide alongthe shaft to the level of the medullary canal.Position the guide mediolaterally, and check theposition by looking through both windows of theguide to ensure that the medullary canal is notvisible through either.

Note: Remove any osteophytes that interfere with instrument positioning.

While holding the Mini A/P Sizing Guide in plasecure the guide to the resected distal femurusing 3.2mm (1/8 inch) Headed Screws or predriand insert Hex-head Holding Pins into one orboth of the holes in the lower portion of theguide. Do not overtighten or the anterior portionwill not slide on the distal femur.

Note: Remove the Threaded Handle before usingthe Screw Inserter/Extractor.

Slightly extend the knee and retract soft tissues texpose the anterior femoral cortex. Clear any sotissue from the anterior cortex. Ensure that theleg is in less than 90 of flexion (70 -80 ). This

will decrease the tension of the patellar tendon tofacilitate placement of the guide.

Attach the MIS Locking Boom to the Mini A/PSizing Guide. Ensure that the skin does not putpressure on the top of the boom and potentiallychange its position. The position of the boomdictates the exit point of the anterior bonecut and the ultimate position of the femoralcomponent. When the boom is appropriatelypositioned, lock it by turning the knurledknob (Fig. 17).

Fig. 16

Fig. 17


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Read the femoral size directly from the guidebetween the engraved lines on the sizing tower(Fig. 18). There are eight sizes labeled A throughH. If using an anterior referencing technique,and the indicator is between two sizes, thesmaller size is typically chosen to help preventexcessive ligament tightness in flexion. If using aposterior referencing technique, and the indicatoris between two sizes, the larger size is typicallychosen to help prevent notching of the anteriorfemoral cortex. (For more information on in-between sizing for the posterior referencingtechnique, see Appendix 1 on page 32.)

If using a posterior referencing technique,remove the Mini A/P Sizing Guide and go topage 22, Step Four Finish the Femur, PosteriorReferencing Technique.

There are four External Rotation Plates: 0 /3 Left, 0 /3 Right, 5 /7 Left, and 5 /7 Right.Choose the External Rotation Plate that

provides the desired external rotation for theappropriate knee. The 0 option can be usedwhen positioning will be determined by the A/Paxis or the epicondylar axis. Use the 3 optionfor varus knees. Use the 5 option for knees with

a valgus deformity from 10 to 13 . The 7 optionrequires a standard exposure, and is for knees withpatellofemoral disease accompanied by bone lossand valgus deformity greater than 20 . In this case,use the A/P axis to double check rotation.

Attach the selected plate to the Mini A/P SizingGuide (Fig. 19). Place two Headless Holding Pinsin the plate through the two holes that correspondto the desired external rotation, and impact them(Fig. 20). Leave the pins proud of the guide. Thiswill establish the desired external rotation fromthe posterior condyles.

Note: Do not impact the Headless Holding Pins

flush with the External Rotation Plate.

Fig. 18

Fig. 19

Fig. 20


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Careful attention should be taken when placingthe headless pins into the appropriate ExternalRotation Plate as these pins also set the A/Pplacement for the MIS Femoral Finishing Guide inthe next step of the procedure. It is important tomonitor the location of the anterior boom on theanterior cortex of the femur to help ensure theanterior cut will not notch the femur. Positioningthe anterior boom on the high part of the femurby lateralizing the location of the boom can oftenlessen the likelihood of notching the femur.

Unlock and rotate the boom of the guide mediallyuntil it clears the medial condyle. Then remove

the guide, but leave the two headless pins. Thesepins will establish the A/P position and rotationalalignment of the Femoral Finishing Guide.

STEP FOURFINISH THE FEMUR

Anterior Referencing TechniqueSelect the correct size MIS Femoral FinishingGuide (silver colored) or MIS Flex FemoralFinishing Guide (gold colored) as determined bythe measurement from the A/P Sizing Guide.An additional 2mm (approximately) of bone isremoved from the posterior condyles when usingthe Flex Finishing Guide.

Place the finishing guide onto the distal femur,

over the headless pins (Fig. 21). This determinesthe A/P position and rotation of the guide.Remove any lateral osteophytes that mayinterfere with guide placement. Position thefinishing guide mediolaterally by sliding it on thheadless pins. The width of the finishing guidereplicates the width of the NexGen CR FemoralComponent. The width of the flex finishing guidreplicates the width of the NexGen LPS, LPS-Flex,

and CR-Flex Femoral Components.

Fig. 21


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When the M/L position of the Femoral FinishingGuide is set, use the Screw Inserter/Extractorto insert a 3.2mm Headed Screw or predrilland insert a Hex-head Holding Pin through thesuperior pinhole on the beveled medial side of theguide (Fig. 22). Then secure the lateral side in thesame manner. For additional stability, predrill andinsert two Short-head Holding Pins through theinferior holes on one or both sides of the guide.

Remove the headless pins from the FemoralFinishing Guide (Fig. 23) with the HeadlessPin Puller.

Use the Resection Guide through the anterior

cutting slot of the finishing guide, and check themedial and lateral sides to be sure the cut willnot notch the anterior femoral cortex (Fig. 24).

Fig. 22

Fig. 23

Fig. 24


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Optional Technique:To check the location of the anterior cut anddetermine if notching will occur, securely tightenthe Locking Boom Attachment to the face of the finishing guide. Make certain that the attachment sits flush with the Femoral Finishing Guide (Fig. 25).Connect theMIS Locking Boom to the attachment(Fig. 26). The boom indicates the depth at which theanterior femoral cut will exit the femur.

Use a 1.27mm (0.050-in.) narrow, oscillating sawblade to cut the femoral profile in the followingsequence for optimal stability of the finishingguide (Fig. 27):

1) Anterior condyles 2) Posterior condyles

3) Posterior chamfer

4) Anterior chamfers

Fig. 27

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32

Fig. 25

Fig. 26


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Fig. 28

Use the Patellar/Femoral Drill Bit to drill the postholes (Fig. 28).

Use the 1.27mm (0.050-in.) narrow, reciprocatingsaw blade to cut the base of the trochlear recess

(Fig. 29) and score the edges (Fig. 30). Removethe finishing guide to complete the trochlearrecess cuts.

Fig. 29

Fig. 30


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Posterior Referencing TechniqueSelect the correct size MIS Femoral FinishingGuide (silver colored) or MIS Flex FemoralFinishing Guide (gold colored) as determined bythe measurement from the A/P Sizing Guide.An additional 2mm (approximately) of bone isremoved from the posterior condyles when usingthe flex finishing guide.

Attach the Posterior Reference/Rotation Guide tothe selected femoral finishing guide (Fig. 31). Lockthe femoral position locator on the rotation guideto the zero position (Fig. 32). This zero settinghelps to ensure that, when the feet are flush with

the posterior condyles, the amount of posterior

bone resection will average 9mm when usingthe standard MIS Femoral Finishing Guides, andapproximately 11mm when using the MIS FlexFemoral Finishing Guides.

Place the finishing guide on the distal femur,bringing the feet of the rotation guide flushagainst the posterior condyles of thefemur (Fig. 33).

Set the rotation of the finishing guide parallelto the epicondylar axis. Check the rotation ofthe guide by reading the angle indicated bythe Posterior Reference/Rotation Guide. Theepicondylar line is rotated externally 0 to 8 ,

(44 ), relative to the posterior condyles. Theexternal rotation angle can also be set relativeto the posterior condyles, lining up thedegrees desired.

Fig. 32

Fig. 33

Fig. 31


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If desired, attach the MIS Locking Boom to theface of the finishing guide to check the locationof the anterior cut and determine if notching willoccur (Fig. 34). The boom indicates where theanterior femoral cut will exit the bone.

Remove any lateral osteophytes that mayinterfere with guide placement. Position thefinishing guide mediolaterally. The width of thefinishing guide replicates the width of the NexGen CR Femoral Component. The width of the flexfinishing guide replicates the width of the NexGen LPS, LPS-Flex, and CR-Flex Femoral Components.

When the proper rotation and the mediolateraland anteroposterior position are achieved, securethe finishing guide to the distal femur. Use theScrew Inserter/Extractor to insert a 3.2mmHeaded Screw or predrill and insert a Hex-headHolding Pin through the superior pinhole on thebeveled medial side of the Femoral FinishingGuide (Fig. 35). Then secure the lateral side in thesame manner. For additional stability, predrill andinsert two Short-head Holding Pins through theinferior holes on one or both sides of the guide.

Fig. 35

Fig. 34


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Use a 1.27mm (0.050-in.) narrow, oscillating sawblade to cut the femoral profile in the followingsequence for optimal stability of the finishingguide (Fig. 36):

1) Anterior condyles

2) Posterior condyles

3) Posterior chamfer

4) Anterior chamfers

Fig. 36

Use the Patellar/Femoral Drill Bit to drill the postholes (Fig. 37).

Fig. 37

Fig. 38

Fig. 39

Use the 1.27mm (0.050-in.) narrow, reciprocatinsaw blade to cut the base of the trochlear recess(Fig. 38) and score the edges (Fig. 39). Remove tfinishing guide to complete the trochlearrecess cuts.


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STEP FIVECHECK FLEXION/EXTENSION GAPSUse the Spacer/Alignment Guides to check

the flexion and extension gaps. With the kneein extension, insert the thinnest appropriateSpacer/Alignment Guide between the resectedsurfaces of the femur and tibia (Fig. 40). Insertthe Alignment Rod into the guide and checkthe alignment of the tibial resection (Fig. 41). Ifnecessary insert progressively thicker Spacer/Alignment Guides until the proper soft tissuetension is obtained.

Then flex the knee and check ligament balanceand joint alignment in flexion. When using the MIS Flex Femoral Finishing Guide, the flexiongap will be approximately 2mm greater than theextension gap. For example, if the extension gapis 10mm, the flexion gap will be 12mm. The 2mmend of the Tension Gauge can be used to tightenthe flexion gap when checking ligament balance.

If the tension is significantly greater in extensionthan in flexion, re-cut the distal femur using theappropriate instrumentation. This will enlarge theextension space.

If the tension is significantly less in extension

than in flexion, either downsize the femur orperform additional ligament releases.

Fig. 40

Fig. 41


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STEP SIXPREPARE THE PATELLASharply dissect through the prepatellar bursa

to expose the anterior surface of the patella.This will provide exposure for affixing theanterior surface into the Patellar Clamp.

Remove all osteophytes and synovialinsertions from around the patella. Be carefulnot to damage tendon insertions on thebone. Use the Patellar Caliper to measure thethickness of the patella (Fig. 42). Subtract theimplant thickness from the patella thicknessto determine the amount of bone that shouldremain after resection.

Fig. 42

PATELLA THICKNESS IMPLANT THICKNESS= BONE REMAINING

IMPLANT THICKNESSES

Micro Standard

26mm 7.5mm

29mm 7.5mm 8.0mm

32mm 8.0mm 8.5mm

35mm 8.0mm 9.0mm

38mm 9.5mm

41mm 10.0mm

Note: At least 11mm of total bone will remain toallow for implant pegs if the Patella Reamer is used.


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Fig. 43

Fig. 44

RESECT THE PATELLA

Patellar Reamer Technique Total SurfacingProcedure

Use the Patellar Reamer Surfacing Guides astemplates to determine the appropriate size guideand reamer. Choose the guide which fits snuglyaround the patella, using the smallest guidepossible (Fig. 43). If the patella is only slightlylarger than the surfacing guide in the mediolateraldimension, use a rongeur to remove the medialor lateral edge until the bone fits the guide.

Insert the appropriate size Patellar Reamer

Surfacing Guide into the Patella Reamer Clamp(Fig. 44). Turn the locking screw until tight.


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Apply the Patellar Reamer Clamp at a 90 angleto the longitudinal axis with the Patellar ReamerSurfacing Guide encompassing the articularsurface of the patella. Squeeze the clamp untilthe anterior surface of the patella is fully seatedagainst the fixation plate (Fig. 45). Turn theclamp screw to hold the instrument in place. Theanterior surface must fully seat upon the pins andcontact the fixation plate.

Turn the depth gauge wing on the PatellarReamer Clamp to the proper indication for thecorrect amount of bone that is to remain afterreaming (Fig. 46).

Attach the appropriate size Patellar ReamerBlade to the appropriate size Patellar ReamerShaft (Fig. 47). Use only moderate hand pressureto tighten the blade.

Do not overtighten the blade. Insert thePatellar Reamer Shaft into a drill/reamer. Insertthe reamer assembly into the Patellar ReamerSurfacing Guide. Raise the reamer slightly offthe bone and bring it up to full speed. Advanceit slowly until the prominent high points arereamed off the bone. Continue reaming withmoderate pressure until the step on the reamershaft bottoms out on the depth gauge wing ofthe Patellar Reamer Clamp. Remove the reamerclamp assembly.

Proceed to Finish the Patella on page 30.

Fig. 45

Fig. 46Fig. 47


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Insetting TechniqueUse the Patellar Reamer Insetting Guides astemplates to determine the appropriate size guideand reamer. Choose the guide which will allowapproximately 2mm between the superior edgeof the patella and the outer diameter of theguide (Fig. 48).

Insert the appropriate size Patellar ReamerInsetting Guide into the Patellar Reamer Clamp.Turn the locking screw until tight. Apply thePatellar Reamer Clamp at a 90 angle to thelongitudinal axis with the Patellar ReamerInsetting Guide on the articular surface. Squeezethe clamp until the anterior surface of the patellais fully seated against the fixation plate. Turn theclamp screw to hold the instrument in place. Theanterior surface must fully seat on the pins andcontact the fixation plate.

Turn the clamp wing to the inset position.

Attach the appropriate size Patellar ReamerBlade to the appropriate size Patellar ReamerShaft (Fig. 49). Use only moderate hand pressure

to tighten the blade.Do not overtighten theblade. Insert the Patellar Reamer Shaft into adrill/reamer.

Use the Patellar Reamer Depth Stops to controlthe amount of bone to be removed based on thethickness of the implant chosen.

Note: If using a Primary Porous Patella withTrabecular Metal Material, all implants are10mm thick.

The depth gauge wing on thePatellar ReamerClamp can be used instead of the stops to controlthe amount of bone remaining, rather than theamount of bone removed.

Insert the reamer assembly into thePatellar Reamer Insetting Guide. Raise the reamer slightly

off the bone and bring it up to full speed. Advanceit slowly until the prominent high points arereamed off the bone. Continue reaming withmoderate pressure. Remove the reamer clampassembly. Proceed to Finish the Patella onpage 30.

2mm


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Universal Saw Guide TechniqueApply the Universal Patellar Saw Guide in linewith the patellar tendon. Push the patella upbetween the jaws of the saw guide. Level thepatella within the saw guide jaws and use thethumbscrew to tighten the guide.

The amount to be resected across the top ofthe saw guide jaws should be approximatelythe same on all sides. Check to be sure that the10mm gauge does not rotate beneath the anteriorsurface of the patella. If the gauge hits theanterior surface of the patella as it is rotated, thisindicates that at least 10mm of bone stock will

remain after the cut (Fig. 50).

FINISH THE PATELLA

For the NexGen Primary Porous PatellaWith Trabecular Metal MaterialCenter the appropriate Patellar Drill Guide overthe resected patella surface with the handle onthe medial side of the patella and perpendicular tothe tendon. Press the drill guide firmly in place sothat the teeth fully engage and the drill guide sitsflat on the bone surface (Fig. 52). Drill the peg holmaking sure the drill stop collar contacts the topof the drill guide (Fig. 53).

Note: The Primary Porous Patellar Clamp may be use

to fully seat the drill guide on hard scleroticbone surfaces.

Fig. 51

Fig. 50

Fig. 52

Fig. 53

Cut the patella flat so that a smooth surfaceremains (Fig. 51).


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Apply cement to theTrabecular Metal surfaceand post while in a doughy consistency. Locatethe drilled post hole and use the Primary PorousPatellar Clamp to insert and secure the patella inplace. Fully open the jaws of the clamp and alignthe teeth to the anterior surface of the patella andthe plastic ring to the posterior surface of theimplant. Use the clamp to apply a significantamount of pressure to the implant to fully seatthe implant on the patellar surface (Fig. 54).Removeexcess cement.

Note: If the implant post begins to engage atan angle, the implant should be removed and repositioned perpendicular to the resected surface.

Insert the patella again and reclamp, applying aneven distribution of pressure on the patellar surface.

For the NexGenAll-Polyethylene PatellaCenter the appropriate Patellar Drill Guide overthe patella with the handle on the medial side

of the patella and perpendicular to the tendon.Holding the drill guide firmly in place, drill thethree peg holes using the Patellar/Femoral DrillBit (Fig. 55).

Apply cement to the anterior surface and pegsof the patellar component while in a doughyconsistency. Locate the drilled peg holes anduse the Patellar Clamp to insert and secure thepatella in place. Fully open the jaws of the clampand align the teeth to the anterior surface ofthe patella and the plastic ring to the posteriorsurface of the implant. Use the clamp to applya significant amount of pressure to the implantto fully seat the implant on the patellar surface.Remove excess cement.

Fig. 54

Fig. 55


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APPENDIX 1

In-Between Sizing for PosteriorReferencing TechniqueTypically, the larger size femoral componentis selected. This means, however, that thepatellofemoral joint may be overstuffed. In-between placement means selecting the smallerfemoral component size and shifting the A/Pposition to resect slightly more posterior bonethan with the described posterior referencetechnique. The posterior referencing guide canalso be used to correctly position the femoralcomponent on the distal femur.

The 3 distal femoral cut can facilitate this shiftand protect against potential anterior notching.The Posterior Reference/Rotation Guide helpsdetermine in-between placement. The zeromark on the Posterior Reference/Rotation Guidemeasures an average 9mm posterior resectionfor standard guides (CR femorals), which is thestandard resection, and provides a scale whichindicates any variance from that 9mm average.Likewise, the zero mark measures approximately11mm posterior resection for flex guides (LPS,LPS-Flex and CR-Flex femoral components).


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APPENDIX 2

Crossover Technique(When crossing over to a posterior

stabilized design)

MIS PS Notch GuidePosition the appropriate size MIS PS Notch Guideonto the femur so it is flush against the resectedsurfaces both distally and anteriorly. The MIS PS Notch Guide will not contact the anteriorchamfer. Use the previously prepared trochlearrecess and/or the femoral post holes to position

the MISPS Notch Guide mediolaterally.

Fig. 56

Secure the MISPS Notch Guide to the femur withtwo 3.2mm (1/8 inch) Headed Screw or predrilland insert two 3.2mm (1/8 inch) Holding Pins(Fig. 56). Use a reciprocating saw to cut the sidesand the base of the intercondylar notch (Fig. 57).Then remove the MISPS Notch Guide (Fig. 58).

Fig. 57

Fig. 58


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EPI Notch/Chamfer GuidePlace the EPI Notch/Chamfer Guide flush withthe anterior and distal surfaces of the femur.Use the previously prepared trochlear recessand/or femoral post holes to locate the guidemediolaterally. Pin the guide to the femur and usethe appropriate saw to cut the sides of the notch(Fig. 59). Then use an osteotome to removethe notch.

5-in-1 Femoral Finishing GuidePlace the appropriate size 5-in-1 FemoralFinishing Guide onto the femur. It will rest on thresected surfaces of the anterior and distal femurThe guide will not contact the anterior chamfer.Use the previously prepared trochlear recess andor femoral post holes to locate the guide.

Secure the guide to the femur with two Short-threaded Silver Spring Pins using the Female HeDriver and drill/reamer. The pins are designed toautomatically disengage the pin driver when fullengaged on the guide.

Optional Technique:

The guide can also be attached with standard1/8 inch pins through the holes in the anteriorand distal portion of the guide. Ensure that the proper size holes are selected for the spring pinsor 1/8 inch pins.

Use a reciprocating saw to cut the sides and thebase of the intercondylar notch.

Optional Technique:

An oscillating saw with a small width blade mayalso be used. Or use a normal blade to cut the sides and a chisel or osteotime to cut the base ofthe recess.

Fig. 59


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Notch Chamfer GuidePlace the Notch Chamfer Guide on the cut surfaceof the distal femur with the anterior tab restingin the trochlear recess. Pin the guide to the boneand use a saw to cut the sides of the notch(Fig. 60). Then use an osteotome to removethe notch.

Fig. 60


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1 Vaughan LM. TKR through a mini incision. 17th Annual Vail OrthopaedicSymposium. State-of-the-art total hip and knee replacement controversies andsolutions. January 19-24, 2003.

2 Liem MS, Van Der Graaf Y, Van Steensel CJ, et al. Comparison of conventionalanterior surgery and laparoscopic surgery for inguinal-hernia repair. The NewEngland Journal of Medicine. 1997;336(22):1541-1547.

3 Repicci JA, Eberle RW. Minimally invasive surgical technique for unicondylarknee arthroplasty. J South Orthop Assoc . 1999;8(1):20-27.

4 Romanowski MR, Repicci JA: Minimally invasive unicondylar arthroplasty:Eight year follow-up. J Knee Surg . 2002;15:17-22.

5 Hofmann AA, Plaster RL, Murdock LE. Subvastus (Southern) approach forprimary total knee arthroplasty.Clin Orthop. 1991;269:70.


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