Zimmer NexGen LPS Flex Mobile Surgical Technique
Zimmer NexGenMIS LPS-Flex MobileImplant System Surgical TechniqueIMAGE TOCOMESafely Accommodating Deep Flexion
Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical TechniqueZimmer NexGen MISLPS-Flex Mobile ImplantSystem Surgical TechniqueTable of ContentsIntroduction2Developed in conjunction withPatient Selection3Preoperative Planning4Surgical Technique5Patient Preparation5Incision and Exposure5Jean Noël Argenson, MDMarseille, FranceMark A. Hartzband, MDHackensack, NJMichael Kelly, MDHackensack, NJGiles R. Scuderi, MDNew York, NYStep One: Resect Proximal Tibia11Step Two: Establish Femoral Alignment15Step Three: Cut the Distal Femur17Step Four: Check Extension Gap18Step Five: Size Femur and Establish External Rotation19Step Six: Finish the FemurOption 1: Anterior Referencing TechniqueOption 2: Posterior Referencing Technique212123Step SevenOption 1: MIS Notch/Chamfer Trochlear GuideOption 2: MIS QS Notch Guide252527Step Eight: Check Flexion GapBalance Flexion/Extension Gaps2828Step Nine: Prepare the Tibia29Step Ten: Perform Trial Reduction31Step Eleven: Finish the Tibia33Step Twelve: Prepare the Patella35Optional Patella Protectors40Step Thirteen: Perform a Final Trial Reduction41Step Fourteen: Implant Components42Closure44Rehabilitation Protocol44
Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical TechniqueIntroductionSuccessful total knee arthroplasty (TKA)depends in part on re-establishment ofnormal lower extremity alignment, properimplant design and orientation, secureimplant fixation, adequate soft tissuebalancing and stability.NexGen MIS LPS-Flex MobileBearing KneeThe NexGen MIS LPS-Flex MobileBearing Knee is a posterior stabilizedprosthesis designed to accommodategreater range of motion for appropriatepatients, such as those who arephysically capable or whose culturalcustoms or recreational/work activitiesrequire deep flexion.The development of the LPS-Flex MobileBearing Knee is the result of an analysisof a knee prosthesis as it undergoesdeep flexion beyond 120 . For example,the interaction of the posterior condyleson the articular surface was carefullystudied. As a result, efforts have beenmade to optimize the contact areaas the posterior condyles roll back toflexion angles up to 155 (Fig. 1). This isaddressed by thickening the posteriorcondyles, thereby extending the radius.Fig. 1 Contact area at 155 The tibial articular surface was alsoconsidered in the design. In deep flexion,the extensor mechanism experiences ahigh level of stress as the soft tissuesare stretched and pulled tightly againstthe anterior tibia and distal femur. TheLPS-Flex Mobile Bearing Knee is designedto help relieve these stresses througha larger, deeper anterior cutout on thearticular surface (Fig. 2). This cutoutaccommodates the extensor mechanismin deep flexion.MIS LPS-Flex MobileTibial ImplantThe MIS Tibial Component is the firsttibial implant designed to simplify theinsertion of the tibial plate through aminimally invasive incision. The stem/fin geometry fits within the minimal20mm gap created after bone resection.The stem lengths are 17mm or 19mm,depending on implant dimension.The MIS LPS-Flex Mobile TibialComponent incorporates the samebottom geometry (Fig. 3).Fig. 2Additionally, the cam/spine mechanismhas been modified to provide greaterjump height as the knee prosthesisundergoes deep flexion between 120 and 155 . The cam/spine mechanisminduces mechanical rollback whileinhibiting posterior subluxationof the tibia.These design features accommodatehigh-flexion activities and, togetherwith proper patient selection, surgicaltechnique, and rehabilitation, increasethe potential for greater range of motion.The LPS-Flex Mobile Bearing KneeComponents can be implantedusing any of the NexGen KneeInstrument Systems.Fig. 3Broad fins are located in the proximaltibial region with the highest bonedensity providing resistance to bendingmoments.1 This fin position wasestablished based on the experiencewith the post position in the TrabecularMetal Monoblock Tibial Plates.
Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical TechniqueMIS Multi-Reference 4-in-1 InstrumentsPatient SelectionMIS Multi-Reference 4-in-1 Instrumentsare designed to help the surgeonaccomplish the goals of total kneearthroplasty by combining optimalalignment accuracy with a simple,straight-forward technique. Theinstruments promote accurate cuts tohelp ensure secure component fixation.Total knee arthroplasty using a lessinvasive technique is suggested fornonobese patients with preoperativeflexion greater than 90 . Patients withvarus deformities greater than 17 orvalgus deformities greater than 13 are typically not candidates for theMIS technique.The MIS Multi-Reference 4-in-1Instruments provide a choice of eitheranterior or posterior referencingtechniques for making the femoralfinishing cuts. The anterior referencingtechnique uses the anterior cortex toset the A/P position of the femoralcomponent. The posterior condyle cutis variable. The posterior referencingtechnique uses the posterior condylesto set the A/P position of the femoralcomponent. The variable cut is madeanteriorly. The posterior referencingtechnique will help provide a consistentflexion gap. Femoral rotation isdetermined using the posterior condylesor epicondylar axis as a reference.A common view among orthopaedicsurgeons is that certain patients havegreater potential for achieving higherflexion after knee replacement. Patientswith good flexion preoperativelytend to get better range of motionpostoperatively.The instruments and technique assistthe surgeon in restoring the center of thehip, knee, and ankle to lie on a straightline, establishing a neutral mechanicalaxis. The femoral and tibial componentsare oriented perpendicular to this axis.The NexGen LPS-Flex implants aredesigned to safely accommodate highflexion of up to 155 .To optimize use of the high-flexiondesign elements, the following criteriashould be considered: The patient should have a needand desire to perform deep-flexionactivities. This need may be dictatedby activities specific to daily living,leisure and recreation or jobperformance that may require highflexion capability, as well as culturalor social customs where practicessuch as frequent kneeling, sitting“cross-legged”, and squattingare common. The patient should be capableof reaching 110 of flexionpreoperatively with a reasonableprobability of achieving a range of125 postoperatively. The length of time the patient hasnot performed high-flexion activitiesshould be considered. In patients with severe deformitypreoperatively, patient expectationfor achieving high flexion shouldbe considered.To prepare the patient for surgery,it may be helpful for the patient toperform mobility exercises to preparethe ligaments and muscles for thepostoperative rehabilitation protocol.Please refer to the package insertsfor complete product information,including contraindications, warnings,precautions, and adverse effects.
Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical TechniquePreoperative PlanningThe surgical technique helps the surgeonensure that anatomic alignment of 4 to6 valgus angulation to the mechanicalaxis is achieved. A full leg A/P radiographmay be helpful in preoperativeassessment and planning. Longradiographs are useful for determiningthe mechanical axis relative to theanatomical axis of the femur and foridentifying deviations from the axis anddeformities in the diaphyseal area of thefemur and tibia that might be overlookedin more localized radiographs.Verify that the femoral and tibialcomponent sizes approximated willbe compatible. Check the appropriateknee implant size matching chart forcomponent matching instructions.Mismatching may result in poor surfacecontact and could produce pain,decrease wear resistance, produceinstability of the implant, or otherwisereduce implant life.The mechanical and anatomical axesof the leg can be precisely plottedand the femoral angle α, representingthe difference between the two, canbe determined (Fig. 4). This angle,which is usually about 6 , but may varydepending on morphology and patientsize, is important for choosing theappropriate femoral angle bushing andtherefore a correct positioning of thedistal femoral cut.ABCDEαAnatomical axis of femurAxis of the tibiaMechanical axis of the legMechanical axis of the femurResection depth of the tibia (mm)Valgus angleαAαDBy lengthening the line of the anatomicalaxis of the femur, it can be shown thatthe entry point for the intramedullaryalignment guide does not necessarily liein the center of the femoral condyle, butmost of the time slightly medial tothis point.The primary objective of templating is toestimate the size of the components tobe used. Use the various templates toapproximate the appropriate componentsizes. The final sizes will be determinedintraoperatively. Therefore, at the timeof surgery, sizes larger and smaller thanthose estimated in templating shouldbe available.ACC.PreoperativePostoperativeBFig. 4E
Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical TechniqueSurgical TechniqueSurgical technique is an importantfactor to consider when attemptingto maximize range of motion in totalknee arthroplasty. Close attentionmust be paid to balancing the flexionand extension gaps, clearing posteriorosteophytes, releasing the posteriorcapsule, and reproducing the joint line.Although the joint line may change as aresult of a posterior cruciate substitutingprocedure, it is important that an attemptbe made to maintain the joint line whenhigh flexion is a priority. Depending onthe degree, altering the joint line cancause patellofemoral issues and limitthe degree of flexion. An elevated joint,for example, can cause tibiofemoraltightness in rollback and thusrestrict flexion.2When using the gap technique, it ispossible that the joint line may bemoved proximally, especially if thereis a preoperative flexion contracture orif the selected femoral component issmaller than the A/P dimension of thefemur. The alteration of the joint line canbe minimized by accurately measuringfor the femoral component size andperforming a posterior capsulotomyto correct flexion contractures.Patient PreparationTo prepare the limb for total kneearthroplasty, adequate muscle relaxationis required. This will facilitate theeversion of the patella, if desired, andminimize tension in the remainingquadriceps below the level of thetourniquet. It is imperative that themuscle relaxant be injected prior toinflation of the tourniquet. Alternatively,spinal or epidural anesthesia shouldproduce adequate muscle relaxation.If using a tourniquet, apply the proximalthigh tourniquet and inflate it with theknee in hyperflexion to maximize thatportion of the quadriceps that is belowthe level of the tourniquet. This will helpminimize restriction of the quadricepsand ease patellar eversion.Once the patient is draped and preppedon the operating table, determine thelandmarks for the surgical incision withthe leg in extension.Incision and ExposureThe skin incision can be made at thesurgeon’s discretion with the leg inflexion or extension. Most surgeons findit easier to make the incision with theknee flexed. This provides skin tautness,and some retraction on the skin edges.The initial incision is based on palpablelandmarks and should initially extendapproximately 1cm below the jointline and 1cm above the superior poleof the patella with the knee flexed.In a well-placed incision with supplesoft tissues, this incision length canbe adequate for the procedure. Largeramounts of subcutaneous fat, largeamounts of fibrotic synovium, or thickinelastic quadriceps musculature mayrequire more generous exposure and thesurgeon must be cautious in retraction toavoid excessive tension on the skin.The estimated size of the femoralcomponent influences the length of theincision. Although the goal of a lessinvasive technique is to complete thesurgery with an approximately 10cm14cm incision, it may be necessaryto extend the incision if visualizationis inadequate or if there is excessivetension on the skin. If the incision needsto be extended, it is advisable to extendit gradually and only to the degreenecessary. However, the advantage ofthis MIS technique is minimizing damageto the extensor mechanism and failure toconsider excessive tension on the skinmay lead to wound problems.Make a slightly oblique parapatellarskin incision, beginning approximately2cm proximal and medial to the superiorpole of the patella, and extend itapproximately 10cm to the level of thesuperior patellar tendon insertion at thecenter of the tibial tubercle (Fig. 5). Becareful to avoid disruption of the tendoninsertion. This will facilitate access tothe vastus medialis obliquus, and allowa minimal split of the muscle. It willalso improve visualization of the lateralaspect of the joint obliquely with thepatella everted.Divide the subcutaneous tissues to thelevel of the retinaculum.Adjustments in incision placement maybe performed by incision lengtheningand repositioning as exposure proceeds.Raising full thickness flaps along thelength of the incision improves mobilityof the patella and facilitates partialeversion for patellar preparation whilesimultaneously improving mobility ofthe skin and reducing tension on theskin flaps during minimally invasiveexposure.Fig. 5
Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical TechniqueMIS Medial ParapatellarArthrotomyDeveloped in conjunction with Giles R.Scuderi, M.D.Minimally invasive total kneearthroplasty has become a popularprocedure with surgeons using a varietyof surgical exposures including thelimited medial parapatellar arthrotomy;the midvastus approach; subvastusapproach; and Quad Sparing approach.The MIS medial parapatellar arthrotomyis a versatile approach that can be easilyconverted to a traditional approach ifnecessary. Advantages of this techniqueinclude diminished post-operativemorbidity, less post-operative pain,decreased blood loss, and an earlierfunctional recovery.3-7 However, whilelimiting the exposure, the integrity ofthe total knee arthroplasty must notbe compromised. Following specificguidelines in patient selection andsurgical technique, the clinical outcomecan be predictable.The MIS medial parapatellar arthrotomyis a versatile approach because itevolved from the traditional approachperformed by most surgeons. Thelearning curve for this technique is shortas surgeons gradually reduce the lengthof the skin incision and the arthrotomyinto the quadriceps tendon in order togain exposure of the knee joint. Withlateral subluxation of the patella, insteadof eversion, both the femur and tibia canbe visualized without extendingthe arthrotomy high into thequadriceps tendon.Begin by making a straight anteriormidline incision from the superior aspectof the tibial tubercle to the superiorborder of the patella. The skin incisionis made as small as possible in everypatient, but should be extended asneeded during the procedure to allow foradequate visualization and avoidanceof excess skin tension. Skin under theappropriate tension should form a ‘V’at the apices. If the skin forms a ‘U’, theincision should be lengthened.Following subcutaneous dissection,develop full-thickness medial and lateralflaps to expose the extensor mechanism.Release of the deep fascia proximallybeneath the skin and superficial tothe quadriceps tendon facilitatesmobilization of the skin and enhancesexposure. In addition, with the kneein flexion the incision will stretch anaverage of 3.75cm due to the elasticity ofthe skin allowing broader exposure.7The goal of minimally invasive surgery isto limit the surgical dissection withoutcompromising the procedure. The MISmedial parapatellar arthrotomy is ashortened version of the traditionalapproach. Initially incise the quadricepstendon for a length of 2-4cm abovethe superior pole of the patella. Thearthrotomy should be of a sufficientlength to sublux rather than evert thepatella laterally or if the patella tendonis at risk of injury, extend the arthrotomyproximally until adequate exposure isachieved (Fig. 6).Once the exposure is achieved, thebone preparation begins with the kneeflexed at 90 , retractors are placedboth medially and laterally to helpaid in exposure, avoid undue skintension, and to protect the collateralligaments and the patella tendon. Inorder to aid visualization and avoidundue tension to the skin, the surgicalassistants are instructed in properplacement of retractors and positioningof the knee. This will create a “mobilewindow” of exposure. With experience,it will become obvious that the bonepreparation and resection is performedat different angles of knee flexion. Inaddition as the bone is resected from theproximal tibia and distal femur, there ismore flexibility to the soft tissue envelopeand greater exposure is achieved.Fig. 6
Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical TechniqueMIS Midvastus ApproachDeveloped in conjunction withAaron G. Rosenberg, M.D.The capsular incision from thesuperomedial corner of the patelladistally to the tissue overlying the medialtibia is routine in all medial capsularapproaches. Preserve approximately 1cmof peritenon and capsule medial to thepatellar tendon to facilitate completecapsular closure. Split the superficialenveloping fascia of the quadricepsmuscle proximally over a length ofseveral centimeters to identify the vastusmedialis obliquus (VMO) fibers insertinginto the extensor mechanism. This willhelp mobilize the quadriceps and allowfor significantly greater lateral translationof the muscle while minimizing tensionon the patellar tendon insertion.The approach becomes “midvastus” ata point proximal to the superomedialpole of the patella. Variations on theangle at which the proximal part of thecapsular incision enters the musclebelly of the VMO will result in variousamounts of the muscle being incised aswell as variation in the amount of forcerequired to sublux the patella laterally.Additional variables include the actualpoint of insertion of the VMO fibers intothe patella. This insertion is variable andcan take place very high (actually on thequadriceps tendon proper and not onthe patellar border at all), or lower (at themidpoint of the medial patellar border),or anywhere in between. The higher theinsertion of the VMO, the shorter thelength of the incision into the muscleproper. The lower the insertion, the morea “low incision” into the VMO will makethe exposure more like a subvastusapproach and may make subluxationof the patella more difficult. It is veryimportant to carry the capsular incisionall the way to the superior border of thepatella before incising the muscle bellyof the VMO.collateral ligament from its insertion onthe proximal tibia. This occurs while theknee is flexed but may be carried out inextension at the surgeon’s discretion.This is adequate for exposure of themedial side of the knee. The experiencedsurgeon may want to proceed withany medial capsular releases that arepredicted to be necessary to align thelimb and balance the knee, or thesemaneuvers may be saved for later inthe procedure. At this point the medialcapsular retractors are removed from thewound for exposure of the lateral side.Fig. 7After identifying the characteristics ofthe VMO insertion, the vastus medialisobliquus muscle belly is split by sharpdissection approximately 1.5cm-2cm(Fig. 7). The superficial muscle has onlya flimsy investing fascia and this fascia,along with the muscle belly, may besplit by blunt dissection; however, thedeepest layer of muscle is adherent tothe more robust fascia of the VMO, whichshould be incised sharply.The use of a rake to retract the capsularedges medially will reveal variableamounts of synovium. The synovium maybe minimal, exuberant and inflamed, orfibrotic. Removal of excessive synoviumfrom the medial border of the capsule atthe most proximal part of the exposuredistally will improve exposure and, if thesynovium is fibrotic, will also reduce thetension required for exposure.Routine medial capsular exposureproceeds by sharp dissection andremoval of the anterior third of themedial meniscus, and is followed bysharp dissection of the deep medialThe knee is in extension for thepreliminary portion of the lateral kneeexposure. First, the mobility of thepatella is determined. Rakes are used togently mobilize the patella. Mobilizationmay be inhibited, however, by fibrosisof the fat pad inferiorly or scarring of thesuprapatellar synovium superiorly. Bothconditions can be established by carefulpalpation and appropriate releasesperformed by sharp dissection. Largepatellar osteophytes may be removed atthis point to make patellar mobilizationeasier. If partial eversion—bringingthe patella perpendicular to the joint(90 )—is possible, no further dissectiondistally in the fat pad or proximally viasuprapatellar synovectomy is needed.With the patella partially everted, thebulk of the fat pad can be debrided atthe surgeons discretion. The tighter theexposure, the more fat pad debridementwill facilitate visualization and cuttingguide placement.The lateral joint space is then exposedby flexing the knee. It is important toavoid disrupting the extensor insertionby gently mobilizing the patella, slowlyflexing the joint, and externally rotatingthe tibia while applying gentle pressureon the patella. An excessively thickpatella may make exposure more difficultand it may help to make a standard
Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical Techniquepatellar cut to decrease the thicknessof the patella. If this is necessary, thepatella must be protected from retractionforces with an appropriate patellarprotection device.Once the patella is subluxed, one ortwo standard-size Hohmann retractorsplaced along the lateral flare of the tibialmetaphysis will maintain the eversion ofthe patella and the extensor mechanism.If present, the anterior cruciate ligamentis released. A subperiosteal dissectionalong the proximal medial and lateraltibia to the level of the tibial tendoninsertion can be performed as neededto mobilize the tissue envelope andto help adequately expose the bone.Release of the lateral patellofemoralligament and/or limited release of thelateral capsule (less than 5mm) mayoccasionally, but rarely, be required tohelp minimize tension on the extensormechanism. Pointed Hohmann and kneejoint retractors may be used to mobilizethe skin and arthrotomy incision tocreate the “mobile window” throughwhich the remainder of the procedureis performed.It is very important to maintainobservation of the patellar tendonand the wound margins throughoutthe procedure to ensure that tensionon these tissues are kept to anacceptable level.MIS Subvastus ApproachDeveloped in conjunction withRussell G. Cohen, M.D.Becoming accustomed to operatingthrough a small incision and adoptingthe concept of a mobile window may befacilitated by starting with a shortenedmedial parapatellar arthrotomy. Thiswill help to improve visualization ofthe anatomy during the initial stages ofbecoming familiar with an MIS approach.When comfortable with the MIS medialparapatellar approach, performingthe arthrotomy through a midvastusapproach will help preserve thequadriceps tendon and a portionof the medial muscular attachment.As this procedure becomes morefamiliar, the level of the midvastusincision should be lowered to maintainmore muscle attachment.The subvastus arthrotomy providesexcellent exposure through an MISincision. The oblique portion of theincision starts below the vastusmedialis obliquus (VMO) attachmentand will preserve all the medial muscleattachments, including the retinacularattachment to the medial patella. Akey aspect of the subvastus approachis that it is not necessary to evert thepatella. This helps avoid tearing of themuscle fibers and helps maintain musclecontraction soon after surgery.The longitudinal incision should extendonly to the point of insertion of the VMOinferiorly, not to the proximal pole.Begin the arthrotomy at the medialedge of the tubercle and extend it alongthe border of the retinaculum/tendon toa point on the patella corresponding to10 o’clock on a left knee or 2 o’clock ona right knee. Then continue the incisionobliquely 1cm-2cm just below andin line with the VMO fibers (Fig. 8).Do not extend the oblique incisionbeyond this point as it creates furthermuscle invasion without providingadditional exposure.performing a more conservative medialrelease to avoid over-releasing analready attenuated tissue complex.With the knee in extension and a rakeretractor positioned to place tensionon the patella, remove the retropatellarfat pad. Then excise a small pieceof the capsule at the junction of thelongitudinal and oblique retinacularincisions. This release allows the patellato retract laterally. Undermine thesuprapatellar fat pad, but do not exciseit. This helps ensure that the FemoralA/P Sizer will be placed directly on bonerather than inadvertently referencingoff soft tissue, which may increase thefemoral size measurement.Placement of a lateral retractor is veryimportant for adequate retraction of thepatella. With the knee extended, slipthe retractor into the lateral gutter andlever it against the retinaculum at thesuperomedial border of the patella.As the knee is flexed, the patella isretracted laterally to provide goodvisualization of the joint.Perform a medial release according tosurgeon judgment, depending on thedegree of varus or valgus deformity.To facilitate a medial release, place theknee in extension with a rake retractorpositioned medially to provide tensionthat will assist in developing thisplane. For valgus deformities, considerFig. 8
Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical TechniqueZimmer MIS Quad-Sparing ArthrotomyAfter accessing the knee joint, balancingof the soft tissue structures and removalof osteophytes is initiated. Osteophytesmay tent the medial capsule andligamentous structures, and removalcan produce a minimal correctionbefore beginning the soft tissue release.Posteromedial osteophytes may needto be removed after the proximal tibiais resected.Training available at The Zimmer Institute.Prior experience with the MIS Midvastus,Subvastus or Medial Parapatellarapproach is helpful before attending theMIS Quad-Sparing Arthrotomy Course.When using a posterior stabilizedimplant, removing the posterior cruciateligament (PCL) will make it easier tobalance the collateral ligaments. It isnecessary to completely resect the PCL.Varus ReleaseTo correct most fixed varus deformities(Fig. 10), progressively release thetight medial structures until they reachthe length of the lateral supportingstructures. The extent of the releasecan be monitored by inserting laminarspreaders within the femorotibial jointand judging alignment with a plumbline. To facilitate the release, exciseosteophytes from the medial femur andtibia. These osteophytes tent the medialcapsule and ligamentous structures,and their removal can produce aminimal correction before beginningthe soft tissue release. Posteromedialosteophytes may need to be removedafter the proximal tibia is resected.Fig. 9Soft Tissue ReleasesTotal knee arthroplasty is a softtissue operation as well as a boneresection operation. The objective ofthis procedure should be to distributecontact stresses across the artificial jointas symmetrically as possible.8Soft tissue balancing is vital to helpassure implant stability. The basicprinciple for ligament release entailsthat the tight contracted concave sideis lengthened to match the convex side.The goal is to maintain a consistent andrectangular, not rhomboidal flexion andextension gap.LaxWith the knee in extension, elevate asubperiosteal sleeve of soft tissue fromthe proximal medial tibia, includingthe deep medial collateral ligament,superficial medial collateral ligament,and insertion of the pes anserinustendons. Continue the elevation with aperiosteal elevator to free the posteriorfibers. To improve exposure during therelease, retract this subperiosteal sleeveusing a Hohmann retractor.Release the insertion of thesemimembranosus muscle from theposteromedial tibia, and concurrentlyremove posterior osteophytes.Continue the release distally on theanteromedial surface of the tibia for 8cm10cm and strip the periosteum mediallyfrom the tibia. This should be sufficientfor moderate deformities. For more severedeformities, continue subperiostealstripping posteriorly and distally.For a fixed varus deformity, themedial release includes the deep andsuperficial medial collateral ligament,the semitendinosus tendon and the pesanserinus tendons.When varus malalignment is present witha flexion contracture, it may be necessaryto release or transversely divide theposterior capsule.TensedContractureLMFig. 10LM
10Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical TechniqueValgus ReleaseWhen correcting a fixed valgusdeformity, the lateral release willinclude the arcuate complex, iliotibialband and lateral collateral ligament.When possible the popliteus tendon ispreserved to maintain flexion stability.LaxTensedContractureLMLMFig. 11In contrast to that of a varus release,the principle of a valgus release isto elongate the contracted lateralstructures to the length of the medialstructures. Though lateral osteophytesmay be present and should be removed,they do not bowstring the lateralcollateral ligament in the same way asosteophytes on the medial side.This is because the distal insertion of thelateral collateral ligament into the fibularhead brings the ligament away from thetibial rim.For a valgus release, a “piecrust”technique may be preferable. Thistechnique allows lengthening ofthe lateral side while preserving acontinuous soft tissue sleeve, as well aspreserving the popliteus tendon, whichensures stability in flexion.With the knee in extension anddistracted with a laminar spreader,use a 15 blade to transversely cut th
Zimmer NexGen MIS LPS-Flex Mobile Implant System Surgical Technique Fig. 5 Surgical Technique Surgical technique is an important factor to consider when attempting to maximize range of motion in total knee arthroplasty. Close attention must be paid to balancing the flexion and extension gaps
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Zimmer’s growth in the near term. That is especially true in our two largest product categories, knees and hips. In knees, growth will come from the Gender Solutions brand and our Zimmer NexGen LPS-Flex Mobile Knee, designed to accommodate an increased range of motion. The Zimmer M/L
the Zimmer NexGen Knee family of replacement knee joints: 1) the so-called “Flex” or . minimally invasive surgery technique (i.e., a much smaller incision). The NexGen MIS . Defendant Zimmer Orthopaedic Surgical Products, Inc. is a corporation organized and existing under the law
Zimmer NexGen Complete Knee Solution LPS Surgical Technique 7 Place the Tibial Milling Depth Resection Guide onto the template. Adjust the Tibial Milling Base to the proper level (Fig. 11). Keep a finger on the
jects received the Zimmer NexGen High-Flex Gender Solutions knee prosthesis. Of the 97 knees, the first 39 TKAs with follow-up data through one year were included in the analysis to yield equal group sizes. A total of 28 of these gender specific implants were Nex-Gen CR-Flex, while the remaining 11 were NexGen LPS-Flex.
AGMA American Gear Manufacturers Association AIA American Institute of Architects. AISI American Iron and Steel Institute ANSI American National Standards Institute, Inc. AREA American Railway Engineering Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and .
