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ADVANCE Medial-PivotThe StoryMany patients complainof a loss of stabilitydue to total knee replacement, and this is sometimes calledanterior femoral sliding. In the literature this is referred to as“paradoxical motion.” This term was made prominent byRick Komistek, PhD, who is a prominent fluoroscopic researcher.This femoral sliding or “paradoxical motion” may be caused by anincreased flexion gap or total knee incongruity from an implantthat was designed to allow rollback.1,2In general, total knees may reduce the natural stability of theknee. Instead of rolling back, the femoral component slidesanteriorly. This is considered a paradox because total kneesare designed to rollback, but instead they slide forward. In atypical total knee replacement, as the knee goes into flexionat approximately 20 , the weight of the body pushes thefemur forward along the tibia. The femur will continue to slideforward until it’s stopped by the PCL or remaining musculature.Furthermore, this sliding forward puts added stress on theremaining soft tissues.FIGURE 1 Medial compartmentThis “paradoxical motion” is also present in posterior-stabilizedknees.1,2 Many surgeons believe that posterior-stabilized knees areunable to slide forward due to the post and cam articulation. Thishas been shown in the literature to be false. Posterior-stabilizedtotal knee replacements slide forward until they contact the post.In terms of the four-bar link theory, once the cam engages thepost, the rotational axis of a traditional posterior-stabilized kneebecomes the post.The MRI images shown in FIGURES 1 and 2 are visual examples ofhow the normal knee moves.3 These were MRIs provided as partof a study from Mr. Michael Freeman, a British surgeon, and VeraPinskerova, a Czechoslovakian PhD. The medial compartment ofthe tibial plateau is concave and “rocks” from a relatively posteriorcontact to anterior contact. FIGURE 1 The meniscus, the centerof the contact area and the penetration point of the flexion axis,moves forward with extension, but the medial femoral condyledoes not.3-5Unlike the medial side, the lateral meniscus moves forward withthe femur during extension. Thus, the tibiofemoral contact areaalso moves forward with extension resulting in an arcuate zone ofcontact. FIGURE 2FIGURE 2 Lateral compartmentADVANCE Medial-PivotADVANCE Medial-Pivot KneeKneeSystemSystem88

There are several features in the normal knee that make itstable: the musculature, capsule, collateral ligaments, the ACL,and PCL. Nearly 60% of body weight is transferred through themedial side of the knee. The medial side of the tibial plateauis concave in shape and, along with the medial intercondylareminence, acts to prevent anterior translation of the medialfemoral condyle. The opposite is true, however, for the lateralcompartment of the knee. This side is convex in shape and,coupled with a “humped” intercondylar eminence, allows arcuatetranslation. These structures create a knee that is more stable onthe medial side than the lateral side. Differences in stability led tothe concept of medial-pivot kinematics. FIGURE 3A medial-pivoting tibial insert is provided in the ADVANCE KneeSystem, designed to reproduce the rotational and translationalkinematics of the normal knee. On the lateral side there is anarcuate path, which allows 15 of motion around a medial-pivotpoint. That pivot point is on the medial side and is provided by aspherical concave surface. The anterior lip is designed to preventanterior slide, while the posterior lip is designed to replace theACL and prevent posterior slide. FIGURE 4Medial posterior lipreplaces ACL andstops posterior slideLateral meniscalpath allows for 15 of motionAFIGURE 4 MedialPivot InsertCBMedial anterior lip replacesPCL and stops anterior slideMedial meniscal“socket” providesstabilityDLateral meniscusallows motionPCL stopsanterior slideACL stopsposterior slideMedial meniscusand concave surfaceprovide stabilityFIGURE 5 The ADVANCE femur features spherical femoral condylesFIGURE 3 Superior view of the tibial plateauThe ADVANCE femoral implant has a constant sagittal radius of curvature extending from full extension to 90 degrees flexion. FIGURE 6The curvature values for each femoral implant were chosen from a detailed analysis of 130 cadaveric femora performed by Dr D. Blaha.In the study, the radius of curvature of the femur was measured between the average flexion-extension axis and the distal surface of thefemur every 10 degrees to 90 degrees flexion.6 The ADVANCE Medial-Pivot Knee also matches the sagittal radius with the radius in thecoronal plane to create the partial sphere of the femoral components. FIGURE 5In the sagittal plane the femoral component also features a smaller closing radius which has been shown to increase range of motion.7 FIGURE 7To further increase range of motion, the shape of the femoral component is complemented by the anterior stability of the ADVANCE Medial-Pivot tibial inserts. These components provide a robust anterior lip which maintains the femoral component in the posterior thirdof the articular surface. FIGURE 8 This creates a long quadriceps lever arm and reduces anterior sliding in flexion.1REFERENCESClosing Radius90 FIGURE 8 Femoralposition of ADVANCE Medial-Pivot Knee60 0 30 FIGURE 6 Constant radiusfrom 0 to 90 flexionFIGURE 7 Smallerclosing radius1/3 A-PA-P1. Komistek R. In vivo fluoroscopic analyses ofthe normal human knee. Clin Orthop RelatRes. 2003;410:69-81.2. Schmidt R. Fluoroscopic analyses of cruciateretaining and medial pivot knee implants.Clin Orthop Relat Res. 2003;410:139-147.3. Freeman M. The movement of the normaltibiofemoral joint. J Biomechanics.2005;38:197-208.4. Pinskerova V. Knee imaging study shedsnew light on fl exion, rollback. OrthopaedicsToday. 1999.5. Freeman. The movement of the knee studiedby magnetic resonance imaging. Clin OrthopRelat Res. 2003;410:35-43.6. Blaha JD. Using the transepicondylar axis todefi ne the sagittal morphology of the distalpart of the femur. JBJS 2002; 84:S48-55.7. Iwaki et al, JBJS 82-B, n 8 (2000): 1189-95ADVANCE Medial-Pivot Knee System9

ADVANCE Medial-PivotDesignFeaturesADVANCE Medial-Pivot Knee System10

ADVANCE Medial-Pivot Femoral ComponentConstant RadiusDesigned to restore the sagittal curvature of the femur withconstant radii from 0 to 90 , which delivers constant contactarea in flexion and extension.The single radius of curvature extends from 0 to 90 on the medial andlateral condyle. Additionally, the coronal radius is equal to the sagittalradius. These features provide the “ball” in the “ball-in-socket” design andcreate an extension geometry on the medial condyle that is equal to theflexion geometry. Coupled with the spherical medial side of the tibia, thisfeature prevents “paradoxical motion” (anterior translation of the femuron the tibia as the knee goes into flexion), but also maintains contact areaand prevents laxity throughout the range of motion.Extension ReliefIndentation on the medial flange allows the surgeon to adjustposterior slope while still ensuring full extension.An “extension relief” is built into the transition of the single radius of themedial condyle to permit clearance with the anterior lip of each tibialinsert. This indentation allows for optimized stability and contact area and isintended to reduce pain and risk of impingment during hyperflexion.1Medial Condylar“Extension Relief”Trochlear Groove3.6 Optimizes patellar tracking.FIGURE 1The trochlear groove features a lateral anatomic flare designed tooptimize the patella tracking. This trochlear groove has been designedwith the intent of minimizing strain in the lateral retinacular tissues anddecreasing the need for lateral retinacular releases.2 FIGURE 1FIGURE 2The trochlear groove is deepened on the femoral implant which isdesigned to reduce overstuffing and allow proper function of extensormechanism. FIGURE 2Anatomic TrochlearGroove DepthAdditionally, the trochlear groove has been extended posteriorly, sothe patella has full contact with the femoral implant into deep flexion.This is also proven to significantly reduce patellofemoral complicationscompared to PS designs.3 FIGURE 3ADVANCE Knee SystemAnatomic TrochlearGroove Depth RestoredCompetition:Heightened TrochlearGroove DepthFIGURE 3ADVANCE KneeCompetitive KneesADVANCE Medial-Pivot Knee System11

ADVANCE Medial-Pivot Femoral ComponentTrochlear Groove (continued)A lateral anterior flange which rises 2mm-6mm above the floor of thetrochlear groove provides resistance to lateral subluxation.42mm-6mmThis design feature maintains patellar tracking in the early stages of flexion.5Anterior Flange6 Designed to prevent femoral notching.The anterior flange of the femoral implants for the ADVANCE Medial-PivotKnee System is configured at a 6 angle. This angle of this anterior flangeresection is designed to help the surgeon avoid notching of the anteriorcortex.Femoral Peg LocationsSimplifies implant downsizing.The ADVANCE Medial-Pivot femurs are designed to maintain a commondistance from stabilizer pegs to the anterior flange resection (anteriorreferencing). When downsizing only the posterior cut is modified whileleaving the anterior reference untouched.Overlay of ADVANCE Size 1 and 6 Femoral ComponentsPosterior CondylesAllows for greater contact area up to 90 of flexion.Sizes 1-5: 8mmSize 6: 9mmThick posterior condyles allow for achievement of maximum flexion potential,but also require sacrificing femoral bone.6The ADVANCE femoral condyles have been designed to compromisebetween conservation of posterior femoral bone and achievement of goodflexion potential.14 The constant thickness for the ADVANCE posteriorcondyles allows for a smooth blending radius and an increased contact area inflexion in comparison to competitor’s design.15Sizes 1-5: 8mmSize 6: 9mmPatellaClinically proven implants.The femoral components interact with a domed patella, which is clinicallyproven in ADVANCE Knee Systems for over a decade.7,8 The forgivingspherical dome design permits freedom of patellar tilt and rotation seenduring normal functional activities after knee replacement.9-11ADVANCE Medial-Pivot Knee System12

ADVANCE Medial-Pivot Tibial Insert ComponentCondylar GeometryDesigned to restore natural kinematics.The ADVANCE coronal and sagittal radii for each of the medial and lateral femoral condyles produces two partial spheres. The spherical medial femoral condylepivots about the matching spherical depression on the tibial insert, while 15 of rotation around the medial-pivot point is allowed with an arcuate path on thelateral articular surface. This “ball-in-socket” medial-pivot mechanism maximizes medial congruency while providing controlled A-P translation on the lateralarticular surface.A comparative fluoroscopic evaluation has shown the ADVANCE Medial-Pivot design closely reproduces the motion of the normal knee, and avoids theparadoxical motion demonstrated in traditional total knees.12Cross Section Through the Lateral Condyle:Less Constrained Than Medial SideRotationAround Medial CondyleLateral compartmentallows for rotationaround medial pivotMedial compartmentallows for anteriorposterior stability,replacement of ACLand PCLCoronal and sagittal radii are equalon the femoral component.The coronal radius is matchedin the polyethylene insert.Cross Section Through the Medial Condyle:“Ball-in-Socket” CongruencyBone Conservation0,8Medial-PivotDesigned to substitute the PCL and not sacrifice bone.0,7Standard PSAs a posterior cruciate sacrificing device, the ADVANCE Medial-Pivotinsert is more bone conserving than traditional posterior stabilizedknees which requires resection of the femoral bone for the spine/cammechanism engagement.130,60,50,40,30,20,10Volume/Cubed InchesInstead of a traditional spine/cam mechanism, the insert features ananterior lip which provides a vertical jumping distance of 11mm for allsizes. The horizontal jumping distance for this lip is size dependent, andvaries between 23mm-32mm.ADVANCE Medial-Pivotvertical jumping distance is11 mm. Horizontal jumpingdistance ranges from 23 mmto 32 mm (size dependent).11 mm23 mm-32 mmADVANCE Medial-Pivot Knee System13

ADVANCE Medial-Pivot Tibial Tray ComponentTibial SizingImproved bone coverage and fit.Eleven tibial tray sizes are available within the ADVANCE Medial-Pivot KneeSystem. Within these sizes, six are known as “standard” and five as “plus”options, which configure a smaller locking mechanism on a larger tibial baseprofile. These have been generated to accommodate the interchangeabilityneeds for the system.For example, the tibial tray size 3 features the same dimension of the tibialtray size 4 and the femoral component size 3 can be implanted with tibial traysize 3 or 3 , as shown in the Table.FEMURINSERTTIBIAL TRAY111 or 1 222 or 2 333 or 3 444 or 4 555 or 5 666Dovetail Locking MechanismDovetail capture reduces micromotion.Applied loadthrough femurPeripheraldovetailThe locking mechanism of the ADVANCE Medial-Pivot Knee System relies ona dovetail capture and an interference fit to reduce micromotion.PeripheraldovetailOrientation MarkingsFacilitate rotational alignment.Orientation markings have been incorporated into the anterior portion of thetibial base implant to allow the surgeon to identify rotational position of thetibial base implant during final impaction.The orientation markings aid in properly aligning the tibial base. This is accomplished byaligning the center orientation marking with the medial one-third of the tibial tubercle.The other markings allow versatility to help align the base for any exposure.ADVANCE Medial-Pivot Knee System14

ADVANCE Medial-Pivot Tibial Tray ComponentKeelSize 1Size 6Proportional increase with sizes.The tibial stem of the ADVANCE Medial-Pivot Knee System has been madeincreasing proportional with the size. This allows for easier insertion for thesmaller components of the range.35mm50mmBuilt-In Posterior SlopePosteriorStem and keel incorporate 3 posterior slope.The ADVANCE Medial-Pivot tibial base keels are angled 3 posteriorly. Thisensures that even if posterior slope is resected on the proximal tibia the keel isoriented properly down the cortex of the tibia. The thickness of the tibial baseimplant is 4mm. This number correlates to the thickness of the selected tibialinsert thickness.6mm4mmFor instance, if a 10mm thick insert is selected, the actual thickness of thebearing surface is 6mm. The 10mm thickness read on the label is actually acombination of the insert base thickness and the bearing surface thickness.The ADVANCE Medial-Pivot tibial inserts have 0 slope build into the implant:the articular surface is parallel to the bottom of the insert.3 Posterior SlopeREFERENCES1. Pinskerova et al “The shapes and relative movements of the femur and tibia in the unloaded cadaveric knee: a study using MRI as an anatomic tool” JBJS 82-B, (2000)2. Eckhoff D. et al, Sulcus Morphology of the Distal Femur, Clinical Orthopaedics and Related Research, Number 331, pp.23-28, 1996.3. Anderson et al “Patellofemoral complications after posterior-stabilized total knee arthroplasty” JoA 17, 4, 2002.4. Data on file at MicroPort Orthopedics.5. Kujala, U.M., Österman, K., Lormano, M., Nelimarkka, O., Hurme, M., Taimela, S.: Patellofemoral relationships in recurrent patellar dislocation. The Journal of Bone and Joint Surgery71B: 788, 1989.6. Walker PS. Factors affecting the impingement angle of fixed and mobile bearing total knee replacement, a laboratory study. J Arthroplasty. 2007; 22(5):745-52.7. Karachalios T. A mid-term clinical outcome study of the ADVANCE Medial -Pivot Knee arthroplasty. The Knee, 2009; 16(6): 484-8.8. 2010 Danish Knee Arthroplasty Register.9. Feinstein WK. Anatomic alignment of the patella groove. Clin Orthop Relat Res. 1996; 331:64-73.10. Lee TQ. Component positioning in total knee arthroplasty. Clin Orthop Relat Res. 1999;336:274-81.11. Stiehl JB. Kinematics of the patellofemoral joint in total knee arthroplasty. J Arthroplasty. 2001;16(6):706-14.12. Schmidt R, Komistek RD, Blaha JD, Maloney JW Fluoroscopic analyses of cruciate-retaining and medial pivot knee implants Clin Orthop Relat Res. 2003 May;(410):139-47.13. WMT Internal Data.14. Shakespeare D. Flexion after total knee replacement. A comparison between the Medial Pivot knee and a posterior stabilised implant. Knee. 2006 Oct;13(5):371-3. Epub 2006 Jul 715. MicroPort Orthopedics Engineering Report, ER97-0059ADVANCE Medial-Pivot Knee System15

ADVANCE Medial-PivotKinematicsThe goal of any totalknee implant systemis to provide the patient with a long-lasting solution that addressestheir knee pain. However, patient expectations and satisfactionlevels have steadily increased and patients require an option thatmost closely replicates the function of the normal knee. Multiplestudies have characterized the movement of the normal knee,illustrating greater posterior translation of the lateral condyle overthe medial condyle with increasing flexion.1,2 The normal knee hasthe ability to achieve higher ranges of active and passive flexionthan conventional knee implants.3 As such, the need for a longlasting knee system that can achieve normal knee kinematics, isstable throughout the range of motion, and incorporates featuresthat assist in maximizing permissible flexion is desirable.Conventional knee implants have been developed to rely either onsoft tissue or a post and cam mechanism to predictably roll back,providing posterior translation of the femur on the tibia duringflexion. However, many studies have illustrated that the rollbackphenomenon does not occur with many conventional kneedesigns, especially those that incorporate a symmetric tibial insert.These implants illustrate “paradoxical motion,” where the femoralcomponent translates anterior during early stages of flexion,instead of rolling back.3-8 This type of motion has been describedby patients as feeling like “walking on ice”. It is also one of the mai

22. Biomet Surgical Technique for Ascent TKA. 23. Johnson & Johnson, DePuy Surgical Technique for PFC Sigma Rotating Platform TKA. 24. Zimmer Surgical Technique for NexGen TKA. 25. Biomet Surgical Technique for Vanguard TKA. 26. Knee product review, Smith & Nephew, 2006 27. Stryker