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Assessment of patellofemoral instability after total knee arthroplasty
By G. Demey in category FOLLOW-UP
Lyon Ortho Clinic, 29b avenue des sources, 69009 LYON
Patellofemoral instability after total knee arthroplasty is a cause of revision, with an incidence ranging from 0.5 to 0.8%.1,2 The instability usually presents as partial patellar dislocation rather than actual dislocation. The incidence of patellofemoral instability as a symptom is probably widely underestimated as a result of underdiagnosis and the fact that it does not systematically lead to surgical revision.
During the 2010 Lyon Knee Surgery Conference, a multi-centre retrospective study was conducted within the Lyon group.3 Of 1,459 posterior-stabilized TKAs with minimum 3-year follow-up (patients undergoing surgery between 2002 and 2006), 8 cases of patellar instability were identified (0.5%). Among these patients, the surgical report contained nothing to suggest possible future instability, since the knee kinematics were satisfactory and stable and there was no lateral retinacular release. Six of these patients underwent revision surgery involving a range of treatments: one isolated reconstruction of the medial patellofemoral ligament (MPFL), three isolated anterior tibial tubercle (ATT) osteotomies, one change of femoral component with ATT osteotomy, and one vastus medialis obliquus (VMO) plasty. The results were poor, with one case of sepsis, one...
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