The journal of knee surgery
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Recent developments in patellar instability have focused on the passive restraints against mediolateral patellar motion. Viewed from this perspective, muscle alignment is considered secondary because, although muscle forces are important, their ability to cause or prevent patellar dislocation depends on passive stability or the lack thereof. In the normal knee, the patella seats quickly in the trochlea in early flexion, so that the ligamentous restraints are important only near full extension. ⋯ Lateral release has no role in the treatment of a hyperlax patellofemoral joint, as it adds additional laxity to a system that is already unstable. If surgery is performed, current evidence suggests techniques aimed at repair or reconstruction of the passive retinacular restraints are as effective as more extensive procedures at preventing subsequent dislocations. Among the latter procedures, realignment procedures use active muscle forces to help seat the patella in the femoral groove; however, biomechanical costs are associated with this approach and superior results have not been demonstrated with distal and combined realignments compared with more limited proximal procedures.