A biomechanical comparison of lateral retinacular releases.

A lateral patellar retinacular release that transects the tendon of the vastus lateralis muscle may result in significant complications. To avoid such complications, the superior extent must be limited, and maximizing the inferior extent may be important in achieving an adequate release. The effective release of the patella from its lateral retinaculum was examined for 2 incision lengths using 10 fresh-frozen human cadaveric knees and comparing the medial displacement of the patella relative to the femur for 3 study groups (control, intact retinacula; Group A, retinacula cut from the inferior third of the vastus lateralis tendon down to the anterolateral arthroscopic portal; and Group B, retinacula cut from the inferior third of the vastus lateralis tendon down to the tibial tubercle) when a 22-N medially directed force was applied to the patella with the knee at 30 degrees and 60 degrees of flexion. The extended release (Group B) resulted in a significantly more effective release when compared with the standard release (Group A) or control group. This technique may allow an adequate release of the patella while preserving the function of the vastus lateralis muscle.