Patellar tracking.

Patellar tracking patterns were studied in 20 cadaver knees. The predominant pattern (Type 1) found in 17 knees included medial shift and medial tilt of the patella with respect to the tibial tubercle during extension of the knee. The remaining three knees (Type 2) showed a tendency toward lateral shift and tilt. Release of the lateral retinaculum had no effect on patellar tracking in most knees, while release of the medial retinaculum produced abnormal tracking in many Type 1 knees and all Type 2 knees. The "proximal realignment" (medial imbrication-lateral release) procedure increased the tendency of the patella to tilt and shift medially during extension.