Stability of the patellofemoral articulation through physiologic knee motion is a result of native patient anatomical features including lower extremity alignment, rotation, soft tissue tension, and osseous anatomy. Anatomic stabilizers of the patella include osseous morphology of the trochlear groove, the extensor mechanism alignment, and soft tissue ligamentous restraints both medially and laterally.1, 2, 3, 4, 5 Healthy knees balance these forces such that the patella tracks smoothly through the center of the trochlear groove as the knee moves into flexion. An overly tight lateral retinaculum creates an abnormal lateral force on the patella, predisposing patients to increased lateral contact pressures in the patellofemoral joint and increasing the risk of early development of osteoarthritis.6, 7, 8, 9 Lateral patellar maltracking can be the source of debilitating pain for patients and cause limitations to activities of daily life and participation in sports and recreation.

Lateral retinaculum lengthening and lateral release procedures have been described to help restore normal patellar tracking and patellofemoral contact pressures. These procedures historically were performed in isolation with relatively poor outcomes, particularly at longer-term follow up and may even lead to iatrogenic medial instability.10 More recently, lateral retinacular lengthening as opposed to a complete lateral release is typically performed in conjunction with a patellar stabilizing procedure such as reconstruction of the medial patellofemoral ligament (MPFL) and/or tibial tubercle osteotomy (TTO) for management of lateral patellar instability. Lateral retinacular lengthening can also reduce lateral patellar tilt resulting in offloading the lateral compartment of the patellofemoral joint and reducing the excessive force between the patellar and trochlear cartilage that causes osteoarthritis.7,9,11,12 This chapter will explore the indications, techniques, and outcomes of lateral lengthening and release.