Current concepts of etiology and treatment of chondromalacia patellae.

Chondromalacia patellae is a distinct clinical entity characterized by retropatellar pain that is associated with recognizable changes in the articular cartilage of the posterior surface of the patella. Several factors may be involved in the etiology, such as severe patella alta, trauma, and, in rare cases, abnormal patellar tracking. Clinical symptoms and signs are reliable in only 50% of cases, but measurable quadriceps wasting, palpable patellofemoral crepitus, and effusion are strongly suggestive. Diagnosis must be confirmed by arthroscopy or direct examination of the posterior surface of the patella. Radiologic measurements of patellofemoral relations are of limited value in diagnosis. The initial pathologic finding is usually surface cartilage breakdown. Radioisotope studies show cartilage cell replication which suggests a healing capacity in early cases following treatment that alters the load through the affected cartilage. There is no evidence of progression to patellofemoral osteoarthritis, which is probably a different entity. The treatment should be conservative where possible with isometric quadriceps exercises and simple anti-inflammatory drugs such as aspirin. Operative treatment is indicated for patients with persistent pain and macroscopic involvement of more than half a centimeter of the articular cartilage surface. The simplest effective procedure that avoids quadriceps dysfunction and fibrosis is a distal patellar tendon medial realignment with lateral release and medial reefing of the quadriceps expansion. Patellectomy is indicated in more extensive involvement of the patella of 2 or more centimeters in diameter, but this must be performed only when the patient has excellent quadriceps function before surgery and is motivated to exercise after surgery.