Missing cruciate ligament in congenital short femur.

We are reporting six cases of congenital absence of one or both cruciate ligaments of the knee in patients with mild proximal femoral focal deficiency. Three patients had considerable laxity of the knee with a positive anterior and posterior drawer sign. Three patients had an isolated anterior drawer sign without posterior instability. Radiographic examination showed changes in the tibial spine in all affected knees. Arthroscopic examination showed complete absence of both cruciate ligaments in all three patients who had the combined sagittal laxity. The three patients with anterior laxity alone had no vestige of an anterior cruciate ligament. None of the patients in our study had any arthroscopic or important radiographic signs of osteoarthritis. One patient was followed until she was sixty years old. Her case suggests that knee instability may persist without causing osteoarthritis.