Patellofemoral problems after anterior cruciate ligament reconstruction

Between 1982 and 1986, 126 patients who had under gone ACL reconstruction were followed in a prospec tive manner. One year follow-up statistics were re viewed for the presence of 13 different complications. The most prevalent complications were quadriceps weakness, flexion contracture, and patellofemoral pain. Quadriceps weakness (strength less than 80% of the normal side) was present in 65% of patients and cor related positively with flexion contracture, patellar irrit ability, and ACL reconstructions using patellar tendon grafts. Flexion contracture of 5° or more was present in 24% of patients and correlated positively with in creased age and patellar irritability. Patellofemoral pain was present in 19% of patients and correlated positively with flexion contracture. Clinical relevance: The three most common compli cations of knee ligament surgery are shown to be strongly interrelated. It is likely that a causal relationship is present in which flexion contracture causes patello femoral irritability, and that both of these factors, alone or in combination, result in quadriceps weakness. If this theory is correct, then it is crucial that postoperative rehabilitation programs place a major emphasis on the avoidance of flexion contracture.