[Effect of constitutional ligament laxity and physical stress on development of patellar tip syndrome]

Studies were performed in order to obtain information on the pathogenesis of patellar tip syndrome (PTS). Using a finger hyperextensiometer, ligamental laxity tests were performed on athletes, non-athletes and controls. Ninety-eight PTS patients who did not indulge regularly in sports, 39 patients from the German federal volleyball league, and 400 healthy controls were examined. No difference in the extensibility of ligaments was found between the patients from the group of competitive athletes and the controls. However, a significantly increased extensibility of the finger joints was found in all age and sex groups with "spontaneous" PTS. The authors conclude that 1) constitutional laxity of the ligaments is a key predisposing factor for PTS, and 2) PTS is triggered by physical stress. Susceptibility to microtrauma at the insertion of the patellar ligament is a function of the constitutional strength of the ligaments.