Arthroscopy in acute traumatic hemarthrosis of the knee. Incidence of anterior cruciate tears and other injuries.

In a prospective study, all injured knees that had traumatic hemarthrosis and absent or negligible instability on clinical examination underwent arthroscopy and examination under anesthesia. Eighty-five knees (eighty-three patients) were examined over a 125-week period. Some degree of disruption of the anterior cruciate ligament was found in sixty-one (72 per cent) of the knees (a partial tear in 28 per cent and a complete tear in 44 per cent), frequently associated with an injury of varying severity to other joint structures. These included minor ligament sprains without laxity in 41 per cent, a major associated ligament injury in 21 per cent, meniscal tears in 62 per cent (partial in 30 per cent and complete in 70 per cent), and a femoral chondral fracture or surface defect in 20 per cent. A popping sensation at injury occurred in 33 per cent of knees with a normal anterior cruciate ligament and in 36 per cent of those with a disruption. One-third of the knees had no to slight pain at the time of injury. The anterior drawer test without anesthesia was positive in only 24 per cent of the knees with a torn anterior cruciate ligament. We concluded that: (1) a traumatic hemarthrosis indicates a significant knee injury; (2) examination under anesthesia plus arthroscopy allows a more accurate diagnosis of injury to joint structures; and (3) such data are required for a rational treatment program to be outlined.