The absent posterior drawer test in some acute posterior cruciate ligament tears of the knee.

Over a 10 year period, 24 of 54 acute PCL tears in cases of straight medial instability demonstrated an absent or an equivocal posterior drawer test. Most of these (22, 91.6%) were contact injuries, and in the 11 cases where the mechanism of injury was known (45.8%), were incurred by a blow to the outer aspect of the leg while the foot was planted. The ACL was normal in 6 of the 24 knees. The abduction stress test at 0 degree extension was severely positive (2+ or more) in 21 of the 24 knees (87.5%). The phenomenon of an absent or equivocal posterior drawer test in the situation of acute straight medial instability is felt to occur when the mechanism of injury does not stress, strain, or tear the arcuate complex. If the PCL tear is not discovered and repaired, repeated stressful activity stretches the arcuate complex, and the chronically unstable knee subsequently presents with a positive posterior drawer test.