The effect of exercise on anterior-posterior translation of the normal knee and knees with deficient or reconstructed anterior cruciate ligaments

Exercise may result in increased laxity in the knee. Anterior translation i n 40 normal knees, 33 consecutive anterior cruciate ligament-deficient knee s, and 30 randomly chosen anterior cruciate ligament-reconstructed knees wa s measured using the KT-1000 arthrometer before and after the participants ran for 15 minutes on a neutral-incline treadmill. A single observer blinde d to the status of each knee tested all participants. There was a significa nt increase in anterior translation in the normal (mean, 0.75 mm), anterior cruciate ligament-deficient (mean, 0.62 mm), and anterior cruciate ligamen t-reconstructed knees (mean, 0.25 mm) after exercise. In addition, the amou nt of anterior translation after exercise was significantly different when these groups were compared with each other. Post hoc analysis using Tukey's procedure indicated that anterior translation in the anterior cruciate lig ament-reconstructed knee was significantly less than in the normal and ante rior cruciate ligament-deficient knees. Therefore, repetitive loading exerc ise contributes to an increase in anterior translation in normal, anterior cruciate ligament-deficient, and anterior cruciate ligament-reconstructed k nees, and the anterior cruciate ligament-reconstructed knee does not respon d to repetitive loading in the same manner as a normal knee.