Sagittal tibial translation during exercises in the anterior cruciate ligament-deficient knee.

The aim of this study was to describe and compare the sagittal tibial translation and electromyographic activity of muscles v. medialis and lateralis, gastrocnemius and hamstrings, during common rehabilitation exercises, in patients with anterior cruciate ligament (ACL) deficiency and non-injured controls. Sagittal tibial translation was registered with the CA-4000 electrogoniometer, in 12 patients and 17 controls, during Lachman test (static translation) and five exercises (dynamic translation). The exercises were grouped according to muscle work and joint compression (active extension, heel raises, cycling, one-legged squat and chair squat). The non-weight-bearing exercise with isolated muscle work (active extension) produced a large amount of tibial translation. During weight bearing, the total anterior-posterior tibial motion was halved compared to the non-weight-bearing exercises, but tibia was anterior positioned. Heel raising resulted in equal translation as the one-legged squat and chair squat, whereas cycling produced the smallest amount of tibial translation. The subjects utilized different amounts of their individual joint play (static translation) during the exercises, which may explain why there are no correlation between static translation and the patients functional outcome. These results enhance understanding on tibial translation during activity and gives indications on which exercises can be used early after ACL injury and reconstruction.