Tibial rotation affects anterior displacement of the knee

The purpose of this study was to assess anterior translation of the tibia using the Tibial Fixator Device (a mechanical leg stabilizer that controls tibial alignment) with the leg in three positions: neutral (N), internal rotation of 15° (IR), and external rotation of 15° (ER). Displacement was measured using a modified KT-1000 arthrometer. Eleven subjects with anterior cruciate ligament lesions were examined bilaterally in the three positions at 45, 67, and 89 newtons of anterior force. Three-factor repeated-measures ANOVA revealed a significant position effect regardless of force (p < .001). This effect was significant in the injured and noninjured legs. Displacement was greatest in ER and least in IR. These data indicate that the position of the tibia, maintained with an external leg restraint, has a significant effect on anterior displacement of the knee. Control of tibiofemoral alignment and modifications to the KT-1000 provide new potentials for instrumented arthrometry.