The Effect of Tibial Rotation on the Presence of Instability in the Anterior Cruciate Ligament Deficient Knee.

The effects of tibial rotation after ACL injury have not yet been well determined. Objective: To show whether clinical outcomes such as the amount of tibial rotation can affect functional outcomes in normal and ACL deficient knees. Design: Case control study. Setting: Research laboratory. Participants: Twenty normal subjects (Control) and 20 subjects with ACL deficient knees (ACL). Main Outcome Measures: Tibial rotation at 30 and 90 degrees of knee flexion was measured using an inclinometer. One-legged hop, crossover hop, figure-of-eight running and 10-m running tests were used and determined the effect(s) of tibial rotation on the outcome of the functional tests. Results: There were significant between-group differences in internal and external rotation. The relationship between external tibial rotation and the figure-of-eight index was significantly negatively correlated. Conclusions: The amount of tibial rotation is greater in ACL ruptured knees than in uninjured knees, and these greater amounts of tibial rotation affected the figure-of-eight running index. [ABSTRACT FROM AUTHOR]