Kinematic predictors of subjective outcome after anterior cruciate ligament reconstruction: an in vivo motion analysis study.

PURPOSE: The purpose of this study was to test whether rotational knee kinematics during dynamic pivoting activities are predictive of subjective functional outcome (IKDC, Lysholm), objective laxity scores (KT max), and activity levels (Tegner) in patients after anterior cruciate ligament reconstruction (ACLR).

METHODS: Thirty-one patients with single-bundle ACLR were evaluated prospectively with 3D-motion analysis during (1) descending a stairway and pivoting and (2) landing from a jump and pivoting. The side-to-side difference of tibial rotation range of motion (SSDTR) between the ACLR and the contralateral intact knee was calculated for the pivoting phase of each task. Linear regression models were applied with SSDTR, for each task predictors of the subjective IKDC score, Lysholm score, anterior tibial translation, and Tegner activity level.

RESULTS: SSDTR for descending and landing were predictive of the IKDC subjective score (R(2) = 0.46, p < 0.001 and R(2) = 0.40, p < 0.001, respectively) with "medium" effect sizes and of the Lysholm score (R(2) = 0.13, p < 0.05 and R(2) = 0.09, n.s.) with "small" to "none" effect sizes. SSDTR was not predictive of anterior translation or Tegner activity level (n.s.).

CONCLUSIONS: Restoring rotational kinematics during dynamic pivoting activities after ACLR is predictive of functional outcome. The ability of the athlete after ACLR to control tibial rotation during pivoting activities may be predictive of functional outcome.

LEVEL OF EVIDENCE: Case series study. Level IV.