Association between sensory function and medio-lateral knee position during functional tasks in patients with anterior cruciate ligament injury

BACKGROUND Patients with anterior cruciate ligament (ACL) injury often exhibit reduced movement quality during functional tasks in the form of a knee-medial-to-foot position (KMFP). This movement pattern is suggested to be more common in women than in men, but the possible contributing sensorimotor factors for this altered knee position are poorly studied in these patients. The aim of this study was to evaluate the association between sensory function and medio-lateral knee position during functional tasks in men and women with ACL injury. METHODS Fifty-one patients (23 women) aged 18-40 years with ACL injury were included in this cross-sectional study. Measures of sensory function were assessed by the threshold to detection of passive motion (TDPM) for knee kinesthesia and by the vibration perception threshold (VPT) for vibration sense. Movement quality was assessed by visual observation of the position of the knee relative to the foot during the following four functional tasks with different degrees of difficulty: the single-limb mini-squat, stair descending, the forward lunge, and the drop-jump. Spearman's rank correlation coefficient was used to determine the relationship between the sensory measures and the medio-lateral knee position during the functional tasks. Differences in TDPM and/or VPT between subjects with good and poor movement quality were evaluated using the independent t-test. Separate gender analyses were performed. RESULTS Worse TDPM was associated with a KMFP during the drop jump in men. Worse VPT at the toe and ankle was associated with a KMFP during stair descending and the forward lunge in women, but no associations were found in men. CONCLUSION Worse kinesthesia, measured by TDPM, might be associated with KMFP during the drop jump in men with ACL injury while worse vibration sense, measured by the VPT, at the foot and ankle might be related to KMFP in women. Further studies are needed to confirm these results.