Between-leg differences in challenging single-limb balance performance one year following anterior cruciate ligament reconstruction

Following anterior cruciate ligament (ACL) rupture, reconstructive surgery (ALCR) is often performed to mechanically stabilise the knee, however functional deficits often persist long after surgery. Impaired single-limb standing balance has been observed in the ACLR limb compared to healthy individuals. However, it remains inconclusive as to whether these same balance deficits exist between the injured and contralateral uninjured limbs, during challenging balance tasks, and at a time when patients are permitted to return to sport. 100 adults who had undergone a primary hamstring-tendon ACLR 12 months previously (68 male; median[IQR] age: 28.1[14.1] years) performed tests of single-limb standing with the knee in a functional position of 20-30° flexion, with their eyes closed, over 20 s (Nintendo Wii Balance Board). Two repetitions were performed on the ACLR and uninjured limb. Measures of postural control included centre of pressure (CoP) path velocity, anterior-posterior and mediolateral range and standard deviation, and were averaged across the two trials. Wilcoxon signed-rank tests showed no significant between-leg differences in single-limb balance for any of the CoP measures of interest (all P values > 0.686). Further, multiple linear regression analyses showed no significant associations between concomitant meniscectomy or chondral lesions noted at the time of ACLR and measures of single-limb balance on the ACLR limb one year later (all P values > 0.213). In the context of prior research, these findings suggest bilateral balance deficits may exist prior to ACL injury, or appear post ACL-injury or ACLR. Treatment of balance deficits should therefore consider both limbs after ACLR.