An Evaluation of Postural Balance in Single-leg and Double-leg Conditions in Patients with Reconstruction of the Anterior Cruciate Ligament and Healthy Controls

Purpose: Following anterior cruciate ligament reconstruction (ACL-R) and rehabilitation, individuals undergo a series of evaluations to ensure a safe return to sports participation. The high re-injury rates that have persisted following ACL-R indicate that the current assessments may not be able to accurately identify persistent deficits. This investigation was designed to evaluate the balance control of ACL-R individuals and healthy controls in different task conditions (single and double legs). Methods: The study involved twenty-seven participants: 13 ACL-R (age: 24.46 ± 2.73 years; height: 1.78 ± .09 m; body mass: 77.00 ± 10.35 kg; BMI: 24.10 ± 2.19 kg/m2) and 14 healthy controls (age: 25.36 ± 3.37 years; height: 1.77 ± .06 m; body mass: 77.93 ± 14.65 kg and BMI: 24.84 ± 4.07 kg/m2). The postural balance was assessed by measuring the center of pressure (CoP) displacement in the medio-lateral and anterior-posterior directions under various conditions, including static and dynamic, open and closed eyes, and single-leg and double-leg support. To quantify the activity of the lower limb muscles (vastus lateralis, biceps femoris, tibialis anterior, and lateral gastrocnemius), the sEMG activity was recorded synchronously with the CoP in the various tasks. Results: There were no differences observed between the limbs of either group (P > .05). In comparison to the control group, the ACL-R exhibited a significantly higher CoP displacement (medio-lateral) in the double-leg dynamic condition (P < .05). In contrast, the two groups did not show any significant differences in CoP in the single-leg condition (P > .05). sEMG analysis revealed significantly higher tibialis anterior activity in the ACL-R group than the control group during dynamic double-leg balance (P < .05). Conclusions: In contrast to healthy controls, individuals who underwent ACL-R appeared to exhibit a persistent postural balance deficit, particularly in dynamic double-leg conditions. The tibialis anterior of both legs exhibited abnormal neuromuscular activation patterns, which characterized these alterations. Therefore, the comparison of operated and non-operated limbs in the assessment of postural balance may not be a reliable criterion for determining the alterations and, ultimately, the safe return to sports play of individuals with ACL-R.