Standing balance and inter-limb balance asymmetry at one year post primary anterior cruciate ligament reconstruction: Sex differences in a cohort study of 414 patients

Background Static standing balance can be safely assessed early following anterior cruciate ligament reconstruction (ACLR), and deficits may have important implications for long-term outcomes. This study includes a large cohort of people post-ACLR and has the primary aim of establishing whether inter-limb and sex differences exist, with a secondary aim of assessing the association between static balance variables and other outcome measures. Methods A total of 414 patients with a primary ACLR performed a 30-s static single leg balance test. Centre of pressure (COP) path length, antero-posterior (AP) and medio-lateral (ML) sway range and slow and fast speed COP path-length were examined. Additional measures included single and triple hop distance and symmetry, knee flexion range of motion, ligament laxity and the International Knee Documentation Committee (IKDC) subjective knee evaluation form. Results No significant inter-limb balance differences were present in females. Significant, yet small to negligible effect size (ES) differences were present in males for ML range (ES = 0.19), and AP and ML axis slow speed path length (ES = 0.11 and 0.23 respectively). Significant, negligible to moderate effect size (ES range =