ACL Reconstruction and Lower-Limb Asymmetries

Abstract

Research Question: What are the musculoskeletal and morphological lower-limb asymmetries between those who have undergone anterior cruciate ligament reconstruction (ACLR) and non-surgical controls, and how does sex affect these asymmetries and perceptions of knee function in ACLR patients? This research question will be addressed via cross-sectional cohort analysis.

Background and Significance: Recovery from ACL reconstructive surgery can last around nine months, and even longer for athletes planning to make a return to sport. Even after, deficits in quadriceps morphology and strength between the affected and unaffected limbs may persist for up to five years, with an increased likelihood of developing osteoarthritis in the reconstructed knee. Inconsistencies in lower-limb symmetry, along with graft-type influences, may impact recovery timeline in post-ACLR patients, particularly those aiming to return to sports. Females may have a greater risk of ACL injury than males with worse subjective post-ACLR outcomes. This study seeks to examine the degree of lower-limb musculoskeletal tissue asymmetries between male and female patients who have undergone ACLR, with the goal of identifying what areas of musculoskeletal tissue may require advanced monitoring in post-ACLR rehabilitation to benefit recovery and prevent risk of future re-injury.

Materials and Methods: Individuals (female n=11, male n=11) with a history of ACLR and matched controls (female n=10, male n=9) completed Dual-energy X-ray Absorptiometry (DXA) scans to measure lower-body bone mineral content (BMC), Fat%, and lean mass (LM). Self-reported perceptions of knee function were captured via the International Knee Documentation Committee 2000 (IKDC) instrument, and inter-limb asymmetry indices (AI%) were calculated for each DXA outcome. Surgical groups and sexes were compared using independent t-tests (p<0.05) and Cohen’s effect sizes (d). Additionally, Pearson’s Correlations Coefficients evaluated the association between AI% and IKDC scores.

Results: The ACLR group showed greater lower-body asymmetries, specifically less BMC and LM and greater Fat% in the ACLR limb (p=0.044; d=0.63–0.87). ACLR group sex comparisons found that females had lower IKDC scores, greater asymmetries for BMC and LM (p=0.027, d=0.40–0.74), and these asymmetries were negatively correlated with IKDC scores (all r=0.755; p=0.007) while males demonstrated no such correlations.

Conclusion: Individuals with a history of ACLR have persistent musculoskeletal tissue asymmetries of the non-surgical leg. These asymmetries were greater in female than male patients and were associated with lower self-perceptions of knee function. Post-ACLR rehabilitation and post-surgical monitoring will likely benefit from comprehensive musculoskeletal imaging.