Persistent bone and muscle deficits after anterior cruciate ligament reconstruction : implications for post-traumatic osteoarthritis risk.

Aims: Anterior cruciate ligament reconstruction (ACLR) is associated with persistent strength deficits and thigh muscle atrophy, which may contribute to post-traumatic osteoarthritis (PTOA). Other potential musculoskeletal alterations, such as changes in bone morphology and mechanical properties, are less well understood. No study has comprehensively examined multi-tissue deficits post-ACLR, limiting insight into potential structural contributors to long-term joint vulnerability. Consequently, this cross-sectional study investigated differences in muscle size and quality, bone morphology, and mechanical properties between the ACLR and contralateral uninjured leg. The influence of leg dominance on musculoskeletal outcomes in a control population and the identification of distinct recovery profiles in the ACLR group were explored. Methods: A total of 32 individuals with a history of ACLR (1 to 6 years post-surgery) and 32 matched uninjured controls underwent peripheral quantitative computerised tomography at the shank (66% tibial length) and thigh (20% and 50% femoral length). Outcomes included muscle cross-sectional area, muscle density, subcutaneous fat, cortical and trabecular bone area and density, and bone resistance to bending, torsion, and compression. Clustering techniques were applied to explore potential high- and low-recovery profiles. Results: The ACLR leg demonstrated reduced muscle size and density, smaller cortical bone area, lower trabecular density, and impaired resistance to bending and compressive forces in comparison to the uninjured contralateral leg. Clustering revealed a low-recovery profile in 69% of ACLR participants, characterized by widespread musculoskeletal deficits. Conclusion: Persistent musculoskeletal alterations after ACLR may reflect compromised structural integrity associated with PTOA risk. Recovery profiling may help identify those at greatest risk, informing targeted interventions to improve long-term joint health.