Heterogeneity of quadriceps muscles atrophy following anterior cruciate ligament reconstruction: A longitudinal MRI study.

Abstract

Objectives This study used MRI to longitudinally assess the differences in atrophy among individual quadriceps muscles and the association between muscle volume and strength recovery following ACL reconstruction (ACLR). Design Longitudinal within-subject. Setting Laboratory. Participants 13 subjects with unilateral ACLR. Main outcome measures MRI and isokinetic strength of bilateral quadriceps muscles were acquired at 6 months and 1 year post-ACLR. The volumes of the 4 quadriceps muscles (vastus medialis, VM; vastus lateralis, VL, vastus intermedius, VI; rectus femoris, RF) were measured. The degree of atrophy for each muscle was calculated as % difference of the uninjured leg. Results At both time points, all 4 quadriceps muscles of the ACLR legs were significantly smaller than the uninjured legs (P 0.171). Quadriceps volume and strength recovery in the ACLR legs were not significantly correlated (r = 0.50, P = 0.09). Conclusions Persistent quadriceps atrophy was found 1 year post-ACLR with greater atrophy in VL/VM than VI/RF. Limited and heterogeneous muscle hypertrophy over time and the lack of strong association between hypertrophy and strength recovery highlight the need for rehabilitation promoting both morphological and functional recovery.