Gracilis tendon harvest for ACL reconstruction impairs gracilis muscle volume recovery and may adversely affect adjacent thigh musculature. MRI-based outcomes from a subgroup of patients enroled in the DOSTAR randomized controlled trial.

PURPOSE: Segmentation of magnetic resonance imaging (MRI) allows accurate calculation of muscle volumes. The Dual Or Single Tendon Anterior cruciate ligament Reconstruction (DOSTAR) study is a prospective randomized controlled trial investigating a semitendinosus (ST) graft with adjustable button tibial fixation versus a dual tendon semitendinosus and gracilis (STG) graft with screw tibial fixation in anterior cruciate ligament reconstruction (ACLR). The purpose of the present study is to investigate differences in thigh muscle volume at 6 and 12 months between these treatment groups.

METHODS: Patients were randomized and underwent ACLR using either a ST or STG graft construct. MRI of bilateral thighs was completed at 6 and 12 months post-operatively. Muscle volumes were measured in both thighs at both time points in both groups.

RESULTS: A total of 38 patients underwent MRI scanning at 6 and 12 months. There was a significant difference in the interval volume change of gracilis in the STG group compared to the ST group (-1.6 cm3 ± 4.6 vs. +2.8 cm3 ± 6.8, p = 0.026). Interval gracilis hypertrophy occurred in 35% (7/20) of cases in the STG group and 67% of cases (12/18) in the ST group (p = 0.103). Adductor longus (AddL) also demonstrated a significant difference in interval volume change between the STG and ST group (-2.4 cm3 ± 12.0 vs. +11.1 cm3 ± 21.2, p = 0.020). AddL hypertrophy occurred in 30% of cases (6/20) in the STG group and 72% (13/18) in the ST group (p = 0.022). All other muscles had no significant differences noted in muscle recovery between groups. Linear regression analysis demonstrated a significant positive relationship between interval changes in gracilis and AddL volumes (p < 0.001).

CONCLUSIONS: The present study provides MRI evidence that gracilis tendon harvest was associated with persistent impairment of gracilis muscle recovery and may also adversely affect AddL. This adds to the growing body of evidence supporting the use of ST with adjustable button graft constructs for hamstring ACLR.

LEVEL OF EVIDENCE: Level II, subgroup analysis of prospective, double-blinded, randomized controlled trial.