Thigh Muscle Volume Remains Decreased on 3-Dimensional Magnetic Resonance Imaging at Minimum of 5 Years After Patellar Tendon but not Allograft Anterior Cruciate Ligament Reconstruction

Abstract

Purpose

To evaluate thigh muscle volume differences in patients undergoing anterior cruciate ligament reconstruction (ACLR) with either allograft tissue or bone−patellar tendon−bone (BPTB) autografts, using 3-dimensional magnetic resonance imaging (MRI) modeling.

Methods

This is a retrospective, single-center study of patients undergoing primary ACLR with either ipsilateral BPTB autograft or allograft tissue. Inclusion criteria were age 18-45 years, 5 to 8 years of follow-up, and body mass index <30. Patients were excluded if they had multiligamentous knee injuries, surgical treatment of meniscus tears (repair or reconstruction), and any subsequent knee procedures after the index ACLR. 3D MRI of the bilateral thighs was performed and images were rendered with 3D modeling software and the total thigh, anterior-, posterior-, and medial-thigh compartment musculature were individually segmented and the volumes were calculated. Data were evaluated using a t test, and muscle volumes were standardized as a percentage of the corresponding nonoperative extremity and then tested in comparison with the alternative graft type.

Results

Ten allograft and 10 patients with BPTB were included. Patients with allograft were older at surgery (mean age 34.6 vs 23.4 years (P < .001) and at study MRI (mean age 40.9 vs 29.7 years; P < .001). Allografts showed no differences in total thigh or compartmental muscle volumes between the operative and nonoperative limbs. BPTB showed a statistically significant reduction in total thigh volume on the operative side (103 cm³, 97.0%, P = .013), whereas compartment volumes remained similar between limbs. Percentage changes in volume comparing injured with contralateral thigh volume was not significantly different between graft type groups.

Conclusions

No significant side-to-side differences were found in individual thigh compartments or total volume after allograft ACLR. BPTB ACLR has a modest effect (∼3%) on long-term total thigh muscle volume.

Level of Evidence

Level III, retrospective cohort study.