ACL Size and Notch Width Between ACLR and Healthy Individuals: A Pilot Study.

BACKGROUND

Given the relatively high risk of contralateral anterior cruciate ligament (ACL) injury in patients with ACL reconstruction (ACLR), there is a need to understand intrinsic risk factors that may contribute to contralateral injury.

HYPOTHESIS

The ACLR group would have smaller ACL volume and a narrower femoral notch width than healthy individuals after accounting for relevant anthropometrics.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Magnetic resonance imaging data of the left knee were obtained from uninjured (N = 11) and unilateral ACL-reconstructed (N = 10) active, female, collegiate-level recreational athletes. ACL volume was obtained from T2-weighted images. Femoral notch width and notch width index were measured from T1-weighted images. Independent-samples tests examined differences in all measures between healthy and ACLR participants.

RESULTS

The ACLR group had a smaller notch width index (0.22 ± 0.02 vs 0.25 ± 0.01; = 0.004; effect size, 1.41) and ACL volume (25.6 ± 4.0 vs 32.6 ± 8.2 mm/(kg·m); = 0.025; effect size, 1.08) after normalizing by body size.

CONCLUSION

Only after normalizing for relevant anthropometrics, the contralateral ACLR limb had smaller ACL size and narrower relative femoral notch size than healthy individuals. These findings suggest that risk factor studies of ACL size and femoral notch size should account for relevant body size when determining their association with contralateral ACL injury.

CLINICAL RELEVANCE

The present study shows that the method of the identified intrinsic risk factors for contralateral ACL injury could be used in future clinical screening settings.