Summary

A higher Posterior tibial slope and narrow Notch width index can be regarded as anatomic intrinsic risk factors for ACL injury

Abstract

Background

Evaluation of risk factors both modifiable and non-modifiable may help to design neuromuscular training programs or prevention strategies in preventing Anterior cruciate ligament (ACL) injuries.

Methods

In this prospective case control study we compared various anatomic lower limb parameters in ACL intact versus ACL deficient knees using radiography in Indian population. 50 patients (15 - 40 years) diagnosed with ACL tear were taken as Cases & 50 normal individuals matched by age, sex, height and weight were taken as Controls.
We measured - Mechanical Axis (MA) deviation from vertical axis, Tibiofemoral angle (TFA), Hip-Neck-Shaft angle (HNS) on scanogram; Posterior Tibial Slope (PTS) on standard lateral view & Notch Width Index (NWI) on tunnel knee radiograph. We compared injured with uninjured side of cases and injured side of Cases with dominant side of Controls.

Results

Injured & uninjured knees of Cases were not significantly different in terms of MA deviation from vertical axis (3.34 vs 3.21º, p=0.478), TFA (5.2º vs 5.7º, p=0.33), PTA (13.15º vs 13.36º, p=0.735), HNS (128.61º vs 127.26º, p=0.81) & NWI (0.26 v. 0.27, p=0.40). ACL-deficient and ACL-intact knees were comparable but not significant in terms of MA deviation from vertical axis (3.34º vs 3.36º, p=0.886), TFA (5.28º vs 6.32º, p=0.324 and HNS angle (128.61º vs. 129.67º, p=0.272. PTS (13.15º vs. 10.87º, p=0.001) was significantly larger and NWI (0.30 vs. 0.32, p=0.014) significantly smaller in ACL-deficient than ACL-intact knees.

Conclusions

We suggest that higher PTS and narrow NWI can be regarded as anatomic intrinsic risk factors for ACL injury