Evaluation of risk factors of anterior cruciate ligament (ACL) Injury: A prospective comparative analysis

Introduction: Anterior Cruciate Ligament (ACL) is the most frequently injured knee ligament. Combination of valgus force with internal rotation is the most common mechanism involved in ACL injury. Both modifiable and non-modifiable risk factors are responsible for the ACL injury. Purpose: To determine the risk factors causing ACL injury by comparing lower limb anatomical features, ACL size and body mass index (BMI) between ACL deficient and ACL intact knees. Materials and Methods: Mechanical axis deviation from vertical axis, tibiofemoral angle, hip neck-shaft angle, posterior tibial slope, notch width index were compared using radiography. BMI and ultrasonographic (USG) diameter of ACL were also measured for comparison. Results: Among the anatomical lower limb parameters mechanical axis deviation from vertical axis, hip neck shaft angle and tibiofemoral angle showed non-significant (p value>0.05) differences while there were significant differences of femoral notch width index (p= 0.014) and posterior tibial slope angle (p < 0.001) between the two groups. ACL diameter (size) and BMI also showed significant differences (p < 0.05). ACL deficient knees have higher BMI (mean 25.82 vs 23.33: p < 0.001) and lesser diameter (mean 7.31 mm vs 7.99 mm; p < 0.001) compared to the ACL intact knees. Conclusion: Higher posterior tibial slope and smaller notch width index are associated with higher risk of ACL injury. Individuals with lesser diameter of ACL or higher BMI have more chances of injury to the ligament.