790 BO21 – Ultrasound-based risk assessment for hamstring strain injury prediction in football players

Background and Objective Hamstring Strain Injuries (HSI) are increasingly common in football players. Ultrasound screening assesses muscle predispositions linked to HSI risk. This study aims to identify ultrasound-measurable risk factors for HSI prediction. Study Design and Participants We targeted 56 legs of 28 Japanese professional footballers, mean age 24.6±2.4 years. Fascicle length corrected with femur length, pennation angle (PA) and muscle stiffness of the biceps femoris long head (BFlh) were measured using ultrasound elastography before the 2022 season where new HSI occurrences were prospectively observed. Risk Assessment and Main Outcomes The dependent variable was HSI occurrence, with putative risk factors being ultrasound-defined anatomical predispositions. Statistical analysis used SPSS version 28 with a 5% significance level. Results During the 2022 season, 8 new HSIs occurred. BFlh stiffness was significantly higher in the HSI group (30.53±3.38 kPa) than the non-HSI group (22.49±6.21, p<0.01). Fascicle length was shorter in the HSI group (2.42±0.1 mm/cm) than the non-HSI group (2.56±0.1, p<0.01). PA was greater in the HSI group (16.3±1.3 degrees) than the non-HSI group (14.2±2.0, p<0.01). Logistic regression analysis revealed that a 5 kPa stiffness increase raised the odds ratio (OR) for HSI occurrence (OR=2.98, 95%CI=1.3–6.7, p=0.008). Similarly, a 3-degree PA increment increased HSI risk (OR=7.06, 95%CI=1.6–31.6, p=0.01). ROC curves were constructed, with stiffness having an area under the curve of 0.86, sensitivity of 87%, and specificity of 33% at a 26kPa cut-off and the relative risk was 12.8. For PA the area was 0.815 with a sensitivity of 87% and specificity of 29% at a 15-degree cut-off and the relative risk was 5.09. Conclusion Our findings confirm that shorter BFlh fascicle length and greater PA can predict HSI. Additionally, increased muscle stiffness is a predictor for HSI. Ultrasound-measurable risk factors can effectively predict HSI occurrences and may enhance preventive strategies.