Reliability of MRI assessment of acute musculotendinous groin injuries in athletes

To describe a multi-dimensional MRI assessment approach with a focus on acute musculotendinous groin lesions, and to evaluate scoring reproducibility. Male athletes who participated in competitive sports and presented within 7 days of an acute onset of sports-related groin pain were included. All athletes underwent MRI (1.5 T) according to a standardized groin-centred protocol. From several calibration sessions, a system was developed assessing grade, location and extent of muscle strains, peri-lesional haematoma, as well as other non-acute findings commonly associated with long-standing groin pain. Kappa (K) statistics and intraclass correlation coefficients (ICCs) were used to describe intra- and inter-rater reproducibility. Seventy-five athletes (mean age 26.6 ± 4.4 years) were included in the analyses, and 85 different acute lesions were observed. Adductor longus lesions were most common (42.7 %) followed by rectus femoris lesions (16.3 %). Kappa values ranged between 0.70 and 1.00 for almost all categorical features for acute lesions, with almost perfect intra- and inter-rater agreement (K = 0.89-1.00) for presence, number, location and grading of lesions. ICCs ranged between 0.77 and 1.00 for continuous measures of acute lesion extent. A standardized MRI assessment approach of acute groin injuries was described and showed good intra- and inter-rater reproducibility. • A multidimensional MRI assessment approach for acute groin injuries was described. • Standardized MRI assessment of acute musculotendinous groin injuries has high reproducibility. • Injury location and injury extent can be scored reliably using 1.5 T MRI