Quadratus femoris muscle edema in children

Objective To assess the prevalence and clinical relevance of quadratus femoris muscle edema (QFME) in pediatric pelvic MRI. Materials and methods The axial T2-W with fat saturation sequence of pelvic/hip MRI examinations of pediatric patients (≤ 18 years) and a control group of young adults aged 19–45 years was retrospectively and independently evaluated by two musculoskeletal radiologists for the presence of QFME in each hip. Demographics, indication for imaging studies, and pain location were documented. The prevalence of QFME was compared between the groups on a patient level and on a hip level. Results The study group included 119 children (164 MRI examinations; F:M 1:1.08, mean age 11.4 ± 3.6 years), and 120 young adults, > 18, < 45 years old, served as controls (F:M 1:0.9, mean age 33.7 ± 6.4 years). QFME was significantly more prevalent among the study compared to the control group, both on a patient level (15% and 4.2%, respectively, p < 0.05) and on a hip level (12.1% and 2.5%, respectively, p < 0.05). This significant difference was also seen in the subgroup of MRI studies performed for orthopedic indications but not for non-orthopedic indications. There was no correlation between the side of localized pain and the side with QFME. Conclusion QFME is significantly more prevalent in pediatric patients compared to adults under 45 years old, especially in subjects scanned for orthopedic indications. The clinical relevance of QFME in children and adolescents is unclear.