Fascia lata attachment at the iliac crest: refining our diagnostic criteria of injury on magnetic resonance imaging

Objective: The objective of this study was to determine the prevalence and spectrum of pathology of the fascia lata attachment at the iliac crest (FLAIC) on MRI in asymptomatic patients in order to refine our diagnostic criteria for clinically relevant FLAIC injury. Methods and material: Two readers retrospectively evaluated the FLAIC on each side on coronal large field-of-view short tau inversion recovery images on 100 musculoskeletal pelvic MRI exams performed in patients without hip pain (total n = 200). Pathology of the FLAIC was graded using a 3-point Likert scale and discrepancies were resolved by consensus. Results: Of the 200 FLAIC included in the study, 72.5% demonstrated normal size and signal intensity. Low to moderate grade pathology of the FLAIC was identified in 27% and high-grade partial thickness pathology was seen in 0.5%. No cases of complete FLAIC rupture were identified. Inter rater agreement between the two readers was good (k=0.660, p < 0.001). There was no statistical difference in FLAIC scores according to gender or age. FLAIC score was positively correlated with higher body mass index. Conclusion: Incidental low to moderate grade FLAIC pathology is commonly seen on MRI in asymptomatic patients. Abnormal MRI findings of the FLAIC should hence be correlated with explicit clinical symptoms and physical exam findings. Advances in knowledge: The Fascia lata is a complex anatomic structure. Its attachment to the iliac crest is an under recognized pathology and sometimes overlooked during evaluation for pelvis and lateral hip pain. Evaluation of the FLAIC is easily done with MRI and abnormality should be correlated to the clinical symptomatology as low grade abnormality is frequently seen in asymptomatic population.