External snapping hip: classification based on magnetic resonance imaging features and clinical correlation

Abstract

Background: With the increasing sport population, the number of patients with external snapping hip (ESH) has also increased. To detect and visualise pathological soft tissue changes, magnetic resonance imaging (MRI) has been 1 of the most useful modalities. However, only limited studies have investigated MRI and its clinical value in the treatment of ESH in the past. Materials and methods: Between May 2017 and November 2018, 104 patients were diagnosed with ESH at our institution. We excluded patients who did not undergo an MRI (n = 11), had complaint of bilateral symptom (n = 17), were not diagnosed hip problems previously (n = 2), and were lost–follow-up within 6 months (n = 19). After applying the exclusion criteria, 55 patients remained. We classified the patients into 2 groups according–MRI findings: tensed iliotibial band (ITB) and hypertrophied gluteus maximus (GM). We investigated the clinical findings, such as mean age, symptom duration, pain score, grading based on symptom severity, and other radiological findings such as soft tissue signal change and ITB thickness. The variables were compared between the groups. Results: Between the 2 groups defined by MRI findings, the group characterised by tense ITB showed a relatively short symptom duration than the hypertrophied GM group (p < 0.001). No significant differences in the other variables were found between the groups. Conclusions: ESH has 2 types of MRI features. Compared with the hypertrophied GM group, the tense ITB group showed a shorter symptom duration and a more reversible status. © The Author(s) 2020.