Sonographic pathoanatomy of greater trochanteric pain syndrome.

Aims: To identify and highlight pertinent US features that could serve as imaging biomarkers to describe different patient phenotypes, within Great Trochanteric Pain Syndrome (GTPS) clinical diagnosis.

Materials and methods: Using ultrasound we evaluated eighty-eight clinically diagnosed patients with GTPS, for tendon matrix changes and calcium deposits in the gluteus medius (superoposterior and lateral aspects) and in the gluteus minimus. Peritrochanteric examination included fascia lata, trochanteric bursa, cortical irregularities and the presence of enthesophytes. The association of pathological changes with pain and functionality was evaluated using multivariate regression models.

Results: Out of the 88 patients, 86 examinations (97.7%) detected gluteus medius tendinopathy, and 54 patients (61.4%) had gluteus minimus tendinopathy in addition. Calcium deposits were present in 97.7% of patients, associated with tenderness (p = 0.009), and most often located in the gluteus medius rather than in the gluteus minimus (p = 0.014); calcifications were associated with tendon thickness (p = 0.042), hypoechogenicity (p = 0.005) and the presence of partial tears (p = 0.030). Bursa swelling occurred in 36 patients (40.9%); multivariate regression models predicted less pain in patients with bursa distension (p = 0.008) and dysfunction in patients with gluteal muscle atrophy (p = 0.001) and loss of fibrillar pattern in the gluteus medius (p = 0.002).

Conclusion: GTPS involves both degenerative calcifying gluteal tendinopathy and alterations in the peritrochanteric space associated with physical function and pain. The severity of GTPS can be assessed using ultrasound imaging biomarkers.