Spencer-Gardner, Luke

Abstract Introduction Abductor tendon pathology is a common cause of greater trochanteric pain syndrome. The gluteus minimus tendon inserts on the anterior facet of the greater trochanter; the gluteus medius tendon inserts at both the lateral and posterosuperior facets. The Dunn view brings the anterior facet into profile and allows for differentiation of the anterior facet and the insertion of the gluteus minumus from the insertion site of gluteus medius. We hypothesize isolated enthesophytes at the anterior facet best seen on the Dunn view are associated with gluteus minimus tendon pathology. Methods Fifty patients with a history of lateral hip pain with hip radiographs and ipsilateral hip MRI were reviewed. Patients were excluded if the time between radiographs and MRIs >6months or if the patient had prior surgery on the affected side. The radiographs were reviewed by a single-reader to identify enthesophytes (≥ 2mm) at the anterior facet on the Dunn views and lateral facet on the AP view. MRIs were reviewed to categorize the gluteus minimus and medius tendons into the following: normal, tendinopathy, partial thickness tear and full thickness tear. Results The mean age of the fifty patients was 62 (range 19-79; 80% were females). 28 patients had left hip pathology and 22 had right hip. The mean difference between the time between radiograph and MRI was 53 days. Out of the 50 patients, 38 had anterior facet enthesophytes on Dunn views. 97% of these patients had gluteus minimus tendon pathology on MRI, including 76% with tendon tears (positive predictive value [PPV] of 89%). 30 patients had lateral enthesophytes on AP views. 87% of these patients had gluteus medius pathology, including 70% tears (PPV of 83%). Only 3 out of 50 patients had posterosuperior facet enthesophytes. All 3 of these patients had abductor pathology (PPV of 67%). Conclusion There is a correlation between enthesophytes at the greater trochanter anterior facet and lateral facet with respective gluteus minimus and medius tendon pathology. Dunn views add value in detecting anterior facet enthesophytes not visible on AP views and are highly predictive of gluteus minimus tendon pathology.