Ischiofemoral impingement: a retrospective analysis of cases in a specialist orthopaedic centre over a four-year period.

BACKGROUND: Ischiofemoral impingement is a recently identified cause of chronic hip pain, the pathophysiology and clinical features of which are poorly understood.
 AIM: To determine the clinical significance of MRI findings of ischiofemoral impingement.
 MATERIALS AND METHODS: Retrospective search for cases of ischiofemoral impingement in the Nuffield Orthopaedic Centre, Oxford, over a 4 year period, and review of medical notes to identify correlation between clinical and MRI features.
 RESULTS: Sixteen hips in 13 patients with MRI signs of ischiofemoral impingement were identified. All patients were females with a median age of 36 years (range 17-80 years). In six patients the symptoms corresponded to the side of the quadratus femoris abnormality and narrowed ischiofemoral distance. In two patients the symptoms were on the same side as the abnormality but were more consistent with back pain and sciatica. In five patients the symptoms were not anatomically related to the abnormality. Abnormalities identified; seven patients had muscle oedema (six unilateral, one bilateral) and six had muscle wasting (four unilateral, two bilateral). Of the patients with quadratus femoris oedema, two had gluteus medius enthesopathy and one had hamstring enthesopathy. Two patients presented with a chronic loud clunking of the hip on walking.
 CONCLUSIONS: Ischiofemoral impingement on MRI is seen in patients with pain localised to the ipsilateral buttock and in patients with symptoms unrelated to the abnormality. The condition may be associated with wasting or oedema of the quadratus femoris muscle on MRI and may occur secondary to injury in other muscles controlling movement of the hip such as the hamstrings and gluteus medius. Ischiofemoral impingement is a cause of a clunking hip.

Case report: imaging and surgical treatment of a snapping hip due to ischiofemoral impingement.

An association between hip pain and quadratus femoris MRI abnormality with concurrent narrowing of the ischiofemoral space has been reported in a number of patients to date, raising the possibility that the muscular damage observed is due to ischiofemoral impingement. Possible impingement has been noted primarily in middle-aged females either with or without a history of trauma or surgery, and associated snapping of the hip is a rarely described feature. We report here on a 17-year-old girl who presented with post-traumatic hip pain; she later developed evidence of ischiofemoral narrowing and quadratus femoris edema on MRI in addition to an audible snapping. Surgical resection of the lesser trochanter was performed, relieving both her hip pain and the snapping. To our knowledge, this is the first reported case of non-iatrogenic ischiofemoral impingement with surgical confirmation. The diagnosis of ischiofemoral impingement should be considered in patients complaining of a snapping hip.