Transient osteoporosis of the hip is a rare condition of unknown aetiology affecting middle aged men with no risk factors and women in their third trimester of pregnancy. The condition invariably resolves spontaneously, however, due to its rarity and initially normal plain radiographs, the syndrome is often not appreciated early in its development, and particularly represents a diagnostic problem of differentiation from osteonecrosis.

We present a case of unilateral transient osteoporosis of the hip in a 52 year old male and a case of bilateral hip involvement in a 32 year old female in her 35th week of pregnancy. Both cases include the initial and follow-up plain radiographs, MRI and DEXA scan findings, through to symptomatic resolution.

We present a literature review of the disease and analyse the current evidence on aetiology, the problems in diagnosis and the current treatment modalities.

Introduction: Hip fractures are usually evident on plain radiographs. Some are not obvious and require further investigation. A review of the pertinent literature reveals different treatment algorithms for such patients but MRI is recommended as the investigation of choice. Little is stated about the clinical findings in patients with an occult fracture of the hip.

Aims: To investigate any correlation between clinical findings and the presence of fracture on MRI in occult fracture of the hip and use this as a means of speeding the diagnosis of such patients.

Methods: We report a prospective, multi-centre trial. 22 patients admitted with a suspected occult fracture of the hip were assessed clinically for evidence of resting deformity, ecchymosis, point tenderness, hip pain on heel percussion or pistoning and ability to straight leg raise (SLR). The same features were assessed in the contralateral limb. All patients were alert and orientated as to comply with examination. Plain radiograph and MRI findings of both hips were recorded in each case.

Results: Of 22 patients, 17 were unable to perform SLR on the affected side, 5 were able to do so. Of the 18 patients, all had a fracture of either the acetabulum or proximal femur on MRI. Of the group of 5, 2 had normal MRI scans, 1 had a pubic ramus fracture, 1 had bone marrow oedema secondary to osteoarthritis and 1 patient had a six week old valgus impaction fracture. All patients could SLR and had normal MRI of the contralateral hip.

Conclusions: Under the conditions of this study straight leg raise test is 95% sensitive and 95% specific for predicting the presence of fracture in either the acetabulum or proximal femur. We recommend that this simple test can be used to help speed up the diagnosis of and further management of occult fractures of the hip