MRI was used to diagnose occult hip pathology in patients with a clinically suspected femoral neck fracture where no abnormality was detected on plain x-ray. All patients admitted into our unit with post traumatic hip pain, an inability to weight bear, and no abnormality found on a series of plain radiographs, underwent an MRI scan of the pelvis and affected hip to look for an occult femoral neck fracture.

The study included 102 consecutive patients who were prospectively studied over a 10 year period between 1997 and 2007. Four patients were excluded due to contraindications or an inability to tolerate having an MRI scan. Of the remaining 98 patients 81 had abnormalities detected (83%). 42 of these patients had evidence of a proximal femoral fracture. 23 patients underwent an operative procedure.

Eight incomplete intertrochanteric fractures were treated non-operatively with good results. One patient had a primary diagnosis of malignancy made on the basis of the MRI scan. One patient had a known primary malignancy but this was the first diagnosis of bony metastatic disease. Seventy five patients were scanned within 48 hours of admission (average 2.4 days).

The use of MRI in our unit was felt to be appropriate in patients with a high suspicion of proximal femoral fracture. Our results show that there is a significant incidence of fractures that are not apparent on plain x-rays. MRI led to early diagnosis and initiation of definitive management, potentially reducing cost and complications of immobility. It was most useful in showing the extent of the fracture, and picked up on other occult pathologies of the hip and pelvis. We recommend stabilisation of femoral neck fractures and non operative management of all incomplete intertrochanteric fractures if able to non weight bear. There must be a high index of suspicion of undiagnosed malignancy

MRI is a well-tolerated, short procedure that would provide an early, accurate and cost effective diagnosis in elderly patients with negative plain films and persistent post-traumatic hip pain, thereby facilitating their correct management.

It is 100% sensitive and specific to occult hip fractures and does not involve ionising radiation.

Fractured necks of femur in the elderly population are common. This group of patients are responsible for a significant proportion of health care costs and efforts today. The diagnosis of hip fractures is not always clear-cut and plain radiographs may not show an undisplaced fracture. The management of this patient group is dependant upon the correct diagnosis via imaging and treatment decisions are based on these findings. If these fractures are missed, there is a significant chance of displacement and avascular necrosis presenting at a later date. This would complicate matters and result in more complex surgery. This also increases health care costs due to an extra admission, more expensive and difficult surgery with longer rehabilitation and after care. In our study, the management of the patients reviewed was significantly altered due to the imaging process used.

We performed MRI scans on thirty-six patients who had post-traumatic hip pain and negative plain radiographs (reported as normal or equivocal). Twenty-three (64%) of the patients sustained a fracture, of which sixteen (44%) involved the neck of the femur, all of whom were above the age of 71 years. 100% of the elderly age group scanned were positive for a femoral neck fracture and eleven (31%) received operative intervention. The five patients who did not undergo operative management were deemed too unwell for surgery. Only three patients’ scans were negative.

These results confirm that MRI (in the 71 years and above age group), is indicated in order to diagnose an undisplaced fractured neck of femur not recognised on plain radiographs, which requires operative intervention in the form of dynamic hip screw or cannulated hip screws to prevent further deterioration or displacement.