Stress fracture of femoral stem of hip resurfacing a cause of sudden onset hip pain- A case report and review of literature.

Resurfacing arthroplasty of the hip has had a difficult last decade. Fracture of the femoral neck has been a known complication of resurfaced hip replacement; however, fracture of the metal peg within the femoral component has only been reported twice. We encountered and treated a patient with a unique type of metal failure. A 45 year old lady had advanced arthritis of her left hip secondary to rheumatoid disease. In 2006, an ASR resurfacing arthroplasty was performed and excellent function of the hip was achieved. After 9 years, she experienced an acute pain in the hip without trauma. Serial radiographs before & after the onset of symptoms did not reveal any significant abnormality. MRI scan did not suggest any adverse features too. No evidence emerged in favour of adverse reactions to metal debris (ARMD). Decision to revise the hip was taken with suspicion of an occult fracture. At surgery, the stem of the femoral component was found fractured at its junction with the dome, the dome being still well fixed with the femoral neck. The acetabular component was well fixed. Till date she is very satisfied with the revised hip. Fracture of the femoral peg at its junction to the dome is a complication of hip resurfacing that has not been previously reported in the literature. On the retrieved specimen, instead of 'beach lines' indicative of failure of the material over a prolonged period, we observed only a notched area of bending on the medial side of the implant. This is indicative of an acute event. We wish to make surgeons aware of this particular complication when investigating a similar Case presentation. There is unlikely any standard investigation that diagnoses the fractured implant accurately.