Osteoid osteoma distal to a hip arthroplasty.

The authors report a case of osteoid osteoma distal to a hip prosthesis in a 56-year-old patient. This rare association was difficult to diagnose; at first, the pain seemed to be of mechanical origin, suggesting a delayed painful reaction to the prosthesis. The results of bone scan as well as the CT scan ones helped orient the diagnosis. Excision biopsy, using bone trephining, completed by an iliac bone auto-graft resulted in a cure with no residual instability of the prosthesis above the tumor. Bone scan with radio-isotopes to localize the lesion was particularly helpful in this instance to secure the final diagnosis.