Technetium 99Tcm pyrophosphate scanning in the assessment of the painful hip prosthesis.

Technetium 99Tcm pyrophosphate bone scans were done on 35 patients who complained of persistent hip following total hip replacement. The scans of six patients were normal and the symptoms of these patients either resolved (three) or greatly improved (three) without further treatment. Twenty-nine patients had abnormal scans. Seventeen of these were due to infection or loosening of the prosthesis. Paget's disease of bone, protrusion of the prosthesis and heterotopic ossification also caused scan abnormalities. These causes could not be distinguished from one another on the scan. A radiograph of the hip is essential for interpreting the scan correctly. Scanning of the painful hip prosthesis helps to detect patients in whom serious complications are present or are likely to develop.