Indications of 99mTc-MDP scintigraphy bone scan in the evaluation of painful hip arthroplasties

The purpose of this study was to determine the indication of bone scintigraphy in hip prosthesis complications. Thirty-six patients and 38 hip prosthesis have had a 99Tc-MDP scintigraphy in our laboratory between 1995 and 1997. It concerns 32 cemented total prosthesis, 3 intermediate prosthesis and 3 non-cemented total prosthesis. For 14 prosthesis, complication (loosening or infection) was confirmed by surgical operation in 12 cases (4 isolated acetabular complications, 2 isolated femoral loosening, 3 global loosening and 3 infections) or by concordant data from different examinations in 2 cases (global loosening) where intervention was unrealizable. About other patients, absence of complication was confirmed by a favourable evolution lasting at least 12 months. A cetabular and femoral complications were detected by scintigraphy respectively with a sensitivity of 100 % and 90 %, a specificity of 85 % and 78 %, a PPV of 75 % and 60 % and NPV of 100 % and 96 %. High negative predictive value allows to eliminate a prosthesis complication in the case of a normal scintigraphy and to override decision when the clinic and the radiography are doubtful. Scintigraphy may recognize other bone fixation abnormalities which may be responsible of clinical symptomatology. (authors)