BACKGROUNDThe imaging evaluation of pain in patients who have had a hip arthroplasty (HA) is challenging, and traditional imaging techniques, including magnetic resonance imaging (MRI) and computerized tomography (CT), are limited by metallic artifact. The purpose of the present study was to investigate the use of modified MRI techniques to visualize periprosthetic soft tissues and the bone-implant interface, and to evaluate the value of MRI for the assessment of patients with painful hip arthroplasty.

METHODSFifty-six painful hips in fifty-six patients following primary HA were assessed using optimized MRI, CT and standardized radiographs. The diagnosis of MRI was correlated with intraoperative findings as well as with microbiological and histological examinations (when available). The sensitivity and the specificity of MRI diagnosis were determined according to final diagnosis. The chi-square test was performed to detect a difference between MRI and final diagnosis.

RESULTSForty-eight patients have received revision surgery and final diagnosis were established. MRI was demonstrated high sensitivity and specificity in detecting aseptic loosening (93% and 95%), periprosthetic infection (94% and 97%), adverse local tissue reaction (100% and 100%) and periprosthetic fracture (100% and 100%). MRI was determined to be the most sensitive technique in detecting implant loosening for any reason, with a sensitivity of 93.8% for acetabular shell and 97.1% for femoral stem, compared to 81.3% and 80.0% on CT, 75.0% and 77.1% on radiographs.

CONCLUSIONSOptimized MRI was effective for the assessment of the periprosthetic soft tissues and bone. The use of modified magnetic resonance imaging parameters provided a useful adjunct to conventional examinations for the evaluation of patients with painful hip arthroplasty.