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The role of aspiration and contrast-enhanced arthrography in evaluating the uncemented hip arthroplasty.

OBJECTIVE
The purpose of this study was to determine the value of aspiration and contrast-enhanced arthrography in evaluating uncemented total hip arthroplasty components. A retrospective study was performed to determine the sensitivity, specificity, and accuracy of these procedures.


MATERIALS AND METHODS
Preoperative aspiration of the hip joint and contrast-enhanced arthrography were performed by a skeletal radiologist in 33 hips with uncemented components before exploration or revision. In one patient, the hip aspiration yielded grossly purulent fluid and arthrography was not performed. Twenty-one uncemented acetabular components and 29 uncemented femoral components were evaluated by arthrography. The aspiration of the hip provided fluid for culture in 33 hips; in one hip, no fluid could be obtained.


RESULTS
A preoperative diagnosis of infection based on growth on solid media was made in five hips (15%). An additional infection was determined to be present in the hip in which no fluid was obtained when purulent fluid was found at operation. On the basis of the operative findings, contrast-enhanced arthrography of the 21 acetabular components had a sensitivity of 50%, a specificity of 77%, and an accuracy of 68%. Arthrography of the 29 femoral components had a sensitivity of 63%, a specificity of 64%, and an accuracy of 63%.


CONCLUSION
Aspiration of the hip joint before revision of uncemented hip arthroplasties was valuable because the diagnosis of infection was made preoperatively in five of six hips. However, contrast-enhanced arthrography was not valuable, with a low sensitivity and specificity for both uncemented acetabular and uncemented femoral components. Only a preoperative aspiration of the hip joint is recommended before revision of uncemented components.