Painful infection at the site of hip prosthesis: CT imaging.

PURPOSE

To prospectively determine the accuracy of computed tomography (CT) in the detection of painful infection at the site of hip prosthesis before surgery.

MATERIALS AND METHODS

Helical CT examinations of hip prostheses were prospectively performed before surgery after a standard clinical and radiologic examination of 65 patients. CT scans and conventional radiographs were reviewed for periprosthetic bone abnormalities, and CT scans were reviewed for periprosthetic soft-tissue abnormalities (joint distention, fluid-filled bursae, and fluid collection in muscles and perimuscular fat). Patients subsequently underwent revision arthroplasty within 1 month, and infection was diagnosed in 12 (19%) patients.

RESULTS

Infection was detected clinically in 25% of patients. Periprosthetic bone abnormalities did not allow differentiation of infection from complications not related to sepsis, except for periostitis, with 100% specificity but only 16% sensitivity. Soft-tissue findings were accurate for detection of infection, with 100% sensitivity and 87% specificity. Fluid collection in muscles and perimuscular fat had a 100% positive predictive value, and absence of joint distention had a 96% negative predictive value.

CONCLUSION

CT is accurate in the diagnosis of painful infection at the site of a hip prosthesis on the basis of soft-tissue findings, whereas periprosthetic bone abnormalities are not useful.