CT-guided aspiration in potentially infected total hip replacements complicated by heterotopic bone

Aspiration of the hip joint in the setting of a potentially infected total hip replacement is occasionally unsuccessful under fluoroscopic guidance because of periarticular heterotopic bone. Of 136 consecutive patients with total hip replacements who were referred to the radiology department for hip aspiration because of suspected infection, successful intraarticular needle placement was achieved in 132 (97%) under fluoroscopic guidance. In four (3%) cases, the attempted aspiration was unsuccessful because heterotopic bone prevented the needle tip from reaching the joint; a second attempt was performed successfully under CT guidance. CT confirmed that the anterior approach was completely blocked by heterotopic bone and that there was a gap in this bone elsewhere through which a needle could be passed into the joint. The increased cost of CT was modest because it was necessary in only a small percentage of patients.