Computed tomography in the preoperative evaluation of masses arising in or near the joints of the extremities.

Knowledge of the precise anatomical relationship of a mass lesion to a joint is helpful in the preoperative planning of surgery. We have evaluated this relationship in 23 patients with a variety of benign and malignant lesions related to the knee and other major joints. In 15 patients, the lesion-joint relationship was assessed by routine computed tomographic (CT) scans followed within 24 hours by arthrography. In nine of these 15 patients, CT demonstrated that the lesion either was remote from the joint or clearly invaded it, and arthrography could have been avoided in these patients. In six patients, the CT findings were indeterminate and further evaluation by arthrography was indicated. CT scans limited to the joint area and obtained immediately after arthrography were available in 14 patients. In general, postarthrography CT did not add significant information to that provided by prearthrography CT scans or by arthrography. However, it may be helpful in occasional cases in which arthrography is not definitive.