ASSESSMENT AT CT OF THE RHEUMATOID SHOULDER WITH SURGICAL CORRELATION

Eleven shoulders in 10 patients with rheumatoid arthritis were examine d by conventional radiography and CT prior to cup hemiarthroplasty of the humeral head and the results were compared with the surgical findi ngs. There was good agreement between preoperative CT and surgical fin dings. Humeral head cavities and erosions, with cortical boundaries, c ould be seen more accurately at CT than at conventional radiography. T he HU of their contents corresponded to those of soft tissue, being gr anulomatous in nature at surgery. In 8 humeral heads CT disclosed larg e areas of fatty degeneration of bone marrow with HU between - 10 HU a nd -76 HU that were not visible on the conventional radiographs. These ''fatty cysts'' had no cortical boundaries, unlike inflammatory granu lomas, but both lesions may influence the surgical approach to hemiart hroplasty.