Sternocostoclavicular hyperostosis: its progression and radiological features. A study of 12 cases.

Twelve cases of sternocostoclavicular hyperostosis were followed up over four to 16 years. The patients underwent repeated radiological examinations of the sternocostoclavicular joints and the sternum, and the extrasternal osseous manifestations of the disease were studied to show changes in the radiological features during long term follow up. Five of 12 (41%) patients had extrasternal manifestations. With the exception of one patient extrasternal manifestations were first detected by scintigraphs because they were asymptomatic. With respect to the sternal manifestations the initial radiological diagnosis was made during an acute phase while painful swelling over the sternum and decreased mobility of the shoulders occurred. The radiological examinations showed the signs of a proliferative destructive arthritis in most patients. In contrast with the frequent occurrences of clinical symptoms, the radiological signs of progression take several years to become detectable. There are no specific bacteriological, serological or histological findings. Usually a permanent increase in the erythrocyte sedimentation rates is found. Sternocostoclavicular hyperostosis is a slowly progressing disease, characterised by a chronic aseptic destructive sternoclavicular arthritis with a reactive low turnover sclerosis that begins in a similar way to an enthesopathy and ends after several decades with total ankylosis. The radiological identification of retrosternal proliferation of soft tissue by computed tomography was found to be a valuable criterion for the differential diagnosis from other benign hyperostotic processes of the sternoclavicular region.