Abstract
It is commonly known that rheumatoid arthritis involves the elbow joint with joint destructive change. However, the natural history of the elbow joint and surgical indications based on this course is not well recognized yet. The goals of the present study were to document the natural history of the elbow joint in patients who have rheumatoid arthritis and to determine the stage at which the natural progression should be interrupted by surgical treatment. Methods : . We randomly reviewed the medical records and radiographs of the 296 (17.2%) elbow out of 1725 patients who have rheumatoid arthritis ; we could follow the natural history of 28 elbows of 22 patients in a long clinical term. Twenty-eight elbows could be categorized into one of three groups : Group A, No radiological progression at elbow joint (50.0%) ; Group B, Chronic and slowly development (over 6 years) of elbow joint destruction (17.9%) ; Group C, Acute or subacute development (Grade 0 to Grade 4, 5 in Larsen classification during 3-6 years) (32.1%) . Coronoid Height Ratio (CoHR) of the ulnar Coronoid process and Curvature Radius (R) of the ulnar sigmoid notch were measured radiologically. Results : There were no significant differences of the Coronoid Height Ratio in groups A and B. Acute or subacute progression of joint destruction was seen in the elbow that had a CoHR of over 60%. These findings were most frequent in group C. There was no relationship of Curvature Radius of the ulnar sigmoid notch between groups A, B and C. The Coronoid Height Ratio could be classified as stage I (<50%), II (50-59%), and ID (≥60%) . The results indicated that natural history of the rheumatoid elbow could be classified into stage I which could be recognized as almost normal, stage II which has a high risk of progression, and stage III which needs surgical treatment. Conclusions: Rheumatoid arthritis of the elbow joint commonly has the potential to progress rapidly, resulting in severe joint destruction. The Coronoid Height Ratio, one of the valuable parameters of the natural history, provides useful diagnostic information, particularly prognosis for progression of joint destruction. Through knowledge of the natural history is essential in the planning of appropriate and timely treatment to prevent progression of joint destruction and functional disturbance.
