Rheumatoid arthritis of the wrist. Classification related to the natural course.

The authors introduce a new functional classification of rheumatoid arthritis of the wrist. Unlike the classifications used today, it includes the aspect of the natural course of rheumatoid arthritis. The goal of this paper is to identify radiologic indicators that will classify rheumatoid arthritis into stable forms of the disease (Types I and II) and unstable forms of the disease (Type III). Of 144 wrists examined, the first available radiograph and the radiograph obtained at the time of the first surgery were assessed. The indicators measured were: carpal height ratio, ulnar translocation, radial rotation, and scapholunate dissociation. Noting the changes that occurred each year in these indicators, it was possible to identify a significant difference between stable forms (Types I and II) and unstable forms (Type III) for the parameters carpal height ratio, ulnar translocation, and scapholunate dissociation. The distribution of the indicators allowed the definition of three values: the 100% value, the cut off point, and the lower threshold value. Combining the three radiologic parameters at those values markedly enhanced the possibility to classify rheumatoid arthritis of the wrist. With the help of the three radiologic indicators carpal height ratio, ulnar translocation, and scapholunate dissociation, it is possible to classify wrists with an early stage of rheumatoid arthritis according to the Schulthess classification. The early identification of destabilizing forms of rheumatoid arthritis becomes possible, making the choice and timing of the surgical intervention easier. Wrists with a progressive unstable form of rheumatoid arthritis may be stabilized earlier.