Determination of the Carpal Unstability in Patients with Rheumatoid Arthritis

Abstract

Introduction: The carpal instability is a biomechanical alteration with multiple pathogenesis. It ensues due to disturbance of the normal ligament and bone connections that control the wrist. There are four major types of carpal instability: 1 Dorsal intercalated segment instability (DISI) 2.Volar intercalated segment instability (VISI) 3.Ulnar translocation, and 4. Medial carpal instability. Instability in the wrist in Rheumatoid arthritis (RA) appears as a result of incongruity between joint and bone surfaces, capsular and ligament laxity and muscle-tendon imbalance, and to evaluate carpal instability in RA and to determine the type of carpal instability using radiography. Material and methods: In 30 patients with diagnosed RA we made anteroposterior and lateral radiographies in neutral position of both hands. On anteroposterior radiographies we measured carpal-ulnar distance. For evaluation of the bone set ups on lateral radiographies we used the axial Linscheid method for drawing carpal axes that enable measurements of angles which can define position of the carpal bones: scaphoid-lunate, radio-lunate and capitatelunate angles. Results: Of 60 rheumatoid hands in 50 we found carpal instability: ulnar translocation (32 hands), VISI (14 hands), DISI (4 hands). We detected isolated form of carpal instability in 38 hands, while in part we found complex carpal instability i.e. combination of two types of instability (12 hands). Conclusion: This radiographic method enables evaluation of carpal instability and quantitative analysis for determination of the type of the carpal instability in RA.