Displacement response of juvenile arthritic wrists during grasp

Objective. To analyze the displacement response of juvenile arthritic wrist s during grasp in order to diagnose early ligamental laxity and facilitate early splinting. Methods. X-rays of the wrists, made under standardized conditions, of 30 ch ildren with juvenile chronic arthritis (mean age 10.4 years, range 4.5-16.9 ) were analyzed after being digitalized. Osseous landmarks were identified, and coordinates were calculated from measured angles and lengths with an a ccuracy of 0.01'. Lunate and carpal-ulnar distance were obtained according to Youm, and ulnar variance according to Hafner. Results. Overall, an increase in ulnar-lunate displacement and carpal narro wing and a decrease in ulnar variance were found. However, not all wrists r esponded to the same extent. Radial displacement of the lunate, though slig ht, was found in 2 wrists and the amount of ulnar displacement varied subst antially (3.1% to 22.5%). The variance in amount of displacement could sugg est that juvenile wrists do not respond to increased compressive forces to the same extent. Conclusion. The changes found are similar to those found in the healthy wri st. Furthermore, our findings suggest that the juvenile wrist acts in accor dance with the generally accepted explanation for the development of malali gnment in adult wrists. It seems that laxity of ligaments can be diagnosed early by the force grip maneuver during x-ray. It would have a significant impact on the moment of orthotic intervention as well as the design of the orthotic device. Further study along this line seems justified.