Wrist ligament strain during external fixation: A cadaveric study

The purpose of this study was to evaluate the change in strain (elongation) that occurs in 2 extrinsic ligaments of the wrist (volar radioscaphocapita te and dorsal radiotriquetral) as the wrist is sequentially distracted with an external fixator. Six fresh cadaver specimens were dissected to expose the dorsal radiotriquetral and volar radioscaphocapitate ligaments. A diffe rential variable reluctance transducer strain gauge was applied to both lig aments and the wrist was serially distracted in increments of 5 mm with an Agee WristJack (Hand Biomechanics Laboratory, Sacramento, CA). The distract ion increments were measured on the WristJack. X-rays were obtained at each level of distraction. At 10 mm of WristJack distraction, the strain in bot h the volar radioscaphocapitate and dorsal radiotriquetral ligaments increa sed to greater than 20%. An increase to a 0.63 carpal height index resulted in an increase in strain of 20%. This increased strain may contribute to w rist stiffness. (J Hand Surg 1999;24A:102-107. Copyright (C) 1999 by the Am erican Society for Surgery of the Hand.).