A dynamic simulator to evaluate distal radio-ulnar joint kinematics

In order to perform cadaveric biomechanical studies of the human forearm an d distal radio-ulnar joint, a dynamic simulator has been constructed. The d evice is based upon a Plexiglas frame, to which the ulna is secured in a ve rtical orientation and the humerus in a horizontal orientation. The hand is secured in a sliding bar linkage to a stepper-motor that is used to rotate the forearm. The tendons to be loaded are connected to pneumatic actuators that provide agonist and antagonist muscle loading resulting in torque alo ng the forearm axis. The muscle loading profiles and magnitudes are program mable as a function of the pronation-supination position and direction. A m agnetic tracking system is used to collect three-dimensional kinematics dat a of up to four segments, in conjunction with the muscle tendon loads, fore arm torque and other prescribed experimental measures. All functions are un der PC control using custom software written with LabVIEW(TM) (National Ins truments, Austin, TX). For the DRUJ tearing, the validity of the tendon loa ding protocol to produce physiologic torque/rotation patterns was verified using in vivo data. The relationship of individual muscle forces to forearm torque was determined by a cadaveric study. (C) 2001 Elsevier Science Ltd. All rights reserved.