Fig. 3: Device for kinematic data acquisition using the 3­Space Isotrack magnetic field technology.

The source and radius are rigidly fixed on the same platform. Fiberglass rods are inserted in the scaphoid, trapezium and first metacarpal. These fiberglasrods are placed without opening the joint capsule or sectioning neither the retinaculae nor the carpal ligaments. To these rods the sensors of the Isotrack system were rigidly fixed. The rod in the 3rd metacarpal is used to guide the motion during FEM and RUD of the wrist. The thumb was rigidly fixed to the 3rd metacarpal to avoid relative motion at the STT joint level. The tendons proximal to the wrist are prepared. All tendon sheaths and the transverse carpal ligament remain intact. All tendons of the finger­, thumb­ and wrist­muscles are loaded using two different loading conditions ("LL" = 1.4 kg and "HL" = 23.5 kg).