Abstract
Wrist arthrodesis is a common surgical procedure that provides a high level of functional outcome and pain relief among patients.[1] Upon partial arthrodesis, the wrist experiences changes in load transmission that are influenced by the type of arthrodesis performed. Measuring the load through the wrist joint is difficult, however, combined with computational models [2], it is possible to obtain data regarding the load mechanics of the wrist joint. Although successful fusion rates among patients have been reported, it remains unclear what the biomechanical consequences are.
The aim of the study is to quantify pre and post operative load transmission through a cadaveric wrist which has undergone simulated arthrodesis of the radiolunate(RL) joint. An embalmed human wrist was dissected dorsally exposing distal radius, radiocarpal and carpometacarpal joints, and dorsal ligaments. The radioscaphoid(RS) ligament was sacrificed to accommodate insertion of a PPSEN-09375 force sensitive resistor (FSR) into the RS joint. The FSR was calibrated prior to measuring the contact force on the RS joint.
The wrist was aligned in the neutral position in cardboard piping, and secured proximally and distally with Dental Plaster (OthoBock Healthcare Plc, Surrey, UK). The midsection of piping was windowed to permit placement of the FSR in the RS joint, and fixation of the RL joint using 2 Kirschner wires. The window was completed circumferentially and the specimen was placed in the Instron where a graduated axial compression was applied at 20 N/min.
The results showed that when the radiolunate joint is fused, and a total axial load of 100N is applied, the load transmitted through the RS joint was approx 65N. i.e. 65% of the force. This is greater than the 56% measured experimentally by Blevens et al (1989) in an unfused specimen[3]. We plan to repeat our measurements and compare to an untreated cadaveric wrist.
