A biomechanical study on torque resistance of distal radioulnar joint by extra-and intra-articular reconstruction

Abstract

Objective To compare the torque resistance effect with different types of reconstruction of the distal radioulnar joint (DRUJ) dislocation,in order to explore biomechanical basis for clinical practice.Methods Six adult cadaver forearm were used,including 4 males and 2 females.The average death age was 64.9 years (range,36-78 years).Three were right side,3 were left side.The DRUJ dislocation model was made after the standardized resection of the palmar and dorsal DRUJ ligament.Clinic reconstruction methods of the DRUJ include trans-bone tunnel renconstruction (intra-articular reconstruction) and Looptie up reconstruction (extra-articular reconstruction).The mechanical properties as follows:torque velocity:5°/min,maximum torque angulation:90°,maximum torsion force:1 N· mm.Each limb was detected for the torque mechanic under four conditions:normal,DRUJ dislocation,intra-articular reconstruction and extra-articular reconstruction.Results Each limb was inspected for intact mechanic baseline and without the visual damage to the bone.The average pronation torque resistance on normal condition was (0.44±0.10) N·mm,(0.37±0.09) N·mm on DRUJ dislocation group,(0.45±0.09) N-mm on intra-articular reconstruction group,and (0.42±0.09) N·nun on extra-articular reconstruction group.Pronation torque resistance of DRUJ dislocation group was apparently lower than the normal group (t=2.043,P=-0.047).The pronation torque resistance reconstruction group had no significant difference with normal group.The average supination torque resistance on normal condition was (0.56±0.16) N·mm,while on DRUJ dislocation group was (0.42±0.11) N-mm,on intra-articular reconstruction group was (0.54±0.16) N·mm,on extra-articular reconstruction group was (0.51±0.13) N·mm.There were no apparent differences among four groups.Conclusion Both internal and external reconstruction could recover the rotation stability and normalize the torque resistance,without statistical difference. Key words: Forearm Injuries; Joint Instability; Ligaments; Reconstructive surgical procedures; Rotation; Biomechanics