Effects of distal radius malunion on distal radioulnar joint mechanics—an in vivo study

Abstract

Patients with a malunited distal radius often have painful and limited forearm rotation, and may progress to arthritis of the distal radioulnar joint (DRUJ). The purpose of this study was to determine if DRUJ congruency and mechanics were altered in patients with malunited distal radius fractures. In nine subjects with unilateral malunions, interbone distances and dorsal and palmar radioulnar ligament lengths were computed from tomographic images of both forearms in multiple forearm positions using markerless bone registration (MBR) techniques. The significance of the changes were assessed using a generalized linear model, which controlled for forearm rotation angle (À608 to 608). In the malunited forearm, compared to the contralateral uninjured arm, we found that ulnar joint space area significantly decreased by approximately 25%, the centroid of this area moved an average of 1.3 mm proximally, and the dorsal radioulnar ligament elongated. Despite our previous findings of insignificant changes in the pattern of radioulnar kinematics in patients with malunited fractures, we found significant changes in DRUJ joint area and ligament lengthening. These findings suggest that alterations in joint mechanics and soft tissues may play an important role in the dysfunction associated with these injuries. ß

Three-Dimensional Assessment of Bilateral Symmetry of the Radius and Ulna for Planning Corrective Surgeries

“…1 A malunion may cause pain, reduced motion, reduced grip strength, carpal instability, and, eventually, osteoarthritis. [2][3][4] Sometimes, a corrective osteotomy is performed to reduce the pain and improve function. The goal of the osseous correction is to restore normal relations in the distal radioulnar joint.…”

Load Transfer at the Distal Ulna Following Simulated Distal Radius Fracture Malalignment

“…Joint incongruity produced by dorsal angulation and dorsal translation causes an interosseous membrane tightness 22 and dorsal radioulnar ligament strain. 21 Distal radius malalignment increased the load by 165% of the native condition, and transecting the ligaments decreased the load to 60% of the native condition. These studies support our finding that the biomechanics of the DRUJ can be altered with relatively small changes in native osseous position and ligamentous integrity.…”

Correction of Forearm Malunion Guided by the Preoperative Complaint

“…Although the occurrence of DRUJ instability resulting from shaft deformity was reported , it is far less common than after malunion of the distal radius [6,8,38]. Cases of DRUJ instability resulting from forearm malunions in which bone osteotomies alone resulted in joint stabilization have been reported [38].…”

“…Numerous biomechanical studies have investigated the effects of angular and axial malunions of the forearm bones on limitation of ROM and DRUJ instability [3,4,6,8,12,19,20,24,25,31,33,37]. Different isolated or combined axial malunions of the radius and ulna may result in comparable forearm stiffness [12].…”