Influence of distal radioulnar joint subluxation on restricted forearm rotation after distal radius fracture

Purpose: To analyze the influence of subluxation of the distal radioulnar joint (DRUJ) on restricted forearm rotation after distal radius fracture. Methods: Twenty-two cases of healed unilateral distal radial fracture with restricted forearm rotation were included in the study. The subluxation of the DRUJ was evaluated using helical computed tomography scan at neutral, maximum pronation, and maximum supination and presented as the percent displacement of the ulnar head in both the injured and uninjured sides. The radiographic parameters of palmar tilt, radial inclination, dorsal shift, radial shift, and ulnar variance were measured on plain x-ray films and the rotational deformity of the distal radius was evaluated from the computed tomography scan. The differences of each radiographic parameter from the uninjured side were calculated. The relationships between the restricted forearm rotation and the percent displacement of the ulnar head and each of the radiographic parameters were analyzed statistically. Results: When forearm pronation was restricted the ulnar head was located palmarly at neutral, maximum supination, and maximum pronation with severe dorsal tilt of the distal radius. When supination was restricted the u1nar head was located dorsally at maximum supination with severe ulnar-positive variance. Conclusions: The subluxation of the DRUJ was related to restricted forearm rotation. The radiographic parameters of palmar tilt and ulnar variance showed an adverse influence on the position of the ulnar head at the DRUJ, which might lead to restricted forearm rotation after distal radial fracture.