抄録
In order to better understand the mechanism of midcarpal instability caused by malunited fractures of the distal radius and the effect of corrective osteotomy of the radius, a cineradiographic study was performed. Twenty-five cases of simple Colles' fractures and 4 patients treated with corrective osteotomy of the radius for malunited Colles' fractures were studied.
At first it appeared that dorsal intercalated segment instability (DISI) occurred in malunited Colles' fractures. Being skeptical of this, however, the carpal angle data previously measured in the injured wrist was adjusted based on the difference between the tilting angle of the injured and uninjured wrists. If no effect was produced on the carpal alignment by the dorsif lexed deformity resulting from the malunited fracture, the alignment between the fragment of the distal radius and carpal bones had to be normal. However, the carpal alignment of malunited Colles' fractured wrists with severe residual dorsal tilt exhibited a DISI malalignment. Therefore, the residual dorsal tilt in Colles' fractures was not being compensated for at the radiocarpal joint but at the midcarpal joint. Although the range of motion in volar flexion and ulnar deviation appeared to be restricted, the adjusted data showed that the range of motion was actually impaired in dorsal flexion and radial deviation. Thus there appeared to be an abnormally severe stress at the midcarpal in the case of a malunited fracture of the distal radius, ultimately resulting in midcarpal instability.
After corrective osteotomy was performed, complaints subsided in all cases. Carpal alignment was improved in 3 out of 4 patients after this operation. This seems to show that the corrective osteotomy of the distal radius is a viable solution to the problems resulting from malunited fractures of the distal radius.
