[Distal radius malunions in flexion]

In this paper we will differentiate the clinical management of distal radial fractures with malunion in extension from those with malunion in flexion. Malunions in flexion are rare and radial shortening does not contribute significantly to the deformity. There is always a decrease in the range of motion, especially prono-supination. Besides the usual causes of these malunions, a new iatrogenic cause is becoming prevalent: malunion in flexion occurs when a fracture in extension is treated by posterior intrafocal pinning but the surgery is performed poorly or performed when it is contra-indicated because of volar comminution.

We report a retrospective study of 20 cases of distal radius malunion in flexion. The series includes relatively young patients with a mean age of 39.3 of age (24-66). Three types of surgery are compared: 1) an isolated radius extension osteotomy (group 1); 2) an isolated procedure on the ulna (group 2); 3) combined procedures on radius and ulna (Group 3).

Results of the three techniques on prono-supination are almost the same, resulting in an almost normal range of motion. Pain decreased from 2.1 (pain for significant strains) to 0.7 (no or climatic pain) in a five-scale classification from 0 to 4. Strength increased by 23% to reach 83.3% of the opposite side. Some differences with malunions in extension should be noted: 1) volar carpal subluxation relative to the radius is present in less than 1/3 of the cases (6/20); 2) adaptive carpus is very rare and independent of the volar displacement (2/20), 3) palmar flexion exists without significant shortening (bone graft rarely necessary); 4) Pronation of the distal fragment results in distal radioulnar joint incongruity.

The best treatment for young patients is combined radial and ulnar osteotomy. Although a more radical procedure, it is worthwhile for the younger patient in order to recover normal anatomy. Isolated radial osteotomy may be sufficient if pronosupination and radioulnar joint congruity are regained. However, isolated procedures on the distal ulna are only indicated in the elderly, or in patients with little discomfort.