BRACING OF STABLE SHAFT FRACTURES OF THE ULNA

In the laboratory an ulnar osteotomy was performed in 10 cadaveric spe cimens, which included 5 distal-third junctions and 5 middle-third jun ctions. The interosseous membrane was left intact. Each specimen was r otated through full pronation and full supination. Displacement less t han half shaft width was considered stable. The interosseous membrane was subsequently released 2 cm proximal and 2 cm distal to the osteoto my. Repeated pronation and supination range of motion documented gross displacement greater than half of the width of the shaft and was diag nosed as unstable. To evaluate this hypothesis, a clinical trial of 30 stable ulnar shaft fractures of the middle and distal thirds were tre ated with functional bracing between 1984 and 1990. A simple protocol was followed: A long arm cast was applied for approximately 5-7 days u ntil the patient experienced only mild pain. At 5-7 days, a prefabrica ted forearm brace was fitted and the patient began physical therapy, a dvancing the upper extremity to full functional use. The bracing was c ontinued until radiographic union had occurred. Twenty-nine clinical c ases were evaluated to fracture union. The mean time to union was 7.3 weeks (range: 6-9 weeks). One delayed union was reported in the series . At 16 weeks surgical intervention was recommended and an open reduct ion and internal fixation with cancellous bone grafting was performed. Twenty-nine patients regained full range of motion, and one had limit ed supination/pronation due to a previous injury of the radial head. I n conclusion, functional bracing of stable ulnar shaft fractures leads to a high incidence of fracture union and achieves good to excellent functional results. The success of this technique is dependent on the proper selection of a stable ulnar fracture as related to the integrit y of the interosseous membrane.