DISI Deformity and Post-Operative Symptoms of Scaphoid Non-Union.
The correlation between the residual dorsal intercalated segmental instability (DISI) deformity and symptoms of the wrist was investigated in 20 patients with healed scaphoid non-union who had open reduction and bone grafting. In seven patients, inlay corticocancellous bone grafting (modified Russe procedure) was performed. In four of the seven patients, an additional Herbert bone screw was used for internal fixation. The remaining 13 patients were treated with open reduction, anterior bone grafting, and internal fixation with Herbert bone screw. Average duration of follow-up period after operation was 20 months (range, 6 to 57 months). The average extension-flexion arc of the injured wrists was 129 degrees, which was 31 degrees less than that of the uninjured wrists. The average grip strength of the injured wrists was 89% of that of the uninjured wrist. Before the operation, all 20 patients were symptomatic and complained of wrist pains. Post-operatively, three patients experienced mild pains and only one complained of moderate wrist pains. Post-operative radiolunate angle ranged from 0 degrees to 34 degrees (average 10 degrees ). DISI deformity remained uncorrected in eight patients. Post-operative symptoms were compared amongst the eight patients who had DISI deformity and 12 patients who had no deformity. There was no significant difference in range of motion, grip strength, and incidence of pain between these two groups of patients. The presence of DISI deformity after bone grafting for a symptomatic scaphoid non-union was not predictive of post-operative symptoms of the wrist.