Arthrodesis for chronic static scapholunate dissociation: a prospective study in 12 patients.

Twelve patients had limited arthrodesis between the scaphoid and the lunate for chronic static scapholunate dissociation using internal plate osteosynthesis. The median time between the injury and surgery was 50 months (range 9-180). They were followed up for a year postoperatively. Preoperative symptoms were pain, functional impairment, and restricted movement. During operation the scapholunate interosseous ligament was completely torn and the scaphoid malrotated in all patients. The range of motion was measured preoperatively and postoperatively, and the unaffected side used for control. For all patients except one postoperative extension, flexion, and radial deviation had considerably decreased. However, supination increased in seven of 12 patients postoperatively and so did pronation in seven of 12 patients. One patient (case 12) had an improved range of motion postoperatively in all directions. The mean grip strength was 76% of the unaffected side preoperatively, and has increased to 85% postoperatively. We found that bone healing was rare and most arthrodeses healed by a fibrous union. We found no correlation with preoperative arthrosis and clinical outcome. One patient had retired from work before operation because of back pain and one because of age. Two patients had taken early retirement because of wrist pain, and one patient was still on sick-leave at the follow-up a year postoperatively. Five patients returned to full-time work and two patients to part-time work. Four patients were on long-term sick-leave preoperatively and three of them returned to their previous occupations. Analysis of the patients' subjective outcome (including pain and functional scores) showed overall satisfaction, and objective data show that scapholunate arthrodesis for chronic static scapholunate dissociation provides substantial improvement over the preoperative condition.