[Scapho-trapezo-trapezoidal arthrodesis or triscaphe arthrodeses. Study of 36 reviewed cases]

From May 1983 to September 1988, we performed 41 triscaphe arthrodeses, 36 of which underwent clinical and radiologic follow-up examination. The 36 preoperative diagnoses were classified as: Kienböck's disease (16 cases), chronic rotatory subluxation of the scaphoid (static scaphoid-lunate dissociation) (13 cases), degenerative arthritis of the scapho-trapezio-trapezoid joint (4 cases), traumatic lesion of the scapho-trapezio-trapezoid joint (2 cases), 1 case of midcarpal instability with a non-dissociative VISI pattern. Average length of follow-up was 28 months. Analysis of results showed on the whole good improvement on pain and average improvement of strength; range of motion varied greatly with etiology. For example, the range of motion on the fused side in Kienböck's disease averaged 38 per cent of that of the unoperated side, whereas in other conditions it averaged 60 per cent. Radiographic analysis confirmed the efficacy of triscaphe arthrodesis in preserving normal carpal height but revealed radial styloid impingement in 34 per cent of the cases. Use of this procedure should be limited to stage 3 Kienböck's disease and to scaphoid-lunate dissociation without arthritis. Peroperative radiographic study is indispensable to verify appropriate reduction of the scaphoid and to measure the radial-scaphoid angle. Partial radial styloidectomy should be included routinely in the procedure.