進行期 Kienböck 病に対する橈骨骨切り術の検討-X線学的解析-

抄録

Radial osteotomy has been recommended for stages II and III-a of Kienböck's disease because of it's load decreasing effect on the lunate. Recently usefullness of this procedure in the tratment of advanced stage Kienböck's disease has been demonstrated clinically by several authors. In contrast, the effects of this procedure on the biomechanics of the degenerative arthritis of wrist advanced Kienböck's disease are unclear. In this study, we studied 17 patients with stage III and IV Kienböck's disease to analyse the precise radiographic consequence of radial wedge osteotomy for progressive stage Kienböck's disease.
12 patients who underwent the radial closing wedge osteotomy and 5 patients who underwent radial shortening osteotomy for the treatment of advanced Kienböck's disease were reviewed clinically and radiographically. There were 7 males and 10 females, whose average age was 51 years. 5 were stage III-a, 10 were III-b and 2 were stage IV. The average follow-up period was 2 years and 3 months. The following measurements were made for radiographic assessment: the angle of radial inclination, ulnar variance, carpal height ratio, Ståhl index, radio-lunate angle, radio-scaphoid angle, scapho-lunate angle, carpal-ulnar distance ratio, lunate covering ratio, and ring to proximal pole distance.
The radial inclination decreased from 26.8° to 15.7 in the wedge osteotomy group. The ulnar variance increased 2mm in the radial shorening group. The carpal height ratio decreased from 0.509 to 0.504 and Ståhl index increased from 36% to 37%, both without statistical significance (p<0.01) in the wedge osteotomy group. In addition, the radio-scaphoid angle increased significantly (p<0.01) in the wedge osteotomy group.
The increased lunate covering ratio is believed to increase the area of distribution of the axial load through the lunate by increasing the contact area with the radius. In addition, the increased radio-scaphoid angle is believed to correct the radio-carpal malalignment in patients with advanced stage Kienböck's disease. The satisfactory clinical outcome of radial closing wedge osteotomy is believed to be due to both these effects on carpal alignment.