[Long-term results of endoprosthetic replacement of the scaphoid bone of the wrist joint].

Eighty-nine late results (five to twelve years follow-up) of prosthetic replacement of the scaphoid bone with a silastic spacer are presented. In 76% the clinical course was uncomplicated; 24% needed secondary surgical procedures including two arthrodeses of the wrist joint. Flexion and extension of the wrist improved by 10.9%, radial and ulnar deviation by 15.0% on average. The first carpometacarpal joint showed minor restriction in 24.0%. The power grip was diminished by 32.0%, the lateral pinch by 25.0% on average. In 43.0% of the cases development or increase of intraosseous cysts was noticed, most of the patients being free of symptoms. Potential underlying factors were investigated. The silastic material seems not to have had any influence. Only slight advancement of the osteoarthritis was found and in some cases the process was arrested. The prostheses were adequately centered in 77.0%, slightly displaced in 16.0%, and dislocated in 7.0%. Change of intracarpal angles is largely complete by the fifth year. In the majority of cases signs of dorsal instability are obvious. The angle between the scaphoid and lunate is generally increased. The height of the carpus is diminished by 1.7 mm, and the distance between the trapezium and the lunate by 3.7 mm in average. A new score is presented which puts more stress on objective results and the clinical course than on complaints of the patient. Because of the predominantly good results (65%) the prosthetic replacement with a silastic spacer is favoured against other palliative techniques.