Long-term results after silicone prosthesis replacement of the proximal pole of the scaphoid bone in advanced scaphoid nonunion.

The treatment of scaphoid fracture nonunion with a small proximal fragment with disturbed circulation and radioscaphoid arthrosis is difficult, and the result is often unsatisfactory. For this reason, in 1981 the replacement of the proximal fragment by a silicone lunate prosthesis was recommended for such cases. From 1980 to 1984, 11 patients (all male, average age 42 [range, 25-59] years) with the conditions described above were treated by silicone prosthesis partial replacement of the scaphoid. In one patient, the prosthesis had to be removed due to dislocation, and in another patient an arthrodesis of the wrist had to be carried out after 5 years due to increasing pain. All nine remaining patients were followed up after an average of 14 (range, 12-16) years, and were clinically and radiologically re-examined and assessed wing the evaluation scheme proposed by Martini (1999). The overall results were satisfactory. Specifically, the outcome was good in one case, satisfactory in six cases, and poor in two cases. Concerning the individual criteria, the best scores were observed in "subjective overall assessment" and in "work and sports", whilst the worst were found in "movement" ad "X-ray". For all patients, X-ray examination revealed both postoperative arthrosis and extensive multiple cystoid osteolysis, presumably due to silicone synovitis. Nevertheless, most patients were free of symptoms. None of the patients felt that further treatment was necessary. Silicone prosthesis partial replacement of the scaphoid leads to long-term reduction in pain and adequate hand function. However, it is not capable of preventing carpal collapse and carpal arthrosis. Furthermore, since in several cases a progressive silicone synovitis developed, the method was rightly abandoned after 1984.