Two patients who were dissatisfied with the functional results of knee fusion had conversion to total knee arthroplasty at one and 16 years following previously solid fusion. Both patients were over 65 years of age. Unconstrained prosthetic components were used and no special soft tissue stabilizing procedures were needed. At follow-up examinations, five and one-half and three years postoperatively, the results have been gratifying with good stability and adequate range of motion from 0 degrees to 90 degrees of flexion. Both patients were able to walk and climb stairs without support. The patients claimed that quality of function was significantly improved. Whenever possible, fusion of the knee in young people should be done so that this option remains open in later life. Arthrodesis is advised in young patients to allow for possibility of revision to total knee arthroplasty at a later date as technology improves.