Total knee-replacement arthroplasty. Results with the intramedullary adjustable total knee prosthesis

Abstract

One hundred and thirty knees (112 patients) in which the intramedullary adjustable total knee prosthesis was inserted were followed for four to nine years. This prosthesis is designed to permit unconstrained rotation and includes a metal tray supporting the high-density-polyethylene tibial component as well as an intramedullary stem and two condylar intramedullary projections on both the femoral component and the tibial component. Using a rating system in which pain, function, stability, and motion each was graded independently on a scale of 1 to 6, the preoperative scores were 73 per cent poor and 27 per cent fair, while the postoperative scores were 77 per cent good, 15 per cent fair, and 8 per cent poor. If only the patients with unilateral or bilateral involvement of the knee without other functional disabilities were considered, four to nine years after the arthroplasty 92 per cent could be classified as good; 5 per cent, as fair; and 3 per cent, as poor. There were two deaths (one due to pulmonary embolism and the other, to overwhelming sepsis after attempted arthrodesis for a deep would infection) and five deep infections, four of which necessitated reoperation for arthrodesis. In addition, reoperations were necessary in five other knees: in two for secondary closure of the wound, in one for evacuation of a hematoma, in one for synovectomy and skin-grafting because of infection, and in one for recentralization of the patella. At final evaluation, 117 knees had radiographs of sufficiently good quality for assessment, and thirty-seven (32 per cent) of these showed evidence of a nonprogressive radiolucent line about the tibial component. In addition, two were considered clinically loose (one due to a traumatic injury and the other, to malpositioning of the tibial component).