Evaluation of the Noiles hinged knee prosthesis. A five-year study of seventeen knees.

The Noiles hinged knee prosthesis has been reported to diminish sheer and tensile loading on the cement-bone interface. Theoretically, this should eliminate the complication of loosening, commonly reported in hinged total knee prostheses. We reviewed the cases of all of the patients who have been treated with the Noiles knee prosthesis at our institution. Eighteen knees in fourteen patients were available, seventeen of which were followed for more than five years. Although all of the prostheses did well initially, ten knees in eight patients (56 per cent) had failed by an average of thirty-two months postoperatively. These eight patients included four of the five who weighed more than ninety kilograms and all of those who had had a prior arthroplasty. The failures were clearly defined along the lines of sex distribution. Measurements on the radiographs showed a significant difference between sexes in the metaphyseal diameter and thus in the percentage of the femoral canal that was filled by the prosthesis and cement. We concluded that prosthetic design must incorporate cortical cement support to reduce stress at the cement-bone interface, especially in a medullary canal with a larger diameter.