The use of structural allograft for uncontained defects in revision total knee arthroplasty - A minimum five-year review

Background: To our knowledge, the medium to long-term outcome after revisio n knee arthroplasty with structural allograft augmentation for reconstructi on of uncontained defects has not been determined. The purpose of the prese nt study was to assess the outcome for patients managed with such a procedu re. Methods: We prospectively followed fifty patients who had fifty-two revisio n knee replacements with sixty-six structural grafts performed at three ins titutions. Twenty-nine knees (twenty-seven patients) were independently eva luated at a mean of 96.9 months (range, sixty to 189 months) by an investig ator who had not been involved in the index procedure. Twelve knees (23%) h ad a repeat revision at a mean of 70.7 months (range, twenty-six to 157 mon ths). The allograft was retained in two of these patients. Eleven patients died at a mean of ninety-three months (range, sixty-one to 128 months) afte r the procedure; the structural allograft and implants were intact, and the patients were not awaiting revision at the time of death. Results: Clinical evaluation revealed that the mean modified Hospital for S pecial Surgery knee score had improved from 32.5 points preoperatively to 7 5.6 points at the time of the review and the mean range of motion had incre ased from 60.5 degrees preoperatively to 88.6 degrees. Failure was defined as an increase of less than 20 points in the modified Hospital for Special Surgery knee score at the time of the review or the need for an additional operation related to the allograft. Thirteen knee replacements failed, yiel ding a 75% success rate. Five knees had graft resorption, resulting in impl ant loosening. Four knee replacements failed because of infection, and two knees had nonunion between the host bone and the allograft. Two knees (one patient) did not have a 20-point improvement in the knee score. The surviva l rate of the allografts was 72% (95% confidence interval, 69% to 75%) at t en years. On radiographic analysis, none of the surviving grafts had severe resorption, one had moderate resorption, and two had mild resorption. One knee had a loose tibial component, and three knees had nonprogressive tibia l radiolucent lines. All four knees were asymptomatic. Conclusions: Our results demonstrate that allografts used in revision knee replacement in patients with the difficult problem of massive bone loss hav e an encouraging medium-term rate of survival.