Is unicondylar osteoarticular allograft still a viable option for reconstructions around the knee?

Background: Unicondylar osteoarticular allografts (UOAs) represent a possible technique for reconstructing massive bone defects around the knee when only one condyle is affected. The aim of this retrospective study is to evaluate the outcome of UOAs and describe the possible salvage procedures in case of graft failure. Methods: Twenty-five deep-frozen UOAs were implanted at Rizzoli Orthopedic Institute (Bologna, Italy). Twenty-two followed bone tumor resection, two cases were post-traumatic defects and one case followed UOA failure.Mean age at surgery was 33. years (range: 15 to 63). Eighteen UOAs were in distal femur, seven in proximal tibia. Results: Three patients died (only one because of the tumor). One UOA was removed for chondrosarcoma relapse and one for allograft fracture. Mean overall survival with UOA failure as a primary endpoint was 129. months (range 12 to 302), with differences in the femur (85%) and in the tibia (40%) at 150. months. Six UOAs had to be converted into knee prostheses due to osteoarthritis after a mean follow-up of 146. months. No complications were recorded in UOAs converted into knee prostheses after a mean three year follow-up. Fourteen patients with UOAs still in place at the last follow-up (mean 123. months) were radiologically and functionally evaluated: no correlation was found between function and the degree of osteoarthritis. Conclusions: In selected cases, UOAs offer good clinical results and postpone the need for knee prosthesis. Despite short-term encouraging results, longer-term follow-up is needed in order to evaluate the outcome of knee prosthesis after UOA.