Unicompartmental knee replacement provides early clinical and functional improvement stabilizing over time

Purpose: Unicompartmental knee replacement preserves uninvolved osteocartilaginous and soft tissue structures, thereby allowing a more physiological and early clinical and functional recovery. The aim of this study was to report the results of ZUK unicompartmental fixed metal-back prosthesis and how these results change over time. Methods: Between 2005 and 2007, 80 ZUK prostheses were implanted in 80 patients for unicompartmental osteoarthritis or osteonecrosis. Patients were clinically assessed using the International Knee Society scores. Postoperative values of mechanical axis were calculated 12 months after surgery and compared to the preoperative ones. Results: The mean International Knee Society knee and function scores improved, respectively, from 46 ± 9 and 54 ± 8 preoperatively to 82 ± 5 and 94 ± 3 at the last follow-up (P < 0.001). Average flexion increased from 110° ± 9° to 127° ± 8° (P < 0.01). Patients with unicompartmental knee reached good clinical outcome very early and remained at the same level. Age did not significantly influence clinical and functional scores. Conclusions: High success rates of the modern unicompartmental knee implants depend on the materials and design evolution, improvement of the surgical technique, and the strong restriction of indications. Level of evidence: Prospective non-randomized case-series study, Level IV. © 2011 Springer-Verlag.