Long-Term Results of Medial Unicompartmental Knee Arthroplasty for Knee Avascular Necrosis

Abstract : Background : Numerous series have documented short and Mid-term successes with cemented, Metal-Backed modern unicompartmental knee arthroplasty (UKA) for avascular osteonecrosis of the knee (AVN). However data are lacking regarding long-term implant fixation and patient function. The aim of this study was therefore to evaluate the long term clinical outcome and implant survivorship of patients that underwent UKA for medial knee osteonecrosis. Methods: 29 consecutive UKA performed by two senior surgeons (>50 UKA a year) in 28 patients (19 38 women and 9 men with a mean age of 67 years) with medial unicompartmental AVN of the knee between 1989 and 2001 were retrospectively reviewed. AVN was diagnosed using x-ray, MRI scan and finally confirmed by postoperative sample analysis . The mean patient body mass index was 27kg/m2. Etiologies were spontaneous/idiopathic AVN in 19 knees (66%) and secondary AVN in 10 knees (33%). The Mean follow-up was 21 years (15 to 26). Results: At 15 years survivorship of the components free of revision for any cause was 92% (95% CI 47 87 to 97). At latest follow-up, 26 years, survivorship of the components free of revision for any reason was 83 % (95% CI 74 to 95). No survivorship difference was found between the patients suffering from spontaneous or secondary ON of the knee (83% vs 90%, p=0.6). At latest follow-up the mean knee KSS was 89 points (range 68-100) and 83 ( range 66-96) for function KSS