Background: Treatment of medial compartmental osteoarthritis with fixed-bearing all-polyethylene unicompartmental knee
arthroplasty has had many positive results in long-term studies, but there have been no reports of survivorship rates among Thais or other Asian people.

Objective: To study long-term (five to ten year) clinical outcomes and survivorship of fixed-bearing all-polyethylene unicompartmental knee arthroplasty among Thai patients.

Materials and Methods: A retrospective study was conducted of survivorship and clinical outcomes of 67 consecutive unicompartmental knee arthroplasties (59 patients) which had been performed during the period July 2000 through February 2010 using cemented all polyethylene. All the patients had isolated unicompartmental disease. One patient died less than 10 years after the operation, and two patients were lost to follow-up, leaving 56 patients (64 knees) in the study with a minimum of five to ten years of follow-up. The average duration of follow-up was 62.6 months (range 60 to 120). Survivorship was analyzed using the Kaplan Meier survivorship curve, and clinical results were analyzed using the Knee Society score and Functional score.

Results: The average age of the patients at the time of their operation was 65 years (range 48 to 83). Forty-eight patients (74.6%) were female and eight (14.28%) were male. Twenty-eight knees (44%) were right side and thirty-six (56.25%) were left side. The average Knee Society and Functional scores at the last follow-up were 98.23 and 96.25, respectively. At that time, the average knee flexion arch was 138.57 degrees. One patient had undergone revision total knee arthroplasty at the seventh year postoperative due to infection. Kaplan-Meier analysis revealed a survival rate of 98.44% at ten years with revision of any reason as the end point.

Conclusion: The excellent survivorship results indicate that the use of cemented fixed-bearing all polyethylene in unicompartmental knee arthroplasty is safe and yields predictable results in the
Thai population.

Keywords: Unicompartmental knee arthroplasty, All-polyethylene tibial component