Survivorship of Unicompartmental Knee Replacement

Bae, Dae Kyung; Yoon, Kyoung Ho; Ko, Byoung Won; Kim, Yong Chan

Abstract

PURPOSE
To compare the results according to three type of unicondylar prosthesis and analyze the sur- vivorship
MATERIALS AND METHODS
From January 1982 to January 1996, 106 unicompartmental knee arthroplasties were performed. There were 13 Modular II(group I), 47 Microloc(group II) and 46 Allegretto(group III) unicompartmental knee arthroplasties. The average follow up was 11.5 years(range, 4.1 to 18 years). The clinical findings were assessed using the Hospital for Special Surgery (HSS) scoring system. Radiographic measurements were done with Bauer s method. The probability of survival was estimated with use of the Kaplan-Meier survivorship method. ANOVA test was used for statistical analysis.
RESULTS
At the last follow-up, the average HSS knee score was significantly improved from 51 to 90 and average femorotibial angle was corrected from varus 1.5 degrees to valgus 3.5 degrees. Twelve knees were performed revision. The cause of revision was wear in six, loosening in five and one deep infection. The implant type used for the revision was PFC-PS(all from Johnson and Johnson). Bone defects were filled with autogenovs bone graft in six knees and metal wedges were used in two knees. The five year and fourteen year survival rate was 89.7% and 82.5% overally, which matched 100% and 87.5% in group I, 86.0% and 66.3% in group 5 and 90.1% in group g respectively.
CONCLUSION
The average HSS knee score was improved from 51 to 91 points clinically. Among 106 cases twelve knees had total knee arthroplasties and the overall fourteen year survival rate was 82.5%. According to the group, the survival rate was low in group II relatively as 66.3%.