Mid-Term Results of Oxford Medial Unicompartmental Knee Arthroplasty in Young Asian Patients Less than 60 Years of Age: A Minimum 5-Year Follow-up

Abstract

Purpose: The purpose of this study was to evaluate the efficacy of unicompartmental knee arthroplasty (UKA) in young active Asian patients by analyzing clinical outcomes, complications and survival rates.

Materials and methods: Eighty-two knees were evaluated with a minimum follow-up of 5 years after Oxford phase 3 UKA in patients less than 60 years of age at the time of surgery. Their mean age was 54.7 years (range, 44 to 59 years). The mean follow-up period was 8.9 years (range, 5.3 to 12 years). Kaplan-Meier survivorship analysis was used to estimate implant survival.

Results: Including 3 bearing dislocations, 1 medial tibial collapse and 1 lateral osteoarthritis, the total complication rate was 6.1% (5/82). Of the 3 cases of bearing dislocation, 2 cases were resolved by replacing with a thicker bearing and 1 case was converted to total knee arthroplasty (TKA) due to repeated dislocation. The two knees with a medial tibial collapse and a lateral osteoarthritis were converted to TKA. The 10-year cumulative survival rate using Kaplan-Meier survival method was 94.7% (95% confidence interval: 88.7%-100%).

Conclusions: Oxford medial UKA was reliable and effective in young active Asian patients providing good clinical results and survival rate in the mid-term follow-up.

Keywords: Arthroplasty; Asian; Knee; Mobile bearing; Osteoarthritis; Unicompartmental; Young age.

Fig. 1

(A) A 59-year-old female underwent Oxford medial unicompartmental knee arthroplasty 10 years ago. (B) Posterior dislocation of the meniscal bearing occurred 3 months after the operation. (C) She remained pain-free and obtained normal function of the left knee 9.8 years after bearing exchange.

Fig. 2

(A) Medial tibial collapse of a 60-year-old female with a prior history of Oxford medial unicompartmental knee arthroplasty (7 years before the incident). (B) Conversion to total knee arthroplasty was performed with a metal block and a long tibial stem.

Fig. 3

(A) Progressive lateral osteoarthritis of a 65-year-old female with a previous history of Oxford medial unicompartmental knee arthroplasty (9.5 years previously). (B) Conversion to total knee arthroplasty was performed with a metal block and a long tibial stem.

Fig. 4

Kaplan-Meier survivorship curve with conversion to total knee arthroplasty as the endpoint. The cumulative survival rate is 94.7% at 10 years (95% confidence interval: 88.7%–100.0%).