EARLY FAILURE OF UNICOMPARTMENTAL KNEE REPLACEMENT (UKR): THE EFFECT OF AGE AND BODY MASS INDEX, AN ANALYSIS OF 10,104 CASES WITH MINIMUM 2 YEAR FOLLOW-UP

Background There are different opinions amongst surgeons as to the selection criteria for UKR with regards to age and BMI. Many surgeons perceive higher rates of failure in young or overweight patients or often choose TKR for elderly patients. Methods We analysed the registry records (UK National Joint Registry) of 10,104 patients who had undergone UKR with a minimum of two years follow-up from their primary surgery. BMI data was recorded in 1,831 (18%) and age in all. There were 295 deaths and these patients were excluded from our analysis. Patients9 BMI were categorised according to Department of Health and WHO (2004) classification (Normal, Pre-Obese, Obese I, Obese II, Obese III) Results For the 1,831 patients with BMI data recorded, 4.74% had been revised at a mean 3 years post-primary UKR. BMI Category had no significant effect on revision rates. Age less than 50 was a predictor of a significantly higher rate of revision: 35 out of 488 primary UKRs (7%) compared with 138 out of 2,618 (5.5%) in 50-59 year age group, 154 out of 3,810 (4.1%) in 60-69 year age group and 85 out of 2,505 (3.6%) in 70-79 year age group. Revision rates were lowest in patients with age greater than 80 years: 14 out of 562 (2.49%). Conclusion UKR should be recommended with caution in patients with age less than 50. Revision rate decreases significantly with age. BMI Category was found to have no significant correlation with early failure.