Unicompartmental knee replacement - An underrated alternative of total knee replacement: A matched comparative study analysing their benefits and risks in local population

Introduction: The demand of knee arthroplasty is increasing worldwide with aging population. Even though unicompartmental knee replacement is associated with fewer complications namely stroke, myocardial infarction, thrombo-embolism, blood transfusion and mortality, it merely comprises 3-% of knee arthroplasties. The aim of the study is to establish the role of unicompartmental knee replacement by evaluating the benefits and risks of unicompartmental knee replacement versus total knee replacement in Hong Kong population. Methods: All unicompartmental knee replacement performed in our institute from 2011 to 2014 were reviewed. Comparative analyses were performed on pre-operative, operative and post-operative parameters. Primary total knee replacement performed in the same period was chosen as control group with 1: 1 matching for age, sex, BMI and pre-operative range of motion. Results: There were 46 unicompartmental knee replacement. It comprises 3.3% of all knee arthroplasties in our institute. The mean follow-up time was 12.8 months (4-38 months). There was no significant difference in all pre-operative parameters except WOMAC score. All operative parameters favored unicompartmental knee replacement significantly (operation time 76 vs 91 minutes; wound size 7.5 vs 12.4 cm; haemoglobin drop 0.75 vs 2.46g/dl, p < 0.05). Early post-operative parameters also favored unicompartmental knee replacement (Deep vein thrombosis rate 4.3 vs 23.9%; length of stay 5.4 vs 7.0 days, p < 0.05). There was no infection or mortality in both groups. Conclusion: Because of less operative risk and faster rehabilitation, this study suggested that unicompartmental knee replacement is more cost effective and might be a better choice for patients with unicompartmental arthritis in local population.