Early Clinical and Functional Outcome of Primary Total Knee Replacement with Posterior Cruciate Substituting Prosthesis for Primary Knee Osteoarthritis Using 2011 Knee Society Score

Abstract

Background: Primary knee Osteoarthritis (OA) is the commonest articular disease in middle age and elderly people. Primary total knee replacement (TKR) is a known world-wide standard and definitive treatment of primary knee OA following failed adequate non-operative management. It is of clinical importance to assess the clinical and functional outcome of TKR to prognosticate the severity of primary knee OA. The new (2011) knee society scoring system (nKSS) is both surgeons and patients’ assessment tool for the treatment outcome of TKR. Study Design: Prospective interventional analytical study. Aim and Objective: The aim of the study was to determine early clinical and functional outcome of primary total knee replacement in patients with primary knee osteoarthritis using nKSS. The objectives were: 1) To determine the pre-operative nKSS and post operative nKSS; 2) To determine relationships between pre-operative nKSS and post operative nKSS at 6 weeks, 3, 6, 9 and 12 months; 3) To determine the complication rates in patients undergoing primary TKR in the study centre. Methods: A prospective interventional study of 59 patients aged 51 to 70 years who had 67 Total Knee Replacements (TKRs) participated in the study between November 2015 to June 2018 at National Orthopaedics Hospital, Lagos, Nigeria. Patients’ sociodemographic data, pre-operative and post-operative nKSS system were recorded at 6 weeks, 3, 6, 9 and 12 months during follow up. The data were analyzed using Statistical Package for Social Science (SPSS). Results: There were 41 females and 18 males (M:F = 1:2.3). There were total of 67 TKRs with 31 right TKRs, 20 left TKRs and 8 staged bilateral TKRs. The participants’ age ranged from 51 to 70 years with the mean age of 59.5 (±8.5) years. Four patients did not complete the study due to various reasons. The remaining 55 participants completed the study period with progressive improvement of their post-operative nKSS at 6 weeks, 3, 6, 9 and 12 months post-operatively when compared with pre-operative nKSS (P value < 0.05). All the patients studied had improved post-operative nKSS with a faster rate of improvement in those with lower pre-operative nKSS. However, One-way Analysis of Variance (ANOVA) showed no statistical significant relationship between the lower pre-operative nKSS and post-operative nKSS on follow up (P value > 0.5). Conclusion: This study revealed improved early clinical and functional outcome of primary total knee replacement in primary knee osteoarthritis using nKSS in all the studied patients. There is no significant negative effect of lower pre-operative nKSS (and its components) on the post-operative nKSS outcome.