Presentation Abstract

Session: 421-435-Adult Reconstruction Knee V
Date/Time: Thursday, Mar 21, 2013, 3:18 PM - 3:24 PM
Location McCormick Place, Room N427
Presentation Number: Paper 435
Title: Outcome of Total Knee Arthroplasty in Obese Patients
Classification: +Primary TKA (Knee)
Keywords: Total Knee Arthroplasty General Outcome; Total Knee Arthroplasty Complications; Total Knee Arthroplasty Results
Author(s): Chin Tat Lim, MBBS, Singapore, Singapore
Bernard Lau, MBBS, Singapore, Singapore
Li Heng Hee, MBBS, SINGAPORE, Singapore
Krishna Lingaraj, MBBS, Singapore, Singapore
Abstract: INTRODUCTION: Total knee arthroplasty (TKA) has been associated with excellent survival and functional results. However, TKA in obesity has been associated with increased complications with lower clinical function scores. This prospective observational study aims to: I. Explore the differences between obese and non-obese patients at baseline prior to total knee arthroplasty; II. Compare objective and subjective clinical outcomes in both groups of patients after total knee arthroplasty; III. Identify key aspects in the management of the obese patient so that the outcome of surgery can be optimized.
METHODS: We prospectively analyzed all consecutive patients who underwent total knee arthroplasty in a tertiary university center from December 2008 to April 2010. The patients were grouped according to their pre-operative body mass index (BMI) as follows: non-obese (BMI < 30 kg/m2) and obese (BMI ≥ 30 kg/m2). Demographic variables of age, gender and comorbidity were retrieved. Preoperative and two-year postoperative Western Ontario McMaster University Osteoarthritis Index (WOMAC) score, Knee Society Score, Short Form 36, patient satisfactory survey and range of movement were compared across patients. Linear regression models were constructed to assess the independent effects of the various risk factors including obesity on absolute changes in the WOMAC, KSS and SF 36 scores.
RESULTS: There were a total of 301 patients with 77 obese patients and 224 non-obese patients. There were no significant differences in age, side of operation, diagnosis, pre-op alignment, diabetes mellitus, stroke and ischaemic heart disease between the obese and non-obese groups. There was however significantly higher proportion of hypertensives (79.2 vs. 58, p = 0.001) and female (80.5 vs. 66.5, p=0.021) aligned knees in the obese population. Both obese and non-obese groups obtained statistically significant improvements in clinical scorings and range of movement post-operatively (P<0.001). Pre-operative SF36PCS, SF36MCS, KSS Function, KSS Knee, range of movement and maximum extension similar between obese and non-obese patients. The non-obese group has significantly superior pre-operative WOMAC and maximum flexion (p < 0.05). This superior maximum flexion in non-obese group is maintained post-operatively, but the WOMAC is similar between the two groups post-operatively. Post-operatively, the non-obese group also attained superior range of movement (p=0.024) while obese group achieved superior SF36MCS scores (p=0.017). There was significantly more improvement in the obese group in WOMAC score (p = 0.011). Absolute improvements in SF36, KSS Knee score, WOMAC score and range of movement were not significant. There was no statistical significant difference in operative parameters such as patellar management, surgical time and blood loss. There is however statistical significant longer tourniquet time in obese than non-obese patients (p=0.029). There was also no difference in the rate of deep vein thrombosis (DVT) in the two groups of patients. Linear regression analysis taking into account patient characteristics of age, gender, co-morbidities) and corresponding preoperative WOMAC, preoperative flexion and preoperative dependent parameter continue to show obesity as an independent predictor for abolute improvements in SF36MCS.

CONCLUSION: Total knee arthroplasty is a safe and efficacious operation in obese patients with no significantly greater risk of complications. Post-operative clinical scores and absolute improvement in the scores are similar between obese and non-obese patients at two-year follow up.
Disclosures: Presenting Author
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