BODY MASS INDEX DOES IT AFFECT THE OUTCOME IN PRIMARY TKA: A PROSPECTIVE 5-YEAR STUDY

Abstract

A consecutive group of 150 patients undergoing primary TKA performed by a single surgeon using single prosthesis were studied prospectively. The purpose of this study was to compare the clinical and radiographic results of TKA in obese and non-obese patients.

The patients were categorized into two groups: non-obese (body mass index (BMI < 30 kg/m2) and obese (BMI > 30 to 40 kg/m2). The Primary outcome measures: SF-12 and WOMAC scores were used as generic outcome measures, and the Knee Society scores were used to assess clinical outcome of TKA. The scores were done pre-operatively and at 1, 3 and 5 years post-operatively. Secondary outcome measures included patellar position, anterior knee pain, infections, revision rates, deep-vein thrombosis and pulmonary embolism, length of hospital stay and mortality.

Seventeen patients have died since and none were lost to follow-up. Obese patients had less benefit and overall KSS outcome scores at one year (p-value 0.05) but had similar scores at 3 and 5 years (p-values 0.3 and 0.5). Pre-operative WOMAC and SF-12 scores were significantly worst in obese patients (p-value 0.009 and 0.005) but had the similar outcome at 1, 3 and 5 years. Three patients in the series required revision surgery for infection. One patient had DVT and another had PE post-operatively.

Overall obese patients although had lower KSS scores at one year but had better outcome in SF-12 and WOMAC scores at one year. There was no difference at 3 and 5 years. We found that body weight did not influence adversely the outcome of TKA at medium term.