Association of body mass index with knee cartilage damage in an asymptomatic population-based study

Alvin Keng,Savvakis Nicolaou,Ali Guermazi,Joel Singer,Jacek A Kopec,Anona Thorne,Jolanda Cibere,John M Esdaile,Eric C Sayre

doi:10.1186/s12891-017-1884-7

Abstract

BackgroundCartilage changes are an important early finding of osteoarthritis (OA), which can exist even before symptoms. Our objective was to determine the prevalence of knee cartilage damage on magnetic resonance imaging (MRI) in an asymptomatic population-based cross-sectional study and to evaluate the association of body mass index (BMI) with cartilage damage.MethodsSubjects, aged 40-79 years, without knee pain (n = 73) were recruited as a random population sample and assessed for BMI (kg/m2), including current BMI (measured), past BMI at age 25 (self-reported) and change in BMI. Knee cartilage was scored semi-quantitatively (grades 0-4) on MRI. In primary analysis, cartilage damage was defined as ≥2 (at least moderate) and in a secondary analysis as ≥3 (severe). We also conducted a sensitivity analysis by dichotomizing current BMI as <25 vs. ≥25. Logistic regression was used to evaluate the association of each BMI variable with prevalent MRI-detected cartilage damage, adjusted for age and sex.ResultsOf 73 subjects, knee cartilage damage ≥2 and ≥3 was present in 65.4% and 28.7%, respectively. The median current BMI was 26.1, median past BMI 21.6, and median change in BMI was a gain of 2.8. For cartilage damage ≥2, current BMI had a non-statistically significant OR of 1.65 per 5 units (95% CI 0.93-2.92). For cartilage damage ≥3, current BMI showed a trend towards statistical significance with an OR of 1.70 per 5 units (95% CI 0.99-2.92). Past BMI and change in BMI were not significantly associated with cartilage damage. Current BMI ≥ 25 was statistically significantly associated with cartilage damage ≥2 (OR 3.04 (95% CI 1.10-8.42)), but not for ≥3 (OR 2.63 (95% CI 0.86-8.03)).ConclusionsMRI-detected knee cartilage damage was highly prevalent in this asymptomatic population-based cohort. We report a trend towards significance of BMI with cartilage damage severity. Subjects with abnormal current BMI (≥25) had a 3-fold increased odds of cartilage damage ≥2, compared to those with normal BMI. This study lends support towards the role of obesity in the pathogenesis of knee cartilage damage at an asymptomatic stage of disease.

Highlights

Cartilage changes are an important early finding of osteoarthritis (OA), which can exist even before symptoms
Kellgren Lawrence (KL) grade 0 was present in 52.7%, KL grade 1 in 39.8%, while 7.5% had radiographic OA (ROA) (5% KL grade 2 and 2.5% KL grade 3)
Current body mass index (BMI) We report that a 5-unit increase in current BMI had a non-statistically significant 1.7-fold increased odds of magnetic resonance imaging (MRI)-based moderate and severe cartilage damage, there was a trend towards statistical significance

Summary

Introduction

Cartilage changes are an important early finding of osteoarthritis (OA), which can exist even before symptoms. Our objective was to determine the prevalence of knee cartilage damage on magnetic resonance imaging (MRI) in an asymptomatic population-based cross-sectional study and to evaluate the association of body mass index (BMI) with cartilage damage. We previously reported that MRI-based knee cartilage damage was highly prevalent in symptomatic subjects despite absent radiographic changes [1]. For prevention of knee OA to be successful, early recognition and diagnosis of these individuals is critical and a better understanding of risk factors for cartilage damage in asymptomatic individuals is important. Body mass index (BMI) is well-established as a risk factor for the development of symptomatic cartilage damage and OA [9]; fewer studies are available on its relationship to asymptomatic cartilage damage

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