Obesity increases the prevalence and severity of focal knee abnormalities diagnosed using 3T MRI in middle-aged subjects—data from the Osteoarthritis Initiative

Abstract

Objective To study the effect of BMI on the prevalence, severity, and 36-month progression of early degenerative changes in the knee by using 3T MRI in middle-aged subjects without radiographic osteoarthritis (OA). Materials and methods We examined baseline and 36-month follow-up MR studies from 137 middle-aged individuals (45–55 years old) with risk factors for knee OA but no radiographic OA from the Osteoarthritis Initiative. Subjects were grouped into three categories: normal BMI (BMI<25 kg/m2, n=38), overweight (BMI 25–29.9 kg/m2, n=37), and obese (BMI ≥ 30 kg/m2, n=62). Using 3T MRI, cartilage, meniscus, and bone marrow abnormalities were graded using the OA Whole-organ MR Imaging Score (WORMS). The statistical analysis was corrected as necessary for differences in age, sex, and OA risk factors other than BMI. Results The overall prevalence of lesions was 64% for meniscus and 79% for cartilage (including low grade lesions). At baseline, the prevalence and severity of knee lesions was positively associated with BMI, with a nearly fourfold increase in meniscal tears and more than twofold increase in high-grade cartilage defects in obese individuals relative to normal-weight subjects. Over the 36-month follow-up period, the number of new or worsening cartilage lesions of any grade was significantly higher in obese subjects (p=0.039), while there was no significant difference in meniscal lesion progression. Conclusion Obesity was associated with both higher prevalence and severity of early degenerative changes in the knee in middle-aged individuals without radiographic OA and with significantly increased cartilage lesion progression (of any grade) over 36 months.

Risk Factors for Meniscal Tears: A Systematic Review Including Meta-analysis

“…5 In another study included in the present systematic review, individuals with a BMI greater than 25 kg/m 2 had an increased risk for meniscal tears compared to those with a BMI less than 25 kg/m 2 (OR = 1.43). 20 Laberge et al 35 found significantly greater prevalence rates of meniscal tears (76% and 74%, respectively) in individuals who were overweight (BMI 25-30 kg/m 2 ) or obese (BMI greater than 30 kg/m 2 ), compared to 34% in individuals with a BMI less than 25 kg/ m 2 (P = .03). The higher risk reported by Laberge et al 35 could be explained by the fact that their population was older (45-55 years of age) and, therefore, already had a higher risk for degenerative meniscal tears.…”

Knee osteoarthritis, body mass index and pain: data from the Osteoarthritis Initiative

“…BMI is divided into the following categories: underweight, < 18.5; normal, 18.524.9; overweight, 25.029.9; obese, > 30.0. BMI is the variable most frequently used to assess the effects of excess weight on knee OA [9,11,13]. Pain was assessed through the WOMAC pain subset.…”

“…Only individuals with a WOMAC pain score of 5 1 were included in statistical tests where WOMAC pain was the pain variable utilized. Multiple studies examining pain use the WOMAC scale [6,13]. The WOMAC pain scale asks about the severity of pain in the last 7 days when the patient engaged in the following activities: walking, going up or down stairs, laying or sitting and standing.…”

“…Covariates that were accounted for include age, whether the patient currently smokes, prior injury that resulted in the inability to walk for more than 1 week and Heberden's nodes; these are common covariates in clinical research [6,9,13,15]. Additional covariates included preventive pain treatments consisting of glucosamine, chondroitin sulphate, cortisone injections and hyaluronic acid injections.…”

“…Over time there has been an increase in knee replacements and in pain, but evidence of an increase in osteological OA severity is unclear [2]. Thus some researchers have assessed the effects of excess weight on OA by analysing self-reported surveys; studies using pain surveys reveal correlations with increased BMI and pain [6,13]. Yet, the clinical literature has unresolved questions regarding pain tolerance in obese individuals [14].…”