Background Obesity is an important risk factor for knee osteoarthritis (OA), Weight loss can reduce the symptoms of knee OA. No prospective studies assessing the impact of weight loss on knee cartilage structure and composition have been performed. Objectives To assess the impact of weight loss on knee cartilage thickness and composition. Methods 111 obese adults were recruited from either laparoscopic adjustable gastric banding or exercise and diet weight loss programmes from two tertiary centres. MRI was performed at baseline and 12-month follow-up to assess cartilage thickness. 78 eligible subjects also underwent delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), an estimate of proteoglycan content. The associations between cartilage outcomes (cartilage thickness and dGEMRIC index) and weight loss were adjusted for age, gender, body mass index (BMI) and presence of clinical knee OA. Results Mean age was 51.7±11.8 years and mean BMI was 36.6±5.8 kg/m 2 ; 32% had clinical knee OA. Mean weight loss was 9.3±11.9%. Percentage weight loss was negatively associated with cartilage thickness loss in the medial femoral compartment in multiple regression analysis (β=0.006, r 2 =0.19, p=0.029). This association was not detected in the lateral compartment (r 2 =0.12, p=0.745). Percentage weight loss was associated with an increase in medial dGEMRIC in multiple regression analysis (β=3.9, r 2 =0.26; p=0.008) but not the lateral compartment (r 2 =0.14, p=0.34). For every 10% weight loss there was a gain in the medial dGEMRIC index of 39 ms (r 2 =0.28; p=0.014). The lowest weight loss cut-off associated with reduced medial femoral cartilage thickness loss and improved medial dGEMRIC index was 7%. Conclusions Weight loss is associated with improvements in the quality (increased proteoglycan content) and quantity (reduced cartilage thickness losses) of medial articular cartilage. This was not observed in the lateral compartment. This could ultimately lead to a reduced need for total joint replacements and is thus a fi nding with important public health implications.

No abstract

The aim of this study was to determine health‐related quality of life and fatigue measures in obese subjects and to compare scores with age‐ and gender‐matched population norms. A total of 163 obese subjects were recruited from laparoscopic‐adjustable gastric banding or exercise and diet weight loss programs between March 2006 and December 2007. All subjects completed the Medical Outcomes Study Short Form 36 (SF‐36), Assessment of Quality of Life (AQoL), and Multidimensional Assessment of Fatigue (MAF) questionnaires. One‐sample t‐tests were used to compare transformed scores with age‐ and gender‐matched population norms and controls. Obese subjects have significantly lower SF‐36 physical and emotional component scores, significantly lower AQoL utility scores and significantly higher fatigue scores compared to age‐matched population norms. Within the study cohort, the SF‐36 physical functioning, role physical and bodily pain scores, and AQoL utility index were even lower in subjects with clinical knee osteoarthritis (OA). However, obese individuals without OA still had significantly lower scores compared to population norms. Obesity is associated with impaired health‐related quality of life and disability as measured by the SF‐36, AQoL, and fatigue score (MAF) compared to matched population norms.

Knee cartilage defects increase with increasing obesity and are associated with both objective and self-reported measures of physical disability. Longitudinal studies are required to assess the potential for change or improvement in cartilage defects with weight loss.