High-fat diet accelerates progression of osteoarthritis after meniscal/ligamentous injury

INTRODUCTION: Increasing obesity and type 2 diabetes, in part due to the high-fat (HF) Western diet, parallels an increased incidence of osteoarthritis (OA). This study was undertaken to establish a causal relation between the HF diet and accelerated OA progression in a mouse model and to determine the relative roles of weight gain and metabolic dysregulation in this progression. METHODS: Five-week-old C57BL/6 mice were placed on HF (60% kcal) or low-fat (lean, 10% kcal) diets for 8 or 12 weeks before transecting the medial collateral ligament and excising a segment of the medial meniscus of the knee to initiate OA. One group was switched from lean to HF diet at the time of surgery. RESULTS: Body weight of mice on the HF diet peaked at 45.9 ± 2.1 g compared with 29.9 ± 1.8 g for lean diets, with only those on the HF becoming diabetic. Severity of OA was greater in HF mice, evidenced by the Osteoarthritis Research Society International (OARSI) histopathology initiative scoring method for mice and articular cartilage thickness and area. To assess the importance of weight gain, short- and long-term HF diets were compared with the lean diet. Short- and long-term HF groups outweighed lean controls by 6.2 g and 20.5 g, respectively. Both HF groups became diabetic, and OA progression, evidenced by increased OARSI score, decreased cartilage thickness, and increased osteophyte diameter, was comparably accelerated relative to those of lean controls. CONCLUSIONS: These results demonstrate that the HF diet accelerates progression of OA in a type 2 diabetic mouse model without correlation to weight gain, suggesting that metabolic dysregulation is a comorbid factor in OA-related cartilage degeneration.