THE INFLUENCE OF BODY MASS INDEX ON MICROSTRUCTURAL AND PATHOLOGICAL CHANGES IN OSTEOCHONDRAL UNIT OF OSTEOARTHRITIC TIBIA PLATEAUS

Osteoarthritis (OA) is traditionally believed to affect the osteochondral unit by wear-and-tear from the superficial zone to the deep zone of cartilage and extended to subchondral plate. Obesity is commonly considered as a risk of OA development and hence total knee replacement (TKR), but the mechanism remains unclear. We hypothesized that obesity accelerated OA development by deteriorating tidemarks and increasing bone remodelling. 616,495 cases of TKR for OA from Australia and British joint replacement registries were collected, and data indicated that patients with higher BMI had TKR at earlier age. Specifically, patients with BMI ≤25kg/m2 showed 8 years younger than patients with BMI ≥40kg/m2 (P<0.0001) when they received TKR. We next examined tibia plateaus of 88 knee OA patients by micro-CT and histomorphometry. Linear regression showed that less cartilage degradation was associated with increased BMI in the load-bear compartment (p<0.05), while 58.3% of patients with BMI≥40kg/m2 demonstrated a clea...