PT - JOURNAL ARTICLE AU - Lianzhi Chen AU - Felix Yao AU - Tao Wang AU - Guangyi Li AU - Peilin Chen AU - Max Bulsara AU - Jessica Jun Yi Zheng AU - Euphemie Landao-Bassonga AU - Marty Firth AU - Praveen Vasantharao AU - Yigang Huang AU - Michelle Lorimer AU - Stephen Graves AU - Junjie Gao AU - Richard Carey-Smith AU - John Papadimitriou AU - Changqing Zhang AU - David Wood AU - Christopher Jones AU - Minghao Zheng TI - Horizontal fissuring at the osteochondral interface: a novel and unique pathological feature in patients with obesity-related osteoarthritis AID - 10.1136/annrheumdis-2020-216942 DP - 2020 Jun 01 TA - Annals of the Rheumatic Diseases PG - 811--818 VI - 79 IP - 6 4099 - http://ard.bmj.com/content/79/6/811.short 4100 - http://ard.bmj.com/content/79/6/811.full SO - Ann Rheum Dis2020 Jun 01; 79 AB - Objectives Obesity is a well-recognised risk factor for osteoarthritis (OA). Our aim is to characterise body mass index (BMI)-associated pathological changes in the osteochondral unit and determine if obesity is the major causal antecedent of early joint replacement in patients with OA.Methods We analysed the correlation between BMI and the age at which patients undergo total knee replacement (TKR) in 41 023 patients from the Australian Orthopaedic Association National Joint Replacement Registry. We then investigated the effect of BMI on pathological changes of the tibia plateau of knee joint in a representative subset of the registry.Results 57.58% of patients in Australia who had TKR were obese. Patients with overweight, obese class I & II or obese class III received a TKR 1.89, 4.48 and 8.08 years earlier than patients with normal weight, respectively. Microscopic examination revealed that horizontal fissuring at the osteochondral interface was the major pathological feature of obesity-related OA. The frequency of horizontal fissure was strongly associated with increased BMI in the predominant compartment. An increase in one unit of BMI (1 kg/m2) increased the odds of horizontal fissures by 14.7%. 84.4% of the horizontal fissures were attributable to obesity. Reduced cartilage degradation and alteration of subchondral bone microstructure were also associated with increased BMI.Conclusions The key pathological feature in OA patients with obesity is horizontal fissuring at the osteochondral unit interface. Obesity is strongly associated with a younger age of first TKR, which may be a result of horizontal fissures.