Occupation and enviroment Mr callus lives on a deer farm it was found in a study that symptomatic OA was significant more prevalent in rural populations when compared to urban populations https

Occupation and enviroment
Mr callus lives on a deer farm it was found in a study that symptomatic OA was significant more prevalent in rural populations when compared to urban populations https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.1790080407. Additionally, assuming Mr Claus was physically able when he became a farmer, it is reasonable to believe that due to the nature of their work, he would’ve spent a large portion of time squatting down and keeling. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3766936/.Study showed that occupations involving squatting or kneeling more than two hours daily were associated with two-fold significantly increased risk of moderate to severe radiographic knee OA
Diabetic and obesity
Mr Claus is a type 2 diabetic, which he manages this solely through his diet. Previous studies have shown a link between the osteoarthritis and type 2 diabetes. However, it is currently unclear if the high prevalence of osteoarthritis in diabetic patients may be due to excess weight of patients with type 2 diabetes or if there is an independent association between the two conditions.
A study… shows that the risk for osteoarthritis is elevated in the diabetic population, however the mechanisms behind how diabetes accelerates the deterioration of the cartilage remains largely unknown. As OA and type 2 diabetes share common risk factors, the independent contribution of T2D on OA is difficult to study. Nonetheless, recent studies have demonstrated an independent association between T2DM status and OA.5,52 Results of a 20-year longitudinal cohort study of 927 individuals suggest that T2DM predicts both joint failure and hip and knee arthroplasty surgery, independently of age, sex, and BMI. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4254543/
Being overweight also may have increased Mr Claus risk of developing osteoarthritis. Increased weight will place larger stress on his joints on weight bearing joints which has shown to affect cartilage wear. Excess body weight has also been associated with misalignment of weight bearing joints (particularly the knee joint), which increases joint stress and promotes cartilage degradation that leads to OA. Moreover, obesity has been linked to decreased strength in muscles necessary for joint stabilisation and therefore decrease ability to sustained mechanical joint stress. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4254543/

ACL injury in past + Previous involvement in high impact sports
It has been found that any sporting activities can lead to knee OA, but the likelihood of it occurring depends on the intensity, frequency and level of involvement in the sport. Moderate exercise has a low risk level, but sports that include high intensity and direct joint impact from contact with other participants increase risk. It is therefore unclear whether Mr Claus’s involvement in rugby, cricket and skiing could’ve predisposed him to knee osteoarthritis. More importantly, the article states that athletes who have previously injured their ACL (isolated or combined with injury to meniscus or collateral ligaments), such as Mr Claus did, showed the first radiologic signs (joint space narrowing) of osteoarthritis (OA) at an average age of about 40 years. https://www.sciencedirect.com/science/article/pii/S1063458405800172
Although Mr Claus is only 52, a study showed that the prevalence of symptomatic knee osteoarthritis increases rapidly starting at age 45 and continues to increase thereafter. A key reason why the prevalence of osteoarthritis increases with age is because with age the knee joints experience “wear and tear” due to mechanical loading of the joints over the years, which in turn results in degradation of the articular cartilage within the joint complex. The study also revealed there was a link between the pathological changes that occur with age and osteoarthritis