Osteoarthritis affects over 450 million people worldwide, and certain groups face a significantly higher chance of developing it. Age is the single strongest predictor, but weight, genetics, occupation, prior injuries, sex, and metabolic health all play measurable roles. Most of these risk factors overlap, meaning the more you have, the greater your cumulative risk.
Age Is the Strongest Risk Factor
Osteoarthritis is overwhelmingly a condition of middle age and beyond. Eighty-eight percent of people with OA are 45 or older, and 43% are 65 or older. The annual rate of new knee OA diagnoses peaks between ages 55 and 64. That doesn’t mean younger people are immune, especially if they carry other risk factors like a history of joint injury or obesity. But age-related cartilage wear, reduced ability of joint tissue to repair itself, and decades of cumulative stress on weight-bearing joints make aging the most consistent driver.
Excess Weight and Joint Stress
Carrying extra body weight dramatically increases the load on your knees and hips with every step. Research from Johns Hopkins found that for a woman of average height, losing just 11 pounds (roughly 2 BMI points) cut the risk of knee OA by more than 50%. Gaining that same amount raised the risk by about 28%.
The population-level numbers are striking. If men with obesity lost enough weight to move into the overweight category, and overweight men reached a normal weight, knee OA cases in men would drop by 21.5%. The same shifts in women would reduce knee OA by 33%. These figures reflect the knees specifically, where every extra pound translates to roughly three to four pounds of force during walking. But weight also raises OA risk in non-weight-bearing joints like the hands, which points to a second mechanism: metabolic inflammation.
Women Face Higher Risk, Especially After Menopause
Women develop osteoarthritis more often than men, particularly in the knees and hands. Several factors contribute: differences in joint biomechanics, inflammatory responses, pain perception, and hormonal shifts. The most significant inflection point is menopause. OA risk rises sharply after menopause, and the leading explanation is that declining estrogen levels accelerate cartilage breakdown. Estrogen appears to have a protective effect on joint tissue, so its loss removes a buffer against degeneration. This sex disparity is one of the most consistent findings in OA research, yet most OA studies have historically been conducted on male participants.
Genetics Account for Over Half the Risk
If your parents or siblings have osteoarthritis, your own risk is substantially higher. Heritability estimates for OA exceed 50% at most joint sites, meaning more than half of the variation in who gets OA can be traced to genetic factors. Researchers have identified several genes involved in cartilage structure, bone growth, and inflammatory signaling that contribute to susceptibility. You can’t change your genetics, but knowing your family history helps you focus on the risk factors you can control, like weight and joint protection.
Previous Joint Injuries
A serious joint injury, particularly a torn ACL, meniscus tear, or fracture that extends into a joint surface, sets the stage for what’s called post-traumatic osteoarthritis. Within 15 years of an ACL injury, up to 41% of people show radiographic signs of OA in that knee. Surgical repair reduces some risk but does not eliminate it. The initial trauma alters the joint’s biology and mechanics in ways that persist long after the injury heals. This is why OA sometimes appears in relatively young adults: a football injury at 20 can produce a worn-out knee by 35.
Physically Demanding Occupations
Jobs that involve repetitive kneeling, squatting, heavy lifting, or prolonged standing significantly raise knee OA risk. A large meta-analysis found the following increased odds compared to sedentary workers:
- Floor layers, bricklayers, and carpenters: roughly 2.5 times the risk
- Agricultural and forestry workers: about 1.9 times the risk
- Farmers specifically: 1.6 times the risk
- Metal workers: 1.85 times the risk
- Construction workers broadly: 1.6 times the risk
- Cleaners and service workers: 1.5 to 1.8 times the risk
- Miners: about 1.5 times the risk
Even housework, when it involves sustained physical labor over many years, was associated with nearly double the odds. The common thread is repetitive mechanical loading on the knee joint over long periods.
Sports and Physical Activity
Moderate recreational exercise, including running, is not a consistent risk factor for knee or hip OA. That’s a reassuring finding for people who worry that jogging will ruin their joints. The picture changes at the elite level. Former professional athletes show higher rates of radiographic OA than non-athletes, with the risk concentrated in team sports like soccer and in power sports rather than endurance activities. The key variable appears to be injury. Sports with high collision and pivoting demands cause more joint injuries, and those injuries are what ultimately drive OA development. Interestingly, former elite athletes report similar levels of clinical OA symptoms and often less hip and knee disability than the general population, possibly because of better muscle conditioning and overall fitness.
Joint Alignment
The natural angle of your leg bones affects how forces distribute across your knee. Bowlegged alignment (varus) concentrates stress on the inner knee, while knock-kneed alignment (valgus) loads the outer knee. In people who already have mild OA, bowlegged alignment increases the odds of disease progression in the inner knee by about fourfold. In moderate OA, either type of malalignment increases progression risk roughly tenfold. Alignment issues can be inherited, can develop after a fracture, or can worsen as OA itself changes the joint. Bracing and wedge insoles can help redistribute forces, and alignment is a major consideration when surgeons plan joint replacement.
Type 2 Diabetes and Metabolic Health
Osteoarthritis has traditionally been viewed as a “wear and tear” disease, but growing evidence links it to metabolic dysfunction. Type 2 diabetes contributes to OA through pathways that go beyond just the extra weight many people with diabetes carry. Chronically high blood sugar leads to the formation of compounds called advanced glycation end products, which accumulate in cartilage and stiffen it, making it less resilient to everyday forces. Insulin resistance triggers persistent low-grade inflammation throughout the body, including in joint tissues. This inflammation accelerates cartilage breakdown while simultaneously impairing the body’s ability to repair it.
Diabetes also disrupts how cells in cartilage produce energy and manage oxidative stress, further weakening the tissue. Abnormal blood lipid levels, common in metabolic syndrome, add another layer of joint damage. The result is a self-reinforcing cycle: metabolic dysfunction promotes joint degeneration, and the resulting pain and immobility worsen metabolic health. This is why OA increasingly appears in joints that bear little weight, like the fingers, in people with metabolic syndrome. Managing blood sugar, inflammation, and cholesterol may protect your joints in addition to your heart.
Overlapping Risks Compound Each Other
Most people who develop OA have more than one risk factor working against them. A 58-year-old woman who is overweight, tore her meniscus playing tennis a decade ago, and works a job that requires frequent stair climbing faces a much higher combined risk than any single factor would suggest. The same logic works in reverse: losing weight, protecting joints from further injury, staying moderately active, and managing metabolic conditions like diabetes can meaningfully reduce your risk even if age, genetics, or sex aren’t in your favor.