Other genetically based traits may result in slight defects in the way the bones and joints fit together so that cartilage wears away faster than usual. The inherited trait known as joint laxity, or double-jointedness, in which the joints bend farther than the usual angles, may also increase the risk for osteoarthritis. Simply inheriting a gene that makes you more susceptible to osteoarthritis doesn’t mean you will get the disease, however. Your lifestyle – that is, the way you eat, exercise, sleep and whether you have bad habits such as smoking – has a tremendous impact on whether you will develop OA.

Weight: Your hips and knees bear the brunt of your body’s weight. Being overweight puts additional pressure on these joints. For every pound you gain, your knees gain three pounds of added stress; for your hips, each additional pound translates into six times the pressure on these joints. Many years of carrying extra pounds can cause the cartilage that cushions your joints tends to break down. Obesity may lead to osteoarthritis on its own, or it may combine with other factors such as genetic susceptibility to produce the disease and worsen its symptoms.

Some research has shown a link between being overweight and having an increased risk of osteoarthritis in the hands, but the reason for that connection is unclear. One theory is that excess fat tissue itself produces inflammatory chemicals that travel throughout the body and are capable of causing damage in places other than weight-bearing joints. 

Injury and overuse: Sometimes repetitive movements or serious injuries to joints (such as a fracture or surgery) can lead to osteoarthritis down the road. Some full-time athletes, for example, repeatedly damage certain joints, tendons and ligaments, which speeds cartilage breakdown. Even joints such as shoulders (which don’t bear much weight and are unlikely to have osteoarthritis) can develop the disease after injuries or repeated stressful activities.

The constant knee bending required by some types of work, such as landscaping, can make cartilage wear away more quickly than moderate use of those joints.

Others: Several other factors may contribute to osteoarthritis. These factors include other bone and joint disorders like rheumatoid arthritis and certain metabolic disorders such as hemochromatosis, which causes the body to absorb too much iron, or acromegaly, which causes the body to make too much growth hormone.