Osteoarthritis (OA) is a complex joint disease as it is often difficult to know the exact cause for why a person develops the disease. What we do know, is that several genetic, environmental and lifestyle factors play a role in increasing the risk of developing OA The more risk factors present, the higher the probability is of developing the disease. Some risk factors can in most cases be changed (such as weight and amount of activity) whereas others such as age and genetics are inevitable.

Risk factors for osteoarthritis

Age

OA often debuts after the age of 45 as it can take years for the disease to develop. Age being a risk factor for OA can partly be due to the length of exposure your joints have had to other risk factors such as being overweight or having a job that involves excessive loading of the joints (for example working as a tiler). However, age playing a role in the development of the joint disease may also have to do with changes in our bodies that come with aging such as the cartilage in our joints becoming more delicate.

Nevertheless, it is important to understand that growing old does not necessarily mean that you will develop OA. Despite the myth that OA is an “old people’s disease”, it is in fact not necessarily always a result of aging.

Gender

Postmenopausal women are twice as likely to develop OA than men of the same age. It is still unclear why, but research has pointed to hormonal factors potentially playing a role.

Heredity

Genes play an important role in the development of OA. If OA runs in the family, the chances of developing the disease are higher. Genetic heritage as a risk factor accounts for approximately 40% of all knee OA and 60% of all hip and hand OA.

Weight

Excess body weight puts a lot of pressure on the body’s knee and hip joints. An obese individual with a Body Mass Index (BMI) over 30 is up to 8 times at higher risk of developing knee OA compared to an individual with a normal BMI (between 18,5-24,9). OA of the hands is also more common amongst overweight people and research has shown that fat secretes inflammatory proteins in the body that may contribute to joint pain.  

Joint injury

A previous joint injury increases the risk of developing OA and around 50% of all individuals who injure their meniscus or anterior cruciate ligament in the knee develop knee OA within 15-20 years. Joint injuries in other joints may also contribute to the development of OA, but this is not as researched as the link between knee injuries and knee OA.

Occupational load

Certain occupations put an increased amount of pressure on the knee, hip, and back joints that can cause severe problems later in life. Individuals with occupations that require a large amount of standing or kneeling are at greater risk of developing knee OA. Those with occupations that require a lot of heavy lifting are at greater risk of developing OA of the knees, hips, hands, shoulders, and back.

Muscle weakness

Having weak muscles affects the body’s ability to carry its own weight which in turn creates joint instability. Muscle weakness is often due to inactivity or muscle injuries although other causes include underlying conditions and side effects from certain medications). Regardless of BMI, you are at risk of developing OA if you live an inactive, sedentary lifestyle for too long as this can lead to the muscles around the joints weakening. Exercising regularly and strengthening your muscles to stabilize your joints can prevent you from developing a number of diseases including OA, later on in life.

Underlying conditions

Congenital disorders or suffering from certain medical conditions as a child can increase the risk of developing OA later on in life, especially of the hip. Such disorders or conditions include untreated dislocation of the hip (dysplasia), physiolysis, Perthes' disease, and osteonecrosis.