What is osteoarthritis?

Osteoarthritis (OA) is a disease that attacks the joints and breaks down articular cartilage (joint cartilage), ligaments, bones, menisci, joint membranes, and muscles. The disease most commonly affects the knees, hips, and small joints in the fingers, but it can also affect the spine, jaw, shoulders, and feet. Basically, any joint in the body can be affected by OA. It is also possible for several joints in the body to be affected by OA at the same time. “Generalized osteoarthritis” is the term used for when this occurs.

OA is one of the world's most common diseases and is according to the World Health Organization (WHO) one of the ten most disabling diseases in developed countries. It is difficult to give an exact number of how many people are affected by OA as not everyone experiences symptoms. However, it is estimated that one in four over the age of 45 in Sweden has sought care for and been diagnosed with the disease. The WHO estimates that the prevalence worldwide of OA is between 10-15% in adults over the age of 60. As it shows, age is a contributing factor for developing OA. More and more people each year suffer from OA, mostly due to the aging of the population and a constant increase in obesity among young people.

In most cases, OA affects middle-aged adults but that is not to say that it cannot affect younger adults too. The disease may also debut already in your 20’s or 30’s. That OA only affects “old” people is therefore not entirely true. OA of the knee or hip is not uncommon amongst younger individuals. For example, young athletes who have suffered from a meniscus or anterior cruciate ligament (ACL) tear very often develop OA later on in life.

What causes osteoarthritis?

It is difficult to pinpoint an exact cause for the breakdown of articular cartilage in an individual. Nevertheless, there are several major risk factors that can contribute to the development of OA.  These include hereditary and lifestyle factors, previous joint injuries, aging, and gender.  For example, OA of the knee is a lot more common in women, especially in postmenopausal women.

A previous joint injury to the knee has been seen to increase the risk of developing knee OA and around 50% of knee injuries lead to OA. However, OA can progress extremely slowly, and it normally takes 10-15 years for the disease to develop after such an injury. A meniscus or ligament tear or a fracture of the knee often causes a deterioration of knee stability and impacts load transmission. Abnormal joint loading due to instability in the knee joint over several years is what may lead to OA after an injury.

OA often develops in a joint that has suffered abnormal strain due to a joint injury, heavy workload, or being overweight. However, the disease may also develop in a joint that has not suffered external stresses but is for some reason already weak.  Such a reason could for example be a hereditary weakness in the structure of the articular cartilage.

How is osteoarthritis diagnosed?

OA should predominantly be diagnosed through a clinical examination based on symptoms, risk factors, and medical history. In most cases, an x-ray isn’t necessary for diagnosis. X-rays only show relatively late stages of OA and are usually conducted to rule out other causes related to symptoms.

Which symptoms are most common?

The most common symptoms of osteoarthritis are stiffness, pain, and swelling of the joint. However, symptoms can vary depending on which joint is affected. In osteoarthritis of the knee, it usually hurts the most when applying pressure on the knee joint, while hip osteoarthritis often hurts when bending over and may even hurt when resting or sleeping.  Osteoarthritis of the fingers can cause lumps on the knuckles which can be very painful, and it may become difficult to open and close the hand properly without experiencing pain or stiffness.

What happens in an osteoarthritis-affected joint?

Despite leading OA scientists acknowledging that OA isn’t entirely a cartilage disease, the majority of existing OA research focuses on the articular cartilage. Therefore, the knowledge about this tissue is the vastest which makes it easier to explain what exactly happens to the cartilage in an OA-affected joint.

Inside a joint two or more bones meet. The bone surfaces are covered by a thin layer of cartilage.  This layer of cartilage protects the bone from damage and wear. Between the cartilage-covered bone surfaces is synovial fluid, that keeps the cartilage lubricated. This helps the bones to slide smoothly against each other which minimizes friction and evenly distributes the joint load when we move. It is the synovial fluid that is responsible for supplying the articular cartilage with nutrients, and therefore it is vital that the joint is both loaded and unloaded so that the synovial fluid is both pushed out of the cartilage and absorbed again. The articular cartilage is similar to a sponge. When pressure is applied on the joint the synovial fluid is squeezed out of the cartilage and when the pressure is relieved the nutrients from the fluid that keeps the cartilage slippery is “sucked” up again.

When a joint is affected by OA, the cartilage starts deteriorating creating difficulty for the bones to smoothly slide against each other the synovial membrane that surrounds the joint becomes irritated. This may result in stiff and painful joints.

How do you treat osteoarthritis?

For overweight individuals, weight loss is a good first step towards relieving knee- and hip OA symptoms, although first-line treatment for OA is education and physical exercise. Learning more about your disease and receiving self-care tips is important, as is regular exercise. Exercise has been proven to reduce joint pain more than or to the same extent as painkillers. It is however crucial to customize your exercise routine to best increase mobility and reduce symptoms. In certain cases, when the pain is unbearable, painkillers such as paracetamol or NSAIDs (for example, ibuprofen, aspirin, and naproxen) may complement first-line treatment methods. However, one should always be cautious when taking painkillers, especially when at risk of developing cardiovascular diseases.

Cortisone injections can also be used as a complement to first-line treatment methods to relieve joint inflammation. For a small amount of OA patients that have not benefited from previously mentioned treatment methods, surgery may be necessary.

Is it possible to prevent osteoarthritis?

The short answer is no, as OA can affect anyone. However, it is possible to minimize the risk of developing the disease by influencing what we in most cases have control over, such as our physical activity and body weight. Moving your joints regularly and trying to maintain a healthy BMI, can therefore both help to potentially prevent OA and alleviate symptoms in those already affected. Nevertheless, it is important to have in mind that very intensive exercise, especially when first diagnosed with the disease, may worsen symptoms.

Certain sports such as handball and football increase the risk of suffering a knee injury, which can lead to the development of OA later in life. Therefore, it is important when partaking in these sports to integrate injury prevention training into your regular training.

Injury prevention training programs exist to help reduce the risk of knee injuries in various sports where there is a relatively high risk of injury. Sports clubs must acknowledge how integral these specific exercises are for their players to help them avoid serious knee injuries that risk leading to OA and/or other joint problems.