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Osteoarthritis from A-Z



The abbreviation for the anterior cruciate ligament. The ACL is one of two cruciate ligaments in the knee that gives the knee stability.


A proteoglycan (a protein to which long carbohydrate chains are attached) is a central component of the extracellular matrix in the articular cartilage. The function of aggrecan is to draw water into the matrix so that the cartilage swells and becomes shock-absorbing.

Arthrodesis (joint fusion)

A surgical procedure that involves inserting bone fragments between two bones so that the joint surfaces grow together and form a new bone.


A surgical procedure that is used to examine or operate a joint by using an arthroscope (see definition below. The surgery is mostly performed on people with meniscus and ACL injuries in the knee joint. Another name for arthroscopy is keyhole surgery.


A thin tube with a video camera that is inserted into a joint through a small incision in the skin to perform arthroscopic surgery.


The abbreviation for body mass index, which measures body fat through a calculation using height and weight. The value provides a general picture of a person's body fat that can be categorized as underweight, normal weight, overweight or obese. However, the calculation does not take muscles into account and a person with a high BMI may not necessarily be overweight.


The abbreviation for Better management of patients with OsteoArthritis. BOA is a collaborative project that was started in 2008 in Sweden with the aim of implementing a nationwide self-management programme delivered by trained physiotherapists and occupational therapists and offered to everyone with OA.

BOA register

A national quality register, measuring the effects the OA self-management programme has as a first-line treatment method for people with OA. By asking patients to answer questions about their symptoms after completing the programme, data can be collected to evaluate and improve the self-management programme.

Bouchard's nodes

Bony bumps that sometimes occur on the middle joints of the fingers (the PIP joints) in patients with hand osteoarthritis.


A connective tissue that exists in our joints, spine, ears, nose and ribs. There are three types of cartilage in the body: hyaline, elastic, and fibrocartilage. It is hyaline cartilage that is found on joint surfaces. Around 80% of hyaline cartilage is water. The remaining 20% ​​consists of proteins, carbohydrates and cartilage cells.


A fibrillar protein that is one of the body's most common proteins and an important building block in bones, articular cartilage and skin, among other things. There are several different types of collagen, but type-I collagen is the most common. However, the main collagen is type II that occurs in the articular cartilage. It is the collagen that gives the cartilage its elasticity.


Cells that produce and maintain the extracellular matrix in the cartilage. The cells are located in small lacunae in the matrix.


A steroid hormone (also known as the body's natural stress hormone) that is produced by the adrenal glands. In addition to helping the body respond to stress, the hormone also regulates our metabolism, fights inflammation and controls blood pressure.


Man-made cortisol that is used as a drug to treat several diseases. Cortisone can, amongst other things, be injected into a joint to temporarily treat OA symptoms by reducing inflammation.

Extracellular matrix

A network surrounding the cartilage cells, consisting of water, proteins, and carbohydrates. The extracellular matrix is crucial for cartilage cell function.

Generalized osteoarthritis

A commonly used term for osteoarthritis that has affected several joints in the body (at least three).

Hallux rigidus

Latin and the medical term for stiff big toe caused by osteoarthritis.

Heberden's nodes

Bony bumps that sometimes occur on the joints closest to the fingertips (the DIP joints) in patients with hand osteoarthritis.

Hyaluronic acid

A sugar molecule produced naturally in the body. It is found in many places in the body including in the articular cartilage and synovial fluid in joints. In joints, hyaluronic acid acts as a lubricant, keeping the joint surfaces smooth.


Crescent-formed cartilage discs that act as shock absorbers between the femur and the tibia in the knee. In each knee, there are two menisci, a medial and a lateral. An injured meniscus increases the risk of developing osteoarthritis.


The abbreviation for Magnetic Resonance Imaging, a type of medical scan that uses strong magnetic fields to take pictures of organs and tissues in the body. An MRI can detect diseases and injuries that are not seen visible on an X-ray.

Neuromuscular training

A training programme which focuses on training the brain and muscle connection. It was developed initially for people with knee damage who needed help with relearning movement patterns to avoid uneven joint load before embarking on other forms of exercise.


The abbreviation for Nonsteroidal Anti-Inflammatory Drugs, a group of drugs that relieve both inflammation and pain. Examples of NSAIDs are ibuprofen, naproxen, and diclofenac.


Bone spurs that grow on the bones near osteoarthritis-affected joints or on the vertebrae.


A surgical procedure that is performed by cutting a part of the tibia or femur to realign it to unload the knee joint.


An orthopaedic aid used to support or align a weakened or painful part of the body. For osteoarthritis patients, knee, wrist and ankle orthoses are common.


A ”fake” treatment or substance that has no active properties. Used by researchers to help understand the effect of a “real” medical treatment or substance.

Placebo effect

The placebo effect is the positive effect you experience from a treatment or substance with no active properties. It demonstrates that the brain has great power over the rest of the body when improving disease symptoms.

Post-traumatic osteoarthritis

Osteoarthritis that arises following a traumatic joint injury (for example a meniscus or an ACL tear).

Rheumatic disease

A disease that mainly affects the joints, ligaments, muscles, bones and/or tendons. Common for most rheumatic diseases is that they cause joint pain, swelling or stiffness.

Risk factor

Something that increases the risk of developing a disease. For example, obesity is a risk factor for developing osteoarthritis.


A term for degenerative changes in the spine. Often used synonymously with osteoarthritis of the spine.


Short for Transcutaneous Electrical Nerve Stimulation. An alternative treatment method for pain relief. Electrodes connected to a small device are attached to the skin around the painful area of ​​the body. By sending low-voltage electrical currents from the device via the electrodes, the body’s nerves are activated to block out pain signals to the brain.