Knee osteoarthritis

What are the symptoms?

The main symptoms are:

  • Pain: Pain is the main symptom of knee osteoarthritis. It may be intermittent or constant, and tends to worsen with physical activity. Pain may be more intense upon arising in the morning or after prolonged periods of rest.
  • Stiffness: Joint stiffness is common in osteoarthritis of the knee. It may be more noticeable in the morning or after periods of prolonged inactivity. Stiffness tends to improve as the knee moves.
  • Inflammation: In some cases, the knee joint may be swollen, hot and red. The swelling is the result of the inflammatory response caused by wear and tear and damage to the cartilage.
  • Limitation of motion: As osteoarthritis of the knee progresses, you may experience a decrease in the range of motion of the joint. You may have difficulty bending or fully straightening the affected knee.
  • Crepitus: You may feel or hear a cracking, popping or rubbing sensation when you move your knee. This is known as crepitus and is caused by friction between the worn bones.
  • Deformity: In more advanced cases of osteoarthritis of the knee, there may be a visible deformity of the joint, such as an inward or outward deviation of the leg.

What treatments are currently available?

Conservative treatment.

Physical therapy:

Physical therapy plays a key role in the treatment of osteoarthritis of the knee. Specific exercises can help strengthen the muscles surrounding the joint, improve mobility, relieve pain and increase knee stability.

Weight loss:

If overweight or obese, losing weight can reduce the load on the knee and reduce the symptoms of osteoarthritis.

Oral pharmacological therapy:

Analgesics and Nonsteroidal Anti-inflammatory Drugs (NSAIDs): Analgesics, such as acetaminophen, can be useful in relieving mild to moderate pain. NSAIDs, such as ibuprofen or naproxen, among others, have more effective analgesic and anti-inflammatory properties in osteoarthritis and may provide greater pain relief by acting to reduce inflammation. However, it is important to keep in mind that NSAIDs can have gastrointestinal and cardiovascular side effects, especially with long-term use.

Selective cyclooxygenase-2 (COX-2) inhibitors: These drugs, such as celecoxib, are a class of NSAIDs that specifically target the COX-2 enzyme involved in inflammation. COX-2 inhibitors can provide pain relief and reduce inflammation with a lower risk of gastrointestinal side effects compared to traditional NSAIDs. However, prolonged use of COX-2 inhibitors has also been associated with increased cardiovascular risk.

Topical pharmacological therapy:

Topical NSAIDs: Topical NSAIDs, such as diclofenac gel, are applied directly to the skin over the affected knee area. These drugs have anti-inflammatory and analgesic properties that can relieve pain and reduce local inflammation. Topical NSAIDs have the advantage of having fewer systemic side effects compared to oral NSAIDs.

Capsaicin: Capsaicin is a compound derived from hot chili peppers that is used in the form of a topical cream. Capsaicin is believed to help relieve pain in osteoarthritis of the knee by reducing substance P, a chemical involved in pain transmission. Capsaicin may cause a burning or stinging sensation on the skin, but this effect generally diminishes over time.

Intra-articular infiltrations:

Corticosteroid Infiltrations: Corticosteroids, such as triamcinolone, are used to reduce inflammation in the knee joint and relieve pain associated with osteoarthritis in patients with synovitis. These drugs have anti-inflammatory and analgesic properties. Corticosteroids are administered by direct injection into the knee joint and may provide short-term pain relief. However, their effect is temporary and they do not have a reparative effect on damaged cartilage.

Hyaluronic acid injections: Hyaluronic acid is a substance found naturally in the synovial fluid of the joints. In the treatment of osteoarthritis of the knee, hyaluronic acid can be injected into the joint to improve lubrication and cushioning, relieving pain and improving mobility. Injectable hyaluronic acid acts as a supplement to replace or augment the deteriorated synovial fluid in the affected knee joint.

Platelet Growth Factor or Platelet Rich Plasma (PRP) Infiltrations: PRP is a product derived from the patient's own blood. It is obtained by taking a blood sample, centrifuging it to separate the components and then injecting the platelet-rich portion into the knee joint. PRP contains higher concentrations of growth factors and proteins that can help stimulate the repair and regeneration of damaged tissue in the knee joint. It is believed that PRP may improve the symptoms of osteoarthritis and promote cartilage regeneration.


Arthroscopy: In some cases, arthroscopy may be performed to treat certain problems associated with knee osteoarthritis, such as removal of cartilage fragments or repair of damaged tissues.

Osteotomy: In selected cases, an osteotomy may be performed, which involves surgical correction of the leg alignment to redistribute the load on the knee joint.

Total knee replacement (knee arthroplasty): If osteoarthritis of the knee is severe and conservative treatments do not provide relief, the option of replacing the knee joint with an artificial prosthesis may be considered.

What treatments are expected in the future?

Knee osteoarthritis is a complex disease involving different biological processes and pathological mechanisms. There are tremendously active lines of research on the four intra-articular targets that are considered key in knee osteoarthritis:

  • Articular cartilage: Articular cartilage is one of the main targets in the treatment of knee osteoarthritis. The goal is to protect and promote regeneration of damaged cartilage. Therapies that stimulate the proliferation and differentiation of cartilage cells, as well as the inhibition of cartilage-degrading enzymes, such as matrix metalloproteinases (MMPs), are being investigated.
  • Synovial membrane: The synovial membrane lining the knee joint also plays an important role in osteoarthritis. Chronic synovial inflammation occurs in osteoarthritis, which contributes to disease progression. Therapies that target the regulation of inflammatory cytokines, such as interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α), are being studied to reduce inflammation in the synovium.
  • Subchondral bone: The subchondral bone, located beneath the cartilage, is also affected in osteoarthritis of the knee. Abnormal bone remodeling occurs, with the formation of bone spurs and changes in bone density. Therapies that regulate the activity of osteoclasts and osteoblasts are being investigated to maintain a proper balance in bone remodeling.
  • Neurogenic inflammation: In osteoarthritis of the knee, there is also a contribution of neurogenic inflammation, which involves the sensory nerves of the knee joint. This inflammation may contribute to sensitization and increased pain. Therapies that target neurotransmitters and receptors in the nervous system are being investigated to modulate the pain response and reduce neurogenic inflammation.


In the case of pain in your knee, you should go to your rheumatologist, receive a clinical assessment, and if necessary, carry out the complementary examinations that your rheumatologist considers in your case. After the evaluation, the risks and benefits of existing therapies should be discussed and then the treatment strategy that fits the specific case should be chosen.