How Hyaluronic Acid Injections Work in the Osteoarthritic Knee?
Research suggests that hyaluronic acid injections may work in several ways to reduce knee osteoarthritis symptoms. For example, hyaluronic acid injections may reduce inflammation and friction, and the slow the degeneration of cartilage and bone. In some cases, it has also been shown to increase the joint’s natural ability to produce synovial joint fluid.
Effects on knee pain and inflammation
Hyaluronic acid injections may reduce knee osteoarthritic symptoms by one or more of its following properties:
- Lubrication. In some people, the viscosity of hyaluronic acid may provide better lubrication and shock absorption in the knee joint. These effects may reduce friction within the joint, thereby reducing pain and stiffness, and preventing the loss of cartilage and bone.
- Anti-inflammatory effects. Research shows hyaluronic acid injections may provide anti-inflammatory effects such as reduced pain, inflammation, and/or swelling in the knee.
- Pain-relieving effects. In some people, hyaluronic acid molecules form a boundary around nerve endings, preventing pain signals from being sent to the brain. These molecules also bind to other cells in the knee that signal pain. Through these mechanisms, knee pain may be decreased.
The viscosity of hyaluronic acid may also have positive effects on the cartilage, bone, and other surrounding tissues in the knee.
Specifically, in some people, hyaluronic acid knee injections may act by:
- Aiding the growth and protection of cartilage by stimulating an increase in the growth of cartilage-producing cells, called chondrocytes. These injections also protect existing chondrocytes, thereby increasing the overall cartilage formation.
- Strengthening existing cartilage by producing important proteins (proteoglycans) and carbohydrates (glycosaminoglycans).
- Strengthening existing bone by altering the density and thickness of the knee’s subchondral bone (bone that lies immediately below the cartilage). The changes in bone structure may help reduce stresses on the cartilage when the knee bears weight.
- Stimulating the body to produce its own hyaluronic acid, in turn restoring the quantity of hyaluronic acid in the knee and providing long-term effects.
These effects may help prevent the progression of osteoarthritis.