Osteoarthritis is a degenerative joint disease that causes pain and loss of mobility or joint function. It can greatly diminish the quality of life of sufferers, particularly when it affects small joints, such as those in the hand.

What is a synovial joint?

Most of the joints in the body are synovial joints. Let’s look at the knee joint in more detail as it can be classed as a typical synovial joint.


Inside the knee joint there are two bones joined together: the femur and tibia. The ends of the bones are covered in a very smooth layer of a tough, rubbery substance known as cartilage. The joint is enclosed in a stiff and elastic capsule made of strong, fibrous tissue. The joint capsule completely encloses the space around the joint surfaces and is lined by a synovial membrane. The joint capsule contains a thick, slippery liquid called synovial fluid.

What is synovial fluid?

OsteoarthritisThe synovial fluid in the joint capsule has four important functions:

  • it keeps the bones slightly apart, protecting their cartilage coverings from wear and tear
  • it absorbs shocks, again protecting the cartilage
  • it lubricates the joint, helping it to work freely and easily
  • it acts as a filter, letting nutrients reach the cartilage, but blocking the passage of harmful cells and substances.

The most important component of synovial fluid is a substance called sodium hyaluronate. It is this substance that lets synovial fluid perform its four different functions all at the same time. Most of the joints in your body are synovial joints. Good examples, besides the knee, include the hip and the shoulder.

What happens in OA?

  • The sodium hyaluronate in the joint space becomes depolymerised and fragmented. The synovial fluid becomes less viscous and its lubricating, shock-absorbing and filtering abilities are reduced.
  • The coating over the surface of the joint breaks down, leaving the cartilage exposed to mechanical and inflammatory damage.
  • The synovial membrane becomes inflamed.
  • The cartilage is gradually destroyed.


What is sodium hyaluronate?

Sodium hyaluronate (also known as hyaluronic acid or hyaluronan) is a natural substance. It is present in the body wherever moisture is stored or lubrication between layers of tissue is required to eliminate friction.

Sodium hyaluronate takes on a variety of functions:

  • Storage: it absorbs and stores moisture in enormous quantities
  • Lubrication
  • Transport medium for nutrients
  • Filter for inflammatory molecules.


OSTENIL is a treatment for the symptoms of osteoarthritis. It can be used in the knee, or in any of the other joints in the body that are classified as ‘synovial’

If you have any further questions after you have read these pages, please either email info@joylaneclinic.co.uk or call 01227 266439.