What happens in osteoarthritis inside the synovial joint?

The sodium hyaluronate in synovial fluid does not stay there for a whole lifetime, but is continuously broken down and replaced. Normally, there is an exact balance between the breakdown of old sodium hyaluronate and the production of new sodium hyaluronate. In osteoarthritis, however, this balance is disturbed and breakdown happens faster than production. As a result, the synovial fluid becomes more watery and stops working properly.

Due to the change in the synovial fluid - and for other, more complex reasons - the cartilage in the joint gradually wears away. In some places, in fact, the cartilage may eventually disappear altogether. The thinning of the synovial fluid and wearing away of the cartilage lead to the symptoms of osteoarthritis, which include pain, stiffness and swelling.

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

Osteoarthritis develops as people get older and is present in almost everybody over the age of 60 (although not everyone in this age group has bad symptoms). Osteoarthritis of the knee or hip may also occur in younger people, usually (but not always) because these joints have been overloaded. Possible causes of overloading include sports, jobs involving a lot of lifting and carrying, too much bodyweight and abnormal joint development.
 

More Information on Osteoarthritis:

More information on osteoarthritis and treatment options is available on the following external pages. Any links provided are for information purposes only and do not constitute advertising or recommendation. Please also note that we are not responsible for the content of any external website. 

		Shoulderdoc. Specialty: Shoulder and elbow problems. https://www.shoulderdoc.co.uk/
		Elbowdoc. Specialty: Elbow problems. https://www.elbowdoc.co.uk/
		The Kneedoc. Specialty: Knee problems. http://www.thekneedoc.co.uk/
		Foot Education. Specialty: Foot and Ankle Conditions. http://www.footeducation.com/
		My Ankle. Specialty: Ankle problems. http://myankle.co.uk/