Osteoarthritis affects 7.3 million people in the UK with a higher prevalence in women than men (NICE 2015). It is the leading cause of pain and disability and impacts of quality of life affecting activities of daily living. Osteoarthritis is one of the most common chronic diseases Fernandez et al (2016). 41% of arthritis is knee, 30% in hands, 19% in the hip arthroplasty.
How your Joints Function
To begin to understand what osteoarthritis is it is important to have a better understanding of joints itself and the tissues that surround them.
In mammal’s bones first start of in the form of cartilage. It is only when the bones mature do the bone create an outer structure. The cartilage has many functions:
1.Prevents frictions between the two ends of the bones
2.Acts as a shock absorber
5.Responsible for growth
The synovial fluid is produced by the synovium also known as the synovium membrane. It lubricates the joints making them easy to move. It also provides nutrients to the cells
Bones forms the structure of our body. As well as provided the vital organs with support, it allows muscles with a point of attachment, the marrow part of the produces new red blood cells. In regards to osteoarthritis they form joints which allows movement of the body.
Process of Osteoarthritis
During the early stages of OA chondrocytes attempt to repair damaged areas and in its attempt forms clusters which results in an imbalance which favours degeneration.
This in turn leads to increased tissue synthesis further increasing apoptosis of chondrocytes and inadequate component of extra cellular matrix leading to a formation of a matrix unable to withstand normal biomechanical stress
This leads to a synthesis where breakdown is more frequent than cell synthesis leading to degenerative changes occurring.
Osteoarthritis and pain
Inflammation- During inflammation or during injury synovium blood vessels become permeable increasing fluid in the knee. This build up in pressure causes pain. Inflammation can have an impact on nerve endings within the knee. Due to intra articular pressure, pressure can also lead to increase afferent firing rate.
Joint trauma and injuries- This can cause instability. Sports injuries may cause damage resulting in soft tissue injury, research show rupture of articular ligaments can cause joint instability and abnormal join loading. Poor healing capability of joints may result in chronic instability and focal loading, joint degeneration and arthritis.
Common Joints affected
The Knee Joint
The knee is the most common joint affected by osteoarthritis. The knee joint is important for weight bearing and walking and having arthritis in the knees can greatly impact on these joints. People with OA of the knee will more than likely have the arthritis prominent in one region of the knee. This includes either medial or lateral compartment OA.
Medial compartment OA is the most common form of osteoarthritis and involves the degeneration of the medial part of the knee. This leads to Varus or bowlegged knees.
Lateral compartment OA is the degeneration of the lateral part of the knees. This leads to lateral valgus knees.
The Hip joint
Hip osteoarthritis is the most common cause for hip replacements. There is an increased amount of younger people with hip replacements. Hip arthritis affects the ability to walk up the stairs, put on shoes and socks, difficulty walking which may affect the hip joint.
Altered biomechanics- is likely reason for maintaining joint pain. An example of that includes Varus and/or Valgus joint deformities in severe osteoarthritis of the knees.
Risk Factors for Developing osteoarthritis
Obesity- increased weight and stress on the joints causes more pressure in the joints resulting in more inflammation and pain. In Varus knees obesity affects incident but not progression. In knees with neutral or valgus alignment obesity affect the progression of OA.
Trauma or injury to a joint- Increased trauma and injury developed during younger years can cause damage to the cartilage and cause osteoarthritis. A study demonstrated that 51% of football players who retired had lower limb OA compared to 25% of players who did not.