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Clinically relevant anatomy

The knee joint itself is made up of the thigh bone (femur) and the shin bone (tibia). On the surface of the each of these bones is articular cartilage which allows smooth movement of the joint. In addition, the knee has two extra layers of cartilage known as menisci that aid the stability of the knee.

Osteoarthritis leads to degeneration of the knee cartilage and can cause pain, swelling and reduced functionality of the knee.

Within a joint there is a very smooth fibrous connective tissue, known as articular cartilage. This covers the areas where each bone comes into contact with one another (articular surfaces). In a normal joint this articular cartilage allows for smooth movement within the joint as well as acting as a shock absorber. In addition to this cartilage is another tissue, known as the synovial membrane, which produces synovial fluid that lubricates the joint.

Osteoarthritis (also called degenerative joint disease) is the degradation and degeneration of this articular cartilage. As the disease progresses, the cartilage itself becomes thinner and in some cases may wear away altogether. In addition, the bones themselves become thicker and may form bony “spurs”. Associated with these changes is the inflammation of the synovial membrane or thin lining which surrounds the knee joint to keep the synovial fluid or lubrication in place.

All of these factors can cause pain and impaired movement in the joint. Osteoarthritis can form in any joint but is more common in weight bearing joints such as the knee and hip.



  • Osteoarthritis of the knee is common in people over 50 years of age, in particular in women. It can affect either one (unilateral) or both (bilateral) sides of the knee joint however it occurs more commonly on the inner (medial) aspect of the knee.
  • Knee osteoarthritis is common in individuals who play intense physical sports, such as football. Previous injury to the knee is a strong indicator for development of osteoarthritis in the future.
  • Symptoms are known to develop slowly over a number of years.

The exact causes of osteoarthritis are unknown however there are a number of factors that are commonly associated with the onset of the disease.

  • Previous Injuries – Previous trauma to a particular joint increases the risk osteoarthritis forming there.
  • Heredity – Some individuals have a defective gene responsible for cartilage production which increases their susceptibility to osteoarthritis.
  • Weight – As osteoarthritis commonly occurs in the weight bearing joints, like the knee and hip, excessive loading on these joints may lead to faster progression of the disease. It is achievable to lose weight and although it takes a lot of discipline there is extensive research that proves that losing weight helps reduce pain and increase function.
  • Repetitive overuse – This may be as a result of excessive exercising or repeated strain on a joint over a number long period of time.
  • Crystal Deposits – Some crystal deposits such as uric acid crystals in gout may accumulate in joints and cause cartilage degeneration and wearing.

Clinical Characteristcs and presentation.

  • Deep aching joint pain, especially with movement
  • Inflammation of the joint
  • Stiffness in a joint, particularly in the morning. This usually decreases with movement.
  • A crunching or grinding sound (crepitus) during the movement of the joint
  • Osteoarthritis of the Knee

Osteoarthritis of the knee


  • History of acute injury to the medial knee for example, meniscal or ligament trauma.
  • Pro-longed and excessive use of the knee joint (ie manual jobs).
  • Previous fracture at that site of the knee.
  • Obesity
  • Genetic (hereditary) factors.

Symptoms of arthritis in the knee

  • Arthritis knee pain is a deep aching pain in the inner knee that is worse after exercise.
  • Stiffness particularly in the morning however lessening with movement.
  • Swelling of the knee.
  • Clicking or cracking noises when moving the knee.


  • Examination by a physio to assess the nature and severity of the pain, impaired function and ROM/special tests.
  • Measure the amount of movement in the joint. Capsular pattern.
  • Take an X-ray of the knee- narrowing of the joint space is a good indicator of osteoarthritis (However caution should be used when looking a t x-Rays as smetimes these do not correlate with clinical findings). Check out the X-Ray section to learn more about this. Bony spurs can also be seen on an X-ray
  • In some cases an MRI scan may be necessary. This allows the clinician to see whether soft tissue changes have taken place within the joint
  • In certain cases a blood sample may be necessary to rule out the presence of other types of types of arthritis.


As yet there is no cure for arthritis however a number of treatments can be put in place to slow the progression of the disease:

  • Knee supports/braces – Valgus unloader braces have been proven to provide pain relief in some cases of medial compartment osteoarthritis, by reducing the load on that compartment. Buy knee supports & braces online – UK / – USA
  • NSAID’s-Non-Steroidal Anti-Inflammatory Drugs such as ibuprofen can provide some temporary pain relief.
  • Weight Loss – As obesity is associated with the onset of osteoarthritis, weight loss, if needed, can have a significant effect on slowing the disease progression.
  • Exercise Program –A specific exercise program can help to maintain healthy cartilage and range of motion of the joint. In addition, keeping the attaching muscles and tendons conditioned and strong will aid in the joint’s stability. If exercising is difficult, hydrotherapy may be useful to reduce the stress on the joints.
  • Muscle relaxants- These are usually administered in low doses and can relieve pain that arises from muscles strained in an attempt to support osteoarthritic joints.
  • Heat and Cold Treatments – Local application of heat and cold can help with relief from pain and inflammation after exercise.
  • Viscosupplementation – A viscosupplement can be administered as an injection by a clinician. This substance helps to lubricate the knee joint and can decrease the amount of inflammation.
  • Knee Replacement – both half and total knee replacements are available in very advanced osteoarthritic knees.

Learn more on treatments for knee OA

Evidence and Recommendations

Thanks to all the researcher’s hard work that makes our lives easier, and updating us on the best clinical care we should be implementing. The PhysioWizz team do our best to present a summary however we urge you to read the original paper to form your own conclusions. PhysioWizz displays the following information under ‘fair use’ provision of copyright law. The following should not be reproduced unless for teaching purposes or with permission of its authors.


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