Osteoarthritis of the Knee

Osteoarthritis is a degenerative joint disease, involving damage to the articulating surfaces of the bones, leading to painful and stiff joints. It is the most common joint disorder and the knee is a common site. This problem is commonly seen in elderly, especially females.

Anatomy of the knee joint:

Although it looks simple, the knee is a very complex joint which is exposed to great stresses, and is more prone to injury than any other joint in the body. Here the upper leg bone the femur joins the lower leg bones, the tibia and fibula, with a small seasamoid bone the patella (the knee cap) covering the front aspect of the joint.c

When we stand erect, our knees need to stay firm in position and not wobble under the body weight. Moreover, when we walk or run, the same joint acts as a hinge, allowing flexion and extension of lower leg, as well as a mild degree of rotation.

The articulating surfaces of the bones in a joint are covered with smooth cartilage caps that glide over each other during movement. These articular cartilages have a protective role, as these not only reduce friction during movement, but also provide cushioning to absorb the stresses inflicted on the bone ends in a joint. A membrane further surrounds the joint, enclosing the articulating bone ends in a cavity bathed by a lubricating fluid, secreted by the same membrane, which further aids to reduce friction during movement. A number of ligaments (cord-like fibrous extensions connecting two bones together) and the adjacent muscles stabilise the joint further.

How does the problem occur?

In osteoarthritis, the articular cartilages start degenerating, becoming thin and eroded. Without the protective cartilaginous covering, the bones rub together during joint movement causing friction and pain.

The body tries to heal the damage by setting up an inflammatory response at the site. The bone underlying the damaged cartilage becomes thick and new outgrowths of bone (bone spurs) develop at the joint margins, to help preserve the articulation.

The surrounding membrane thickens and starts producing extra fluid to ease the friction; this leads to joint swelling. Ultimately the joint structure becomes weak and stiff.

Causes:

• Previous trauma to the knee
• Multiple family members may be affected, suggesting a genetic predisposition to the disease.
• Excess mechanical stress on the knee due to:
  • Excess weight bearing (obesity)
  • Long-term overuse, neglecting to properly tone up the body for aggressive activity
  • Faulty lower limb biomechanics
  • Anatomical deformities of the joint
• Unstable, loose ligament/s that fail to support the joint properly, exposing it to unnecessary stresses
• Recurrent patellar (knee cap) dislocations /fracture
• Other joint diseases such as gout, rheumatoid arthritis, septic arthritis, etc.

Bleeding in the joint space or blockage of blood supply from either trauma or a vascular disorder may also predispose to osteoarthritis.

Symptoms:

Pain and stiffness are the two most common complaints. As one starts the day, the knee feels stiff and difficult to move to the full extent. The situation improves, however, as the body warms up.

Pain is felt deep in the knee and is worse after activity or at the end of the day. Grinding or creaking sounds may be heard on moving the joint. There may also be swelling and bony outgrowths, felt as hard nodules at the sides of the joint.

Diagnosis:

Signs and symptoms point clearly to the diagnosis, confirmed by diagnostic imaging.

X-rays are a great tool in this regard; X-ray indications of osteoarthritis include:

• Obliteration of the space between the bone ends in the joint
• Presence of reactionary bone outgrowths or calcium deposits.

MRI is an excellent aid to discover the soft tissue changes and the extent of damage to the cartilage and adjacent ligaments. Blood tests may be advised to exclude other joint conditions.

Treatment:

As with the cause, a permanent cure is yet to be discovered. Present treatment aims to reduce symptoms and delay the disease process.

Non-steroidal anti-inflammatory painkillers such as acetaminophen (paracetamol) are recommended for controlling pain and swelling. Frequent use may lead to serious side effects, so medical consultation is essential.

Steroids with their strong anti-inflammatory effect provide relief for a few months, although repeated injections over a long period may be harmful.

Artificial joint lubricants (hyaluronate) injected into the joint cavity facilitate joint movement and overcome pain for a few months.

A faulty gait or abnormal joint anatomy should be corrected to reduce stress on the joint. Knee supports and braces are helpful in this regard.

Maintaining optimum weight, routine light exercise and healthy diet help improve the symptoms and delay the progress of disease.

Physiotherapy helps reduce joint stiffness and improve muscle strength to better control joint movement. Hydrotherapy and massage are quite helpful as well.

Surgical options include:

Alteration in the bone alignment or structure (osteotomy)

Debridement of damaged tissue and removal of bone spurs

Partial or complete joint replacement (arthroplasty)

Acupuncture does relieve symptoms, but only for a short term. Alternative medicine has certain remedies for osteoarthritis, however there is little published scientific data on this subject.