The knee joint is formed by the flared ends of the thigh bone (femur) and the shin bone (tibia), as well as a smaller bone, the kneecap (patella), which sits within a large tendon in the front of the knee.

There are three parts of the knee joint – an inside part (medial compartment) and an outside part (lateral compartment) of the knee and the kneecap joint (patella-femoral compartment).

Additional knee structures such as ligaments stabilise while tendons move the knee joint.

Osteoarthritis is a term that describes wear, tear and loss of cartilage within a joint. The compromised cartilage integrity could be as a result of injury to the meniscus/joint cartilage/ligament at a young age, or a natural progression after years of use much later in life (i.e. degenerative osteoarthritis). Family pre-disposition and adverse lifestyle factors contribute to the development of osteoarthritis at all ages.

Early osteoarthritis may simply be uncomfortable and easily tolerated. Advanced osteoarthritis in large weight-bearing joints, such as the knee, may cause severe pain, swelling and deformity. As it limits everyday mobility and affects quality of life, osteoarthritis is a leading cause of disability in the world.

Progressive wear and tear with loss of the knee joint cartilage and bone-on-bone contact in the joint accounts for symptomatic knee osteoarthritis. While conservative management with painkillers, oral and topical anti-inflammatories and knee joint injections may adequately ameliorate moderate knee discomfort, severe pain and loss of mobility can only be addressed with correction of leg alignment (corrective osteotomy) and joint replacement.

Knee replacement can be Partial or Total. Selection of the type of replacement will depend on how the knee is affected, whether osteoarthritis is localised to one or more than one compartment of the joint.