The knee is a complex hinge type joint that is comprises of four bones: the femur (thigh bone), the tibia (shin bone), the fibula (thin bone that runs alongside the shin bone) and the patella (knee cap).

The knee also consists of ligaments (connect bone to bone), tendons (connect muscle to bone), a medial and lateral meniscus (tough cartilage that act as shock absorbers), a capsule (leathery type structure that surrounds the knee joint) and synovial fluid (the type of fluid present in the normal knee joint). Some examples of injuries/problems that may occur at the knee are: fracture, injury to the ligaments, meniscal injury, patellofemoral pain syndrome (PFPS), patellar tendonitis, patellar tendinopathy and osteoarthritis.

Symptoms of injury or a problem at the knee may include: pain, swelling, stiffness, loss of movement, locking or giving way (feeling of instability).