As sports and fitness activities become increasingly more popular, injuries of the knee joint occur more frequently in people of all ages. The types of knee injuries vary greatly - ranging from simple contusion and muscle strains to severe injuries of ligaments and joint surfaces. Serious damage to knee structures can increase the risk of developing secondary osteoarthritis and possible long-term disability. Such severe knee injuries may require changes in sports or work activities that usually place high functional demands on the knee.

Over the past decade, the diagnosis and management of knee disorders have been refined significantly. These advances have greatly improved the ability to persevere knee function, allowing patients to return to their desired level of sporting activities. The treatment of anterior cruciate ligament ruptures (see ACL) has been revolutionised with new surgical techniques being introduced allowing for more aggressive rehabilitation. Arthroscopic treatment of the meniscus (shock-absorber cartilage) now encompasses repair as well as more limited excision compared to traditional techniques in which the whole meniscus was removed through an open incision (see Meniscus). Subsequently more meniscal tissue can be preserved, which is vital in reducing the level of force transmitted through the knee joint.

A variety of operative procedures such as 'microfracture' or 'abrasion-arthroplasty' are available to repair defects on joint surface cartilage. Furthermore advances in the science of tissue engineering and cell biology has given us the ability to implant the patient’s own cartilage cells in areas of surface defects, thus re-establishing a smooth joint surface and normal biomechanics (see autologous chondrocyte implantation). In addition, magnetic resonance imaging (see MRI) greatly improves the diagnosis of many different knee injuries. The latest generation of high power MRI scanners can demonstrate early changes in the surface cartilage (see cartilage) which can pre-date the development of osteoarthritis (see osteoarthritis).

Regardless of the type or severity of the knee injury, most patients usually consult a primary care physician or GP for initial evaluation. Therefore, all physicians who treat athletes, children, or other physically active patients must be able to examine the knee and understand the pathological process in order to institute appropriate treatment. It is particularly important to be able to recognise severe and limb-threatening problems when evaluating any knee injury.