The knee joint is a frequent source of problems requiring the attention of an orthopaedic surgeon.
The joint is primarily formed by the two large bones of the lower limb, the femur (thigh bone) and the tibia (shin bone). The patella (kneecap) articulates with the femur at the front of the knee. The fibula joins with the tibia on the lateral (outside) side of the knee.
Together, the femur, tibia and patella make three compartments (medial, lateral and patellofemoral). Each of the bones has a bearing surface of articular or hyaline cartilage. In addition there is a meniscus in each of the medial and lateral compartments. The
menisci are like cushions or spacers and are made of fibrocartilage. They often simply referred to as the cartilages.
Arthritis is a general term covering more than 100 different conditions.
The term arthritis literally means inflammation of a joint, but is generally used to describe any condition in which there is damage to the cartilage. Inflammation is the body's natural response to injury. The warning signs that inflammation presents are redness, swelling, heat and pain.
The cartilage is a padding that absorbs stress. The proportion of cartilage damage and synovial inflammation varies with the type and stage of arthritis. Usually the pain early on is due to inflammation. In the later stages, when the cartilage is worn away, most of the pain comes from the mechanical friction of raw bones rubbing on each other.
Injuries come in a number of forms, the most common involving damage to the ligaments which require repair or reconstruction.
Recurrent Patellar Dislocation
Patellar dislocation occurs when the patella or kneecap slips out of its groove on the front of the lower end of the femur (thigh bone). A subluxation is a partial dislocation in which the patella slips but immediately goes back into place. In a true patellar dislocation the patella goes back into place as a distinct movement, usually when the knee is straightened. This may occur seconds to hours after the dislocation. The term knee dislocation is often used for a patellar dislocation but this is incorrect. A knee dislocation is a major injury and involves the tearing of the main ligaments around the knee.