[Causes and pathophysiology of infection of the knee joint]

The origin of an infection of the knee joint can be of an endogenous/hematogenous nature or, in posttraumatic cases, of an exogenous nature. Hematogenous infections are found mostly in children, but also in patients with reduced immune functions, e.g. after organ transplantations. Posttraumatic joint infections are caused by open injuries, intraarticular injections, operations, or they can be transmitted from the surroundings. They are relatively rare after accident surgery and orthopedic surgery. Two statements are of special importance for pathophysiology: 1. An intraarticular infection will lead to lesions of the hyaline cartilage within a period of 24 to 48 hours. 2. The substrate exchange is reduced by the reflex immobilization which will result in a additional damage to the cartilage.