Considered as the most dangerous form of acute arthritis, septic arthritis is caused by a bacterial infection in the joint cavity. Usually there is a primary site of infection from where bacteria spread. The site of infection is often along adjacent bone or soft tissue. Bacterial spread is usually through the bloodstream going to the joints. It is estimated that in the general population of 100,000 people, about 2 to 10 of them suffer from septic arthritis.

In medical terms, septic arthritis has also been considered as a medical emergency. This is because it tends to cause severe damage to the bones and cartilages. It is also capable of resulting in to a septic shock. This is a fatal condition!

Septic arthritis comes suddenly with symptoms like intense pain, inflammation and swelling of the affected joint. These symptoms are often accompanied with fever and chills. The infected joint may cause voluntary immobility of the limb. Septic arthritis often affects large joints; specifically the knee. New born or infants who are affected with acute septic arthritis may become irritable and cry relentlessly whenever there is movement; especially when there is hip involvement. Pain is usually present in the groin, upper thigh and buttocks when septic arthritis affects the hip. In adults, knee involvement affects around 50 percent of all cases. The hips, wrist and ankles are also commonly affected with septic arthritis. Some patients may not show external signs of inflammation. Sometimes there is the presence of polyarthritis before the localization of infection. Muscle spasms are a very common occurrence of septic arthritis.

Septic arthritis can majorly affect a person when certain type of infections organisms such as a bacteria reaches a joint. This bacteria can easily get in to a joint via the blood stream or surgery. An injection or injury can also be a main cause of this type of infection.

If this type of arthritis has affected a baby or young child, then it can be because of hemophilus influenza, staphylococci and gram negative bacilli. People who use intravenous drugs or with diseases that have potential for weakening the immune system such as HIV are also vulnerable to septic arthritis.

Septic arthritis is usually characterized by swelling in the joint, severe or acute pain in the affected area, fever and chills. When this arthritis affects the hip, you may experience pain in the groin area. The pain becomes worse and the patient is unable to walk. The joint is sore to touch. Newborns or infants experience painful movement of the limb and cries when the diaper is changed or gets fever. Young children and adults tend to experience intense joint pain, low-grade fever, joint swelling, joint redness and inability to move the limb with the infected joint. Chills may also occur but in rare cases.