It is a known fact that the knee is a complex structure comprised of cartilage, ligaments and other components that allow movement of two adjacent bones. The joint is lubricated by synovial fluid which allows smooth movement. It is important to note that the fluid within the knee joint can become acutely infected which is called septic arthritis. Remember that the knee is one of the usual sites where joint infection can occur. To learn to recognize and manage knee injuries and conditions including knee joint infection, sign up for a class in first aid today.
What are the symptoms?
The symptoms of knee joint infection or septic arthritis includes severe joint pain, high fever, redness, swelling and warmth of the skin overlying the joint as well as diminished joint movement. In some cases, joint effusion initially occurs which is commonly called as water in the knee. Children with knee joint infection appear sick, irritable and have diminished appetite.
What are the possible causes?
There are various ways in which bacteria spreads into the joint space and cause an infection which includes the following:
- Direct trauma the penetrates into the knee
- Spread from an infection situated close to the knee such as cellulitis or deeply embedded skin infection
- Spread of a bacterial infection via the bloodstream or bacteremia
The other risk factors for the development of knee joint infection include diabetes, conditions that weaken the immune system and conditions that involve the joints such as rheumatoid arthritis.
Diagnosing knee joint arthritis
The evaluation of the fluid inside the knee is vital in order to determine a diagnosis as well as identifying the causative bacteria. The doctor will inject a needle under the kneecap to aspirate the fluid. The fluid is sent to the laboratory for culture and to evaluate the number of white blood cells which is a marker of infection. The other tests that might be carried out to help in determining a diagnosis include MRI of the knee which detects bone infection and a blood culture to determine the presence of bacteria in the bloodstream.
Treatment of knee joint infection
The treatment of knee joint infection involves the drainage of fluid present in the joint space and antibiotics. The drainage of fluid will reduce the pressure on the joint and to identify the causative bacteria. Primarily, medical care involves the use of broad-spectrum antibiotics that are administered intravenously which will eliminate a wide range of bacteria.
Once the bacterium is identified, treatment can be changed to orally taken antibiotics. In case there are no microbes identified, an extended course of intravenous antibiotics are required to completely eliminate the infection.
Considerations to bear in mind
Early identification and proper management of knee joint infection is essential in order to avoid long-term complications. If left untreated, knee joint infection can progress to chronic joint inflammation as well as knee deformity which lead to difficulty in walking and limitations on leg movement.