1. ACUTE SUPPURATIVE ARTHRITS Cause and pathology The causal organism is usually Staphylococcus aureus; in children under the age of 3 years Haemophilus influenza is fairly common. The joint is invaded through 1- a penetrating wound 2- as a complication of intraarticular injection 3- as a complication of arthroscopy

2. Clinical features Typical features are acute pain and swelling in a single large joint- commonly the hip in children and the knee in adults. However, any joint can be affected, the patient becomes ill, with a rapid pulse and swinging fever.

3. Many of the local sign maybe elicited only in superficial joints. The skin looks red, the joint is held flexed and it is swollen. There is superficial warmth, diffuse tenderness and fluctuation. All movement are grossly restricted and often completely abolished by pain and spasm (pseudoparesis) In newborn infants the emphasis is on septicaemia rather than joint pain. The baby is irritable and refuses to feed; there is a rapid pulse and sometimes a fever. Infection is usually suspected, but it could be anywhere, the joints should be carefully felt and moved to elicit the local signs of warmth, tenderness and resistance to movement. The umbilical cord should be examined for a source of infection. An inflamed intravenous infusions site should always excite suspicion. NOTE: pseudoparalysis ? If the baby is distressed and won”t move his/her leg, think of hip infection

4. Ultrasonography is the most reliable method for revealing a joint effusion in early cases . Both hips should be examined for comparison . Widening of the space between capsule and bone of more than 2 mm is indicative of an effusion, which may be echo-free (perhaps a transient synovitis) or positively echo genic (more likely septic arthritis).