Acute suppurative arthritis is a joint infection that can occur through direct invasion, spread from adjacent bone, or hematogenous spread. In children under 4 years old, common causal organisms include Staphylococcus aureus, Haemophilus influenzae, streptococcus, E. coli, and proteus. Left untreated, the infection can spread and cause bone and cartilage destruction, deformity, or ankylosis. Treatment involves aspirating joint fluid, administering antibiotics, draining thick pus, and splinting the joint to rest it. Complications can include damage to growth plates and epiphyses in children.