Osteomyelitis in children can be categorized into acute osteomyelitis and chronic osteomyelitis according to the duration of the disease. The specific manifestations are localized severe pain, impaired mobility and other manifestations, as well as deformities, joint ankylosis, cancer and other complications. 1. Primary symptoms (1) Acute osteomyelitis: it mainly manifests as persistent severe pain in the affected limbs, fear of movement, pressure pain, axial percussion pain and circumferential swelling, often accompanied by high fever, coma and other symptoms. Some cases also have symptoms such as irritability, food refusal and weight loss. (2) Chronic osteomyelitis: prolonged inflammatory site pain, pressure pain, abscess rupture can form sinus tracts, sinus tracts long-term flow of pus and odor, long lasting, there may be dead bone discharge, accompanied by the formation of cavities. 2.Complications (1) Deformity: Repeated stimulation of inflammation makes the bone growth abnormal, the length increases or decreases, and the knee joint turns inward or outward deformity occurs. (2) Joint ankylosis: combined with joint inflammation, the joint cartilage will be destroyed and fibrosis, and joint ankylosis and dysfunction may occur. (3) Carcinoma: chronic osteomyelitis abscess will break down and flow out, and the local skin will be irritated repeatedly for a long time, and squamous carcinoma and other lesions will appear, which will be manifested as the change of local skin traits.