3 years, had made it possible to include 150 children aged 0 to 15 years who have had an X-ray and/or an ultrasound exam.Ultrasounds were performed on a Samsung Medison R3 device equipped with a high-frequency linear probe (7-16 MHz). The morphological examination analyzed the bursae, the joint cavity and capsule, the periosteum, the cortical bones, the soft parts (muscles, fascia and subcutaneous cell tissue). Color Doppler and/ or Energy mapping looked for hyperaemia. She had allowed the puncture of joint fluid, collections, metaphyseal or soft tissue for cytobacteriological examination (CBE).The radiographs, taken on a Colenta bone-lung table, included AP and lateral views, taking the joints above and below in the OM, centered on the joint and taking the bone segments above and below when an SA or OA were suspected. The analysis concerned the metaphysis, the epiphysis, the growth plate, the diaphysis, the joint line, the cortex, the periosteum, the fatty edges and the soft tissues. The parameters studied were: -Anamnestics including age: newborn (0-28 days), infant (1-30 months), small child (31-60 months), big child (72-132 months) and adolescent (144-180 months); gender (male or female); the terrain (sickle cell disease, malnutrition); the existence of an initial trauma; time to diagnosis, -Clinics: fever, deterioration in general condition (AEG), pain, functional impotence, lameness, existence of a portal of entry (PE), local inflammatory signs, joint mobility, patellar shock, -Biological: blood count (CBC), C Reactive Protein (CRP), sedimentation rate (SR), -Bacteriological: germs isolated from blood culture or CBE -Ultrasound: collections (intra-articular, sub-periosteal or soft