Osteomyelitis 骨髓炎
Osteomyelitis is an inflammation of bone caused by an infecting organism. It may remain localized,or it may spread through the bone to involve the marrow,cortex,periosteum,and soft tissue surrounding the bone. 化脓性骨髓炎是一种常见病，病因为化脓性细菌感染，它涉及骨膜、骨松质、骨密质与骨髓组织。
acute suppurative osteomyelitis急性血源性骨髓炎

Acute hematogenous osteomyelitis is the most common type of bone infection and is commonly seen in children. In children the metaphyses of rapidly growing long bones are most frequently involved.The infection causes an inflammatory reaction,local ischemic necrosis of the marrow and then bone,and subsequent abscess formation. 在急性化脓性骨髓炎中，急性血源性骨髓炎最多见；约80%以上为12岁以下的儿童，男女比例约为4：1。长骨干骺端为好发部位，其中以胫骨上下端，股骨下端及肱骨上端最多见。其他骨骼也可发生，但较少见。

Bacteremia is an almost daily event in childhood,and other etiological factors, such as localized trauma or debilitation from a chronic illness,malnutrition, or inadequacy of the immune system, must be present for the infectionto develop. 在急性血源性骨髓炎发病前，身体其他部位常有明显或不明显的感染性病灶，当处理不当或机体抵抗力降低时，感染灶内的致病细菌经血液循环至骨内停留而引起骨组织的急性感染。
As the abscess increases in size, intramedullary pressure increases; this causes more bone to become ischemic, and eventually purulent material escapes through the cortex into the subperiosteal space and forms a subperiosteal abscess. If inadequately treated,this process eventually results in extensive sequestra. Pathophysiology of hematogenous seeding. When under pressure,exudate or abscess can extend through Volkmann canals into subperiosteal region and from there into medullary cavity or epiphysis. 大量的细菌停滞在长骨的干骺端渗出形成脓肿，并向各方向扩散。