AVASCULAR NECROSIS
Certain regions are notorious for their propensity to develop ischaemia and bone necrosis after injury (see also Chapter 6). They are: (1) the head of the femur after fracture of the femoral neck or dislocation of the hip); (2) the proximal part of the scaphoid (after fracture through its waist); (3) the lunate (following dislocation) and (4) the body of the talus (after fracture of its neck). Accurately speaking, this is an early complication of bone injury, because ischaemia occurs during the first few hours following fracture or dislocation. However, the clinical and radiological effects are not seen until weeks or even months later.
Clinical features
There are no symptoms associated with avascular necrosis, but if the fracture fails to unite or if the bone collapses the patient may complain of pain. X-ray shows the characteristic increase in x-ray density, which occurs as a consequence of two factors: disuse osteoporosis in the surrounding parts gives the impression of ‘increased density’ in the necrotic segment, and collapse of trabeculae compacts the bone and increases its density. Where normal bone meets the necrotic segment a zone of increased radiographic density may be produced by new bone formation.
Treatment
Treatment usually becomes necessary when joint function is threatened. In old people with necrosis of the femoral head an arthroplasty is the obvious choice; in younger people, realignment osteotomy (or, in some cases, arthrodesis) may be wiser. Avascular necrosis in the scaphoid or talus may need no more than symptomatic treatment, but arthrodesis of the wrist or ankle is sometimes needed.
---from 《Apley’s System of Orthopaedics and Fractures》P720
重点词汇整理：
AVASCULAR NECROSIS缺血性坏死
notorious /noʊˈtɔːriəs/adj. 声名狼藉的，臭名昭著的
propensity/prəˈpensəti/n. 倾向，习性；癖好，偏爱
ischaemia and bone necrosis缺血和骨坏死 /is'ki:miə/n. 局部贫血
scaphoid /'skæfɔɪd/n. 舟状骨adj. 船状的，船形的
lunate /'lʊnet/n. （史前的）半月形工具；月状骨
talus /'teləs/n. 距骨；踝；斜面
density /ˈdensəti/n. 密度
disuse osteoporosis废用性骨质疏松症
necrotic segment坏死的部分
trabeculae 美 /trə'bɛkjələ/n. 骨小梁；萨列阿横梁
arthroplasty/,ɑ:θrəu'plæsti/关节置换术
realignment osteotomy调整截骨术
arthrodesis /ɑ:'θrɔdəsis/n. [外科] 关节固定术
symptomatic treatment对症治疗
百度翻译：
缺血性坏死
某些区域因其损伤后易发生缺血和骨坏死而臭名昭著（另见第6章）。它们是：（1）股骨颈骨折或髋关节脱位后的股骨头；（2）舟骨近端（腰部骨折后）；（3）月骨（脱位后）；（4）距骨体（颈部骨折后）。准确地说，这是骨损伤的早期并发症，因为缺血发生在骨折或脱位后的最初几个小时。然而，直到数周甚至数月后才出现临床和放射效应。
临床特征
没有与缺血性坏死相关的症状，但如果骨折无法愈合或骨头塌陷，患者可能会抱怨疼痛。X射线显示X射线密度的特征性增加，这是由于两个因素造成的：周围部分的废用性骨质疏松症在坏死区给人留下“密度增加”的印象，小梁塌陷使骨致密并增加其密度。在正常骨与坏死节段的交界处，新骨形成可能会产生放射密度增加的区域。
治疗
当关节功能受到威胁时，治疗通常是必要的。在股骨头坏死的老年人中，人工关节置换是明显的选择；在年轻人中，重新定位截骨术（或在某些情况下，关节融合术）可能更明智。舟骨或距骨的缺血性坏死可能只需要对症治疗，但有时需要腕关节或踝关节融合术。
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