骨科英文书籍精读（183）｜骨盆损伤（3）
Pelvic instability
If the pelvis can withstand weightbearing loads without displacement, it is stable; this situation exists only if the bony and key ligamentous structures are intact.
An anterior force applied to both halves of the pelvis forces apart the symphysis pubis. If a diastasis occurs because of capsular rupture, the extent of separation is checked by the anterior sacroiliac and sacrospinous ligaments. Should these restraints fail through the application of a still greater force, the pelvis opens like a book until the posterior iliac spines abut; because the more vertically oriented long posterior sacroiliac and sacrotuberous ligaments remain intact, the pelvis will still resist vertical shear but it is rotationally unstable. If, however, the posterior sacroiliac and sacrotuberous ligaments are damaged, then the pelvis is not only rotationally and vertically unstable, but there will also be posterior translation of the injured half of the pelvis. Vertical instability is therefore ominous as it suggests complete loss of the major ligamentous support posteriorly.
It should be remembered that some fracture patterns can cause instability which mimics that of ligamentous disruption; e.g. fractures of both pubic rami may behave like symphyseal disruptions, and fractures of the iliac wing combined with ipsilateral pubic rami fractures are unstable to vertical shear.（见下图）
---from 《Apley’s System of Orthopaedics and Fractures》
重点词汇整理：
halve/hæv/vt. 二等分；把……减半
diastasis /dai'æstəsis/ 分离
anterior sacroiliac ligaments 骶髂前韧带
posterior sacroiliac ligaments 骶髂后韧带
sacrospinous ligaments骶棘韧带
restraints/rɪ'strents/n. 限制，禁止（restraint的复数）
iliac/ˈɪliˌæk/adj. 髂的；肠骨的；回肠的
spines/spaɪnz/n. [解剖] 脊柱；棘状突起；体刺（spine的复数）
sacrum /ˈseɪkrəm,ˈsækrəm/n. [解剖] 骶骨
tuberous/ˈtuːbərəs/adj.有结节的；隆凸的
pubic /ˈpjuːbɪk/adj. 耻骨的
ischium /'ɪskɪəm/n. [解剖] 坐骨
abut /əˈbʌt/vt. 邻接；毗邻；紧靠vi. 邻接；毗邻；紧靠
sacrotuberous ligaments 骶结节韧带
Vertical instability垂直不稳定
ominous /ˈɑːmɪnəs/adj. 预兆的；不吉利的
mimic/ˈmɪmɪk/vt. 模仿，摹拟n. 效颦者，模仿者；仿制品；小丑
pubic rami耻骨支
rami/'reimai/n. 支（ramus的复数）
symphyseal联合的；耻骨联合；联合腱
ipsilateral /ˌɪpsəˈlætərəl/adj. 身体的同侧的
fractures of both pubic rami may behave like symphyseal disruptions, and fractures of the iliac wing combined with ipsilateral pubic rami fractures are unstable to vertical shear.双侧耻骨支骨折可能表现为耻骨联合断裂，而髂翼骨折合并同侧耻骨支骨折对垂直剪切来说是不稳定的。
百度翻译：
骨盆不稳
如果骨盆能够承受负重负荷而不发生位移，则骨盆是稳定的；这种情况只存在于骨和关键韧带结构完好无损的情况下。
前向力施加于骨盆两半的前向力，分开耻骨联合。如果由于囊膜破裂而发生分离，分离程度由骶髂前韧带和骶棘韧带检查。如果这些约束由于施加更大的力而失效，骨盆会像书本一样张开，直到髂骨后棘邻接；因为更垂直的长柱状骶髂韧带和骶结节韧带保持完整，骨盆仍能抵抗垂直剪切，但旋转不稳定。然而，如果骶髂后韧带和骶结节韧带受损，那么骨盆不仅在旋转和垂直方向上不稳定，而且受伤的半个骨盆也会向后平移。因此，垂直不稳定是不祥的，因为它意味着主要韧带支持完全丧失后方。
需要记住的是，一些骨折模式可能会导致类似韧带断裂的不稳定；例如，双侧耻骨支骨折可能表现为耻骨联合断裂，而髂翼骨折合并同侧耻骨支骨折对垂直剪切来说是不稳定的。