骨科英文书籍精读（155）｜掌指关节脱位
METACARPO-PHALANGEAL DISLOCATION
Usually the thumb is affected, sometimes the fifth finger, and rarely the other fingers. The entire finger is suddenly forced into hyperextension and the capsule and muscle insertions in front of the joint may be torn. There are two types of dislocation:
Simple dislocation
The finger is extended about 75 degrees. It is easily reduced by traction, firstly in hyperextension then pulling the finger around. The finger is strapped to its neighbour and early mobilization is encouraged.
Complex dislocation
The avulsed palmar plate sits in the joint, blocking reduction. Furthermore, the metacarpal head can be clasped between the flexor tendon and lumbrical tendon. The finger is extended only about 30 degrees and there is usually a tell-tale dimple in the palm. Very occasionally the fracture can be reduced closed by hyperextending the MCP joint and flexing the IP joints to release the clasp. If this fails, open reduction is required. A dorsal approach is safest. After reduction the joint is stable and should be mobilized in a neighbour-splint.
Chronic instability in the thumb MCP joint
This is treated by a sesamoid arthrodesis. The abductor sesamoid is fused to the underside of the metacarpal neck. This preserves some flexion yet prevents hyperextension. An alternative is formal arthrodesis. The use of a lowprofile compression plate allows early mobilization. The functional result is usually very good.
---from 《Apley’s System of Orthopaedics and Fractures》
重点词汇整理：
pulling the finger around. 拉手指
strap /stræp/n. 带子，皮带，金属带；鞭打v. 用带捆绑，用带固定；包扎；鞭打
lumbrical /'lʌmbrikəl/n. 蚓状肌adj. 蚓状肌的
clasp /klæsp/n. 扣子，钩子；握手vt. 紧抱；扣紧；紧紧缠绕
tell-tale能说明问题的
dimple /ˈdɪmpl/n. 酒窝；浅凹v. 现酒窝；（使）起涟漪
sesamoid /ˈsesəˌmɔɪd/n. 籽骨，种子软骨adj. 籽骨的；芝麻形的
abductor /æbˈdʌktər/n.外展肌; 诱拐者
百度翻译：
掌指骨脱位
通常拇指受到影响，有时是第五根鳍，其他手指很少。整个手指突然被迫过度伸展，关节前面的关节囊和肌肉插入可能会撕裂。错位有两种类型：
单纯脱位
手指伸出约75度。它很容易减少牵引，首先是在过度伸展，然后拉动手指周围。把手指绑在邻居身上，鼓励尽早行动。
复合位错
撕脱的掌板位于关节内，阻碍复位。此外，掌骨头可夹在屈肌腱和腰肌腱之间。手指只伸30度左右，手掌上通常有一个能说明问题的酒窝。极少数情况下，可通过过度延长MCP关节和弯曲IP关节以释放卡环来减少闭合性骨折。如果失败，则需要打开复位。背侧入路最安全。复位后关节是稳定的，应该在邻近的夹板上活动。
拇指MCP关节慢性不稳定
这是通过籽骨关节融合术治疗的。外展肌籽骨融合在掌骨颈部的下侧。这样既保留了一些屈曲，又防止了过度伸展。另一种选择是正式的关节融合术。使用低剖面压缩板可使早期活动。功能结果通常很好。