FRACTURED HEAD OF RADIUS
Radial head fractures are common in adults but are hardly ever seen in children (probably because the proximal radius is mainly cartilaginous) whereas radial neck fractures occur in children more frequently.
Mechanism of injury
A fall on the outstretched hand with the elbow extended and the forearm pronated causes impaction of the radial head against the capitulum. The radial head may be split or broken. In addition, the articular cartilage of the capitulum may be bruised or chipped; this cannot be seen on x-ray but is an important complication. The radial head is also sometimes fractured during elbow dislocation.
Clinical features
This fracture is sometimes missed, but tenderness on pressure over the radial head and pain on pronation and supination should suggest the diagnosis.
X-ray
Three types of fracture are identified and classified by Mason as:
Type I An undisplaced vertical split in the radial head
Type II A displaced single fragment of the head
Type III The head broken into several fragments (comminuted).
An additional Type IV has been proposed, for those fractures with an associated elbow dislocation.
Special radial head views, rather than simple PA and lateral views are needed to fully assess the fracture. The wrist also should be x-rayed to exclude a concomitant injury of the distal radioulnar joint, which would signify damage to the interosseous membrane (acute longitudinal radioulnar dissociation).
Treatment
An undisplaced split (Type I)
Worthwhile pain relief can be achieved by aspirating the haematoma and injecting local anaesthetic. The arm is held in a collar and cuff for 3 weeks; active flexion, extension and rotation are encouraged. The prognosis for this injury is very good, although there is often some loss of elbow extension.
A single large fragment (Type II)
If the fragment is displaced, it should be reduced and held with one or two small headless screws.
A comminuted fracture (Type III)
This is a challenging injury. Always assess for an associated soft tissue injury:
Rupture of the medial collateral ligament;
Rupture of the interosseous membrane (Essex Lopresti lesion);
Combined fractures of the radial head and coronoid process plus dislocation of the elbow – the ‘terrible triad’.
If any of these is present, excision of the radial head is contra-indicated; this may lead to intractible instability of the elbow or forearm. The head must be meticulously reconstructed with small headless screws or replaced with a metal spacer. A medial collateral rupture, if unstable after replacing or fixing the radial head, should be repaired.
Radial head excision usually gives a good long-term result if there are no contraindications; however, wrist pain from ulnar head impaction, valgus instability of the elbow and trochleo-olecranon arthritis can develop.
Complications
Joint stiffness is common and may involve both the elbow and the radioulnar joints. Even with minimally displaced fractures the elbow can take several months to recover, and stiffness may occur whether the radial head has been excised or not.
Myositis ossificans is an occasional complication. Recurrent instability of the elbow can occur if the medial collateral ligament was also injured and the radial head excised.
---from 《Apley’s System of Orthopaedics and Fractures》
重点词汇整理：
outstretched /ˌaʊtˈstretʃt/adj. 伸开的；扩张的v. 伸出；扩大；伸展得超出…的范围（outstretch的过去分词形式）
pronate /'pronet/vt. 旋前；将手掌向下或向后转动vi. 俯身；伏身
capitulum /kə'pɪtʃʊləm/n.桡骨小头 [组织][生物] 小头，骨端；[植] 头状花序
supination /,sju:pi'neiʃən/n. 旋后；反掌姿势
concomitant /kənˈkɑːmɪtənt/n. 伴随物adj. 相伴的；共存的；附随的
the distal radioulnar joint桡尺远侧关节 /,reidiəu'ʌlnə/adj. 桡尺骨的
the interosseous membrane骨间膜
membrane /ˈmembreɪn/n. 膜；薄膜；羊皮纸
longitudinal /ˌlɑːndʒəˈtuːdnl/adj. 长度的，纵向的；经线的
dissociation /dɪˌsoʊsiˈeɪʃn,dɪˌsoʊʃiˈeɪʃn/
n. 分解，分离；分裂
aspirate/'æspərət/n. 送气音；抽出物
adj. 送气音的vt. 送气发音；吸入
haematoma /,hi:mə'təumə, ,hem-/n. [病理] 血肿
local anaesthetic局部麻醉 /ˌænəsˈθetɪk/n. 麻醉剂；麻药adj. 麻醉的
prognosis /prɑːɡˈnoʊsɪs/n. [医] 预后；预知
Rupture of the medial collateral ligament; 内侧副韧带断裂;
collateral /kəˈlætərəl/adj. 附属的；旁系的；并行的n. 抵押品，担保品；旁系亲属
coronoid process[解剖] 冠突；[解剖] 喙突 /'kɔrənɔid/adj. 冠状的；喙状的
contraindications /ˌkɑːntrəˌɪndɪˈkeɪʃn/
n. [医] 禁忌症；禁忌征候
valgus/'vælɡəs/n. 外翻足的人；外翻足adj. 外翻的
trochleo-olecranon arthritis 滑车鹰嘴关节炎
Myositis/,maiəu'saitis/n. [外科]骨化性肌炎；肌炎，肌肉发炎
百度翻译：
桡骨头骨折
桡骨头骨折在成人中很常见，但在儿童中很少见（可能是因为桡骨近端主要是软骨），而桡骨颈骨折在儿童中更常见。
伤害机制
伸展肘部并且前臂前倾的伸展手上的跌倒导致桡骨头撞击头部。径向头可以分开或断开。另外，头部的关节软骨可能会瘀伤或碎裂；这在x射线上看不到，但是是重要的并发症。radial骨头有时在肘关节脱位时也会断裂。
临床特征
这种骨折有时会漏诊，但桡骨头压力的压痛和旋前和旋后的疼痛应该提示诊断。
X射线
Mason确定并将三种类型的骨折分类为：
类型I径向头中未移位的垂直分裂
类型II头部移位的单个碎片
III型头部分成几个碎片（粉碎）。
对于伴有肘关节脱位的骨折，还提出了另一种IV型。
需要特殊的径向头视图，而不是简单的PA和侧视图来充分评估骨折。手腕也应该进行x光检查，以排除远端桡尺关节的伴随损伤，这将意味着骨间膜的损伤（急性纵向放射性尺骨解离）。
治疗
一个不可移位的分裂（类型I）
通过抽吸血肿和注射局部麻醉剂可以实现有价值的疼痛缓解。手臂保持在衣领和袖口中3周；鼓励主动屈曲，伸展和旋转。这种损伤的预后非常好，尽管肘部伸展经常会有一些损失。
一个大片段（II型）
如果碎片移位，应将其缩小并用一个或两个小型无头螺钉固定。
粉碎性骨折（III型）
这是一个具有挑战性的伤害。始终评估相关的软组织损伤：
内侧副韧带断裂；
骨间膜破裂（Essex-Lopresti病变）；
桡骨头和冠状突的骨折加上肘部脱位-“恐怖三联征”。
如果存在这些中的任何一种，则禁忌桡骨头的切除；这可能导致肘部或前臂的难治性不稳定。头部必须用小型无头螺钉精心重建或用金属垫片代替。如果在更换或固定桡骨头后不稳定，则应修复内侧侧支破裂。
如果没有禁忌症，桡骨头切除通常会产生良好的长期效果；但是，尺骨头撞击会导致手腕疼痛，肘部外翻不稳和滑车鹰嘴关节炎。
并发症
关节僵硬是常见的，可能涉及肘关节和尺桡关节。即使骨折移位最小，肘部也可能需要几个月才能恢复，无论桡骨头是否切除，都可能发生僵硬。
骨化性肌炎是偶发的并发症。如果内侧副韧带也受伤并切除桡骨头，则可能发生肘部反复不稳定。
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