 PRESENTATION Pain with overhead activities 前臂上举疼痛 MR images demonstrate an extra ossicle known as os acro- miale between acromial process and the clavicle. MR图像上，肩峰与锁骨间见一骨化中心就是肩峰骨。 FINDINGS · Calci?c tendinosis of supraspinatus tendon冈上肌腱钙化性肌腱炎 Calcium hydroxyapatite deposition in the tendon and or the bursa of supraspinatus is associated with severe pain and tendinosis. 可见严重疼痛和肌腱炎相关的肌腱内羟磷灰石沉积或是冈上肌滑囊。 · Curved acromion (type II)弯曲肩峰 This curve-shaped acromion process (43% of shoulders) is associated with higher incidence of impingement of the rotator cuff tendon. 这一类型的肩峰与肩袖撞击综合征高度相关。 · Hooked acromion (type III)钩状肩峰 This hook-shaped acromion(40% of shoulders) has the highest association with impingement of the rotator cuff tendon. 这一类型的肩峰与肩袖撞击综合征高度相关。 COMMENTS Os acromiale is an anatomical condition resulting from thefailure of an anterior acromial ossi?cation center to fuse to the acromial process. At age 15, three separate ossi?cation centers appear in the acromion: preacromion, mesacromion,and metacromion. These centers should fuse by age 22 to 25. Failure of one of these three ossi?cation centers causes one of four subtypes of os acromiale: preacromion, mesacro- mion, metacromion, and basiacromion types. The most common sites of fusion failure are at the mesacromion and metacromion. 肩峰骨是前肩峰骨化中心与肩峰融合失败所致的 解剖变异。15岁时，肩峰处有三个独立的骨化中 心： preacromion, mesacromion,and metacromion. 这些中心应于22-25岁融合一体。融合失败导致 四种类型的肩峰骨：preacromion, mesacromion, metacromion, and basiacromion types. 最常见的两种是：mesacromiion和metacromion。 Os acromiale is a relatively rare condition. Its frequency has been documented in radiographic and anatomical studies to be between 1% and 15%, of which 62% are bilateral. Patients may show impingement-like symptoms including chronic pain, stiffness, and weakness of the shoulder with limited range of motion. They will also experience localized tenderness. Os acromiale has strong association with rotator cuff tear. The double-density sign on a standard anteroposterior radiograph of the shoulder and a cortical irregularity on the supraspinatus outlet view are highly suggestive of an os acromiale. MR images of the shoulder of patient with os acromiale demonstrate that the anterior portion of the acromion is ununited with the remainder of the acromion. Os acromiale is often mistaken for a fracture on the axial view。 肩峰骨是一种相对少见的解剖变异。影像和解剖学中 发病率约1%--15%，62%发生于双侧。病人表现为 撞击综合征的症状：慢性疼痛、僵硬、 肩关节无力并活动受限；也可以表现为固点压痛。 肩关节正位片双密度征和冈上肌出口位片肩峰皮质 不规则高度提示肩峰骨。MR图像 显示肩峰前部分未与其余部分融合。肩峰骨轴位常 误诊为骨折。  冈上肌钙化性肌腱炎  |
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