Our literature review indicates that our patient the youngest one diagnosed with chondroblastoma in the talus.

本例是一十八个月大，灶左踝骨，较罕见，手术前诊断也较困难，故加以分析讨论。

The os trigonum is an accessory bone of the foot, locates at the posterolateral tubercle of the talus, and occures in about 7% of population.

摘要附三角骨骨之后外侧节，是脚部的附属骨之一，出现百分之七的正常人中。