spontaneous fracture

例句：

1. 1.He fell down and broke his leg in a spontaneous fracture.
   他摔倒了，腿在一次自发性骨折中断了。
2. 2. The accident was caused by a sudden impact, resulting in a spontaneous fracture of the bone.
   这次事故是由于突然的冲击造成的，导致骨头的自发性骨折。
3. 3. The patient was rushed to the hospital for treatment after sustaining a spontaneous fracture during a fall.
   患者在跌倒后被紧急送往医院接受治疗，因为发生了一次自发性骨折。