骨质疏松症是由于破骨细胞活动过度导致的骨量减少。

Osteoporosis is caused by excessive ___osteoclastic activity leading to bone loss.

骨质疏松患者的骨骼显示出明显的破骨细胞活动迹象。

The bones of osteoporosis patients show clear signs of ___osteoclastic activity.