long-term stiffness

例句：

1. 1. The patient's long-term stiffness has improved significantly since the treatment began.
   自从开始治疗以来，患者的长期僵硬症状已经显著改善。
2. 2.The researcher found that long-term stiffness could be a contributing factor to the patient's pain.
   研究者发现，长期僵硬可能是导致患者疼痛的一个因素。
3. 3. The patient's long-term stiffness is a result of years of immobility.
   患者的长期僵硬是由于多年的固定不动造成的。