knee joint flexion and extension exerciser

例句：

1. 1. This knee joint flexion and extension exerciser helps to strengthen the muscles around the knee joint.
   这个膝关节屈伸锻炼器有助于加强膝盖周围的肌肉。
2. 2. The patient was using this knee joint flexion and extension exerciser for rehabilitation after an accident.
   这位病人在使用膝关节屈伸锻炼器进行康复治疗，以恢复受伤后的腿部功能。
3. 3. The exerciser is designed to help people with limited mobility, such as those with arthritis or osteoporosis, toimprove their range of motion in their knees.
   这种锻炼器旨在帮助行动不便的人，如关节炎或骨质疏松症患者，改善其膝盖的关节活动范围。