Bone density reduction usually refers to the reduction of bone strength, bone calcium ion loss, the details are as follows: a. For young patients, bone density reduction is usually due to the occurrence of injuries to the upper and lower extremities, requiring prolonged braking, and reduced muscle contraction after braking, which can lead to a reduction in bone density, such reduction is a short-term performance, and with the recovery of the disease, bone density will also return to normal. Second, for elderly patients, reduced bone density usually means osteoporosis, the patient is mainly due to age, the bones lose a lot of calcium, resulting in a decrease in bone density, can be improved by anti-osteoporosis drugs to improve osteoporosis, such as Calcium D, Goldilocks, etc., usually also to strengthen nutrition, enhance physical exercise, and eventually be able to improve bone density.