Many people wonder if they have a bad bone in their painful area when they are in great pain. This is because everyone knows that it hurts after an injury, especially if it is a fracture. It is necessary to go to the hospital to see a doctor. Why does the title of this article say “Why does it not hurt after a bone injury”? No, it is not. Because the common sense we are taught is often wrong. First, we need to know what bone is. Bone is the hardest tissue in the body other than the teeth. It plays a supporting role in the body. Without the support of bone, a person would be a mass of flesh. Bone cells come together, much like eggs in a certain arrangement. However, the bone “eggshell” is very thick and fused to each other. What we usually call bone is the fused “eggshell”. Osteocytes are not hard, but live in the gaps of the “eggshell” and are nourished by the fluid contained in the bone tissue (this fluid is permeated from the soft tissue outside the bone). When osteocytes have a lot of content, they cannot be completely penetrated by X-rays and appear white (high density) on X-rays. When there are few bone cells, they can be penetrated by X-rays and appear grayish-black on X-rays (low density), leaving only the bone “eggshell” impervious to X-rays. This is called osteoporosis. Therefore, osteoporosis is a reduction in the content of the bone cell fluid, not a reduction in the “eggshell” (osteocalcin). The claim that calcium supplements treat osteoporosis is unjustified. Because the bone cells are very tightly packed. No other tissues are allowed to enter. So there are no nerve-receiving sensory cells in the bone tissue. Where there are no nerve-receiving cells, no pain can be felt. Therefore, we can know that whether the bone is dense or lax, the bone does not hurt. The perception that osteoporosis is the source of pain throughout the body is wrong. Bone tissue, like other tissues, can become edematous when subjected to external forces. Because it is more dense than other tissues in the body, its swelling is slowest, often taking two to three years to resolve. In clinical practice, bone edema can still be seen through MRI after two or three years, when the pain from the injury has long disappeared. So it is inaccurate for many doctors to use MRI to determine whether a bone injury is fresh or old (because no one gets an MRI before an injury to prove there is no injury). Second, the source of pain. The source of all physical pain is outside of the bone. The soft tissues outside of the bone contain sensory collecting structures for nerves – receptors – nerve endings. Nerve endings can extend to any corner of the soft tissues of the body. So if you touch any part of the body, you will feel it. A sensation that is too strong is pain. Bone is what supports the body. After a fracture, the muscles around the bone are stretched and deformed, resulting in failure to support it properly, which can injure the periosteum and other soft tissues that encase the bone, causing bleeding and swelling of these tissues, stimulating the receptors of the nerve endings and making us feel painful. The joints that form between the bones allow us to make different body postures. The soft tissues that encase the joints are pulled by forces in different directions as we assume different postures, and when they are repeatedly pulled by forces, they become injured and swollen. The edema squeezes the nerve endings and makes us feel pain. For example, long distance walking, repeated bending and straightening of the knee joint will end up with knee pain. Many elderly people who insist on walking exercise have swollen and painful hips, knees and ankles for this reason. In some cases, the joint surfaces of the bone are injured and necrotic over time. The joint surface is destroyed. Although it does not cause pain (for the reasons stated earlier), the structural changes lead to abnormal forces and damage to the soft tissues that encase the bone and joint. This is the cause of pain in all abnormal joint structures. As the saying goes, “I don’t kill the bones, but the bones die because of me”. Although the bone does not hurt, the bone form changes, causing the soft tissues around the joint to move with uncoordinated force and injury, causing joint pain. Many elderly people have pain in their joints when they do not move. The bone in the body is still supporting the limbs of the elderly at this time, and this situation proves that “bone does not hurt. We often go to the doctor for joint pain. Many doctors will ask us not to move during the pain. This request is often taken less seriously than giving medication. In fact, the only effective way to treat pain is to “not move during pain”. Doctors prescribe pain medication, and no medication is better than “don’t move during pain”. By not moving, the injured soft tissues around the joint will have time to recuperate and the pain will disappear. The purpose of this article, “Bones don’t hurt”, is to help all people who have pain to understand the causes of pain in the body. Bone is usually not a problem, except for pain where the bone cannot support the normal shape of the body, where bone damage should be considered. In addition, it also shows that many common bone diseases, such as cervical spondylosis, knee disease, lumbar spondylosis ankle disease, etc., are false grievances. In fact, not only the bone will not be painful after injury, others are cartilage, joint surface cartilage, meniscus, intervertebral disc, etc., will not be painful after injury. The reason is the same, because they do not have internal – “nerve receptors”.