The possible causes of calf pain are trauma, osteoporosis, osteoarthritis, osteosarcoma and so on. 1. Trauma: If the calf is fractured due to the external force caused by a blow from a stick or a car accident, it may be manifested as a symptom of calf pain inside the bone. 2. Osteoporosis: Osteoporosis is caused by the decrease of bone formation and increase of bone resorption, which leads to the related symptoms, such as weakness, back pain, or even generalized bone pain, so the patients may have the symptoms of calf pain inside the bone. 3. Osteoarthritis: the occurrence of osteoarthritis is related to age, obesity, inflammation, trauma and genetic factors, etc. It is the result of the joint action of many factors, and the phenomenon may occur. 4. Osteosarcoma: the main causes of osteosarcoma include viral infection or exposure to radioactive substances, etc. Its earliest symptom is pain, initially persistent hidden pain, dull pain, and the pain is more obvious at night, so the patient may also experience the symptom. Calf pain inside the bone pain may also have other reasons, it is recommended to go to the regular hospital in a timely manner to improve the relevant examination, clear the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.