Spontaneous fractures are common in the elderly and are fractures with no obvious history of trauma. It is mainly distinguished from osteochondrosis, myeloma, osteogenesis imperfecta, and various cancerous bone diseases. 1. Chondromalacia: especially increased organic matrix of bone, but impaired mineralization occurs. There is often a clinical history of gastrointestinal malabsorption, steatorrhea, history of major gastrectomy, or history of renal disease. Early skeletal X-rays are often not easily distinguished from osteoporosis. However, if pseudo-fracture lines (Looser’s bands) or skeletal deformities are present, the disease is mostly osteochondrosis. Biochemical changes are more obvious than osteoporosis. (1) Osteomalacia due to vitamin D deficiency is often associated with low blood calcium and phosphorus, increased blood alkaline phosphatase, and decreased urinary calcium and phosphorus. (2) Sexual bone lesions are mostly seen in renal tubular lesions, and blood phosphorus may be normal or high if there is also a glomerular lesion. Because of low blood calcium and high blood phosphorus, patients have secondary hyperparathyroidism, so the x-ray presentation is actually a mixture of osteochondrosis and systemic fibrous osteitis. In chronic uremic fashion, it can be accompanied by osteosclerosis. 2, myeloma: the typical patient’s skeletal X-ray manifestation often has a clear edge of decalcification, which must be distinguished from osteoporosis. Patients have normal blood alkaline phosphatase, variable blood calcium and phosphorus, but often have increased plasma globulin (immunoglobulin M) and coaguloprotein in urine. 3. Congenital osteogenesis imperfecta: This may be due to the low production of bone matrix by osteoblasts, resulting in osteoporosis. Calcium, phosphorus and alkaline phosphatase in blood and urine are normal. Patients often have other congenital defects, such as deafness. 4.Metastatic cancerous bone lesion: clinically there is a primary cancer manifestation, blood and urine calcium is often increased, accompanied by urinary stones. bone erosion is seen on X-ray.