The thinning of the anterior border of the third lumbar vertebra may be caused by compression fracture, osteophytes and disc herniation. 1. Compression fracture: it is mostly caused by violent injury or long-term cumulative strain. Due to the compression and deformation of cancellous bone under acute or prolonged pressure, the anterior margin of lumbar vertebrae becomes thin, which may be accompanied by pain and swelling in the lumbar region. 2. Osteomalacia: It is caused by degeneration of intervertebral discs, bulging and tearing of annulus fibrosus, and protrusion of nucleus pulposus, which can lead to deformation of the joints, and it is the most common in L3 and L4, and serious osteophytes will cause degeneration of intervertebral discs and deformation of vertebrae, which can be accompanied by lumbar stiffness and pain. 3. Intervertebral disc herniation: after the degenerative disc lesion, the fibrous ring of the intervertebral disc ruptures and the nucleus pulposus protrudes due to external factors, which leads to the stimulation or compression of the adjacent tissues and produces the symptoms of lumbar and leg pain and numbness, etc. The prolonged compression of the narrowing of the intervertebral space can lead to the thinning of the anterior margin of the vertebral body. The third lumbar vertebral anterior margin thinning phenomenon may also be caused by other factors, it is recommended that patients go to the hospital in a timely manner to carry out the appropriate examination, a clear diagnosis for standardized treatment.