Vertebral compression fractures are breaks in the bones that make up the spine, the vertebrae. The most common cause is osteoporosis, a disease that makes the bones fragile as they lose calcium. Other causes include trauma or injury to the back or tumors that affect the bone. Compression fractures may occur suddenly and cause sharp pain, usually felt in the middle or lower spine. Pain can take weeks or months to fade. With osteoporosis, the fractures may develop slowly, at first without symptoms. The resulting hunched posture can lead to numbness, tingling or weakness, difficulty walking, and loss of bowel or bladder control.