Kyphoscoliosis. Frontal X-ray image of the spine of a 30-year-old patient with kyphoscoliosis. This spine deformity consists of both lateral (side-to-side) curves (scoliosis) and dorsal (front-to-back) curves (kyphosis). Scoliosis often starts in infancy or adolescence and is more common in girls. The exact cause is unknown, but some cases are birth defects and others have been linked to polio or an injury. Kyphosis usually results in a humped or bowed upper back and can cause the vertebrae (back bones) to eventually collapse. It can be caused by a birth defect or through bad posture. Severe cases of kyphoscoliosis usually have an operation to correct it, where a metal support is inserted to keep the spine in a straight line.