A patient with kyphosis. Kyphosis is an excessive outward curvature of the spine which causes a hunching of the back, and is the commonest form of acquired bone deformity. Severe cases such as this in young patients occur most frequently as a result of osteochondritis or ankylosing spondylitis, and in the elderly following senile osteoporosis. Treatment depends on the cause, and may include physiotherapy, bracing or spinal osteotomy.