Coloured X-ray of the pelvis of a 4 and a half year old boy with the hip deformity coxa vara due to rickets. In coxa vara the angle between the head, which forms part of the hip joint, and the shaft of the femur (thigh bone) is reduced, causing a limp. Rickets (osteomalacia) is predominantly caused by a deficiency in vitamin D, which is required for normal calcium absorption from the gut. It results in poor bone growth and softening of the bones, leading to deformities such as coxa vara and bowlegs. Other deformities can include an enlarged skull, chest deformities, and enlargement of the liver and spleen. Treatment is of the underlying cause, including vitamin D and calcium supplements.