A common complaint, usually minimal and causing no discomfort, although if more than a centimetre is involved there may be back problems. If the deviation is greater still it causes abdominal slant combined with scoliosis (sideways curvature of the spine). The condition can be congenital, but is usually caused by a fracture, bone or joint inflammation, bone tumours or diseases that lead to damage to the cartilaginous plates during growth; congenital dislocation of the hip joint may also be involved. A small discrepancy can be corrected by building up the heel of one shoe; larger differences can be corrected by arresting growth of cartilaginous plates in the longer bone. Clamps are used to connect bone on either side of the cartilaginous plate (epiphysiodesis).