http://www.footclinic.asia/low backpain and orthotics.html Back pain versus leg length difference! A leg length discrepancy can be congenital or a trauma / accident caused. But a leg length difference may also arise in the growth in children. Abnormal foot teeth or bone structures can also give a leg length difference. For example if one foot is flatter or more inwardly than the other foot. Postoperative leg length difference. In most cases after a knee or hip surgery or fracture!