If a fusion occurs, in order to retain flexibility, think about and use proper posture, says Dr. Ward. "You want fusion to occur in an upright position, not a 'bent-down' position. People learn to accommodate their limitation with workarounds, as it evolves slowly over decades. The neck, versus the low back for example, has the greatest functional problems and can cause trouble when driving. Fusion in the thoracic spine can cause limitations in breathing capacity and impair aerobic activity."