Scheuermann’s kyphosis is an increase of the normal thoracic curve (20-40 degrees). The lumbar spine has to accomodate this increased kyphosis by increasing the lumbar lordosis (backwards curve) to balance the torso over the pelvis. Without this accomodation of the lumbar spine, you would be thrown off forward when walking.
The Wallis device (like the X-Stop or Coflex devices) is an interpositional device that sits between the spinous processes and flexes these segments (bends them forward). By definition, this flexion reduces the lumbar lordosis and reduces your ability to accomodate the increased thoracic curve.
Generally, I am not a fan of these interpositional devices as the problem they attempt to solve (stenosis of the central canal, lateral recess or foramen) can be solved by a surgical decompression of these areas without the need to flex the two vertebra and the attendent problems that this can cause.
Also, these interpositional devices can and do erode into the spinous processes and become non-functional after some period of time.
The thoracic Scheuermann’s surgery will reduce the need for the lumbar spine to extend to accomodate the increased thoracic kyphosis. I cannot comment on the effects of instability in the lumbar spine after the thoracic surgery without a thorough history, physical examination and evaluation of your images.
Dr. Corenman
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.