March 12, 2014
From an excerpt of the Lovell and Winter´s Pediatric Orthopaedics, Volume 1:
“The most common sagital plane deformity in achondroplasia is thoracolumbar kyphosis. The kyphosis is usually decteted at birth and is accentuating when the child is sitting because of the associated hypotonia in this infants. After ambulation begins, the thoracolumbar kyphosis tends to improve. The kyphosis usually does not resolve in children who have more hypotonia. Thoracolumbar kyphosis in 70% of the children and persists in 30%. In one-third of these patients (10%) this kyphosis is progressive.”
Well, lets observe the anatomy of the spine and spinal cord in an average height person:
- Image taken from www.kidport.com
Image from www.spineinfo.co.uk
The spine has 3 moveable curves to it, one at the cervical, one at the upper back/thoracic and one at the lower
back/lumbar. The 4th, or lowest curve, the sacrum/coccyx, has little flexibility. The motion of the three upper curves allows for movement of the body and the healthy spine provides shock absorption. When these curves become immobile or exaggerated with either an increase or decrease in curvature, it may lead to problems with pain and/or decreased function.
In the following image, you can see the anatomy of the spine of a person with achondroplasia:
Image taken from Radiopaedea.org
A Gibbus deformity is a short-segment structural thoracolumbar kyphosis resulting in sharp angulation.
Among many other alterations of the skeletal structure, achondroplasia often presents alterations at the spinal level, which are represented by hyperkyphosis, especially at the thoracolumbar level, with cuneiform deformation of the vertebral bodies, lumbar hyperlordosis caused by the position of the horizontal sacrum and stenosis of the vertebral canal, owing to the pedicles recesses. The treatment can be orthopaedic, by means of corsets or gymnastic, but in many cases, especially in the presence of neurologic injuries, a surgical care may be necessary, with wide decompressive laminectomies, associated with arthrodesis. (1)
In a study published in 2011, the researchers evaluated the cord level and occupancy at thoracolumbar (TL) junction in symptomatic or asymptomatic achondroplasis patients in comparison to an average height population (here I replaced “normal” by” average height”) by magnetic resonance imaging (MRI) (2).
Neurological problems are present in 35-47% of patients with achondroplasia. However, adults usually present with symptoms of spinal stenosis.
These are associated with considerable disability and reduction in the quality of life. The cause of narrow spinal canal in achondroplasia is a disorder of enchondral ossification, which results in early fusion of the pedicles to the vertebral bodies at the neurocentral synchrondosis.
Therefore, the cross-sectional area of spinal canal is consequently narrowed by shortened pedicles and decreased interpedicular distance, which leaves a reduced space available for the neural elements.
In this study, they observed that the spinal cord level was higher in achondroplasia than nonachondroplasia ( p0 =0.003); however, they didn´t see difference in cord level between symptomatic and asymptomatic group ( p0 =0.568). Kyphosis was increasing from nonachondroplasia, asymptomatic and symptomatic patient groups ( p0 <0.001).
These results indicated high level of spinal cord in achondroplasia patients compared to nonachondroplasia individuals. High prevalence of neurological symptoms at TL level in such patients can be associated with high cord level and developing progressive kyphosis at TL level along with degenerative process.
What to do in order to prevent a child with achondroplasia to develop a serious kyphosis?
Early prohibition of unsupported sitting is crucial (3). So the key point is that the initial treatment is delaying sitting in infancy. And if a child whom such prohibition proved to be insufficient, it can be applied the use of bracing.
At the Wheeless’ Textbook of Orthopaedics, it can be read that in 90% of infants, the thoracolumbar kyphosis resolves as they begin to walk. Most flexible kyphotic curves resolve once the patient starts walking.
Bracing it´s useful if flexible kyphosis persists, however, it should be treated w/ extension orthosis (generally after 3 years). Is also indicated for rigid curves with kyphosis greater than 30 deg, preventing surgery.
In relation to bracing with corsets, after my post about the seat made for Clara to prevent the kyphosis, I was delighted to have two other parents talking about their experience with their children.
One father from France but living in the USA since last year, kindly shared his experience with his 3 year-old son bracing.
His son, followed at Necker Hospital, had his spine slightly curved.
“The doctors even hesitated giving him a corset because his spine was going back into place when he was on his tummy. However the corset was necessary to keep his spine straight and not damage the vertebrae.
The back of the corset has many screws. That is because it is adjustable and grows with the child. On the inside they put leather and the screws never touch the skin of the child. Very well done and made. The process for the fitting of the corset was very difficult because they had to hold the child up with about 3 technicians ( we were there of course ) and they wrapped plaster ( like fitting for a body cast ) around the body to get an imprint of his body and form of course. That is the only part that was difficult. After that, the first fitting of the corset helped them mold the plastic at the bottom to conform to his legs so that it doesn’t dig into the skin and they showed us how to put it and take it off (at first it took a while but after about 5 times we were pros ). That is about it, then about every 6 to 8 weeks it got adjusted until he started to walk.
1. Viganò P., Misaggi B., La terapia del paziente acondroplastico. Trattamento delle alterazioni del rachide, Archivio di Ortopedia e Reumatologia, October 2009, Volume 120, Issue 2, pp 6-7
2. Modi HN, Suh SW, Hong JY, Yang JH. Magnetic resonance imaging study determining cord level and occupancy at thoracolumbar junction in achondroplasia – A prospective study. Indian J Orthop 2011;45:63-8
3. Pauli RM, Breed A, Horton VK, Glinski LP, Reiser CA, Prevention of fixed, angular kyphosis in achondroplasia, J Pediatr Orthop, 1997 Nov-Dec;17(6):726-33