Should Adults With Scoliosis Be Braced?
Yes. In many cases, bracing can help reduce scoliosis curvature in adults. A brief review on the reasons bracing is used for scoliosis treatment and an overview about how bone rebuilds itself will help explain why this is so.
Bracing
There are two primary purposes of bracing for treating scoliosis:
1. To stop the curve-forming pressures on the vertebra
2. To reverse and correct any existing vertebra deformity caused by the curvature pressures before bracing treatment began.
The physiologic conditions exist for both adult and child bracing to be effective.
Increased pressures dynamically applied by a brace to the open-wedge side of the vertebra will cause bone to remodel.
Bone Remodeling
Bone is always in the state of remodeling -- reforming itself. In fact, approximately 10% of a person's total bone mass is always in a state of remodeling. There is no age restriction on bone remodeling. However, remodeling of bone occurs at a quicker rate among children and at a slower rate as one ages.
Bone remodeling has been known about for over a century. Julius Wolff published his seminal 1892 monograph on bone remodeling in which he observed that bone is reshaped in response to the forces acting on it.1 Wolff noted that bone is rebuilt more if there are stresses on the bone, less if there are not. His observation of fact became known as Wolff's law.
The physiologic principle behind Wolff's law is that soft tissue and bone respectively heal according to the manner in which they are stressed. Healing tissue responds to stress by reacting along the lines of the given stress. For optimum healing, tissue must be stressed gradually to accept a given force.2 This relationship between the mass and form of a bone to the forces applied to it was also appreciated by Galileo3, who is credited with being the first to understand the balance of forces in beam bending and with applying this understanding to the mechanical analysis of bone.
For centuries, the scientific equipment did not exist to prove that bone remodeling applied to adults as well as children. As a result, the medical community inappropriately applied the physics of the law to children only, as it was believed that bone modeling stopped when a person reached skeletal maturation. However, since 1990, medical evidence has shown that Wolff's law extends to adults as well.4 So, while the medical community has for years accepted bracing for children, the evidence for bracing to be accepted for adults is now clear -- the physiologic principles are the same.
How Bone Remodeling Occurs
Bone remodeling is a dynamic, continuous process that occurs as a result of the two key components of bone tissue and its remodeling: osteoblasts and osteoclasts. Osteoclasts eat away old bone, while osteoblasts create new bone at the site of the old bone.
Osteoclasts are responsible for what is called bone resorption -- the dissolution of mineral crystals along with a breakdown of the bone's matrix. This leaves tunnels within the bone when the bone tissue is destroyed. Osteoblasts deposit new bone tissue in these tunnels, thus forming what is called osteons. These osteons contain their own central blood vessel that supplies nutrients to the rebuilding bone. After the osteoblasts have deposited new bone tissue, they then are termed osteocytes, which continue to maintain the bone.
The interaction of osteoblasts and osteoclasts maintains an approximate steady state through the first half of adult life. In later adult life, bone resorption may predominate slightly, leading to a gradual diminution in bone mass and strength. In the elderly, while remodeling continues, it is slower and less bone may regrow -- thus osteoporosis.5
Bone remodeling is a very powerful force in the body. Medical studies from 1976 have proven that after complete removal of a particular-shaped bone and its replacement with a graft consisting of a completely different bone, the graft becomes remodeled to resemble the original bone.6 This is a powerful example of how dynamic the body is, especially when the conditions exist for the changes to occur. Other examples include bone loss in astronauts and in immobilized patients and more bone growth in stressed regions, such as when a nearby bone is lost, or during fracture repair.
Many relevant observations regarding the phenomenology of bone remodeling have been compiled and analyzed. 7,8 Here are the two most significant findings relevant to the efficacy of bracing as treatment for scoliosis:
**Remodelling is triggered not by principal stress but by "flexure"
**Repetitive dynamic loads placed on bone trigger remodelling; static loads do not.
So, it's easy to see how dynamic bone remodeling applies the vertebra of the spine -- maintain corrective pressures on both sides of the vertebra during motion and they will model into their normal shape. This holds true for children. This holds true for adults.
Bracing For Scoliosis
Bracing for treating scoliosis is the application of repetitive dynamic loads placed on bones to trigger remodeling where curvature has occurred. The process of bone remodeling may take longer the older a person is, and the extent of bone regrowth may lessen as one enters old age, but bracing can frequently help reduce scoliosis curvature in adults.
-References
1. Wolff, J., Das Gesetz der Transformation der Knochen , Hirschwald, Berlin, 1892.
2. Steven R. Tippett, MS,PT,SCS,ATC, and Michael L. Voight, MED,PT,SCS,OCS,ATC., Functional Progressions for Sport Rehabilitation. Published by Human Kinetics, Champlain, IL. Copyright 1995.
3. Galilei, G., Discorsi E. Dimostrazioni Matematiche intorna a due nuove Scienze , pp. 158-172, 1638, Translated by H. Crew and A. deSalvio, Macmillan, NY, pp. 118-134, 1914.
4. Augustus A. White III, MD, and Manohar M. Panjabi, PhD, Clinical Biomechanics of the Spine, Second Edition, 1990, J.B. Lippincott
5. Earl R. Bogoch, MD; Erica Moran, BSc., Can J Surg 1998;41:264-71 From the Orthopaedic Research Laboratory, St. Michael's Hospital -- Wellesley Central Site, University of Toronto, Toronto, Ont. Accepted for publication Dec. 16, 1997
6. Nathan, P.A. and Fowler, A., J. Bone Jnt. Surg ., 58A,719-722, 1976, Remodeling of a metacarpal bone graft in a child..
7. Frost, H. M., Bone remodeling and its relation to metabolic bone diseases, C. Thomas, Springfield, IL, 1973.
8. Frost, H. M., Bone modeling and skeletal modeling errors, C. Thomas, Springfield, IL, 1973.
