Adolescent Idiopathic Scoliosis: Cobb Angle Relative to Overall Balance

1. The definition of a successful orthotic management outcome is generally a stabilization or improvement of the pre-treatment Cobb angle for a patient who had been considered to be at significant risk of progression. The Scoliosis Research Society (SRS) define stabilization as +/- 5 degrees and an improvement as - 6 degrees or more from the pre-treatment Cobb angle. These definitions of successful outcomes are well accepted and used in orthopedics around the world. It is important to define patients suitable for conservative treatment: To prevent over-treatment of potentially minimally or non-progressive curves. To prevent futile treatment of curves where surgery is inevitable. In 2005, the SRS published strict criteria for future brace studies 1 . The purpose of this paper is to allow meaningful comparison of studies carried out with different conservative treatments and to prevent inclusion of inappropriate patients giving false results. The SRS brace study guidelines restrict inclusion criteria to only patients with high risk of progression, and define a minimum two-year post-brace treatment follow-up as an acceptable outcome measurement point. Additionally all recruited patients, including those who are noncompliant, must be counted in the overall percentage outcomes for success or failure. This condition might seem harsh in that it considers as failure any noncompliant patient regardless of outcome as well as patients lost to follow-up, but it does ensure that compliance with the treatment is part of the outcome. Previously, brace studies have been flawed in that they have measured outcomes either at the end of treatment or with very short follow-up. In some studies, outcomes have even been judged in-treatment, which has no validity whatsoever. Defining In-Treatment Goals Definition of in-treatment goals that may ultimately lead to optimal outcomes (two years post brace weaning) must be brace and even curve specific. Oversimplification of this task and the imposition of general rules cannot give optimal outcomes for patients. Initial in-treatment goals by which we may judge potential brace efficiency are not easy to define. The traditional goal of a 50-percent minimum reduction of the pre-treatment Cobb angle and that a larger reduction would be better is now being challenged. Clearly many other factors are involved in producing stabile results post-bracing of which postural balance is only one. SpineCor Dynamic Corrective Bracing seeks to address the neuromuscular as well as the skeletal factors involved in the progression of an idiopathic scoliosis 2,8,9 . The in-treatment objectives of Dynamic Corrective Bracing are very different to those for rigid bracing; a slow progressive reduction in Cobb angle is expected (not necessarily on the day of brace fitting as with rigid braces). Maximum in-brace Cobb angle reductions are normally achieved within six months and may be anywhere between 10-100 percent (not a standard 50 percent as required for rigid bracing). The important difference between SpineCor Dynamic Corrective Bracing and other bracing systems is that the curve reductions achieved in treatment are maintainedpost-treatment even at five-year follow-up 3 . Essentially the Cobb angles archived in treatment are those the patient will end up with at the end of treatment. Comparisons, therefore, of effectiveness in treatment between SpineCor and other braces are not easy to make. Acceptability of the initial dynamic corrective brace fitting Cobb angle reduction is dependent on curve flexibility and therefore potential reducibility. The SpineCor Dynamic Corrective Brace treatment protocol advises a specific radiological method of determining curve flexibility and reducibility. The ultimate treatment goal should be to avoid surgery; beyond this, the measurement of outcomes for all treatments should take into account Cobb angle reduction, postural balance, and cosmesis. 2. The relationship of curve balance to Cobb angle reduction is indeed important since both may impact adult progression and the indication for surgery. There is absolutely no doubt in my mind that we should strive to avoid surgery. Long-term studies now question whether the long-term interests of some patients are better served by surgical fusion or by doing nothing. The question as to whether it is more important to achieve balance or maximum curve reduction during brace treatment is not simple to answer. Generally there should be a balance between the two, and they are not necessarily in conflict with one another, but in certain cases postural balance may be more important than maximum Cobb angle reduction. It is not really possible within the context of this text to detail each and every case where the Cobb angle reduction may be compromised or a compensatory curve created or increased to achieve a better, more stabile postural balance. There are cases where this makes sense within the context of SpineCor Dynamic Corrective Bracing and can be equally true in the context of rigid bracing. 3. In the case of single major right thoracic curves apex T7-T10 with no lumbar compensation and which by definition exhibit a large right lateral shift of the thorax in relation to the pelvis, allowing some lumbar compensation can be beneficial. Such alteration in postural balance could reduce the abnormal mechanical loading of the vertebral growth plates thought to be largely responsible for progression of scoliotic curves. Research 4 by Ian A.F. Stokes, PhD (The Centre for Spinal Studies and Surgery, Queens Medical Centre, Nottingham, NG7 2UH, UK), has produced a hypothesis relating to the etiology of adolescent idiopathic scoliosis (AIS) that has significant implications for future brace design and treatment protocols. While there is no consensus, there is strong evidence to suggest that the initiating factor in AIS is genetic, and several hypotheses have been published on this subject, notably by Caroline Goldberg, MD, 5 and Christine Coillard, MD 6 . Stokes' hypothesis assumes the pre-existing (genetically created 10 ) scoliosis curve initiates mechanically modulated alteration of vertebral body growth that in turn causes worsening of the scoliosis. Stokes used mathematical simulations to test whether the calculated loading asymmetry created by muscles in the scoliotic spine could explain the observed rate of scoliosis increase due to vertebral growth modulation and altered compression. While still the subject of debate, if true, Stokes' mechanical modulation hypothesis does challenge the pathogenesis of progressive AIS generally attributed to the Hueter-Volkmann 7 or Delpech effect on which conventional brace treatment is based. The research of Stokes, Goldberg, and Coillard all points to the need for bracing to have a dynamic effect on the growth plates and to in some way reverse the abnormality of the neuromuscular system created by the scoliosis and its progression. In my past experience, creating compensatory curves in rigid braces eventually leads to a structural deformity. While this compromise might still be better than leaving the patient with very unstable postural balance, this can be avoided using the SpineCor Dynamic Corrective Brace. My experience to date has been the same as the SpineCor research center at Sainte-Justine Hospital, Montreal, Quebec, Canada, in that small compensatory curves created in treatment do not persist as structural curves post-treatment. 4. Research into postural balance versus Cobb angle reduction might well be interesting, but I do not believe this is the direction fundamental research on scoliosis etiology is suggesting bracing should go. I might suggest readers' look at what The International Federation Body on Scoliosis Etiology (IBSE) and its recently introduced Electronic Focus Group (EFG) are doing. The conclusion of Stokes' article (Biomechanical spinal growth modulation and progressive adolescent scoliosisa test of the vicious cycle' pathogenic hypothesis) Scoliosis : 2006, 1:16 reads as follows: "The simulations indicate that a substantial component of scoliosis progression during adolescent growth is biomechanically mediated. It is possible that sustained muscle rehabilitation programs could alter the prevailing spinal loading, since the muscle force analyses [88] indicate that different neuromuscular activation strategies are possible, with differing likelihood of loading the asymmetrically. To avoid the unnecessary treatment of non-progressive curves, a means of identifying progressive curves at an early stage is needed." The SpineCor Dynamic Corrective Brace is such a postural re-education device capable of sustainable (20 hours per day) muscle rehabilitation to alter spinal loading. Development of the SpineCor Dynamic Corrective Brace came out of the fundamental research into the etiopathogenesis of AIS at Sainte-Justine Hospital in the mid-'90s. Over 12 years of clinical studies have shown this approach to be effective providing treatment is initiated before the skeletal deformity is too advanced. Clearly early treatment is important, but at the same time this carries the risk of some unnecessary treatments of non-progressive curves. C.H. Rivard, MD, and Christine Coillard, MD, of Sainte-Justine Hospital have developed methods of evaluating patients at high risk of progression, but these do rely on great experience and high level of skill. Currently another research group at Sainte-Justine is clinically trialing a new test, which promises to clearly identify those patients at certain risk of progression, thus allowing early treatment without risk of unnecessary treatment. Early treatment of idiopathic scoliosis, especially with SpineCor, should give the best possible outcome for the individual patient. This has certainly has been the case in my own clinical experience with SpineCor over the past seven years. 5. Clearly patients could benefit and are crying out for better brace designs. Orthotists are looking for better braces that are more effective and research-based, consider all the progression factors of AIS, are clinically proven, have no side effects, are comfortable and unobtrusive to wear, and allow better compliance. While some misconceptions still exist about SpineCor treatment, it does work, patients prefer it, and it is available in the United States. For further information on the SpineCor Dynamic Corrective Brace, contact Becker Orthopedic, 635 Executive Drive, Troy, MI 48083; 800.521.2192; www.beckerorthopedic.net Andrew J. Mills, CO (UK), is managing director of the SpineCorporation Limited, UK ( www.spinecorporation.com ) Editor's note: This article is for reader information only. The O&P EDGE does not endorse any particular product or service. References Richards, B. S., R. M. Bernstein, C. R. D'Amato, and G. H. Thompson, 2005, Standardization of criteria for adolescent idiopathic scoliosis brace studies: SRS Committee on Bracing and Nonoperative Management: Spine , v. 30, no. 18, p. 2068-2075. Ref. Type: Journal. Ref ID: 78 Coillard, C., M. A. Leroux, J. Badeaux, and C. H. Rivard, 2002, SPINECOR: a new therapeutic approach for idiopathic scoliosis: Stud.Health Technol.Inform ., v. 88, p. 215-217. Ref. Type: Journal. Ref ID: 19 Coillard, C., M. A. Leroux, K. F. Zabjek, and C. H. Rivard, 2003, SpineCor--a non-rigid brace for the treatment of idiopathic scoliosis: post-treatment results: Eur.Spine J , v. 12, no. 2, p. 141-148. Ref. Type: Journal. Ref ID: 20 Stokes, I, A, F, Burwell, R, G and Dangerfield, P, H. Biomechanical spinal growth modulation and progressive adolescent scoliosis-a test of the vicious cycle' pathogenic hypothesis: Summary of an electronic focus group debate of the IBSE. Scoliosis 2006, 1:16 doi: 10.1186/1748-7161-1-16 Goldberg, C, J, Fogarty, E, E, Moore, D, P, and Dowling, F, E. 1997 Scoliosis and Developmental Theory, Adolescent Idiopathic Scoliosis. SPINE Volume 22, Number 19, pp 2228-2236 Coillard, C., and C. H. Rivard, 2001, La scoliose idiopathique: étiologie. La scoliose idiopathique, une dysrythmie de croissance ou pourquoi un système peut devenir chaotique: Résonances Européennes du Rachis , v. 29, p. 1123-1139. Ref. Type: Journal. Ref ID: 111 Castro, F. P., Jr., 2003, Adolescent idiopathic scoliosis, bracing, and the Hueter-Volkmann principle: Spine J , v. 3, no. 3, p. 180-185. Ref. Type: Journal. Ref ID: 15 Coillard, C., and C. H. Rivard, 1996, Vertebral deformities and scoliosis: Eur.Spine J , v. 5, no. 2, p. 91-100. Ref. Type: Journal. Ref ID: 23 Coillard, C., M. A. Leroux, K. F. Zabjek, and C. H. Rivard, 1999, [Reductibility of idiopathic scoliosis during orthopedic treatment]: Ann.Chir , v. 53, no. 8, p. 781-791. Ref. Type: Journal. Ref ID: 21 Bashiardes, S. et al., 2004, SNTG1, the gene encoding gamma1-syntrophin: a candidate gene for idiopathic scoliosis: Hum.Genet. , v. 115, no. 1, p. 81-89. Ref. Type: Journal. Ref ID: 6

Adolescent Idiopathic Scoliosis: Cobb Angle Relative to Overall Balance

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