The two most common spine deformities, scoliosis and kyphosis (more properly hyperkyphosis) have been recognized since antiquity. However, the first successful treatment for moderate to severe scoliosis and kyphosis, spinal arthrodesis, is a recent development. First successfully performed in 1911, it proved to be a difficult therapeutic methodology requiring decades to refine into a reliable operation. This served to focus treatment on the more severe cases and into the hands of orthopedic surgeons, limiting multi-disciplinary study.
The most common etiologies of kyphosis, fractures and tuberculosis revealed themselves relatively easily, and guided prevention and treatment. The same has not been true for scoliosis. For decades poliomyelitis residuals were blamed. However, well before the advent of the successful inactivated vaccine in 1955 removed all doubt, it was realized that most scoliosis was without known cause. The cause (or causes) of this condition, usually of mild to moderate severity, has stubbornly eluded detection, as has the development of universally accepted and obviously effective non-operative treatment.
There can be no doubt that this adolescent, also known as late-onset, idiopathic scoliosis was and is the clinical problem that motivated the formation and motivates the continuation of the IRSSD. It is an unequalled forum for information exchange for a wide spectrum of scientists and clinicians all interested in the puzzle that is idiopathic scoliosis.
Drawings and photographs done before the invention of radiographs in 1895 clearly depicted scoliosis as a three dimensional trunk deformity. Drawings did the same for the spine deformity. Radiographs however reduced visualization of the spine to two planes and largely ignored the trunk deformity. The need to quantify scoliosis as a three-dimensional deformity and advances in computer technology led in the 1980's to the parallel development of trunk surface topography and three-dimensional radiographic spine studies. Initially separate movements; it was desirable and probably inevitable that they come together.
It cannot be said that studies utilizing these techniques have produced a breakthrough in the understanding of idiopathic scoliosis. Even today the techniques have not been found beneficial in practice and are rarely used outside of research setting. However, as the result of these studies and the resulting discussion and collaborations, scoliosis is now widely recognized as a three-dimensional deformity. This has fostered better clinical trunk measurements and better analysis of biplanar radiographs.
Surface topography, anthropometric, stability and electro diagnostic studies have shown these persons to have some subtle but measurable asymmetries; more than comparable normal persons. The same seems to be true of patients with congenital scoliosis, suggesting the asymmetries are more related to the deformity than to the etiology.
Biplanar radiographic images are still the standard for determining the scoliosis deformity phenotype and its severity. Global kyphosis has been identified as a risk factor for associated neural axis abnormalities. Left apex thoracic curves are especially associated with this risk. Addressing the neural axis abnormality, e.g. Chiari 1 malformation and syringomyelia sometimes results in curve reduction and for those patients undergoing instrumentation and arthrodesis, a safer operation. Whether or not a three-dimensional deformity classification system that adds any deeper insights into the pathogenesis of idiopathic scoliosis can be developed remains to be seen.
While the search for etiology or etiologies remains as elusive as ever, these studies have substantially altered thinking about treatment methods to reduce the scoliosis deformity. Thought focused on vertical translational loads, principally distraction has been replaced by thought utilizing combinations of translational and angular loads and counter-loads, addressing the deformity three-dimensionally. This is true for both bracing and surgery. Perhaps fostering this thinking is the greatest clinical contribution of three dimensional studies to date.
Idiopathic scoliosis is both the most common spine deformity and generally it's least severe. A missing part of the treatment puzzle is a natural history study providing guidance for the most beneficial treatment selection at the tipping point between surgery and non-surgery. It is at this point that the health-related quality of life questionnaires, reported on at some of the more recent meetings, may be helpful in selecting treatment. Once crossed, the surgery bridge cannot be re-crossed.
The meetings have always focused on adolescent/late-onset idiopathic scoliosis. In fact, at the first meeting (1992) bringing the surface topography and three-dimensional radiography groups together, there wasn't a single presentation on scoliosis of other etiology. Since then there have been a few papers about other spine problems at each meeting. These problems include hyperkyphosis, osteoporotic fractures, flat back, spine aging, low back pain, spondylolysis and spondylolisthesis, infantile scoliosis, Scheuermann's, adult scoliosis, myelomeningocele, Duchene muscular dystrophy, congenital scoliosis and Prader-Willi syndrome. Though usually related to treatment, a few presentations have focused on the underlying pathology. However, these presentation have served to keep the meetings from becoming too narrow, one of the problems that led to the formation of the IRSSD in the first place!
The biannual IRSSD meetings continue the very useful service of bringing together clinicians with research and clinical scientists of diverse scientific and backgrounds, practices and viewpoints. Although to date idiopathic scoliosis remains just that, it is doubtful that anyone "knowledgeable" about idiopathic scoliosis is surprised. Contemplating the scoliosis puzzle can make you a little crazy! Perhaps like studying fever before knowledge of microbes.