The results of the Lyon Brace Management have been validated by numerous teams in Europe [9, 10]. However, the plaster cast process is quite involved for the patient and physician. Consequently, many teams looked for more convenient and expedient solutions without preliminary plaster cast reduction . The results are debatable .
The Lyon Braces have continued to improve with the progress of technology while adhering to fundamental biomechanical principles. For 20 years, it has been consistently applied and evaluated in several public and private centers in both France and Italy. The results remained the same during successive studies and the variations in time are linked to the screening and an initial angulation which was lower.
The curve reduction and improved spinal alignment achieved in the plaster cast facilitates a better moulding on a more symmetrical and balanced spine. Using his expertise and the x-ray in the plaster cast as a reference, the CPO fabricates and fits the patient with the brace. This reduction enables a night bracing, which is greatly appreciated by the child, when the curve is below 30° (Table 1).
The Lenke curve classification system was found to be most beneficial in helping the physician classify the curve, prescribe the most appropriate Lyon Brace and guide the CPO in constructing it.
The ideal patient population indicated for treatment with the Lyon Brace are adolescents at the age of pubertal growth. They are less susceptible to the corrective forces that can cause a chest wall deformity or tubular thorax in younger juvenile patients.
We do not use only the Lyon brace for AIS, but its adaptability to all types of curvatures is great.
To meet study inclusion criteria the initial angulation is always the one before the plaster cast, even if the patient was previously treated.
The application of a plaster cast at the beginning of the treatment may be a way to select the most motivated patients for whom compliance is the best. In the same way, many "drop-outs" are noted at the end of the treatment and only the motivated ones come to the check-up. These "drop-outs" are not part of the 1338 cases reported.
If a patient eventually undergoes surgery, he is included in the statistics as a bracing failure, and the pre-surgical curve angulation is used for statistical calculations.
The important Standard Deviation of the initial Cobb's angle of our series shows the great range of angular indication, from the weaker curve to the most important. The only variable is going to be the time of wearing the brace.
In evaluating post treatment outcomes, the best results were obtained for lumbar curvatures. The brace is short and well tolerated; unfortunately, these curves are often painful during adulthood and evolve towards rotary dislocation.
The double major curves respond well to the Lyon Brace, despite the short lever arm in the frontal plane.
Similarly, the thoraco lumbar curves respond well to the Lyon type III brace. The excellent lever arm effectively maintains the good correction achieved from the plaster cast. Nevertheless, it is this group that most often progresses towards surgery, even when the treatment is followed acutely. Therefore, strict brace wear is critical, despite the sometimes impressive initial corrections obtained in the plaster cast.
When examining the rotational changes effected by the brace, the rib hump is often better corrected than the angulation. It is frequently reduced by 33% at the thoracic level and more than 50% at the lumbar level. The aesthetic improvement is always better than the X ray appears.
The excellent global index of effectiveness of all the curves is 0.95, and it can be explained by the selection of the patients. The index is only 0.87 for the thoracic curves. The most relevant subjects to judge the effectiveness of the Lyon Brace is the Risser 0 group, of which the index of effectiveness for the most progressive scoliosis is 0.80.
But, if the mean curves of the Risser 0 group are compared with the mean curves of the general statistics, the two curves are almost the same, as if the Lyon Brace was stopping the scoliotic curves whatever the age of the child.
Even if the index of effectiveness seems to be better, it is very hard to compare the results of the Lyon Brace study with any of the other published brace studies. This is, in large part, due to the Lyon treatment protocol requiring plaster casting and physiotherapy. The effectiveness of therapy associated with bracing having been previously established in work by Négrini .
Additionally, adhering to the main treatment indication which is adolescents at pubertal growth, may also help explain the good results.