TO THE EDITOR:
The article concerning pad styles in scoliosis (Harvey Z, Chamis M, Lin R. The impact of lateral pads versus posterolateral pads in the management of idiopathic scoliosis. J Prosthet Orthot 2002;14:165-169) attempts to compare the biomechanical effectiveness of lateral versus posterolateral pads in the treatment of thoracic curves secondary to idiopathic scoliosis. The authors specifically endeavored to compare the in-orthosis correction of both the coronal and sagittal planes.
It is reasonable to suggest that a lateral pad more directly addresses coronal plane motion and, to a lesser degree, transverse plane motion (rotation). The posterolateral pad is designed to address both coronal and transverse planes more uniformly. Although the posterolateral pad addresses the transverse and coronal planes, the article mentions an important concept in preventing any adverse increases in hypokyphosis or sagittal plane motion. This notion stresses the importance of paying attention to sagittal plane alignment in any orthosis used to treat idiopathic scoliosis. Exhaustive research is needed to compare the results of both styles of pads on sagittal plane alignment.
Harvey et al.'s research was limited to the use of a Boston TLSO, specifically concluding that “Posterolateral pads should be used solely in the case of hyperkyphotic scoliotic curves, which is atypical for scoliosis patients.” This statement dangerously conveys to the reader that any posterolateral pad should be avoided with scoliosis patients in general. The data presented do not support such a conclusive statement. More specifically, this conclusion is based on a retrospective review of 15 patients treated with a posterolateral (PL) pad in which the pad shape, position, and size were left undefined. The authors argued use of the PL pads resulted in an average of 6° less kyphosis compared to 23 other patients (also lacking detail on pad placement, etc.) treated with lateral pads (See Figure 4 of article).
This study, at best, can suggest only the need to further test the use of posterolateral pads with the Boston TLSO. Numerous variables exist with respect to both coronal and sagittal changes in spine alignment secondary to the application of an orthosis. Pad style, shape, and position in relation to a curve should be described, as well as possible variances in curve size and maturity status between the two groups. A total of 23 and 15 patients, respectively, is too small a sample size to draw any conclusions on the research questioned asked, when one considers the numerous, confounding variables that can significantly influence the stated results. For instance, if one group had curves that were significantly larger or were made up of a population more mature than the other, less coronal plane in-orthosis correction and greater hypokyphosis deformity would be expected.
No recognition of other styles such as the Wilmington (Dupont Institute, Wilmington, DE) or LOC style pads (Atlantic Rim, Nashua, NH) was mentioned. Description of pad style and shape was omitted when there exist noticeable differences among systems, creating noticeable variables. A Wilmington TLSO, for instance, has the force vectors created through molding the in-orthosis correction in which the rotation is first corrected and then coronal plane deformities such as lateral displacement of the apex from the central sacral line and trunk shifts are corrected by a cast mold. The LOC pads catch the transverse processes, keeping the same thickness throughout the pad only to the greatest angle of rotation, then gradually taper anteriorly to control the lateral curve. In other words, this study can state only findings that are specific to the Boston System and that more research is needed to verify the results that this review can only suggest.
I view this article as the first look at the importance of sagittal plane alignment for in-orthosis correction of thoracic curves secondary to idiopathic scoliosis. I applaud the authors' intentions to address this question. No conclusions, however, can be drawn on this retrospective review of a small sample of patients ranging in age from 7 to 15 years, with unknown curve sizes and unknown placement of corrective pads resulting in a sagittal plane alignment change difference of just 6°.
Keith M. Smith CO
St. Louis, MO