Cadcam In The Treatment Of Idiopathic Scoliosis

Gez Bowman C.O.
Action Orthopedic Company
Reseda, California

Background

Previous studies of bracing indicate that the degree of "in-brace correction" is an indicator of eventual outcome (1-6). Noonan et. al. demonstrated an average of less than 20% showed an ineffective bracing program (1), whereas other studies showing greater than 30% average in-brace correction indicated a successful bracing program (2, 3). Other studies suggested that optimal outcome is achieved with 50% in-brace correction (4-6). It can therefore be reasonably argued that a bracing program must average over 30% in-brace correction to be effective. The U.S. Approach to Bracing generally results in bracing being done by general practice orthotists and the results for the industry are shown to be very inconsistent (1-6). As a result, in the U.S., many physicians are electing not to brace and many that do are limiting their brace selection range to 30-40 degrees.

The approach to scoliosis bracing in most European countries appears to be very different. Bracing is done by specialist scoliosis orthotists and results appear to be more consistently effective. As a result, the bracing selection range appears to be increasing, becoming 15-45 degrees (7-9).

What is needed to improve industry wide outcomes in the U.S. is a consistent effective bracing solution, achievable by orthotists with varying skill levels.

The use of Computer Aided Design-Computer Aided Manufacture (CADCAM) in scoliosis bracing offers the advantages of accommodating unlimited asymmetrical designs, avoiding casting and providing consistency in the application of force. The biggest drawback to CADCAM in scoliosis is the need for an accurate, affordable, simple data acquisition system. CADCAM has been reported in the literature with the Lyon brace (9), Charleston brace (10) and the Providence brace (11). CAD has also been reported as an evaluation tool but not for its design or manufacture with the soft Spincor brace (12). However its effectiveness has been drawn into question (13).

The L.A. Brace ™ is a new design of scoliosis brace that utilizes CADCAM technology along with a new computerized data acquisition system called Algorithm Generated Predictions (AGP).

Brace Design

There are four aspects to the design and manufacture of The L.A. Brace™.

  1. Template Selection

  2. Data Acquisition through AGP

  3. CAD Modeling

  4. Manufacture

1. The L.A. Brace™ templates are based upon a modified King classification that relates specifically to how forces are applied to reposition the scoliotic spine. There are currently 13 scoliosis templates. The shape of any particular finished brace is determined by the template selected.

2. AGP software was developed to provide a more accurate methodology of data acquisition. Through analysis of previous size and shape data, we have developed complex algorithms that can accurately estimate the various dimensions of the patient. AGP identifies key "fixed", "variable," and "measured" data elements from which algorithms can be applied to predict the correct dimensions and shape of the patient. This system is proving to have considerable potential, being less subject to inaccuracies in measurements and providing an accurate yet low cost solution to data acquisition that could be readily adopted by the profession.

3. The patient's AGP dataset is applied to the selected template. The CAD software modifies the templates by reducing and enlarging areas as necessary to appropriately create the CAD model.

4. The CAD model is carved out and the asymmetric L.A. Brace™ is then fabricated from the CAM foam mold out of polypropylene. The total thickness of the brace varies between 1.5mm and 3mm.

Method

A 40-patient study was performed by 4 orthopedic surgeons who prescribed the L.A. Brace™. All patients were adolescents with idiopathic scoliosis, were Risser 0, 1 or 2 and had not worn a brace before. 37 patients were girls, 3 were boys. Average curve size was 31.2 degrees. In addition, results of another 10 patients were tabulated who had worn another type of brace prior to the L.A. Brace™.

Results

Average in-brace correction for the group was 51 degrees. 9 patients progressed more than 5 degrees (18%). Patients who had worn another brace prior to the L.A. Brace™ demonstrated a 30% improvement in their in-brace x-ray in their L.A. Brace™ compared to their previous brace. A survey of these patients' preferences also indicated a 75% preference for the L.A. Brace™.

Conclusion

The L.A. Brace™ is a low profile asymmetrical CADCAM brace which utilizes the new data acquisition technology of AGP. It appears to be an effective alternative to other full time bracing systems and could be a more consistent bracing methodology, with good results potentially achieved with varying orthotist skill levels.

References

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  2. Kehl DK, Morrisy RT. Brace treatment in adolescent idiopathic scoliosis: an update on concepts and techniques. Clin Orthop 1988;229:34-43.

  3. Katz DE, Richards S, Browne RH, et al. A comparison between the Boston brace and the Charleston bending brace in adolescent idiopathic scoliosis. Spine 1997;22:1302-1312.

  4. Eman JB, KaelinA, BancelP, et al. The Boston bracing system for idiopathic scoliosis. Follow up results on 295 patients. Spine 1986;11(8):792-801.

  5. Carr WA, Moe JH, Winter RB, et al. Treatment of Idiopathic scoliosis in the Milwaukee brace: long-term results. J Bone Joint Surg 1980;62:599-612.

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  7. Kotwicki T, Pietrzak S, Szulc A. Three dimensional action of Cheneau brace on thoracolumbar scoliosis. Studies in Heath Technology & Informatics. 2002;88:226-229.

  8. Negrini S, Marchini G, Tomaello L. The Sforzesca brace and SPoRT concept (Symmetric, Patient-orientated, Rigid, Three-dimensional) versus the Lyon brace and 3-point systems for bracing idiopathic scoliosis. Stud Health Technol Inform. 2006;123:245-249.

  9. Cottolorda J, Kohler R, Garin C, et al. Orthoses for mild scoliosis: a prospective study comparing traditional plaster mold manufacture with fast, noncontact, 3-dimensional acquisition. Spine 2005; 30(4):399-405.

  10. Price CT, Scott DS, Reed FE Jr, et al. Nighttime bracing for adolescent idiopathic scoliosis with the Charleston bending brace: long term follow up. J Pediatr Orthop 1997;17:703-707.

  11. D'Amato CR, Griggs S, McCoy B. Nighttime bracing with the providence brace in adolescent girls with idiopathic scoliosis. Spine 2001;26:2006-2012.

  12. Coillard J, Leroux MA, Badeaux J, et al. SPINECOR: a new therapeutic approach for idiopathic scoliosis. Stud Health Technol Inform. 2002;88:215-217.

  13. Weiss H, Weiss GM. Brace treatment during pubertal growth spurt in girls with idiopathic scoliosis: A prospective trial comparing two different concepts. Ped Rehab. 2005; 8(3):199-206.