Dynamic Orthotic CranioplastySM: What it means to be "Dynamic"
Tim Littlefield, Director R&D, Cranial Technologies, Inc.
At the ACPOC meeting in St. Petersburg, FL, a question was raised regarding the use of the word ‘dynamic' in one of the clinical presentations. While the presenter had clearly defined the meaning of the word, the explanation was not widely accepted by the audience.
The problem lies, however, not in the presenter's improper terminology, but rather by our acceptance of the most widely used definition as the only ‘acceptable' definition. Therefore, I would like to clarify the meaning of the word dynamic when used in the context of our treatment program – Dynamic Orthotic Cranioplasty#x2120;.
In mechanical engineering, the first courses we were required to take were in "statics" – meaning the evaluation of stationary objects, and "dynamics" – evaluation of objects in motion. This definition of dynamic is by far the most commonly used and accepted. However, the term dynamic has other meanings. The American Heritage Dictionary defines dynamic as "characterized by continuous change, activity, or progress".1 In engineering the word dynamic is also used to describe a closed feedback loop (Figure 1). In this connotation, the term dynamic conveys the process of continuous monitoring and adjustment that ensures the accuracy of the output.2
Before development of Dynamic Orthotic Cranioplasty, treatment for plagiocephaly involved the use of what has now become known as a "passive" molding helmet. The theory behind these devices was "if the pressure of a rapidly growing brain against a flat surface would flatten the skull, then pressure against a concave surface should round it back again".3 In several clinical studies, cranial symmetry was shown to have improved with use of these devices as the brain grew and filled out the helmet. These helmets were typically worn until the head was the same size as the helmet, and treatment was complete when "the head took on the shape of the helmet".4,5 The concept of the molding helmet is fundamentally sound, and revolutionized the treatment of plagiocephaly in the United States.
The development of the dynamic approach took this concept one step further.6-8 Rather than waiting for the head to grow into a symmetric mold, Cranial Technologies designed a system that immediately applied a corrective force to the prominent areas of the skull where there was no need for growth, while leaving room for growth in the adjacent flattened regions. An inner foam liner was incorporated, and infants were required to be evaluated on a weekly to biweekly basis, for adjustments to this liner, to control the correction being achieved. Because pressures are applied immediately at the onset of treatment, changes are often observed within the first week. This immediate application of corrective forces has also extended the effectiveness of the device well into the second year of life.9 However, it is the process of continuously monitoring the correction being achieved, and then modifying the band based upon this information (therefore modifying the corrective pressures) that is the origin of the word dynamic in Dynamic Orthotic Cranioplasty.
- The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2000 by Houghton Mifflin Company.
- Gene Franklin, J. David Powell, Abbas Emani-Naeini. Feedback Control of Dynamic Systems. Prentice-Hall, 2002.
- Clarren S, Smith D, Hanson J. Helmet treatment for plagiocephaly and congenital muscular torticollis. J Pediatr 1979; 94: 43-46.
- Graham JM. Smith's recognizable patterns of human deformation. Oblique head deformation – Plagiocephaly-Torticollis sequence. 2nd edition. W.B. Saunders Company, Philadelphia 1988.
- Clarren SK. Plagiocephaly and torticollis: etiology, natural history, and helmet treatment. J Pediatr 1981; 98:92-95.
- Ripley CE, Pomatto JK, Beals SP, Joganic EF, Manwaring KH, Moss SD. Treatment of positional plagiocephaly with dynamic orthotic cranioplasty. J Craniofac Surg1994; 5(3): 150-159.
- Littlefield TR, Beals SP, Manwaring KM, Pomatto JK, Joganic EF, Golden KA, Ripley CE. Treatment of craniofacial asymmetry with dynamic orthotic cranioplasty. J Craniofac Surg 1998, 9(1): 11-17.
- Littlefield TR, Pomatto JK, Beals SP, Joganic EF, Manwaring KM, Ripley CE; Efficacy and Stability of Dynamic OrthoticCranioplasty: An Eight Year Investigation. In: Whitaker, ed Craniofacial Surgery VII: Proceedings of the SeventhInternational Congress of the International Society of Craniofacial Surgery. Monduzzi Editore, Bologna Italy.1997; 109-111.
- Littlefield TR, Pomatto JK, Kelly KM. Dynamic Orthotic Cranioplasty: Treatment of the ‘older' infant. A report of four cases. Neurosurg Focus 9(3): Article 5, 2000.