EDITORIAL. “Horses for courses”

One can organize the myriad techniques for managing sagittal synostosis-induced scaphocephaly in a 2 × 2 table according to dynamic and static techniques on one axis and compressive and decompressive procedures on the other, and perhaps even include a third axis for open extensile versus minimal access exposures. The idea of using a dynamic, minimal access decompressive technique is very appealing for a number of reasons, most of all for the opportunity to harness the viscoelastic properties of the infant skull and the powerful functional matrix of the rapidly growing brain in the first few months of life. Therefore, it is exciting to imagine the potential of a simple spring in creating a satisfactory change in cranial configuration and improving craniocerebral disproportion. Spring-assisted cranioplasty seems to fit the bill quite nicely, although this concept is not new. Claes Lauritzen from Göteborg, Sweden, introduced this technique in 1997 and has shared his extensive experience.11–13 Applications of this method have included improvement of hypotelorism in metopic synostosis, correction of brachycephaly in Apert syndrome, working around potentially hazardous anomalous venous drainage, and the correction of nonsynostotic scaphocephaly without cranial osteotomy and ventricular shunt cranial deformity.2,4,5,10,15 The workhorse application of spring-assisted cranioplasty has focused on the correction of nonsyndromic sagittal synostosis scaphocephaly.9 Opponents of the use of springs in the infant skull cite the lack of control and predictability in bone expansion, the immediate effect of the spring that dissipates over time, the potential for dural and/or venous sinus tears, skin erosion, increased complication rate, and the need for a subsequent surgery for removal.14 Regardless, the outcomes of surgery speak for themselves, and the popularity of spring-assisted cranioplasty has not abated. The article by Borghi et al. represents the first notable publication from the Great Ormond Street Hospital for Children (GOSH) group on the use of springs in the management of craniosynostosis.1 This group has been using the spring-assisted cranioplasty technique since 2008, and this is a welcome opportunity to review the progress they have made in applying the minimally invasive surgery and taking advantage of bone-fluid physiology in the correction of scaphocephaly. The focus of their paper is spring biomechanics and kinematics (a separate manuscript that describes the clinical outcomes in 100 consecutive cases of nonsyndromic scaphocephaly has been accepted for publication). As is often the case, a novel idea that seems to have significant clinical application makes the journey from the bench to the bedside. A body of work using an animal model has examined the physiological effects of springs on the craniofacial skeleton.3,6–8 Experimental work in the rabbit by Davis and colleagues has demonstrated that cranial springs alter the growth vector of adjacent sutures, cause thickening of cranial sutures and adjacent cranial bone, and cause differential strain patterns on the endoand ectocranial surfaces.3,6–8 The ability to mould and shape the cranium through the application of spring-derived force is powerful. There is a paucity of literature about the same influences in the human infant. Therefore, the current study represents a welcome opportunity to assess the biomechanics and kinematics of springs in the management of 60 infants (mean age 5.2 ± 0.9 months) with nonsyndromic sagittal synostosis. The surgical technique involves creating paramedian strip craniectomies and placing 2 springs of various thicknesses across the midline. The goal is to achieve an on-table expansion of 3 cm. Spring selection (1.0-, 1.2-, and 1.4-mm thickness springs are available) is arbitrarily based on bone thickness and surgeon expertise. Various combinaEDITORIAL “Horses for courses”