Cranial bone structure in children with sagittal craniosynostosis: Relationship with surgical outcomes

Naiara Rodriguez-Florez,Amel Ibrahim,J Ciaran Hutchinson,Alessandro Borghi,Greg James,Owen J Arthurs,Patrizia Ferretti,David Dunaway,Silvia Schievano,N U Owase Jeelani

doi:10.1016/j.bjps.2017.06.017

Abstract

While spring-assisted cranioplasty has become a widespread technique to correct scaphocephaly in children with sagittal synostosis, predicting head shape changes induced by the gradual opening of the springs remains challenging. This study aimed to explore the role of cranial bone structure on surgical outcomes. Patients with isolated sagittal synostosis undergoing spring-assisted cranioplasty at GOSH (London, UK) were recruited (n=18, age: 3-8 months). Surgical outcome was assessed by the change in cephalic index measured on 3D head scans acquired before spring insertion and after their removal using a 3D handheld scanner. Parietal bone samples routinely discarded during spring-assisted cranioplasty were collected and scanned using micro-computed tomography. From visual assessment of such scans, bone structure was classified into one- or three-layered, the latter indicating the existence of a diploë cavity. Bone average thickness, volume fraction and surface density were computed and correlated with changes in cephalic index. Cephalic index increased for all patients (p<0.001), but individual improvement varied. Although the patient age and treatment duration were not significantly correlated with changes in cephalic index, bone structural parameters were. The increase of cephalic index was smaller with increasing bone thickness (Pearson's r=-0.79, p<0.001) and decreasing bone surface density (r=0.77, p<0.001), associated with the three-layered bone structure. Variation in parietal bone micro-structure was associated with the magnitude of head shape changes induced by spring-assisted cranioplasty. This suggests that bone structure analysis could be a valuable adjunct in designing surgical strategies that yield optimal patient-specific outcomes.

Highlights

Spring-assisted cranioplasty (SAC) has become an increasingly widespread technique to correct scaphocephaly in young infants with sagittal craniosynostosis.1e7 SAC involves the fashioning of sagittal or parasagittal osteotomies and the temporary placement of spring-like metallic distractors, which affect an ongoing intra- and post-operative expansion to widen the biparietal width of the skull
Rodriguez-Florez et al Conclusions: Variation in parietal bone micro-structure was associated with the magnitude of head shape changes induced by spring-assisted cranioplasty
This suggests that bone structure analysis could be a valuable adjunct in designing surgical strategies that yield optimal patientspecific outcomes. a 2017 British Association of Plastic, Reconstructive and Aesthetic Surgeons

Summary

Introduction

Spring-assisted cranioplasty (SAC) has become an increasingly widespread technique to correct scaphocephaly in young infants with sagittal craniosynostosis.1e7 SAC involves the fashioning of sagittal or parasagittal osteotomies and the temporary placement of spring-like metallic distractors, which affect an ongoing intra- and post-operative expansion to widen the biparietal width of the skull. The most common way of assessing surgical outcome in SAC is by measuring the cephalic index (CI), defined as the ratio between cranial width and length.[1,3,6,8,9] After spring removal, a ‘good’ surgical outcome is characterised by a shorter and wider head shape compared to pre-operative shape, which is reflected in an increase in CI. At present, it is unclear which patient and operative factors influence the final change in the CI. Understanding these factors will allow surgeons to make decisions about optimal techniques for individual children

Objectives

Methods

Results

Conclusion