Spring forces and calvarial thickness predict cephalic index changes following spring-mediated cranioplasty for sagittal craniosynostosis.

ABSTRACT

BACKGROUND: Variables interacting to predict outcomes following spring-mediated cranioplasty (SMC) for non-syndromic craniosynostosis, including spring parameters and calvarial thickness, are poorly understood. This study assessed interactions between spring parameters and calvarial thickness to predict changes in cephalic index (CI) following SMC. METHODS: Patients undergoing SMC for non-syndromic sagittal craniosynostosis at our institution between 2014 and 2021 were included. Calvarial thickness was determined from patient preoperative CTs using Materalise Mimics at 27 points in relation to the sagittal suture. Linear mixed effects models were used to determine interactions between anterior, middle, and posterior calvarial thickness with spring force and length. RESULTS: Sixty-nine patients undergoing surgery at mean age 3.7 months were included in this study. Stronger posterior spring force interacted with thinner posterior calvarial thickness to predict greater changes in CI at 3 months postoperatively (p = 0.022). When evaluating spring force and calvarial thickness set distances from the sagittal suture, stronger posterior spring force interacted with thinner posterior calvarial thickness 5 mm (p = 0.043) and 10 mm (p = 0.036) from the sagittal suture to predict changes in CI. Interactions between spring parameters and calvarial thickness in the anterior and middle positions did not significantly predict changes in CI. CONCLUSIONS: Stronger posterior spring force interacted with thinner posterior calvaria to predict greater changes in CI 3 months following SMC for non-syndromic sagittal craniosynostosis. These results suggest dynamic interactions between several variables may impact outcomes following SMC.