Spring-Assisted Cranioplasty in Unicoronal Synostosis: Analysis of Outcomes

Background: Spring-assisted cranioplasty and successful long-term outcomes for sagittal synostosis has been well described in recent literature. However, there is a paucity of data regarding the application of springs to unicoronal synostosis. Unicoronal synostosis (UCS) presents unique challenges in its causation of skull base scoliosis and orbital asymmetry. Many surgeons feel that the fronto-orbital advancement and vault remodeling is the most effective and reliable strategy to counteract these changes. Here we present our experience and outcomes with spring cranioplasty for unicoronal synostosis. Materials and methods: A retrospective review of non-syndromic unicoronal synostosis patients undergoing spring-assisted cranioplasty was performed. Preoperative and postoperative intracranial volume (ICV), orbital volume (OV), orbital height (OH), orbital width (OW), midface twist (MFT), and skull-base twist (SBT) were measured from DICOM CT data. Analysis was performed with Materialize software (Leuven, Belgium). Paired t-tests were performed using Excel. Results: Ten patients (5 females, 5 males) had springs placed at 100.1 days (avg). Average ICV: preop: 608.2 ± 101.4 cc, postop: 995.2 ± 166.1 cc. Differences in orbital volume and height in the preop affected orbit versus non-affected orbit was significant ( P = .01, P ≤ .001 respectively) whereas no significant difference between the two sides postoperatively was observed ( P = .19, P = .58 respectively). Average preop MFT was 81.1 ± 2° and postop was 87.6 ± 2.6° and preop SBT was 171.9 ± 2.7° and postop was 177.6 ± 2.6°; both showing significant improvement after spring cranioplasty (both P ≤ .001). Conclusion: Our experience and early outcomes with spring cranioplasty for UCS demonstrates that when used in younger patients (<5 months) cranial springs can be a safe and effective strategy to minimize skull base scoliosis, facial scoliosis, and orbital asymmetry, as well as increase intracranial volume. Although long-term data needs to be assessed, we are optimistic that early correction of cranial base scoliosis will translate to stable results as patients reach dentoskeletal maturity.