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Risk Factors for Occipital Step-Off Deformities in Posterior Vault Distraction Osteogenesis
Zachary D Zapatero1, Anna R Carlson1, Elizabeth B Card2
1Division of Plastic and Reconstructive Surgery, The Children's Hospital of Philadelphia.
Insights
Older age at posterior vault distraction osteogenesis (PVDO) increases the risk of occipital step-off deformity. Performing osteotomy below the inion is protective against this complication.
Area of Science:
- Craniofacial surgery
- Pediatric neurosurgery
- Orthopedic surgery
Background:
- Posterior vault distraction osteogenesis (PVDO) is a surgical technique used to correct craniosynostosis.
- Occipital step-off deformity is a potential complication following PVDO.
- Understanding factors influencing this deformity is crucial for optimizing surgical outcomes.
Purpose of the Study:
- To identify patient-specific factors and surgical techniques impacting occipital step-off deformity after PVDO.
- To analyze the relationship between age at surgery and the development of deformity.
- To evaluate the protective effect of osteotomy placement on deformity occurrence.
Main Methods:
- Retrospective review of patients who underwent PVDO and had 3D CT scans 1 year post-removal.
- Blinded assessment of occipital step-off severity by two craniofacial surgeons.
- Statistical analysis using multinomial logistic regressions and Mann-Whitney U tests.
Main Results:
- Forty-one patients with multisuture or bicoronal craniosynostosis were included.
- Older age at PVDO was a significant predisposing factor (Cox and Snell = 0.487, P < 0.001).
- Osteotomy height below the inion was associated with decreased step-off severity (P = 0.001).
Conclusions:
- Increased age at PVDO is a risk factor for occipital step-off deformity.
- Performing the occipital osteotomy below the inion appears protective.
- The technique of barrel staves with greenstick outfracture did not reduce the risk in this cohort.
Purpose:
The goal of this study was to investigate patient specific factors and surgical techniques that affect occipital step-off deformity in children undergoing posterior vault distraction osteogenesis (PVDO).
Methods:
Patients who underwent PVDO were retrospectively reviewed and included if a high resolution three-dimensional computed tomography scan was available 1-year post-distractor removal. Two craniofacial surgeons were blinded to individual subjects and presented with 3 still images of three-dimensional bone reconstructions and asked to rate the degree of step off: none, mild, moderate, or severe. The data were analyzed with multinomial logistic regressions and other appropriate statistics.
Results:
Forty-one patients met inclusion criteria. All patients had multisuture or bicoronal craniosynostosis. Multinomial logistic regression identified age at PVDO (Cox and Snell = 0.487, P < 0.001) as a predisposing factor and one potentially protective factor, height of osteotomy (Cox and Snell = 0.394, P = 0.004) in univariate models. Post-hoc pairwise Mann-Whitney U test revealed there was decreased step-off rating when comparing osteotomy below torcula (median 0, [IQR 0, 3]) and above torcula (median 3 [IQR 1, 4]; P = 0.036) as well as a decreased step-off when below inion (median 0 [IQR 0, 1]; P = 0.001) was compared to above the torcula.
Conclusions:
Older age at PVDO predict increased risk of developing an occipital step-off deformity after PVDO, while design of the occipital osteotomy below the inion is protective. Barrel staves with greenstick outfracture did not lower the risk of occipital step-off in this sample, the reasons for which are unclear.
