Premature Ossification After Posterior Vault Distraction in a Child with Alpha-Mannosidosis: A Case Report

Introduction: Alpha-mannosidosis is a rare lysosomal storage disorder characterized by skeletal dysplasia, hearing loss, and neurocognitive impairment. Craniosynostosis has been reported only in isolated cases and is not a well-recognized feature of the disease. We describe a rare case of multisuture craniosynostosis in a child with alpha-mannosidosis complicated by premature consolidation following posterior cranial vault distraction osteogenesis (PVDO). Case Presentation: A 4-year-old female with genetically confirmed alpha-mannosidosis and Chiari I malformation presented with progressive cranial deformity. Computed tomography revealed fusion of the coronal, sagittal, and lambdoid sutures with reduced intracranial volume. She underwent PVDO with concurrent suboccipital decompression to expand the posterior fossa. Postoperatively, distraction was halted early due to rapid re-ossification resulting in hardware failure. Intraoperative imaging confirmed premature bone bridging across the osteotomy sites, necessitating repeat osteotomy and distractor replacement. The patient had been receiving enzyme replacement therapy (ERT) for 4 months before surgery and throughout the perioperative course. She remains neurologically stable on multidisciplinary follow-up. Conclusion: This case illustrates an unusual complication of PVDO in a patient with alpha-mannosidosis, characterized by accelerated bone consolidation potentially associated with ERT. Surgeons should anticipate atypical cranial healing patterns in metabolic bone disease, with consideration of earlier activation, adjusted distraction rates, and closer radiographic monitoring to mitigate premature ossification and hardware failure.