Custom PMMA implant and DBX Cranioplasty for large cranial calavarial defects
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Author: Mary Rhomberg
Published:
Specialties: Craniofacial and Pediatric Plastic Surgery
Schools: Arkansas Children's Hospital
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Loading...Following a post-traumatic head injury from a gun shot wound in a seven year old African American female, a 3D CT was performed to assess for correction of a large cranial calavarial defect using a custom PMMA implant. A trilaminar Cranioplasty was planned using an absorbable plate underlay, demineralized bone graft in between and an onlay of absorbable plate. A post-operative CT was obtained showing the implant in a good position.
Procedure
Additional Information added by Author:
Patient had a history of a gunshot wound to the head (accidental) when she was 5 yo requiring emergent decompressive craniectomy. Three months later after stabilization, the neurosurgeon replaced the bone flap back. She was followed clinically and over the next year and half some of that bone resorbed, leaving the underlying dura uncovered by bone, with pulsations apparent through the scalp. The decision was made now to perform a cranioplasty to establish calvarial continuity.
Reason for the indicationrion for PMMA instead of bone grafts in this case: The discussion was had with the parents about variety of material and the choice was made to use exogenous material partially because of family preference but partly because of surgeon preference for something with little chance of resorption, and to only use the DBX for the smaller more irregular areas of defect, but a custom implant for the larger defect.
Titantium plates were used to fixate the PMMA implant, but resorbable where absorbable plates were used a scaffold to hold the thin layer of DBX in place.
Indications
Relief of symptoms; avoid complications related to trauma to the skull, prevent traumatic brain injury, skull defect
Contraindications
bleeding disorders
Instrumentation
Setup
Mayfield head rest, supine, intubation with oral ray secured down the midline and secured to chin, 2 large bore IVs, arterial line, foley cath, sphinx pillow / positioning (hip abduction pillow modified as shown in the video), padding to avoid pressure, bone-wax and thrombin available, blood & FFP available
Preoperative Workup
History & physical, CBC, basic metabolic panel, PT/PTT, INR, anesthesiology evaluation for ASA class, low dose radiation 3D CT 1mm cuts head-to-hyoid
Anatomy and Landmarks
Scalp anatomy: skin, subcutaneous tissue, galea, periosteum, skull bone. Incision down to bone through periosteum must be mindful of any thin bone or cranial defects where dura is exposed. Identify cranial sutures: coronal and sagittal at the fontanelles. The major cerebral sinuses must be avoided and the dura carefully dissected free of the cranial sutures where it tends to be more adherent.
Advantages/Disadvantages
a. Advantages: Relief of symptoms
b. Disadvantages: Blood loss
Complications/Risks
bleeding, infection, damage to dura mater leading to CSF leak, bone fragments
Disclosure of Conflicts
bleeding, infection, damage to dura mater leading to CSF leak, bone fragments
Acknowledgements
Kumar Patel and Michael Golinko
References
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