Reconstruction of Craniofacial Structural Defects Through Patient-specific 3-D Printed Custom Scaffolds: Development of A Porcine Model
Richard F. Guidry, B.S.1, Silpa Sharma, M.P.H.2,3, Adam Prevot, B.S.1, Ian R. Wisecarver, M.D.1, Luis Marrero, Ph.D.2, Mandi J. Lopez, D.V.M, Ph.D.4, Gerhard S. Mundinger, M.D.2.
1Louisiana State University School of Medicine, New Orleans, LA, USA, 2Louisiana State University Health Sciences Center, New Orleans, LA, USA, 3Children's Hospital of New Orleans, New Orleans, LA, USA, 4Louisiana State University Laboratory for Equine and Comparative Orthopedic Research, Baton Rouge, LA, USA.
PURPOSE: 3-D printed bioresorbable scaffolds for craniomaxillofacial bone regeneration can be custom-made to fill specific defects, and can be commercially printed based on CT scans within days. Additional seeding of scaffolds with autologous stem cell populations may enable improved regeneration of normal bony architecture, minimization of donor site morbidity, enhanced ability to restore complicated three-dimensional shapes, and improved functional outcomes. However, the ability of such scaffolds to regenerate load-bearing bone is untested in large animal models.
METHODS: We developed a craniofacial porcine model of bone regeneration suitable for testing bioengineered custom 3-D printed bone scaffolds to heal non-critical (<6cm) and critical (>6cm) bone defects. Full- thickness defects were made in the body of the right zygoma and angle of the left mandible using 3-D printed custom cutting guides (Figure 1). In the control arm of the study reported here (n=4), no construct was placed. Post-operatively, animals were followed for 6 months, at which time CT imaging and micro-CT/histology of regenerated bone across the defects was evaluated.
RESULTS: The four control animals underwent surgery and achieved the 6-month post-operative study endpoint with no complications or disturbance of masticatory function. 3D printed osteotomy and plating guides facilitated surgical precision and minimized operative times. CT and gross evaluation of zygomatic and mandibular defects was consistent with incomplete heterotopic ossification. ÁCT confirmed the presence of dystrophic bone formation at the ostomy sites with disruption of normal bone architecture. Trichrome histologic evaluation of the experimental zygoma showed disorganized, porous bone compared to contralateral controls. (Figure 2) Study results in these animals supported ongoing work in the experimental arm (n=8 animals), in which beta-tricalcium phosphate (βTCP) defect-specific bone scaffolds (KLS Martin, Mulheim, Germany) were 3-D printed from preoperative CT images and placed into the zygoma and mandible defects.
CONCLUSION: The described model of craniofacial bone reconstruction utilizing 3D printed, defect-specific bone regeneration templates has broad clinical applicability. Ultimately, insights from this model may realize the possibility of reconstructing bony defects of any size, shape, and thickness by harnessing the power of 3D printing and autologous bone stem cell seeding. Additionally, the described technique may enable critical scale-up capability of autologous cell populations across tissue types other than bone for use in post-traumatic and oncologic reconstruction.
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