Establishing cephalometric landmarks for the translational study of Le Fort-based facial transplantation in Swine: enhanced applications using computer-assisted surgery and custom cutting guides.
BACKGROUND
Le Fort-based, maxillofacial allotransplantation is a reconstructive alternative gaining clinical acceptance. However, the vast majority of single-jaw transplant recipients demonstrate less-than-ideal skeletal and dental relationships, with suboptimal aesthetic harmony. The purpose of this study was to investigate reproducible cephalometric landmarks in a large-animal model, where refinement of computer-assisted planning, intraoperative navigational guidance, translational bone osteotomies, and comparative surgical techniques could be performed.


METHODS
Cephalometric landmarks that could be translated into the human craniomaxillofacial skeleton, and that would remain reliable following maxillofacial osteotomies with midfacial alloflap inset, were sought on six miniature swine. Le Fort I- and Le Fort III-based alloflaps were harvested in swine with osteotomies, and all alloflaps were either autoreplanted or transplanted. Cephalometric analyses were performed on lateral cephalograms preoperatively and postoperatively. Critical cephalometric data sets were identified with the assistance of surgical planning and virtual prediction software and evaluated for reliability and translational predictability.


RESULTS
Several pertinent landmarks and human analogues were identified, including pronasale, zygion, parietale, gonion, gnathion, lower incisor base, and alveolare. Parietale-pronasale-alveolare and parietale-pronasale-lower incisor base were found to be reliable correlates of sellion-nasion-A point angle and sellion-nasion-B point angle measurements in humans, respectively.


CONCLUSIONS
There is a set of reliable cephalometric landmarks and measurement angles pertinent for use within a translational large-animal model. These craniomaxillofacial landmarks will enable development of novel navigational software technology, improve cutting guide designs, and facilitate exploration of new avenues for investigation and collaboration.
Baltimore, Bethesda, and Laurel, Md.; and Boston, Mass. From the Departments of Plastic and Reconstructive Surgery and Radiology, Johns Hopkins University School of Medicine; Department of Otolaryngology-Head and Neck Surgery, Walter Reed National Military Medical Center; Harvard School of Dental Medicine, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital; Research and Engineering Development Department, Robotics and Autonomy Group, Johns Hopkins Applied Physics Laboratory; and Naval Postgraduate Dental School, 3D Medical Applications Center, Department of Radiology, Walter Reed National Military Medical Center.
Gabriel F
GF
Santiago
Srinivas M
SM
Susarla
Mohammed
M
Al Rakan
Devin
D
Coon
Erin M
EM
Rada
Karim A
KA
Sarhane
Jamie T
JT
Shores
Steven C
SC
Bonawitz
Damon
D
Cooney
Justin
J
Sacks
Ryan J
RJ
Murphy
Elliot K
EK
Fishman
Gerald
G
Brandacher
W P Andrew
WPA
Lee
Peter
P
Liacouras
Gerald
G
Grant
Mehran
M
Armand
Chad R
CR
Gordon
D059925:Anatomic Landmarks; D000818:Animals; D002102:Cadaver; D002508:Cephalometry / Q000379:methods*; D003817:Dentition; D054445:Facial Transplantation / Q000379:methods; D005260:Female; D006801:Humans; D007568:Jaw / Q000033:anatomy & histology; D008297:Male; D023421:Models, Animal; D056948:Orthognathic Surgical Procedures; D019340:Osteotomy, Le Fort / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013524:Surgical Flaps; D013552:Swine; D013556:Swine, Miniature; D014184:Transplantation, Homologous