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Palmer et al. Plast Aesthet Res 2020;7:2 I http://dx.doi.org/10.20517/2347-9264.2019.34 Page 5 of 8
[25]
make the surgical planning process even more immersive, realistic, and accurate . Virtual rendering of
patient images has also offered intraoperative and postoperative utility. Intraoperative navigation, which
uses a portable localizer and patient CT scans to show the surgeon the real-time position of an instrument,
has demonstrated the ability to accurately locate anatomy and surgical tools within a small margin of
[22]
error . This strategy may be particularly useful in cases of structures that are challenging to visualize
[22]
intraoperatively such as parts of the mandible and the base of the skull . Augmented reality, which allows
for the projection of computer-generated images onto the surgical field in real time, is another promising
computer-based technology that has been applied in various areas of maxillofacial surgery to improve
intraoperative navigation in challenging anatomical scenarios [25,26] . Postoperatively, three-dimensional
rendering of CT scans can be compared via virtual superimposition on surgical plans to confirm results
and evaluate fidelity to the preoperative plan [21,22] . These computer-aided tools have reduced surgical time
and improved precision in multiple craniomaxillofacial applications, making them an attractive technology
for face transplantation [8,24] .

[21]
Jacobs et al. proposed and validated through cadaveric transplantation a planning protocol using CSP
and CAD/CAM technologies that reflects their use in the face transplantation field at large and depicts
their utility. While this team focused on allografts without mandible, their principles have implications
for mandibular reconstruction as accurate handling of the maxilla is necessary for the establishment of a
[21]
functional maxillomandibular relationship . Furthermore, several teams have used similar protocols with
allografts including varying amounts of donor mandible [8,9,27] . First, using preoperative CT images rendered
[21]
in three dimensions, the recipient’s defect is defined . In the virtual workspace, the donor rendering can
[21]
[21]
then be superimposed on the recipient in order to plan appropriate osteotomies . Jacobs et al. advocate
for first virtually establishing optimal donor-to-recipient bony relationships including occlusion and then
using the resulting model to design osteotomy paths that will yield these exact relationships. Other teams
[27]
have since suggested that the osteotomies be defined in a way that preserves functional soft tissue .
In either case, once the osteotomy is depicted virtually, custom cutting guides based on these models
can be manufactured to enable efficient and precise osteotomies designed specifically to establish these
predetermined anatomical relationships [21,27] . In the case of single-jaw transplantation, a custom dental
splint can also be prepared based on the virtual model to further aid in establishment of proper occlusion
[21]
intraoperatively . In cases of bimaxillary transplantation where the landmark of a native recipient jaw
is absent, the donor jaws can be placed in intermaxillary fixation preoperatively for a similar effect [4,8,9] .
Finally, the skeletal aspects of the transplantation procedure can be conducted in the virtual workspace to
[21]
assess outcomes and refine the plan as necessary .

[21]
Using the postoperative overlay analysis described previously, Jacobs et al. found that the surgical result
of their midface transplantation differed from the virtual plan by less than 5 mm. In a series of seven
[27]
cadaveric transplantations including a portion of the mandible, Sosin et al. utilized CSP and CAD/CAM
and also demonstrated close adherence of the postoperative results to preoperative plans. This team also
found that grafts prepared and attached based on these virtual plans did not require time-consuming ad
[27]
hoc intraoperative adjustments . This corroborates the idea that virtual surgical plans can be reproduced
[27]
reliably in the operating room with a time-saving benefit .

Intraoperative applications of computer-based technologies have also been validated through cadaveric face
transplant models. As mentioned above, computer-based strategies that enable precise alignment of skeletal
components may be particularly useful in face transplants that include both the midface and mandible, as
[9]
[8]
recipients in these cases may lack obvious landmarks to guide graft attachment . Brown et al. preformed
10 bimaxillary face transplantations based on CSP principles. In addition to using CSP to plan the
osteotomies and manufacture cutting guides, the team utilized a stereolithographic model of the recipient
[8]
as well as intraoperative navigation during osteotomies and graft inset . The stereolithographic model