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Page 4 of 8 Palmer et al. Plast Aesthet Res 2020;7:2 I http://dx.doi.org/10.20517/2347-9264.2019.34

excursion postoperatively, this was attributed to prior right TMJ injury [6,16] . No facial transplantation
reported to date has included both mandibular condyles, and, accordingly, the feasibility and practicality
of this procedure remain unclear [4,16] . For adequate postoperative jaw function in the case of allografts
including both donor mandibular condyles, the transplanted segment must align with the recipient’s
[16]
glenoid fossae in a way that enables functional articulation . It follows that this may make donor selection
burdensome, as mandible morphology including intercondylar distance is known to vary significantly
[16]
between individuals [4,16] . However, preclinical evidence has been encouraging. Khavanin et al. utilized the
computed tomography (CT) scans of 100 adults to evaluate the viability of bilateral condylar transplant and
concluded that the procedure would be anatomically feasible and clinically practical in most cases given
adequate average interglenoid widths and the fact that the glenoid fossa itself is wider than the mandibular
[4]
[16]
condyle . It should be noted that this study excluded individuals with mandibular trauma or defects .
Candidates for mandibular condyle transplantation may have anatomical changes in the glenoid region that
impact the feasibility of accepting a donor condyle. More targeted research is warranted. Bilateral condyle
transplantation has also been challenged on the grounds that violating the TMJ’s supportive connective
[4]
tissue may result in complications such as ankylosis or joint instability . As a potential solution to these
concerns, it has been suggested that the entire TMJ including donor temporal bone could be transplanted,
[16]
although this would increase procedural complexity and operative time . Additionally, the vascular
anastomoses necessary to support this anatomy have not been demonstrated, and until outcomes of these
procedures are reported, suggesting the superiority of one method over the other remains speculation [4,16] .
With further characterization, transplanting the TMJ along with the mandible may become a valuable
[16]
reconstructive modality for individuals with severe mandibular defects and impairments .

OPTIMIZING SURGICAL PRECISION
Once the skeletal components of the allograft and the general osteotomy locations have been determined,
[8]
two operative procedures must be completed: the donor harvest and the recipient inset . Both of these
procedures are technically challenging and time-intensive [8,21] . The donor harvest demands a thorough
understanding of the recipient’s defect and an appropriate surgical plan; otherwise, the surgical team would
be faced with the time-consuming and error-prone challenge of adjusting the allograft to fit the recipient
during transplantation [7,21] . The recipient procedure, including preparation and allograft attachment,
requires similar precision to yield proper spatial relationships between regional anatomy, a crucial factor
in the restoration of aesthetics and functional parameters such as dental occlusion [5,7,8,22-24] . Achieving
proper alignment between the allograft and the recipient’s native anatomy may be particularly challenging
in face transplantation, where devastating injuries and previous reconstructive efforts can mar regional
anatomy [7,8] . To address these challenges, surgical teams have begun incorporating computer-based
technology, including computerized surgical planning (CSP), computer-aided design and manufacturing
(CAD/CAM), and intraoperative navigation [4,8,21] .

Prior to their use in facial transplantation, these computer-aided techniques demonstrated promise in
[8]
other craniomaxillofacial applications . With this technology, preoperative CT images can be rendered
in three dimensions in a virtual workspace, allowing the user to develop a surgical plan based on virtual
[22]
manipulation and measurement of the patient’s anatomy . This technology obviates the need to design
[22]
a three-dimensional plan off of two-dimensional images . Tangible stereolithographic models may also
[22]
be produced from these virtual representations to further aid in operative planning . In the case of
fibular free flaps for midface or mandibular reconstruction, for instance, the osteotomies can be designed
virtually, corresponding measurements can be used to produce stereolithographic models of these skeletal
elements (a technique termed CAD/CAM), and reconstructive hardware can be pre-formed to these
[24]
patient-specific models prior to surgery . The virtual measurements can also be used to design patient-
[22]
specific cutting guides that facilitate accurate osteotomies in the operating room . Advancing virtual
reality technology and the incorporation of haptic feedback devices into virtual workstations promise to