Three-Dimensional Computer-Assisted Surgical Planning and Manufacturing in Complex Maxillary Reconstruction



Three-Dimensional Computer-Assisted Surgical Planning and Manufacturing in Complex Maxillary Reconstruction




Atlas of the Oral and Maxillofacial Surgery Clinics of North America, 2020-09-01, Volume 28, Issue 2, Pages 151-164, Copyright © 2020 Elsevier Inc.



Key points

  • Maxillary reconstruction is a complex part of head and neck surgery.

  • Considering the defects using the Brown classification and using the concept of midfacial buttresses helps guide surgeons to choosing the appropriate bony reconstruction.

  • A variety of techniques using 3-dimensional computer-assisted planning can be used ranging from printing biomodels, to 3-dimensional printing models, cutting guides, plates, and fixation guides.

Maxillary reconstruction is a challenging area of head and neck reconstructive surgery. Since the advent of microvascular reconstruction, the surgeon has a large armamentarium of options to consider after ablative surgery to the maxilla and midface. With the development of computer-assisted surgical planning, the reconstructive surgeon can now accurately design and plan bony reconstruction of the midface to within millimeter accuracy, and this has changed the way we approach this area. The maxillectomy defect can produce a complex defect often involving a variety of structures, including the tooth bearing alveolus, the palate, paranasal sinuses, nasal cavity, and orbital cavity. Several bones are often involved, including the maxilla, the palatine bone, the ethmoid bone, the zygomatic bone, and less frequently the nasal bones. Loss of these anatomic structures leads to complex functional and aesthetic consequences and, when considering reconstruction in these patients, the surgeon should determine their goals for each individual patient, because these will help to choose the ideal reconstructive option. These goals can include closure of an oronasal communication, achieving midfacial soft tissue support and symmetry, avoiding velopharyngeal insufficiency, maintaining eye position, dental rehabilitation, and bony support for a facial prosthesis.

In this article, we present an overview of the use of 3-D computer-assisted surgical planning to achieve accurate reconstructions of the complex maxillary defect. We briefly discuss the Brown classification system and use it to guide the reader through the various reconstructive options for the complex maxillary defect.


Three-dimensional computer-assisted surgical planning and manufacturing

Significant progress into the development of 3-dimensional (3D) printing and computer-aided design and manufacture has led to a rapid growth in virtual surgical planning options. The main choices for any hospital or department are whether to purchase a 3D printer and the planning software and design everything in house or to outsource to a company with a proprietary workflow. The extent of virtual planning for every case can range from printing of a stereolithographic model alone that allows a 3D analysis of the case and potential for prebending plates, to completely custom planning with 3D printing of models, guides, and plates. In our unit, as an additional workflow of our maxillofacial prosthetics laboratory, 3D printers have been purchased, and Materialize™ software used for surgical planning. The advantages of an in-house system includes rapid prototyping and planning to be performed, allows the surgeons to easily communicate with the technicians and biomedical engineers to make small modifications when necessary, less expensive for the institution, and requires less time for planning and manufacturing ( Table 1 ). In our unit, the planning is all completed virtually, 3D biomodels and cutting guides are printed, and the plates are prebent on the biomodels and sterilized. Prebending reconstruction plates allows for a more cost-effective option than printing in hospital grade titanium. Several cases will be shown to highlight how 3D-assisted surgical planning has revolutionized our practice and improved surgical outcomes in maxillary reconstruction.

Table 1
Planning process in Maxillofacial Laboratory at Queen Elizabeth Hospital, Birmingham for the average oncology case, for virtual planning, design of cutting guides, and reconstruction plate bending in the laboratory. The average time required for each stage and additional steps for proprietary planning are included
Stage Action Average time required Additional steps for proprietary planning
3D planning (PC workup
  • Download of scans

  • Segmentation and clean up of scans

  • Osteotomy and resection planning and planning of graft

  • Guide design

  • Model preparation for print export and save

  • Production of theater images for print out and patient notes

5 h
  • Sending of scans to proprietary server

  • Virtual conference for planning of resection and guide

  • Design plans sent for approval to operative team

  • Approval of plans and commencement of production

  • Can take addition of several days

3D printing and postprocessing of model
  • Reference model print time

  • Printer clean after printing

  • Printed model postprocess and clean up

  • Guide print time

  • Printed guide postprocessing and clean up

14 h
Laboratory process of plate
  • Plate bending and production of location tags – laser welding

  • Predrilling of holes in model and guides – marking plate on the model

  • Plate preparation – sandblasting, ultrasonic treatment with citric acid to anodize

  • Packaging for sterilization

2 h
  • 3D printing of reconstruction plates is often possible for additional cost

  • Delivery time needed from base of proprietary company to institution

Sterilization 6 h
  • Delivery of sterile cutting guides, models and plates

  • Institutional sterilization may also be required

Completion 27 h Variable delivery between 2 and 4 wk
The last column includes additional steps needed if proprietary company used for 3D computer-assisted planning and manufacture.


Classification of midface defects

Several classifications exist for midfacial defects; however, the Brown classification will be used in this article. The Brown classification was described in 2010, provides a framework for considering potential reconstructive options for maxillary and midface defects, and will be used in this report ( Fig. 1 ). The classification consists of 6 vertical and 4 horizontal maxillectomy defect patterns. The vertical classification involves (1) maxillectomy not causing an oronasal fistula, (2) not involving the orbit, (3) involving the orbital floor and potentially the orbital adnexae but the eye remains in situ, (4) with orbital enucleation or exenteration, (5) orbitomaxillary defect (ie, without involving the alveolus), and (6) nasomaxillary defect. The horizontal classification involves (a) a palatal defect only, not involving the dental alveolus, (b) less than or one-half unilateral, (c) less than or equal to one-half bilateral transverse anterior, and (d) greater than one-half maxillectomy. In addition to using this classification, it is also valuable to consider the bony buttresses of the midface. The key bony buttresses to consider in midface reconstruction as per Yamamoto and colleagues are the horizontal–zygomaticomaxillary (infraorbital) and vertical nasomaxillary buttress, and the oblique pterygomaxillary (zygomatic buttress) ( Fig. 2 ). Having an understanding of these buttresses helps the reconstructive surgeon to choose the ideal reconstructive option.

Brown’s horizontal and vertical classification of maxillary and midface defects.
Fig. 1
Brown’s horizontal and vertical classification of maxillary and midface defects.

Skull model demonstrating the principle of midfacial buttresses for reconstruction. NMB, nasomaxillary buttress; PMB, pterygomaxillary buttress; ZMB, zygomaticomaxillary buttress.
Fig. 2
Skull model demonstrating the principle of midfacial buttresses for reconstruction. NMB, nasomaxillary buttress; PMB, pterygomaxillary buttress; ZMB, zygomaticomaxillary buttress.


The Birmingham approach to midfacial defect reconstruction

In this section, we discuss our approach to complex maxillary and midfacial reconstruction and demonstrate various cases where this approach was used ( Fig. 3 ).

Flow diagram reflecting the Birmingham approach to maxillary reconstruction based on the Brown classification. Note each defect type is color coded to include the additional steps for each reconstructive option for that particular defect.
Fig. 3
Flow diagram reflecting the Birmingham approach to maxillary reconstruction based on the Brown classification. Note each defect type is color coded to include the additional steps for each reconstructive option for that particular defect.


Class I defects

In class I and some class II defects (IIa and low-level and posterior IIb), the goal of reconstruction is closure of an oroantral or oronasal fistula and dental rehabilitation. When the patient is dentate, very good results are achieved with either prosthetic obturation or soft tissue reconstruction alone or in combination with zygomatic implants. When the class IIb defect is posterior to the canine or first premolar, there is no advantage to bony reconstruction in these cases.


Class II defects

In anterior or large class IIb, II2, or IId defects, there is significant loss of cheek and upper lip support, which requires an underlying bony framework to preserve facial form and symmetry. In these cases, our preference is the fibula free flap. The fibula is ideal in these cases because it can provide a substantial length of bone, has a long pedicle, has a reliable soft tissue skin paddle, and provides a good bony framework for dental implants. In hemimaxillectomy (class IIb/IIc) defects, the fibula can either be used to recreate the shape of the alveolar arch ( Figs. 4 and 5 ) or it can be reliably used to recreate the pterygomaxillary buttress. In class II defects, the reconstruction can often be done with a single straight strut of fibula ( Fig. 6 ), but it may need to incorporate multiple osteotomies if the anterior maxilla is too prognathic in relationship to the zygoma or if the defect crosses the midline. The fibula used in this way can often provide adequate soft tissue support for the cheek and upper lip and it provides a framework for implant rehabilitation for at least the anterior teeth. Even in a class IId defect, the fibula provides adequate bone length for complete maxillary low-level reconstruction.

Case demonstrating the use of a fibula free flap for a class II low-level defect. This case demonstrates the use of the fibula free flap to recreate the alveolar arch. This case uses computer-aided planning to print a stereolithographic model ( A ), followed by prebending a reconstruction plate. ( B ) Intraoperative image of the defect and reconstruction plate. ( C , D ) Three-dimensional computer-aided planning is used to guide implant placement and rehabilitation, with planned prosthetic position of restoration. ( E ) Final orthopantomogram (OPG) showing fibula position and implant positions. ( F ) Final facial photograph after reconstruction and rehabilitation.
Fig. 4
Case demonstrating the use of a fibula free flap for a class II low-level defect. This case demonstrates the use of the fibula free flap to recreate the alveolar arch. This case uses computer-aided planning to print a stereolithographic model (
A ), followed by prebending a reconstruction plate. (
B ) Intraoperative image of the defect and reconstruction plate. (
C ,
D ) Three-dimensional computer-aided planning is used to guide implant placement and rehabilitation, with planned prosthetic position of restoration. (
E ) Final orthopantomogram (OPG) showing fibula position and implant positions. (
F ) Final facial photograph after reconstruction and rehabilitation.

A case using 3D computer-aided planning to design plan the reconstruction of a class II low-level defect with a 2-piece fibula free flap reconstruction. ( A-C ) demonstrates the planned position of the fibula segments to reconstruct the maxillary alveolus. ( D ) Planned cutting guides for accurate reconstruction.
Fig. 5
A case using 3D computer-aided planning to design plan the reconstruction of a class II low-level defect with a 2-piece fibula free flap reconstruction. (
A-C ) demonstrates the planned position of the fibula segments to reconstruct the maxillary alveolus. (
D ) Planned cutting guides for accurate reconstruction.

Three-dimensional computer-aided planning used to reconstruct the pterygomaxillary buttress in 2 class II defects using a straight strut of fibula for reconstruction. ( A ) This case used computer-assisted planning to print a stereolithic biomodel only, with straightening of the buttress between the alveolus and zygomatic buttress to allow prebending of a reconstruction plate. ( B ) OPG after reconstruction showing straight strut of fibula bone replacing the pterygomaxillary buttress. ( C , D ) A second case showing the use of computer planning to plan the use of a straight strut fibula between the alveolus to the zygomatic buttress to ensure the position is appropriate for implant placement ( E showing a mirror image of the opposite alveolus to demonstrate that the fibula is in the ideal position for implant positions to the upper right first premolar site). ( F ) Post-operative 3-D reformatted CT showing final position of fibula.
Fig. 6
Three-dimensional computer-aided planning used to reconstruct the pterygomaxillary buttress in 2 class II defects using a straight strut of fibula for reconstruction. (
A ) This case used computer-assisted planning to print a stereolithic biomodel only, with straightening of the buttress between the alveolus and zygomatic buttress to allow prebending of a reconstruction plate. (
B ) OPG after reconstruction showing straight strut of fibula bone replacing the pterygomaxillary buttress. (
C ,
D ) A second case showing the use of computer planning to plan the use of a straight strut fibula between the alveolus to the zygomatic buttress to ensure the position is appropriate for implant placement (
E showing a mirror image of the opposite alveolus to demonstrate that the fibula is in the ideal position for implant positions to the upper right first premolar site). (
F ) Post-operative 3-D reformatted CT showing final position of fibula.

An alternative option includes the thoracodorsal angular artery flap (scapula tip) for these defects. The scapula tip can be an effective alternative for maxillary reconstruction and it can be oriented to reconstruct the palatal surface ( Fig. 7 ) or the anterior maxillary wall. The use of the thoracodorsal angular artery scapular tip flap is particularly useful when there is a significant amount of facial skin loss requiring reconstruction. The bone stock of scapular tip has been criticized for consideration of dental rehabilitation; however, implant rehabilitation is still possible in scapular tip flaps, although onlay bone grafting may be required. The deep circumflex iliac artery (DCIA) is rarely used for these defects, but it can be used for a high class II defect when the height of the resection is at least 3 cm to allow for the DCIA height to adequately capture the DCIA vessels. The natural curve of the iliac creates a very good platform for implants and good facial soft tissue support for class II high defects ( Fig. 8 ).

( A ) Three-dimensional computed tomography scan showing the use of a scapula tip for reconstruction of the right palate with teres major muscle used to line the palate. ( B–D ) this mucosalizes well for implant placement in the native maxilla and prosthetic rehabilitation.
Fig. 7
(
A ) Three-dimensional computed tomography scan showing the use of a scapula tip for reconstruction of the right palate with teres major muscle used to line the palate. (
B–D ) this mucosalizes well for implant placement in the native maxilla and prosthetic rehabilitation.

Case demonstrating the use of 3D planning to reconstruct a high level class II defect reconstructed with a DCIA. ( A , B ) Demonstrating the planned resection and showing position of cutting guides for the resection. ( C , D ) DCIA in place during planning showing ideal position of iliac crest. Red marking shows area that needs thinning down to allow plating. ( E ) Demonstrating the shape of the iliac crest harvest 5 cm from the anterior superior iliac spine (ASIS). ( F ) A 3D printed stereolithic model with DCIA in situ, and shows reconstruction plate position in situ. ( G – K ) Intraoperative photographs showing 3D printed cutting guide applied to iliac crest. Reconstruction plate can be placed at hip harvest site. The DCIA is then inset with the reconstruction plate to the planned position, and the internal oblique muscle is used to line the palate. ( L ) A 3D reformatting of the postoperative computed tomography scan of the facial bones showing the final position of the DCIA in situ.
Fig. 8
Case demonstrating the use of 3D planning to reconstruct a high level class II defect reconstructed with a DCIA. (
A ,
B ) Demonstrating the planned resection and showing position of cutting guides for the resection. (
C ,
D ) DCIA in place during planning showing ideal position of iliac crest. Red marking shows area that needs thinning down to allow plating. (
E ) Demonstrating the shape of the iliac crest harvest 5 cm from the anterior superior iliac spine (ASIS). (
F ) A 3D printed stereolithic model with DCIA in situ, and shows reconstruction plate position in situ. (
G
K ) Intraoperative photographs showing 3D printed cutting guide applied to iliac crest. Reconstruction plate can be placed at hip harvest site. The DCIA is then inset with the reconstruction plate to the planned position, and the internal oblique muscle is used to line the palate. (
L ) A 3D reformatting of the postoperative computed tomography scan of the facial bones showing the final position of the DCIA in situ.


Class III defects

With class III defects, in addition to the alveolar bone loss, there is also loss of bony support for the cheek skin, orbital floor, and rim. This defect is the most difficult to reconstruct, and failed reconstruction has a devastating consequence of midfacial soft tissue collapse and loss of orbital bony support, resulting in hypoglobus and enophthalmous. Any reconstructive option being considered should at least aim to address these key features. Historically, the majority of cases reported in the literature have been reconstructed with soft tissue flaps only, mainly the rectus abdominis or the anterolateral thigh flap. Nonvascularized bone grafts, such as iliac crest or calvarium, were often used in conjunction for orbital floor reconstruction. However, this option provides no bony replacement of the alveolus and hence dental rehabilitative options are limited. There is also a risk of bone graft loss or infection, particularly after radiotherapy. Composite microvascular reconstructive options, when possible, are ideal in these cases. In our experience, the ideal microvascular option is the DCIA flap, because its shape and contour allow for restoration of the zygomaticomaxillary, pterygomaxillary, and the nasomaxillary buttresses simultaneously. With the use of 3D computer-aided planning, the patient’s own iliac crest can be scanned and used to determine the exact part and shape of the iliac crest to harvest. We prepare custom cutting guides for the iliac crest, and this allows the surgeon to harvest the exact shape and amount of bone planned to reconstruct the defect ( Fig. 9 ). The bone is secured with either a prebent reconstruction plate or miniplates. An orbital floor titanium mesh is bent on a stereolithic model or a custom orbital floor plate is printed and secured to the DCIA with miniscrews. The thickness and shape of the bone is very good for implant insertion. The internal oblique muscle is used to close the oral communication and this epithelializes to provide an excellent soft tissue platform for future dental rehabilitation (see Fig. 9 ). Pedicle length is often a concern and, to increase its length, the area of bony harvest on the iliac crest can be moved posteriorly to a maximum of 5 cm from the anterior superior iliac spine. This maneuver allows additional length of pedicle without compromising bony vascularity.

Case demonstrating the 3D computer-assisted planning of a class III defect with a DCIA free flap with prefabricated orbital floor reconstruction. ( A , B ) An area of resection and planned lateral cutting guide. ( C ) DCIA planned and shaped to reconstruct the left maxilla. ( D ) Cutting guide designed to harvest the iliac crest bone. ( E ) A Worm’s eye view of a 3D computer-guided reformat demonstrating the symmetry achieved by the DCIA reconstruction. ( F – I ) Showing the clinical result of DCIA reconstruction of the left side of the face after radiotherapy showing good facial symmetry and good mucosalization.
Fig. 9
Case demonstrating the 3D computer-assisted planning of a class III defect with a DCIA free flap with prefabricated orbital floor reconstruction. (
A ,
B ) An area of resection and planned lateral cutting guide. (
C ) DCIA planned and shaped to reconstruct the left maxilla. (
D ) Cutting guide designed to harvest the iliac crest bone. (
E ) A Worm’s eye view of a 3D computer-guided reformat demonstrating the symmetry achieved by the DCIA reconstruction. (
F
I ) Showing the clinical result of DCIA reconstruction of the left side of the face after radiotherapy showing good facial symmetry and good mucosalization.

The scapula free flap, using the lateral surface of the scapula, can also be used for class III defects. It is becoming an increasingly popular reconstruction option ( Fig. 10 ). Also, the ability to use it as a chimeric flap with a second bony segment, skin, and muscle options provides the reconstructive surgeon with the ability to reconstruct complex defects involving midfacial bone and skin. It can even be osteotomized to achieve the ideal orientation required. The scapula tip can also be used for these defects. The scapula tip has a significant advantage over the DCIA in that it has a longer pedicle; however, this advantage is only achieved if no scapular skin is required and in this situation, the teres major can be used to close the oral mucosal defect. Virtual planning can be used to isolate the scapular shape and determine the ideal orientation for reconstruction of the defect in each individual case. Where possible, having the thickest part of the scapula tip facing the alveolus is ideal for implant provision, but this strategy does shorten the pedicle length. Morphologically, the scapula tip has excellent morphologic consistency with the palate and orbital floor.

( A – C ) Case demonstrating the use of a scapula free flap to reconstruct a class III Left maxillary defect with a single osteotomy to recreate the pterygomaxillary buttress. ( D ) Postoperative 3D computed tomography scan showing position of scapula bone and prefabricated orbital reconstruction plate to recreate the orbital floor, secured to the scapula.
Fig. 10
(
A
C ) Case demonstrating the use of a scapula free flap to reconstruct a class III Left maxillary defect with a single osteotomy to recreate the pterygomaxillary buttress. (
D ) Postoperative 3D computed tomography scan showing position of scapula bone and prefabricated orbital reconstruction plate to recreate the orbital floor, secured to the scapula.

The fibula free flap has a limited role in class III defects. Although it can be used to reconstruct all 3 bony buttresses, this would involve 2 osteotomies and very sharp angles between them, leaving a central area with no bony support mid cheek. Another option is double barreling the fibula, orientating it horizontally while removing a segment in between (on the nasal side). These techniques lead to significant challenges with regard to orientation of the skin island and inset. Also, the need for multiple osteotomies compromises the pedicle length, which is a crucial concern, especially in midface defects. Hence, most authors feel that the fibula free flap is inadequate for class III and IV defects. ,


Class IV defects

When the maxillectomy is associated with orbital exenteration, the need to reconstruct the orbital floor is no longer necessary to support the eye position. The goals of reconstruction should be to reestablish midfacial projection, close the oroantral communication, and provide a platform for prosthetic replacement of the eye or obliteration of the defect. In our experience, similar to a class III defect, a DCIA with internal oblique muscle has been found to appropriately replace the bony framework of the midface ( Fig. 11 ). The inferior aspect of the reconstruction can be used to support implants for dental rehabilitation, and the superior aspect can be used to support implants for an orbital prosthesis ( Fig. 12 ). The scapula free flap can also be used here with or without the latissmus dorsi muscle, which can be used to close the oral communication and obliterate the orbital cavity if needed as well. The use of muscle to obturate the orbit allows for favorable contraction to provide space for an orbital prosthesis. This is particularly necessary when the eyelids have been resected as part of the ablation. When a significant amount of skin is resected in a class IV defect, then a scapula free flap is the ideal option, although over time, the skin sags with gravity. Secondary procedures are often necessary to remove excess skin, and maintain tone.

( A , B ) Case of a class IV maxillary resection with orbital exenteration. A Stereolithic model was printed and a reconstruction plate prebent to it. ( C , D ) The exact shape of the planned DCIA was used and a cutting guide fabricated to reconstruct the midface with primary closure of the eyelids to close the orbital cavity defect. ( E ) Postoperative 3D computed tomography view of the reconstruction.
Fig. 11
(
A ,
B ) Case of a class IV maxillary resection with orbital exenteration. A Stereolithic model was printed and a reconstruction plate prebent to it. (
C ,
D ) The exact shape of the planned DCIA was used and a cutting guide fabricated to reconstruct the midface with primary closure of the eyelids to close the orbital cavity defect. (
E ) Postoperative 3D computed tomography view of the reconstruction.

( A ) Case of a right sided class IV defect reconstructed with a DCIA free flap reconstruction secured with miniplates. ( B – F ) Radiographs showing reconstruction in situ and orbital and oral implants placed for orbital prosthesis and dental rehabilitation.
Fig. 12
(
A ) Case of a right sided class IV defect reconstructed with a DCIA free flap reconstruction secured with miniplates. (
B
F ) Radiographs showing reconstruction in situ and orbital and oral implants placed for orbital prosthesis and dental rehabilitation.


Class V and class VI defects

Class V defects include the maxilla, orbital rim, and occasionally orbital exenteration without involving alveolar resection. These resections often involve skin as well. In these cases, the role of a composite reconstruction is to reconstruct the zygomaticomaxillary buttress for facial support, to allow for application of an orbital floor prosthesis, or to provide a bony framework for implants to be inserted for orbital prosthetic replacement. Class VI defects are rare and often involve a significant aspect of nasal resection. When nasal bone or nasomaxillary defects are created, these often require composite reconstruction to create a framework to support the soft tissue.

Owing to the limited amount of bone needed, a composite radial forearm free flap is often used to reconstruct the infraorbital rim or the nasal bone framework. Three-dimensional computer planning allows for construction of a 3D-printed stereolithographic model of the radius, calculation of 40% circumference of the radius and preparation of a cutting guide. The shape of radius bone needed can be planned, and osteotomies are preplanned to guide the surgeon to achieve the most accurate result. The 3D-printed radius model can also be used to prebend a distal radius plate to ensure accurate adaptation at the time of surgery and reduce the risk of radius fracture ( Fig. 13 ).

( A ) Case demonstrating a class V defect without orbital floor resection. ( B ) A 3D computer-assisted planning was used to predict the amount of bone required for orbital rim reconstruction and a composite radial forearm flap was chosen. ( C ) Cutting guides for radius in situ. ( D ) Cutting guide in situ after harvest of radius bone. ( E ) Distal radius prefabricated plate was used to prevent radius fracture. ( F ) Intraoperative photograph showing bone reconstruction in situ and overlying radial forearm skin paddle. ( G , H ) Postoperative 3D computed tomography images show the position of the osteotomized radius bone to reconstruct the orbital rim.
Fig. 13
(
A ) Case demonstrating a class V defect without orbital floor resection. (
B ) A 3D computer-assisted planning was used to predict the amount of bone required for orbital rim reconstruction and a composite radial forearm flap was chosen. (
C ) Cutting guides for radius in situ. (
D ) Cutting guide in situ after harvest of radius bone. (
E ) Distal radius prefabricated plate was used to prevent radius fracture. (
F ) Intraoperative photograph showing bone reconstruction in situ and overlying radial forearm skin paddle. (
G ,
H ) Postoperative 3D computed tomography images show the position of the osteotomized radius bone to reconstruct the orbital rim.

When total rhinectomy defects are created and the plan is for autologous reconstruction, a composite radial forearm can be used to provide bony support and the radial skin used for nasal line, and a paramedian forehead flap can be used to replace the overlying skin for a better color match.


Complex multiclass defects

Computer-assisted 3D surgical planning has also significantly improved the way we reconstruct complex midface defects, such as combined rhinectomy and maxillectomy defects. With 3D computer-assisted planning, the planned reconstructions can be designed to facilitate reconstruction of the maxilla first, followed by provision of implants to support a dental and a nasal prosthesis ( Fig. 14 ). Care needs to be taken to ensure adequate upper lip length to create a natural appearing nasolabial fold between skin and nasal prosthesis, and to maintain lip competence. In cases where there is significant tissue loss, using computer-aided planning, midface structures can be superimposed to facilitate planning of the reconstruction. Such advances in virtual planning software have greatly improved the ability to reconstruct complex defects such as gunshot wounds with great precision ( Fig. 15 ).

Case of secondary reconstruction patient referred for reconstruction of anterior maxilla and rhinectomy defect. ( A , B ) Anterior and lateral photographs of patient with maxillary obturator and nasal prosthesis in situ. Note concave facial profile from maxillary deficiency. ( C , D ) Intraoral photographs demonstrating deformity. ( E ) Frontal photograph after fibula free flap reconstruction of the maxillary defect and insertion of glabella implant. ( F , G ) Virtual planning of maxillary and nasal implants. ( G ) The implant-supported nasal prosthesis in situ. ( H ) Intraoperative photograph of maxillary drill guide in situ. ( I ) Postimplant OPG shoring implants in situ. ( J ) Facial profile with final prostheses in situ.
Fig. 14
Case of secondary reconstruction patient referred for reconstruction of anterior maxilla and rhinectomy defect. (
A ,
B ) Anterior and lateral photographs of patient with maxillary obturator and nasal prosthesis in situ. Note concave facial profile from maxillary deficiency. (
C ,
D ) Intraoral photographs demonstrating deformity. (
E ) Frontal photograph after fibula free flap reconstruction of the maxillary defect and insertion of glabella implant. (
F ,
G ) Virtual planning of maxillary and nasal implants. (
G ) The implant-supported nasal prosthesis in situ. (
H ) Intraoperative photograph of maxillary drill guide in situ. (
I ) Postimplant OPG shoring implants in situ. (
J ) Facial profile with final prostheses in situ.

Case with a complex midfacial defect caused by a shotgun ( A ). The patient sustained complex midfacial, mandibular, and orbital fractures and, after multiple debridements and open reduction and fixation of bilateral zygomatic and mandibular fractures ( B ), the resultant defect was a mixed class III and class VI defect ( C ) with bilateral blindness. The images demonstrate the use of 3D planning to simulate a maxilla to replace the missing maxilla ( D – F ), which guided the position of a final fibula free flap to reconstruct the maxilla for future oral and nasal prosthetic rehabilitation. ( G ) Biomodel showing planned position of fibula and used for prebending reconstruction plate. ( H ) Intraoperative photo showing fibula in situ with pedicle in hand. ( I,j ) Final 3D reformatted position of fibula postoperatively.
Fig. 15
Case with a complex midfacial defect caused by a shotgun (
A ). The patient sustained complex midfacial, mandibular, and orbital fractures and, after multiple debridements and open reduction and fixation of bilateral zygomatic and mandibular fractures (
B ), the resultant defect was a mixed class III and class VI defect (
C ) with bilateral blindness. The images demonstrate the use of 3D planning to simulate a maxilla to replace the missing maxilla (
D
F ), which guided the position of a final fibula free flap to reconstruct the maxilla for future oral and nasal prosthetic rehabilitation. (
G ) Biomodel showing planned position of fibula and used for prebending reconstruction plate. (
H ) Intraoperative photo showing fibula in situ with pedicle in hand. (
I,j ) Final 3D reformatted position of fibula postoperatively.


You're Reading a Preview

Become a DentistryKey membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Was this article helpful?

Three-Dimensional Computer-Assisted Surgical Planning and Manufacturing in Complex Maxillary Reconstruction Omar Breik MBBS, BDSc, MClinSc, FRACDS(OMS) , Matthew Idle BDS, MBBS, FRCS(OMFS) , Timothy Martin BDS, MBBS, MSc, FRCS(OMFS) , Prav Praveen BDS, MBBS, FRCS(OMFS) and Satyesh Parmar BDS, MBBS, FRCS(OMFS) Atlas of the Oral and Maxillofacial Surgery Clinics of North America, 2020-09-01, Volume 28, Issue 2, Pages 151-164, Copyright © 2020 Elsevier Inc. Key points Maxillary reconstruction is a complex part of head and neck surgery. Considering the defects using the Brown classification and using the concept of midfacial buttresses helps guide surgeons to choosing the appropriate bony reconstruction. A variety of techniques using 3-dimensional computer-assisted planning can be used ranging from printing biomodels, to 3-dimensional printing models, cutting guides, plates, and fixation guides. Maxillary reconstruction is a challenging area of head and neck reconstructive surgery. Since the advent of microvascular reconstruction, the surgeon has a large armamentarium of options to consider after ablative surgery to the maxilla and midface. With the development of computer-assisted surgical planning, the reconstructive surgeon can now accurately design and plan bony reconstruction of the midface to within millimeter accuracy, and this has changed the way we approach this area. The maxillectomy defect can produce a complex defect often involving a variety of structures, including the tooth bearing alveolus, the palate, paranasal sinuses, nasal cavity, and orbital cavity. Several bones are often involved, including the maxilla, the palatine bone, the ethmoid bone, the zygomatic bone, and less frequently the nasal bones. Loss of these anatomic structures leads to complex functional and aesthetic consequences and, when considering reconstruction in these patients, the surgeon should determine their goals for each individual patient, because these will help to choose the ideal reconstructive option. These goals can include closure of an oronasal communication, achieving midfacial soft tissue support and symmetry, avoiding velopharyngeal insufficiency, maintaining eye position, dental rehabilitation, and bony support for a facial prosthesis. In this article, we present an overview of the use of 3-D computer-assisted surgical planning to achieve accurate reconstructions of the complex maxillary defect. We briefly discuss the Brown classification system and use it to guide the reader through the various reconstructive options for the complex maxillary defect. Three-dimensional computer-assisted surgical planning and manufacturing Significant progress into the development of 3-dimensional (3D) printing and computer-aided design and manufacture has led to a rapid growth in virtual surgical planning options. The main choices for any hospital or department are whether to purchase a 3D printer and the planning software and design everything in house or to outsource to a company with a proprietary workflow. The extent of virtual planning for every case can range from printing of a stereolithographic model alone that allows a 3D analysis of the case and potential for prebending plates, to completely custom planning with 3D printing of models, guides, and plates. In our unit, as an additional workflow of our maxillofacial prosthetics laboratory, 3D printers have been purchased, and Materialize™ software used for surgical planning. The advantages of an in-house system includes rapid prototyping and planning to be performed, allows the surgeons to easily communicate with the technicians and biomedical engineers to make small modifications when necessary, less expensive for the institution, and requires less time for planning and manufacturing ( Table 1 ). In our unit, the planning is all completed virtually, 3D biomodels and cutting guides are printed, and the plates are prebent on the biomodels and sterilized. Prebending reconstruction plates allows for a more cost-effective option than printing in hospital grade titanium. Several cases will be shown to highlight how 3D-assisted surgical planning has revolutionized our practice and improved surgical outcomes in maxillary reconstruction. Table 1 Planning process in Maxillofacial Laboratory at Queen Elizabeth Hospital, Birmingham for the average oncology case, for virtual planning, design of cutting guides, and reconstruction plate bending in the laboratory. The average time required for each stage and additional steps for proprietary planning are included Stage Action Average time required Additional steps for proprietary planning 3D planning (PC workup Download of scans Segmentation and clean up of scans Osteotomy and resection planning and planning of graft Guide design Model preparation for print export and save Production of theater images for print out and patient notes 5 h Sending of scans to proprietary server Virtual conference for planning of resection and guide Design plans sent for approval to operative team Approval of plans and commencement of production Can take addition of several days 3D printing and postprocessing of model Reference model print time Printer clean after printing Printed model postprocess and clean up Guide print time Printed guide postprocessing and clean up 14 h – Laboratory process of plate Plate bending and production of location tags – laser welding Predrilling of holes in model and guides – marking plate on the model Plate preparation – sandblasting, ultrasonic treatment with citric acid to anodize Packaging for sterilization 2 h 3D printing of reconstruction plates is often possible for additional cost Delivery time needed from base of proprietary company to institution Sterilization – 6 h Delivery of sterile cutting guides, models and plates Institutional sterilization may also be required Completion – 27 h Variable delivery between 2 and 4 wk The last column includes additional steps needed if proprietary company used for 3D computer-assisted planning and manufacture. Classification of midface defects Several classifications exist for midfacial defects; however, the Brown classification will be used in this article. The Brown classification was described in 2010, provides a framework for considering potential reconstructive options for maxillary and midface defects, and will be used in this report ( Fig. 1 ). The classification consists of 6 vertical and 4 horizontal maxillectomy defect patterns. The vertical classification involves (1) maxillectomy not causing an oronasal fistula, (2) not involving the orbit, (3) involving the orbital floor and potentially the orbital adnexae but the eye remains in situ, (4) with orbital enucleation or exenteration, (5) orbitomaxillary defect (ie, without involving the alveolus), and (6) nasomaxillary defect. The horizontal classification involves (a) a palatal defect only, not involving the dental alveolus, (b) less than or one-half unilateral, (c) less than or equal to one-half bilateral transverse anterior, and (d) greater than one-half maxillectomy. In addition to using this classification, it is also valuable to consider the bony buttresses of the midface. The key bony buttresses to consider in midface reconstruction as per Yamamoto and colleagues are the horizontal–zygomaticomaxillary (infraorbital) and vertical nasomaxillary buttress, and the oblique pterygomaxillary (zygomatic buttress) ( Fig. 2 ). Having an understanding of these buttresses helps the reconstructive surgeon to choose the ideal reconstructive option. Fig. 1 Brown’s horizontal and vertical classification of maxillary and midface defects. Fig. 2 Skull model demonstrating the principle of midfacial buttresses for reconstruction. NMB, nasomaxillary buttress; PMB, pterygomaxillary buttress; ZMB, zygomaticomaxillary buttress. The Birmingham approach to midfacial defect reconstruction In this section, we discuss our approach to complex maxillary and midfacial reconstruction and demonstrate various cases where this approach was used ( Fig. 3 ). Fig. 3 Flow diagram reflecting the Birmingham approach to maxillary reconstruction based on the Brown classification. Note each defect type is color coded to include the additional steps for each reconstructive option for that particular defect. Class I defects In class I and some class II defects (IIa and low-level and posterior IIb), the goal of reconstruction is closure of an oroantral or oronasal fistula and dental rehabilitation. When the patient is dentate, very good results are achieved with either prosthetic obturation or soft tissue reconstruction alone or in combination with zygomatic implants. When the class IIb defect is posterior to the canine or first premolar, there is no advantage to bony reconstruction in these cases. Class II defects In anterior or large class IIb, II2, or IId defects, there is significant loss of cheek and upper lip support, which requires an underlying bony framework to preserve facial form and symmetry. In these cases, our preference is the fibula free flap. The fibula is ideal in these cases because it can provide a substantial length of bone, has a long pedicle, has a reliable soft tissue skin paddle, and provides a good bony framework for dental implants. In hemimaxillectomy (class IIb/IIc) defects, the fibula can either be used to recreate the shape of the alveolar arch ( Figs. 4 and 5 ) or it can be reliably used to recreate the pterygomaxillary buttress. In class II defects, the reconstruction can often be done with a single straight strut of fibula ( Fig. 6 ), but it may need to incorporate multiple osteotomies if the anterior maxilla is too prognathic in relationship to the zygoma or if the defect crosses the midline. The fibula used in this way can often provide adequate soft tissue support for the cheek and upper lip and it provides a framework for implant rehabilitation for at least the anterior teeth. Even in a class IId defect, the fibula provides adequate bone length for complete maxillary low-level reconstruction. Fig. 4 Case demonstrating the use of a fibula free flap for a class II low-level defect. This case demonstrates the use of the fibula free flap to recreate the alveolar arch. This case uses computer-aided planning to print a stereolithographic model ( A ), followed by prebending a reconstruction plate. ( B ) Intraoperative image of the defect and reconstruction plate. ( C , D ) Three-dimensional computer-aided planning is used to guide implant placement and rehabilitation, with planned prosthetic position of restoration. ( E ) Final orthopantomogram (OPG) showing fibula position and implant positions. ( F ) Final facial photograph after reconstruction and rehabilitation. Fig. 5 A case using 3D computer-aided planning to design plan the reconstruction of a class II low-level defect with a 2-piece fibula free flap reconstruction. ( A-C ) demonstrates the planned position of the fibula segments to reconstruct the maxillary alveolus. ( D ) Planned cutting guides for accurate reconstruction. Fig. 6 Three-dimensional computer-aided planning used to reconstruct the pterygomaxillary buttress in 2 class II defects using a straight strut of fibula for reconstruction. ( A ) This case used computer-assisted planning to print a stereolithic biomodel only, with straightening of the buttress between the alveolus and zygomatic buttress to allow prebending of a reconstruction plate. ( B ) OPG after reconstruction showing straight strut of fibula bone replacing the pterygomaxillary buttress. ( C , D ) A second case showing the use of computer planning to plan the use of a straight strut fibula between the alveolus to the zygomatic buttress to ensure the position is appropriate for implant placement ( E showing a mirror image of the opposite alveolus to demonstrate that the fibula is in the ideal position for implant positions to the upper right first premolar site). ( F ) Post-operative 3-D reformatted CT showing final position of fibula. An alternative option includes the thoracodorsal angular artery flap (scapula tip) for these defects. The scapula tip can be an effective alternative for maxillary reconstruction and it can be oriented to reconstruct the palatal surface ( Fig. 7 ) or the anterior maxillary wall. The use of the thoracodorsal angular artery scapular tip flap is particularly useful when there is a significant amount of facial skin loss requiring reconstruction. The bone stock of scapular tip has been criticized for consideration of dental rehabilitation; however, implant rehabilitation is still possible in scapular tip flaps, although onlay bone grafting may be required. The deep circumflex iliac artery (DCIA) is rarely used for these defects, but it can be used for a high class II defect when the height of the resection is at least 3 cm to allow for the DCIA height to adequately capture the DCIA vessels. The natural curve of the iliac creates a very good platform for implants and good facial soft tissue support for class II high defects ( Fig. 8 ). Fig. 7 ( A ) Three-dimensional computed tomography scan showing the use of a scapula tip for reconstruction of the right palate with teres major muscle used to line the palate. ( B–D ) this mucosalizes well for implant placement in the native maxilla and prosthetic rehabilitation. Fig. 8 Case demonstrating the use of 3D planning to reconstruct a high level class II defect reconstructed with a DCIA. ( A , B ) Demonstrating the planned resection and showing position of cutting guides for the resection. ( C , D ) DCIA in place during planning showing ideal position of iliac crest. Red marking shows area that needs thinning down to allow plating. ( E ) Demonstrating the shape of the iliac crest harvest 5 cm from the anterior superior iliac spine (ASIS). ( F ) A 3D printed stereolithic model with DCIA in situ, and shows reconstruction plate position in situ. ( G – K ) Intraoperative photographs showing 3D printed cutting guide applied to iliac crest. Reconstruction plate can be placed at hip harvest site. The DCIA is then inset with the reconstruction plate to the planned position, and the internal oblique muscle is used to line the palate. ( L ) A 3D reformatting of the postoperative computed tomography scan of the facial bones showing the final position of the DCIA in situ. Class III defects With class III defects, in addition to the alveolar bone loss, there is also loss of bony support for the cheek skin, orbital floor, and rim. This defect is the most difficult to reconstruct, and failed reconstruction has a devastating consequence of midfacial soft tissue collapse and loss of orbital bony support, resulting in hypoglobus and enophthalmous. Any reconstructive option being considered should at least aim to address these key features. Historically, the majority of cases reported in the literature have been reconstructed with soft tissue flaps only, mainly the rectus abdominis or the anterolateral thigh flap. Nonvascularized bone grafts, such as iliac crest or calvarium, were often used in conjunction for orbital floor reconstruction. However, this option provides no bony replacement of the alveolus and hence dental rehabilitative options are limited. There is also a risk of bone graft loss or infection, particularly after radiotherapy. Composite microvascular reconstructive options, when possible, are ideal in these cases. In our experience, the ideal microvascular option is the DCIA flap, because its shape and contour allow for restoration of the zygomaticomaxillary, pterygomaxillary, and the nasomaxillary buttresses simultaneously. With the use of 3D computer-aided planning, the patient’s own iliac crest can be scanned and used to determine the exact part and shape of the iliac crest to harvest. We prepare custom cutting guides for the iliac crest, and this allows the surgeon to harvest the exact shape and amount of bone planned to reconstruct the defect ( Fig. 9 ). The bone is secured with either a prebent reconstruction plate or miniplates. An orbital floor titanium mesh is bent on a stereolithic model or a custom orbital floor plate is printed and secured to the DCIA with miniscrews. The thickness and shape of the bone is very good for implant insertion. The internal oblique muscle is used to close the oral communication and this epithelializes to provide an excellent soft tissue platform for future dental rehabilitation (see Fig. 9 ). Pedicle length is often a concern and, to increase its length, the area of bony harvest on the iliac crest can be moved posteriorly to a maximum of 5 cm from the anterior superior iliac spine. This maneuver allows additional length of pedicle without compromising bony vascularity. Fig. 9 Case demonstrating the 3D computer-assisted planning of a class III defect with a DCIA free flap with prefabricated orbital floor reconstruction. ( A , B ) An area of resection and planned lateral cutting guide. ( C ) DCIA planned and shaped to reconstruct the left maxilla. ( D ) Cutting guide designed to harvest the iliac crest bone. ( E ) A Worm’s eye view of a 3D computer-guided reformat demonstrating the symmetry achieved by the DCIA reconstruction. ( F – I ) Showing the clinical result of DCIA reconstruction of the left side of the face after radiotherapy showing good facial symmetry and good mucosalization. The scapula free flap, using the lateral surface of the scapula, can also be used for class III defects. It is becoming an increasingly popular reconstruction option ( Fig. 10 ). Also, the ability to use it as a chimeric flap with a second bony segment, skin, and muscle options provides the reconstructive surgeon with the ability to reconstruct complex defects involving midfacial bone and skin. It can even be osteotomized to achieve the ideal orientation required. The scapula tip can also be used for these defects. The scapula tip has a significant advantage over the DCIA in that it has a longer pedicle; however, this advantage is only achieved if no scapular skin is required and in this situation, the teres major can be used to close the oral mucosal defect. Virtual planning can be used to isolate the scapular shape and determine the ideal orientation for reconstruction of the defect in each individual case. Where possible, having the thickest part of the scapula tip facing the alveolus is ideal for implant provision, but this strategy does shorten the pedicle length. Morphologically, the scapula tip has excellent morphologic consistency with the palate and orbital floor. Fig. 10 ( A – C ) Case demonstrating the use of a scapula free flap to reconstruct a class III Left maxillary defect with a single osteotomy to recreate the pterygomaxillary buttress. ( D ) Postoperative 3D computed tomography scan showing position of scapula bone and prefabricated orbital reconstruction plate to recreate the orbital floor, secured to the scapula. The fibula free flap has a limited role in class III defects. Although it can be used to reconstruct all 3 bony buttresses, this would involve 2 osteotomies and very sharp angles between them, leaving a central area with no bony support mid cheek. Another option is double barreling the fibula, orientating it horizontally while removing a segment in between (on the nasal side). These techniques lead to significant challenges with regard to orientation of the skin island and inset. Also, the need for multiple osteotomies compromises the pedicle length, which is a crucial concern, especially in midface defects. Hence, most authors feel that the fibula free flap is inadequate for class III and IV defects. , Class IV defects When the maxillectomy is associated with orbital exenteration, the need to reconstruct the orbital floor is no longer necessary to support the eye position. The goals of reconstruction should be to reestablish midfacial projection, close the oroantral communication, and provide a platform for prosthetic replacement of the eye or obliteration of the defect. In our experience, similar to a class III defect, a DCIA with internal oblique muscle has been found to appropriately replace the bony framework of the midface ( Fig. 11 ). The inferior aspect of the reconstruction can be used to support implants for dental rehabilitation, and the superior aspect can be used to support implants for an orbital prosthesis ( Fig. 12 ). The scapula free flap can also be used here with or without the latissmus dorsi muscle, which can be used to close the oral communication and obliterate the orbital cavity if needed as well. The use of muscle to obturate the orbit allows for favorable contraction to provide space for an orbital prosthesis. This is particularly necessary when the eyelids have been resected as part of the ablation. When a significant amount of skin is resected in a class IV defect, then a scapula free flap is the ideal option, although over time, the skin sags with gravity. Secondary procedures are often necessary to remove excess skin, and maintain tone. Fig. 11 ( A , B ) Case of a class IV maxillary resection with orbital exenteration. A Stereolithic model was printed and a reconstruction plate prebent to it. ( C , D ) The exact shape of the planned DCIA was used and a cutting guide fabricated to reconstruct the midface with primary closure of the eyelids to close the orbital cavity defect. ( E ) Postoperative 3D computed tomography view of the reconstruction. Fig. 12 ( A ) Case of a right sided class IV defect reconstructed with a DCIA free flap reconstruction secured with miniplates. ( B – F ) Radiographs showing reconstruction in situ and orbital and oral implants placed for orbital prosthesis and dental rehabilitation. Class V and class VI defects Class V defects include the maxilla, orbital rim, and occasionally orbital exenteration without involving alveolar resection. These resections often involve skin as well. In these cases, the role of a composite reconstruction is to reconstruct the zygomaticomaxillary buttress for facial support, to allow for application of an orbital floor prosthesis, or to provide a bony framework for implants to be inserted for orbital prosthetic replacement. Class VI defects are rare and often involve a significant aspect of nasal resection. When nasal bone or nasomaxillary defects are created, these often require composite reconstruction to create a framework to support the soft tissue. Owing to the limited amount of bone needed, a composite radial forearm free flap is often used to reconstruct the infraorbital rim or the nasal bone framework. Three-dimensional computer planning allows for construction of a 3D-printed stereolithographic model of the radius, calculation of 40% circumference of the radius and preparation of a cutting guide. The shape of radius bone needed can be planned, and osteotomies are preplanned to guide the surgeon to achieve the most accurate result. The 3D-printed radius model can also be used to prebend a distal radius plate to ensure accurate adaptation at the time of surgery and reduce the risk of radius fracture ( Fig. 13 ). Fig. 13 ( A ) Case demonstrating a class V defect without orbital floor resection. ( B ) A 3D computer-assisted planning was used to predict the amount of bone required for orbital rim reconstruction and a composite radial forearm flap was chosen. ( C ) Cutting guides for radius in situ. ( D ) Cutting guide in situ after harvest of radius bone. ( E ) Distal radius prefabricated plate was used to prevent radius fracture. ( F ) Intraoperative photograph showing bone reconstruction in situ and overlying radial forearm skin paddle. ( G , H ) Postoperative 3D computed tomography images show the position of the osteotomized radius bone to reconstruct the orbital rim. When total rhinectomy defects are created and the plan is for autologous reconstruction, a composite radial forearm can be used to provide bony support and the radial skin used for nasal line, and a paramedian forehead flap can be used to replace the overlying skin for a better color match. Complex multiclass defects Computer-assisted 3D surgical planning has also significantly improved the way we reconstruct complex midface defects, such as combined rhinectomy and maxillectomy defects. With 3D computer-assisted planning, the planned reconstructions can be designed to facilitate reconstruction of the maxilla first, followed by provision of implants to support a dental and a nasal prosthesis ( Fig. 14 ). Care needs to be taken to ensure adequate upper lip length to create a natural appearing nasolabial fold between skin and nasal prosthesis, and to maintain lip competence. In cases where there is significant tissue loss, using computer-aided planning, midface structures can be superimposed to facilitate planning of the reconstruction. Such advances in virtual planning software have greatly improved the ability to reconstruct complex defects such as gunshot wounds with great precision ( Fig. 15 ). Fig. 14 Case of secondary reconstruction patient referred for reconstruction of anterior maxilla and rhinectomy defect. ( A , B ) Anterior and lateral photographs of patient with maxillary obturator and nasal prosthesis in situ. Note concave facial profile from maxillary deficiency. ( C , D ) Intraoral photographs demonstrating deformity. ( E ) Frontal photograph after fibula free flap reconstruction of the maxillary defect and insertion of glabella implant. ( F , G ) Virtual planning of maxillary and nasal implants. ( G ) The implant-supported nasal prosthesis in situ. ( H ) Intraoperative photograph of maxillary drill guide in situ. ( I ) Postimplant OPG shoring implants in situ. ( J ) Facial profile with final prostheses in situ. Fig. 15 Case with a complex midfacial defect caused by a shotgun ( A ). The patient sustained complex midfacial, mandibular, and orbital fractures and, after multiple debridements and open reduction and fixation of bilateral zygomatic and mandibular fractures ( B ), the resultant defect was a mixed class III and class VI defect ( C ) with bilateral blindness. The images demonstrate the use of 3D planning to simulate a maxilla to replace the missing maxilla ( D – F ), which guided the position of a final fibula free flap to reconstruct the maxilla for future oral and nasal prosthetic rehabilitation. ( G ) Biomodel showing planned position of fibula and used for prebending reconstruction plate. ( H ) Intraoperative photo showing fibula in situ with pedicle in hand. ( I,j ) Final 3D reformatted position of fibula postoperatively. Additional factors to consider when planning maxillary reconstruction One of the challenges with virtual and computer-assisted planning is the difficulty in visualizing the overall effects of the virtual surgical plan in practice. Some key concepts should be considered when planning to ensure a successful outcome, and to minimize complications. First, ensure adequate bony contact between the native bone and the grafted bone to increase the chance of bony union. This is vital to ensure stable long-term results, and predictable implant and prosthetic planning. Second, minimize the use of hardware. Several authors report the use of plates and large sheets of titanium mesh in class III defects, , however, our concern is that with irradiation, these are likely to get infected, or exposed. Although we have been prebending 2.0-mm reconstruction plates for our maxillary reconstructions, we feel that even these are prone to getting infected and potentially causing sinuses, which can be disfiguring and necessitate plate removal. The use of miniplates is likely to cause less infection. Additionally, reconstruction plates and screws may interfere with implant placement, and removal of these plates is difficult and causes significant morbidity. Miniplates are easier to remove if necessary owing to infection or for implant placement. We advocate for the use of the minimal amount of hardware possible to achieve stability of the graft. A solution to this may be to 3D print fixation guides that help to locate the accurate final position of the bone graft, which can then be removed once plated in position with miniplates. , And last, when virtually planning, it is important to consider the soft tissue limitations of the areas being reconstructed. By predicting the incisions required for access, the surgeon could ensure to minimize underlying hardware near incision lines to reduce the risk of exposure. Also, particularly midfacial areas have very thin skin, especially the medial canthus region, and hence avoiding hardware in these areas will reduce the risk of dehiscence and exposure. Being aware of possible problems, and considering them during surgical planning will hopefully decrease the risk of complications. Summary Maxillary reconstruction is a challenging part of head and neck reconstruction. The advent of 3D planning and manufacturing has significantly improved the ability to plan and accurately reconstruct midface defects. In-house planning and manufacturing has led to timely planning and provision of quality composite reconstructions for complex defects in our institution. Acknowledgments The authors would like to acknowledge the contribution of Heather Goodrum and Hitesh Koria from the Maxillofacial Prosthetics Laboratory at the Queen Elizabeth Hospital for helping prepare some of the virtual planning images for this manuscript. Disclosure The authors have nothing to disclose. References 1. Numajiri T., Morita D., Nakamura H., et. al.: Using an in-house approach to computer-assisted design and computer-aided manufacturing reconstruction of the maxilla. J Oral Maxillofac Surg 2018; 76: pp. 1361-1369. 2. Wilde F., Cornelius C.-P., Schramm A.: Computer-assisted mandibular reconstruction using a patient-specific reconstruction plate fabricated with computer-aided design and manufacturing techniques. Craniomaxillofac Trauma Reconstr 2014; 7: pp. 158-166. 3. Brown J.S., Shaw R.J.: Reconstruction of the maxilla and midface: introducing a new classification. Lancet Oncol 2010; 11: pp. 1001-1008. 4. Yamamoto Y., Kawashima K., Sugihara T., et. al.: Surgical management of maxillectomy defects based on the concept of buttress reconstruction. Head Neck 2004; 26: pp. 247-256. 5. Butterworth C.J., Rogers S.N.: The zygomatic implant perforated (ZIP) flap: a new technique for combined surgical reconstruction and rapid fixed dental rehabilitation following low-level maxillectomy. Int J Implant Dent 2017; 3: pp. 37. 6. Miles B.A., Gilbert R.W.: Maxillary reconstruction with the scapular angle osteomyogenous free flap. Arch Otolaryngol Head Neck Surg 2011; 137: pp. 1130-1135. 7. Mertens C., Freudlsperger C., Bodem J., et. al.: Reconstruction of the maxilla following hemimaxillectomy defects with scapular tip grafts and dental implants. J Craniomaxillofac Surg 2016; 44: pp. 1806-1811. 8. Santamaria E., Cordeiro P.G.: Reconstruction of maxillectomy and midfacial defects with free tissue transfer. J Surg Oncol 2006; 94: pp. 522-531. 9. Thomas C.V., McMillan K.G., Jeynes P., et. al.: Use of a titanium cutting guide to assist with raising and inset of a DCIA free flap. Br J Oral Maxillofac Surg 2013; 51: pp. 958-961. 10. Pagedar N.A., Gilbert R.W., Chan H., et. al.: Maxillary reconstruction using the scapular tip free flap: a radiologic comparison of 3D morphology. Head Neck 2012; 34: pp. 1377-1382. 11. Futran N.D., Wadsworth J.T., Villaret D., et. al.: Midface reconstruction with the fibula free flap. Arch Otolaryngol Head Neck Surg 2002; 128: pp. 161-166. 12. Eskander A., Kang S.Y., Teknos T.N., et. al.: Advances in midface reconstruction: beyond the reconstructive ladder. Curr Opin Otolaryngol Head Neck Surg 2017; 25: pp. 422-430. 13. Thomas C.V., McMillan K.G., Jeynes P., et. al.: Use of a titanium cutting guide to assist raising the composite radial forearm free flap. Int J Oral Maxillofac Surg 2013; 42: pp. 1414-1417. 14. Zhang W.B., Wang Y., Liu X.J., et. al.: Reconstruction of maxillary defects with free fibula flap assisted by computer techniques. J Craniomaxillofac Surg 2015; 43: pp. 630-636. 15. Fu K., Liu Y., Gao N., et. al.: Reconstruction of maxillary and orbital floor defect with free fibula flap and whole individualized titanium mesh assisted by computer techniques. J Oral Maxillofac Surg 2017; 75: pp. 1791.e1-1791.e9. 16. Morita D., Numajiri T., Tsujiko S., et. al.: Secondary maxillary and orbital floor reconstruction with a free scapular flap using cutting and fixation guides created by computer-aided design/computer-aided manufacturing. J Craniofac Surg 2017; 28: pp. 2060-2062. 17. Numajiri T., Morita D., Nakamura H., et. al.: Designing CAD/CAM surgical guides for maxillary reconstruction using an in-house approach. J Vis Exp 2018; pp. 58015.

Related Articles

Leave A Comment?

You must be logged in to post a comment.