Introduction
Composite midface oncologic defects are among the most challenging reconstructive cases, as optimal aesthetic and functional results strongly rely on the precision of the reconstruction. For ideal results, two conditions must be met: the substrate used for reconstruction must be adequate and positioning of the substrate must be extremely precise.
Regarding selection of the optimal substrate, the virtues of the angular branch-based scapular tip free flap have been claimed by many. Specifically, its long pedicle, its anatomic similarity with the hard palate and the rapid re-epithelialisation of its muscular surface are definite advantages.Reference Piazza, Paderno, Taglietti and Nicolai1 Moreover, the possibility of dental implantation has been demonstrated for this flap,Reference Tang, Bearelly and Mannion2 and it is possible to proceed to greenstick osteotomies to use different angulations of bone for different components.Reference Haring, Marchiano, Stevens, Malloy, Casper and Prince3
As for optimising positioning of the free flap, surgical navigation devices are a subject of particular interest. Use of intraoperative electromagnetic or infrared image guidance is well established for sinus surgery.4 In head and neck surgery, it has been particularly used for intraoperative control of resection margins for advanced tumoursReference Feichtinger, Pau, Zemann, Aigner and Kärcher5 and to guide craniofacial approaches for anterior skull base oncologic surgeries.Reference Nakamura, Stöver, Rodt, Majdani, Lorenz and Lenarz6 In reconstructive surgery, a growing literature supports its use for guiding complex reconstructions. While the existing literature is mostly centred on its use for orbital floor reconstructions and the preparation of osteotomies, some authors have used navigation specifically for refining the positioning of peronealReference Hanasono, Jacob, Bidaut, Robb and Skoracki7 and latissimus dorsiReference Kokemueller, Tavassol, Rücker and Gellrich8 free flaps for midface reconstructions.
We developed an approach for reconstruction of complex midface defects combining angular branch-based scapular tip free flaps and electromagnetic navigation in an innovative way. In our opinion, this method yields optimal aesthetic and functional outcomes. We hereby present a summary of our approach, illustrated by four clinical cases.
Material and methods
Participants
Patients operated at the Centre Intégré Universitaire de Santé et de Services Sociaux de l’Estrie – Centre Hospitalier Universitaire de Sherbrooke (CIUSSS de l’Estrie – CHUS) for midface malignancies using the combination of a surgical navigation device and an angular branch-basedscapular tip free flap reconstruction were seen at regular follow up according to National Comprehensive Cancer Network (NCCN) guidelines. Patients were contacted for consent and their files were retrospectively studied to collect the data presented in this series.
Materials
A conventional electromagnetic surgical navigation system was used for every case (Fusion ENT Navigation System, Medtronic, Minneapolis, Minnesota). To enable mobility of the head during surgery without restricting the surgical access, a reference system, consisting of a Cranial Dynamic Fixation Frame (Medtronic, Minneapolis) was fixed to the patient’s skull. This system, although more expansive than the standard surface sticker registration, is more precise and more versatile, as it can be installed anywhere on the calvarium and thus does not interfere with craniofacial resections.
Surgical technique
For every case, a pre-operative computed tomography (CT) scan and magnetic resonance imaging of the facial bones with navigation protocol sequences, as for computer-assisted sinus surgery, were obtained and downloaded in the electromagnetic navigation device (Figure 1).
Figure 1. T2 sagittal MRI demonstrating a squamous cell carcinoma of the nasal septum with extension to the hard palate, ethmoids and sphenoid sinuses (patient #1).
At the beginning of the surgery, the electromagnetic device is draped and positioned freely at the head of the patient, for easy access throughout the case. The reference device is installed, and calibration is undertaken according to the manufacturer’s protocol (Figure 2). During the resection, the navigation device may be used in establishing appropriate cuts in remote bony margins, notably at the level of the pterygoid plates.
Figure 2. Operative setup for patient #1. The navigation system (A) is positioned at the head of the patient. The reference system, a Cranial Dynamic Fixation Frame (B) Medtronic, Minneapolis, has been fixed to the patient skull. The electromagnetic emission device (C) is draped and positioned freely at the head of the patient, for easy access during surgery. The device pointer (D) is used for calibration of the navigation system at the beginning of the surgery.
To harvest the angular branch based-scapular tip free flap, a triangular cushion is positioned under the lateral thorax before draping of the donor site side, thus exposing the scapula upon tilting of the table. The muscular triangle delimited by the teres major, teres minor and triceps is palpated, and a curvilinear incision is made from the triangle inferiorly to incorporate the tip of the scapula. Exposition and inferior retraction of the latissimus dorsi muscle shows the intermuscular septum between the latissimus dorsi and teres major. Further dissection enables identification of the thoracodorsal artery after dividing the teres major, giving off the angular artery, which is followed to its entry point at the tip of the scapula on its lateral aspect. The appropriate amount of bone is resected, and the vascular pedicle is followed all the way to the origin of the subscapular artery (Figure 3).
Figure 3. Scapular tip free flap for palatal reconstruction (patient #1). Reconstruction plates are fixed posteriorly to the scapular tip free flap. In this situation, the flap has been positioned horizontally to reconstruct a total palatal defect. The anatomic similarity of this flap with the bony palate, along with the rapid reepithelialization of its muscular surface, make it an ideal option for such reconstructions. Also depicted is the significant pedicle length of this flap.
During the inset of the flap, surgical navigation is used to match the position of the flap with pre-existent anatomic bony landmarks (Figure 4).
Figure 4. Operative use of the navigation system for optimal positioning of the free flap (patient #3).
Results and analysis
Table 1 describes the cases and the utility of neuronavigation for each one of the four cases. Figure 5 depicts post-operative results for patient 1.
Figure 5. Postoperative result for patient #1.
Table 1. Summary of our case series of complex midface reconstruction with scapular tip free flaps and surgical navigation device
Discussion
As described by Santamaria,Reference Santamaria and Cordeiro9 maxillectomy defects present three specific reconstructive challenges: (1) restoration of an adequate orbital support, (2) restoration of the oronasal separation and of the functional aspects of both elements, and (3) reestablishment of the facial contour. The four cases presented in this article reflect all these challenges.
Angular branch-based scapula tip free flaps are both reliable and versatile for midface reconstruction.Reference Piazza, Paderno, Taglietti and Nicolai1 Their versatility allows for optimal adaptation to the deficit, with both vertical and horizontal positioning being possible, depending on the architecture of the osteotomies. No complications specifically related to the flap have been encountered in this series.
As suggested by Feinchtinger et al.,Reference Feichtinger, Pau, Zemann, Aigner and Kärcher5 navigation is helpful in assessing the bony margins of resection, which are often challenging for midface. In all these cases, navigation also allowed optimal positioning of the scapular tip free flaps. This tool has been particularly useful for securing the height of the reconstructed palate and the alignment of the nasal spine, evaluating nasal and malar projection, and assessing orbital floor position for reconstruction of total maxillectomy defects. A typical pitfall is to base the appreciation of a reconstruction on the appearance of overlying soft tissues. Because most head and neck cancer patients will undergo adjuvant post-operative radiotherapy, it is predictable that significant modifications and resorption of the soft tissues will occur. Such a situation may often lead to good immediate post-operative aesthetic results, which will, however, decline in the longer term. Navigation-assisted bony reconstruction of midface defects allows for precise free flap positioning and compensation for the expected post-radiation soft tissue volume variations.
Previously published studies concerning the use of surgical navigation to guide various reconstructions have come to similar conclusions. Harbison et al.,Reference Harbison, Shan, Douglas, Bevans, Li and Moe10 compared mandibular alignment following segmental mandibulectomy on cadavers using surgical navigation, surgical templates and freehand techniques. Surgical navigation proved to be similar to template-guided reconstruction, but with the added benefit of permitting real-time adjustment independently of the initial resection and reconstruction plans, and was superior to freehand reconstruction.
The use of computer-assisted design with pre-operative 3D printing has gained popularity in the recent decades. However, computer-assisted designs require additional time for pre-operative virtual planning and involves a significant learning curve for the surgeon.Reference Sozzi, Filippi, Canzi, De Ponti, Bozzetti and Novelli11 Furthermore, computer-assisted design incurs costs exceeding up to $10,000 per case and models cannot be adjusted if cutting guides are incorrectly positioned or if resection margins need updating during the case.Reference Harbison, Shan, Douglas, Bevans, Li and Moe10 In our hospital, current prices are between $3,300 and $3,700 Canadian per case for 3D planning, whereas the neuronavigation equipment costs approximately $790 Canadian per case (Instrument Tracker (wire) – Navigation-Fusion: $150; Cranial Navigation Tracker (screw) – Navigation-Fusion: $640).
Since navigation-assisted functional endoscopic sinus surgery has become the standard of care in many situations,4 navigation equipment is often readily available for the reconstructive surgeon. In our experience, the few minutes spent calibrating the machine are more than made up by the expedited flap positioning. We have found that the use of a stand for the electromagnetic device, such as in functional sinus surgery, is not practical. Therefore, we have elected to drape the electromagnetic device in a sterile fashion and move it near the midface whenever a reading is needed.
The principal caveat that has been encountered in our experience is the tendency for the navigation device to decalibrate throughout surgery. The causes of these decalibrations, which have been discussed by Sorriento et al.,Reference Sorriento, Porfido, Mazzoleni, Calvosa, Tenucci and Ciuti12 include metal and ferromagnetic sources in the operating theatre, such as nearby cell phones. This remains, however, unusual. Calibration of the instruments should be verified periodically throughout the case using reliable anatomical landmarks in proximity to the resection site, such as the glabella and lateral orbit, and the instruments should be recalibrated if required.
• Scapular tip flaps provide versatile and reliable tissues for complex midface defects.
• Surgical navigation facilitates accurate positioning of free flaps, with real-time adjustments accommodating variations in patient anatomy, thus optimising aesthetic and functional outcomes.
• Proper calibration and verification of navigation systems is essential to optimise accuracy throughout surgery.
• Surgical navigation minimises additional costs compared to other advanced imaging and planning technologies, making it a cost-effective option for complex midface reconstructions.
Conclusion
Judging from our practice, optimal results for complex midface reconstructions can be obtained by combining the intrinsic advantages of the angular branch-based scapular tip free flap with the use of a surgical navigation system. In our opinion, the minimal additional operative time and low cost justify its integration to assist in reconstruction of complex craniofacial defects.
Funding
The authors have no financial interest or commercial association with any of the subject matter or products mentioned in this manuscript.
Open access
