Innovations and Future Directions in Head and Neck Microsurgical Reconstruction

Head and neck reconstructive microsurgery is constantly innovating because of a combination of multidisciplinary advances. This article examines recent innovations that have affected the field as well as presenting research leading to future advancement. Innovations include the use of virtual surgical planning and three-dimensional printing in craniofacial reconstruction, advances in intraoperative navigation and imaging, as well as postoperative monitoring, development of minimally invasive reconstructive microsurgery techniques, integration of regenerative medicine and stem cell biology with reconstruction, and the dramatic advancement of face transplant.

Key points

  • Integration of virtual surgical planning and three-dimensional printing has enabled improved surgical accuracy, efficiency, and dealing with more complex reconstructions.

  • Novel intraoperative navigation, imaging, and perfusion assessment have led to ease of flap design, avoidance of vital structures, and innovative flap monitoring.

  • The development of minimally invasive reconstructive microsurgery has advanced oncological head and neck reconstruction.

  • The integration of regenerative medicine, tissue engineering, and stem cell biology presents novel methods of osteogenic flap prefabrication as well as research in ex vivo generation of patient-specific craniofacial bone and tissue.

  • Facial composite tissue allotransplant is an innovation in craniofacial surgery for patients who have exhausted the traditional reconstructive plastic surgery armamentarium.

Introduction

“Pourquoi pas?” Paul Tessier, known as the father of modern craniofacial surgery, would often answer questions about his innovative procedures with this response of “Why not?” This expression, which eventually became the motto of the International Society of Craniofacial Surgery, should continue to drive this field of innovation and multidisciplinary advances, encouraging craniofacial and head and neck reconstructive surgeons to think creatively and outside the confines of the discipline. In few other surgical fields do advances in science, technology, and surgical ingenuity combine to better patient outcomes in such dramatic and visible ways.

Large-scale innovations often occur when there is a convergence of knowledge across disciplines, leading to new ideas or the coalescence of ideas to make advances. The development of microsurgery is an example of this. The combination of a series of advances in different fields in the early twentieth century led to the innovation of clinical microsurgery. This innovation includes advancement in surgical technique, with the reporting of the triangulation method of end-to-end anastomosis in 1902. However, advances in basic science were also needed to aid in anticoagulation, and the 1916 discovery of heparin thus enabled the patency of microvascular anastomoses. Perhaps most vitally, in the early 1920s, the introduction of the operating microscope as well as fine microsurgical suture and instruments provided necessary bioengineering advances. These multidisciplinary innovations led to the first successful microvascular anastomosis in 1960, thus dramatically changing reconstructive surgery.

In the current era of head and neck microsurgical reconstruction, clinicians again have embraced the coalescence of multidisciplinary fields leading to innovation and future advances, including the integration of virtual surgical planning and three-dimensional (3D) printing technologies in craniofacial surgery, enabling planning of complex procedures before entering the operating room as well as the creation of patient-specific surgical guides and implants. Novel imaging methods enable assessment of flap design and immediate perfusion outcomes intraoperatively. Innovations in postoperative perfusion monitoring incorporate technological advances, including infrared thermography and oxygenation. In addition, smartphone capabilities have also led to dramatic advances in early detection of flap problems, thereby decreasing flap failure rates. Innovation in surgical technique has led to minimally invasive reconstructive procedures, including transoral reconstructive capabilities for oropharyngeal cancer and endoscopic skull base reconstruction. Advances in regenerative medicine and tissue engineering show the potential of merging stem cell biology with reconstructive craniofacial microsurgery, which has already shown advances in prefabrication techniques. In addition, face transplant provides an ideal example of disruptive innovation in craniofacial surgery for patients who have exhausted the armamentarium of plastic surgery options.

Introduction

“Pourquoi pas?” Paul Tessier, known as the father of modern craniofacial surgery, would often answer questions about his innovative procedures with this response of “Why not?” This expression, which eventually became the motto of the International Society of Craniofacial Surgery, should continue to drive this field of innovation and multidisciplinary advances, encouraging craniofacial and head and neck reconstructive surgeons to think creatively and outside the confines of the discipline. In few other surgical fields do advances in science, technology, and surgical ingenuity combine to better patient outcomes in such dramatic and visible ways.

Large-scale innovations often occur when there is a convergence of knowledge across disciplines, leading to new ideas or the coalescence of ideas to make advances. The development of microsurgery is an example of this. The combination of a series of advances in different fields in the early twentieth century led to the innovation of clinical microsurgery. This innovation includes advancement in surgical technique, with the reporting of the triangulation method of end-to-end anastomosis in 1902. However, advances in basic science were also needed to aid in anticoagulation, and the 1916 discovery of heparin thus enabled the patency of microvascular anastomoses. Perhaps most vitally, in the early 1920s, the introduction of the operating microscope as well as fine microsurgical suture and instruments provided necessary bioengineering advances. These multidisciplinary innovations led to the first successful microvascular anastomosis in 1960, thus dramatically changing reconstructive surgery.

In the current era of head and neck microsurgical reconstruction, clinicians again have embraced the coalescence of multidisciplinary fields leading to innovation and future advances, including the integration of virtual surgical planning and three-dimensional (3D) printing technologies in craniofacial surgery, enabling planning of complex procedures before entering the operating room as well as the creation of patient-specific surgical guides and implants. Novel imaging methods enable assessment of flap design and immediate perfusion outcomes intraoperatively. Innovations in postoperative perfusion monitoring incorporate technological advances, including infrared thermography and oxygenation. In addition, smartphone capabilities have also led to dramatic advances in early detection of flap problems, thereby decreasing flap failure rates. Innovation in surgical technique has led to minimally invasive reconstructive procedures, including transoral reconstructive capabilities for oropharyngeal cancer and endoscopic skull base reconstruction. Advances in regenerative medicine and tissue engineering show the potential of merging stem cell biology with reconstructive craniofacial microsurgery, which has already shown advances in prefabrication techniques. In addition, face transplant provides an ideal example of disruptive innovation in craniofacial surgery for patients who have exhausted the armamentarium of plastic surgery options.

The integration of virtual surgical planning and three-dimensional printing with craniofacial reconstruction

The ability to plan and virtually execute complex craniofacial surgical procedures has revolutionized head and neck reconstruction. Virtual surgical planning starts with a high-resolution computed tomography (CT) scan with thin cuts; the potential for virtual surgical planning depends on the ability to obtain such scans ( Fig. 1 ). The 3D reconstruction is then performed in one of the US Food and Drug Administration (FDA)–approved computer-aided design or computer-aided modeling software environments. A Web conference is conducted between the surgeon and biomedical engineers to virtually plan the surgery, including osteotomy placement, resection margins (in the case of oncological surgery), bone graft placement, and positional alignment. This virtual conference allows the surgeon to plan the procedure in a less time-sensitive environment before surgery rather than relying on intraoperative judgement as the main method of deciding on osteotomies. Virtual surgical planning also requires the declaration of surgical intention, allowing a lower-stress environment in which to decide on recipient vessel choice as well as osteotomy placement. Furthermore, in the case of oncological head and neck reconstruction, virtual surgical planning can avoid any potential conflicts between the resection and reconstruction teams caused by uncertainty or change of plans in the operating room. Most importantly, virtual surgical planning enables surgeons to attempt multiple approaches and reconstructive options in a virtual environment, thereby determining the optimal surgical outcome before entering the operating room.

Fig. 1
The process of planning a Le Fort III–based face transplant. The process of virtual surgical planning begins with a high-resolution CT scan. This scan is then 3D reconstructed and, in a virtual planning session between engineers and the surgeon, osteotomy locations are planned. Then 3D printed guides are designed to guide these osteotomies, which are then printed, sterilized, and used in the surgery.

The integration of virtual surgical planning with 3D printing furthers the frontier of craniofacial reconstruction. Using 3D printed models of patient-specific craniofacial anatomy enables hands-on evaluation of the surgical approach. Models of a defect site and transferred bone can be created so that surgeons can evaluate positioning, aesthetic outcomes, and fixation methods in a 3D manner. In the past, this has proved important in congenital cardiothoracic surgery and is now also another innovative tool for craniofacial surgeons. In particular, using 3D printed models for prebending fixation plates has been shown to reduce operative time and improve reconstruction outcomes. In addition, these models are invaluable to medical education so residents, as well as the rest of the surgical team, can fully understand the operative plan.

Virtual surgical planning can also be used to generate patient-specific cutting guides, templates, and implants that enable surgeons to accurately transform plans into operative reality. Stereolithographic snap-fit guides are 3D printed for osteotomies, thereby enabling accurate recapitulation of the planned cut site. Fibula-to-mandible reconstruction has greatly benefited from this technology because the surgical success largely depends on restoration of facial symmetry. A systematic review of fibula-to-mandible oncological reconstruction showed that, in 93% of cases, virtual surgical planning increased the accuracy of the reconstruction and, in 80% of cases, operative time decreased.

Virtual surgical planning and 3D guide creation has also greatly innovated craniosynostosis surgery, in which reconstruction is often solely based on the surgeon’s vision of a normal head shape and subjective intraoperative decisions ( Fig. 2 ). Using virtual surgical planning, the child’s skull can be overlaid to a normative skull of the same age group. Osteotomies and positional reorganization can then be virtually planned to yield the best aesthetic results ( Fig. 3 ), and 3D printed osteotomy and positional alignment plating guides are then created to enable this plan to be executed in a straightforward manner intraoperatively ( Fig. 4 ).

Fig. 2
Preoperative and postoperative views of a child with sagittal suture craniosynostosis whose operation was planned and performed using virtual surgical planning and 3D-printed surgical and positional guides.

Fig. 3
Virtual surgical planning of cranial vault remodeling surgery of sagittal suture craniosynostosis. The preoperative views show osteotomy placement, and postoperative views show the planned rearrangement of cranial segments.

Fig. 4
A 3D osteotomy guide for cranial vault remodeling ( A ). The osteotomized cranial segments are then repositioned in a positioning guide ( B ), in which they are internally plated to ensure correct positional alignment according to virtual surgical plan ( C ). The rearranged, plated segments are then plated externally.

The combination of virtual surgical planning and 3D printing also enables patient-specific implants for head and neck reconstruction. Patient-specific polyetheretherketone (PEEK) implants have been designed virtually and 3D printed to reconstruct cranial, frontal, malar, and mandibular defects. Recently, the FDA approved the first 3D printed titanium craniofacial implant, which additionally adds to the armamentarium of implant options. In the case of orbital floor reconstruction, free-hand manipulation of implants is challenging because of the constrained location, potential damage to the eye, and complexity of bone anatomy. Using 3D printed porous polyethylene custom-created implants now offers alternatives to intraoperative manipulation of titanium mesh implants. Furthermore, custom orbital implants may offer a more aesthetically pleasing, symmetric result, because the contour of the implant generally matches that of the patient’s uninjured orbit. In addition, 3D printed models can be used to shape arch forms or titanium spacers to provide optimal shape while bone integration takes place in mandible reconstruction. These implants thus reduce operative time as well as contributing to a more successful functional and aesthetic reconstructive outcome.

Novel intraoperative navigation and imaging

Intraoperative navigation has greatly improved the accuracy of craniofacial reconstruction as well as preventing damage of vital structures in complex reconstructions. Neurosurgery was the first discipline to adopt intraoperative navigation because of the technology’s ability to minimize trauma and surgical perturbation of the brain. Navigation was originally stereotactic, and although this greatly improved outcomes in brain biopsy, electrode placement, and small tumor resection, it did not allow real-time monitoring of operative location, required more invasive fixation of the stereotactic frame, and reduced the operative working space. The advent of frameless navigation led to the adoption of intraoperative navigation in other surgical fields, including craniofacial reconstruction.

In modern frameless intraoperative navigation, reference structures (commonly reflective marker spheres) are placed on the patient. Preoperative imaging is obtained with the markers present. In the operating room, a stereoscopic camera emits infrared light that tracks the 3D position of the marker spheres ( Fig. 5 ). These marker spheres are correlated with the markers shown on the CT scan as well as in relation to the stereotactic probe, which also contains a marker sphere. Using the marker sites, the computer can determine the location of the probe and correlate this in real time with the CT scan, thereby enabling visualization of location. This technology is similar to how a car may navigate using GPS; metaphorically, the car is the probe and the satellites in space are the marker probes on the patient. The created map in this analogy is the CT scan with the probe shown in real time.

Fig. 5
Intraoperative navigation. Before surgery, preoperative imaging is obtained with markers in place. A stereoscopic camera in the operating room (OR) then emits infrared light that tracks the position of the markers on both the patient and the navigation probe, which correlate with position on the CT scans, enabling real-time feedback about probe position.
(Copyright © by AO Foundation, Switzerland. Source: AO Surgery Reference, www.aosurgery.org .)

Intraoperative navigation has broad innovative applications in head and neck reconstruction. Navigation has improved surgical outcomes in orthognathic surgery, including ensuring the optimal osteotomy placement for aesthetic outcomes. Navigation has also proved effective in midface distraction for facial deformities, including midface hypoplasia caused by cleft lip/palate or Crouzon syndrome, allowing the avoidance of vital structures as well as ensuring that vectors and tracking of internal distraction devices follow the surgical plan. Furthermore, navigation has improved outcomes in setback of the anterior table of the frontal sinus for pneumosinus dilatans as well as midface reconstruction for Treacher Collins syndrome. In addition, intraoperative navigation has enabled the reconstruction of a delayed orbitozygomaticomaxillary fracture, which allowed anatomic reduction without an otherwise necessary coronal incision and zygomatic arch exposure ( Fig. 6 ). Intraoperative navigation has been used as an alternative to stereolithographic osteotomy guides in fibula free-flap reconstruction, thus following the operative plan by determining osteotomy placement and subsequent mandible inset using the stereotactic probe. This method provides another means to ensure operative planning success if 3D printing is not available, too time intensive, or cost prohibitive.

Fig. 6
Intraoperative navigation used in delayed reconstruction of an orbitozygomatic complex fracture. This technology enables accurate, real-time feedback about positional information, preventing the need for zygomatic arch exposure.
( From Morrison CS, Taylor HO, Sullivan SR. Utilization of intraoperative 3D navigation for delayed reconstruction of orbitozygomatic complex fractures. J Craniofac Surg 2013;24(3):e284–6; with permission.)

Furthermore, intraoperative navigation has been used to ensure correct placement of 3D printed osteotomy guides and custom implants intraoperatively when snap-fit guides are not possible or reliable because of complex bony anatomy. Navigation has been shown to improve orbital reconstruction following posttraumatic and postablative defects; using this technology to identify correct implant placement led to excellent restoration of the orbit and globe.

The future and potential increase in popularity of intraoperative navigation in craniofacial and head and neck surgery depends on the advancement of this system’s capabilities. In a commentary on navigation in craniofacial surgery, Gordon and colleagues note that, if modern GPS (global positioning system) was limited to simply showing where a car is on the map, it most likely would not be as popular. However, GPS now offers directions, route planning, and even avoidance of traffic. Modern intraoperative navigation is similar to the limited capability of early GPS. In the future, the authors foresee navigational tools integrating the operative plan, craniofacial cephalometrics, and the surgeon’s end goal into an interactive interface that enables real-time feedback on intraoperative decisions. This potential has begun in the innovation of the Computer-Assisted Planning and Execution (CAPE) system in face transplant, an intraoperative navigation system that incorporates the surgical plan with intraoperative guide placement and desired outcome analysis ( Fig. 7 ). This system is in early large-animal testing, and provides a hopeful insight into the future of intraoperative navigation in complex craniofacial procedures.

Fig. 7
The newly developed CAPE workstation was created to assist with planning and execution of facial transplants. The system enables real-time assessment of reality versus surgical plan because of intraoperative navigation. In addition, Transmission Control Protocol/Internet Protocol (TCP/IP), the basic communication language of the internet, enables seamless communication between donor and recipient surgical teams.
( From Gordon CR, Murphy RJ, Coon D, et al. Preliminary development of a workstation for craniomaxillofacial surgical procedures: introducing a computer-assisted planning and execution system. J Craniofac Surg 2014;25(1):273–83.)

An alternative to intraoperative navigation is intraoperative imaging, made possible by the advent of advanced imaging technology in head and neck reconstruction. CT scans have long been the standard for presurgical planning. However, the innovation of cone-beam CT (CBCT) systems (such as the C-arm), which were originally developed for dental practices, has enabled high-quality intraoperative imaging ( Fig. 8 ). CT scans can present high radiation exposure to both patient and health care providers in the operating room (OR) and are not cost-effective for intraoperative imaging. Mobile CBCT systems enable immediate 3D imaging analysis of operative results so that any necessary corrections can be made before the patient leaves the OR. This ability is particularly important in the reduction of craniofacial fractures, which have high postsurgical complication rates if reduction is not complete. It was shown that such intraoperative imaging improved outcomes in zygomaticomaxillary complex fractures, mandibular angle fractures, and bimaxillary repositioning osteotomies. Therefore, the innovation of CBCT systems for intraoperative imaging may improve craniofacial reconstructive outcomes and prevent subsequent returns to the OR.

Fig. 8
How the C-Arm system can be used to aid in facial fracture reduction. The system can be used to obtain nasal bone on lateral view ( A ), zygoma view at 70° to 90° to the skull’s coronal plane and 0° to the skull’s sagittal plane ( B ), and mandibular subcondyle on lateral view ( C ).
( From Hwang SM, Kim JH, Kim HD, et al. C-arm fluoroscopy for accurate reduction of facial bone fracture. Arch Craniofac Surg 2013;14:96–101.)

Innovations in perfusion assessment and monitoring

Innovations in both intraoperative and postoperative monitoring of free flaps have broad implications in head and neck reconstruction. Reconstructive success in these cases depends on both quality perfusion of the flap and rapid identification and salvage of failing flaps. Microvascular reconstruction has always depended on a thorough understanding of subvisible human anatomy. Innovations such as Doppler ultrasonography and angiography dramatically improved surgeons’ abilities to make decisions regarding each patient’s unique anatomy and options for microvascular reconstruction. In particular, head and neck reconstruction presents large challenges to reconstructive surgeons because patients often have oncological or traumatic abnormalities affecting standard clinical anatomy. Angiosome size, cutaneous perforator perfusion, and periosteal perfusion (in osteocutaneous flaps) all affect the potential for partial and complete flap loss.

Laser-assisted fluorescent angiography (SPY Elite) offers an innovative means for perfusion monitoring intraoperatively. In this system, indocyanine green (ICG) is injected intravenously, which then binds to plasma proteins circulating in the bloodstream. ICG fluoresces on exposure to laser light emitted by the SPY machine, and is detected by a high-speed imaging system that is sensitive to the ICG wavelength ( Fig. 9 ). A perfusion map is then constructed, which allows assessment of perforator vasculature as well as an evaluation of venous and arterial flow. Thus, SPY can be used to aid in free-style flap design and harvest, in which SPY can be used to center the design over the angiosome perfusion center. In addition, in the anterolateral thigh flap, a disadvantage is that the pedicle’s septocutaneous or myocutaneous perforating vessels often have irregular derivations from the descending branch of the lateral circumflex artery. SPY enables reliable raising of this workhorse flap as well as other free flaps for head and neck reconstruction.

Nov 21, 2017 | Posted by in Dental Materials | Comments Off on Innovations and Future Directions in Head and Neck Microsurgical Reconstruction
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