Three-Dimensional Computer-Assisted Surgical Planning, Manufacturing, Intraoperative Navigation, and Computed Tomography in Maxillofacial Trauma

Key points

  • Virtual surgical planning, surgical navigation, intraoperative imaging, and customizable implants have emerged as reliable tools in implant surgery and orthognathic surgery and are gaining traction in the trauma setting.

  • In the trauma patient, difficulty exists in restoring the 3-dimensional facial skeleton for several reasons.

  • The technological options discussed in this article can be used either independent of one another or in concert, depending on the case, surgeon preference, and hospital resources. The approaches can be implemented for both the acute trauma patient or for secondary repair.

Over the past decade, the utilization and implementation of various technologies into the trauma workflow have increased substantially in oral and maxillofacial surgery.

Virtual surgical planning, surgical navigation (SN), intraoperative imaging, and customizable implants have emerged as reliable tools in implant surgery and orthognathic surgery and are gaining traction in the trauma setting as well. Adoption of these modalities has been driven by a desire from surgeons to improve accuracy, predictability, and precision while reducing time and cost, therefore improving patient outcomes. Correction of orbital volume, re-creation of facial symmetry, and establishment of premorbid occlusion continue to elude many practitioners who manage the complex trauma patient.

In the trauma patient, difficulty exists in restoring the 3-dimensional (3-D) facial skeleton for several reasons. Poor visualization from the overlying soft tissue envelope, difficulty assessing deep skeletal junctions, and inaccurate plate bending/internal fixation all can yield suboptimal results. Intraoperative errors often can have a cumulative result, yielding a patient with facial asymmetry, diplopia, malocclusion, occlusal cants, and the like.

The technological options discussed in this article can be used either independent of one another or in concert, depending on the case, surgeon preference, and hospital resources. The approaches can be implemented both for the acute trauma patient or for secondary repair.

Three-dimensional computer-assisted (virtual) surgical planning

Three-dimensional computer-assisted surgical planning–computer-aided design/computer-assisted manufacturing (CAD/CAM) technology in oral and maxillofacial surgery has become a reliable resource in all aspects of the specialty. Proprietary CAD/CAM software exists for many applications of oral and maxillofacial surgery, which can be applied to the trauma patient. An aspect that may need consideration for the trauma patient is the scanning protocol of the emergency or trauma services. Trauma patients may have a maxillofacial computed tomography (CT) scan from the emergency department; however, they may require a second CT suitable for Digital Imaging and Communications in Medicine (DICOM) formatting and CAD/CAM utilization. When desiring a DICOM data set, either a medical grade CT scan using 1.25mm cuts or cone-beam CT (CBCT) should be obtained.

The CAD/CAM software allows a surgeon to import the DICOM data set and generate a 3-D virtual representation of the patient’s craniomaxillofacial skeleton. A simulated surgical repair can be carried out using mirroring, segmentation, reduction, or virtual osteotomies ( Fig. 1 ). , The virtual reconstruction/data set then can be used in several ways.

Fig. 1
Two examples of CAD/CAM modeling. The top image represents a virtual reconstruction of bilateral NOE, ZMC, Le Fort, and mandible fractures. The bottom image represents a CAD/CAM virtual surgery for the design of a custom reconstruction plate with bone grafting crib in the treatment of a gunshot wound injury.

The simplest application is to allow the surgeon to manipulate the data set via segmentation, mirroring, reflection, or insertion to establish a treatment plan. The next application is the fabrication of a stereolithic model of the virtual reconstruction. In addition, patient-specific implants (PSIs) can be manufactured from the virtual session. Finally, the surgical plan can be uploaded to a SN instrument for real-time intraoperative feedback, discussed later in the article.

Preoperative CAD/CAM virtual surgery is the most straightforward application of this technology and does not add significant down time or increase the length of hospital stay, in general. Once the digital workflow is established, there are few limitations to its access. A conversation with the emergency department/trauma team about admission CT scanning protocols avoids the need for a second scan because of poor quality. Surgical manipulation and planning in the trauma patient can take place once the DICOM data set has been uploaded to the system. There are no additional equipment needs and it does not rely on a capitol purchase by the hospital; therefore, it can be widely adopted in most clinical settings. A DICOM formatted disc is submitted to a third-party vendor, and, within hours, the images can be made available for virtual surgery. The surgeon performs the surgery in the virtual setting and then applies the plan in vivo.

A second application of CAD/CAM technology in the trauma patient is the fabrication of stereolithic models as a template for plate contouring. On completion of the virtual surgery, a stereolithic model or models can be printed or milled, representing the virtual reconstruction. The availability of reconstructed models allows the surgeon to contour, or prebend, plates to the desired, new positions ( Fig. 2 ). The plates then are sterilized preoperatively and internally fixated to the patient. This approach is intended to improve accuracy and reduce operating room time.

Fig. 2
Precontoured plates prior to surgery. Plates were fashioned after a stereolithic model was fabricated from the previous CAD/CAM modeling session.

A third application of CAD/CAM technology is the manufacture and printing of customized plates or PSIs. After a virtual modeling/reconstruction session has been completed, hardware can be fabricated specifically to a patient’s needs. The access to customized plating solutions allows the practitioner to achieve precision and accuracy in the most complex cases. Indications include comminution, continuity defects, severe displacement, loss of landmarks, absence of dentition, and malunion cases ( Fig. 3 ).

Fig. 3
A wide array of 3-D printed reconstructive options used in the trauma setting. ( A ) A 3-D printed custom orbital floor plate and reconstruction plate for a self-inflicted gunshot wound. ( B ) A 3-D printed reconstruction plate demonstrating the hooks for perioperative stability. ( C ) A 3-D printed plate used in the treatment of a nonunion mandible fracture. ( D ) A 3-D printed reconstruction plate with custom bone graft crib in the treatment of a gunshot wound. ( E ) Reconstruction plate with included bone graft carrier crib as 1 unit.

Utilization of virtual surgical planning is intended to improve precision; however, in inexperienced hands, this may not always be the case. Mistakes can be introduced into the workflow. Prebending to stereolithic models or custom fabrication of plates to ideal skeletal conditions without the consideration of soft tissue limitations can yield plates that are not practical or achievable once applied to the patient ( Fig. 4 ). Additionally, stereolithic models do not reproduce bone integrity, density, or quality and plating may not have an acceptable recipient site for screw placement once applied to a live patient. Lastly, without a bite registration, stereolithic models and/or custom plate fabrication cannot be relied on for establishing occlusion. Generally speaking, if dentate segments are involved, a dental impression or dental scan should be obtained to assist in the virtual fracture reduction process.

Fig. 4
( A ) The top left panel represents a custom milled reconstruction plate in a comminuted mandible fracture. Placement of the plate was not possible without transection of the mental nerve. The top right panel represents the planning design where oversight of soft tissue structures such as the mental nerve, can be overlooked when designing. ( B ) The bottom right photo features a custom designed orbital patient specific implant (PSI). The bottom left photo demonstrates the wide access necessary to place such a large, bulky implant. Routine approaches to the orbit were not feasible to accommodate the plate.

In some trauma patients, dental impressions may not be possible and malocclusions may occur because of this. As pictured ( Fig. 5 ), a reconstruction plate was adapted to the stereolithic model with precision but without obtaining dental impressions. The resultant anterior open bite was an unfortunate result despite a seemingly excellent adaptation and virtual reduction of the mandible fracture.

Fig. 5
The upper left photo represents a well adapted reconstruction plate to a stereolithic model. The model was fabricated without the use of a bite registration or dental impressions. The upper right photo demonstrates the resultant malocclusion despite excellent plate adaptation. The bottom middle photo is the final panoramic x-ray with an excellent radiographic appearance and position of the reconstruction plate.
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Aug 5, 2020 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Three-Dimensional Computer-Assisted Surgical Planning, Manufacturing, Intraoperative Navigation, and Computed Tomography in Maxillofacial Trauma
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