Navigation-Guided Reduction and Orbital Floor Reconstruction in the Treatment of Zygomatic-Orbital-Maxillary Complex Fractures

Simultaneous Image-Guided Skull Bone Tumor Resection and Reconstruction With a Preconstructed Prosthesis Based on an OsiriX Virtual Resection

BACKGROUND

Skull reconstruction can be challenging due to the complex 3-dimensional shape of some structures, such as the orbital walls, and for cases involving a large cranial vault. In such situations, computer-assisted design and modeling of prostheses is especially helpful to achieve an adequate reconstruction. Simultaneous tumor resection and skull defect reconstruction are also challenging because the preoperative imaging does not display the anticipated defect. Currently, sophisticated methods based on physical prototypes and templates are required to enable simultaneous resection and reconstruction techniques.

OBJECTIVE

To report a new technique for simultaneous tumor resection and skull reconstruction with a custom-made prosthesis.

METHODS

Using OsiriX software, virtual bone resection was performed using preoperative images by carefully delimiting the tumor on each slice. The modified images were integrated to predict the defect and also served as a basis for prosthesis construction. At the time of surgery, the images were projected onto the patient's skull using a surgical navigation system to delimit the area of the craniectomy.

RESULTS

The virtual planning method was simple and accurate and provided a precise preoperative definition of important structures that needed to be spared, such as the frontal sinus. Using this method, simultaneous tumor resection and prosthetic skull reconstruction was successfully achieved for a patient with a wide skull tumor.

CONCLUSION

Simultaneous skull tumor resection and prosthetic reconstruction are possible when a virtual preoperative tumor resection is performed, and a corresponding customized prosthesis subsequently is manufactured and used.

Evaluation of 3 different registration techniques in image-guided bimaxillary surgery

Perioperative navigation is an upcoming tool in orthognathic surgery. This study aimed to access the feasibility of the technique and to evaluate the success rate of 3 different registration methods--facial surface registration, anatomic landmark-based registration, and template-based registration. The BrainLab navigation system (BrainLab AG, Feldkirchen, Germany) was used as an additional precision tool for 85 patients who underwent bimaxillary orthognathic surgery from February 2010 to June 2012. Eighteen cases of facial surface-based registration, 63 cases of anatomic landmark-based registration, and 8 cases of template-based registration were analyzed. The overall success rate of facial surface-based registration was 39%, which was significant lower than template-based (100%, P = 0.013) and anatomic landmark-based registration (95%, P < 0.0001). In all cases with successful registration, the further procedure of surgical navigation was performed. The concept of navigation of the maxilla during bimaxillary orthognathic surgery has been proved to be feasible. The registration process is the critical point regarding success of intraoperative navigation. Anatomic landmark-based registration is a reliable technique for image-guided bimaxillary surgery. In contrast, facial surface-based registration is highly unreliable.

Predictability in orbital reconstruction: A human cadaver study. Part II: Navigation-assisted orbital reconstruction

Preformed orbital reconstruction plates are useful for treating orbital defects. However, intraoperative errors can lead to misplaced implants and poor outcomes. Navigation-assisted surgery may help optimize orbital reconstruction. We aimed to explore whether navigation-assisted surgery is more predictable than traditional orbital reconstruction for optimal implant placement. Pre-injury computed tomography scans were obtained for 10 cadaver heads (20 orbits). Complex orbital fractures (Class III-IV) were created in all orbits, which were reconstructed using a transconjunctival approach with and without navigation. The best possible fit of the stereolithographic file of a preformed orbital mesh plate was used as the optimal position for reconstruction. The accuracy of the implant positions was evaluated using iPlan software. The consistency of orbital reconstruction was lower in the traditional reconstructions than in the navigation group in the parameters of translation and rotation. Implant position also differed significantly in the parameters of translation (p = 0.002) and rotation (pitch: p = 0.77; yaw: p < 0.001; roll: p = 0.001). Compared with traditional orbital reconstruction, navigation-assisted reconstruction provides more predictable anatomical reconstruction of complex orbital defects and significantly improves orbital implant position.

Outcomes of Orbital Floor Reconstruction After Extensive Maxillectomy Using the Computer-Assisted Fabricated Individual Titanium Mesh Technique

PURPOSE

Orbital floor defects after extensive maxillectomy can cause severe esthetic and functional deformities. Orbital floor reconstruction using the computer-assisted fabricated individual titanium mesh technique is a promising method. This study evaluated the application and clinical outcomes of this technique.

PATIENTS AND METHODS

This retrospective study included 10 patients with orbital floor defects after maxillectomy performed from 2012 through 2014. A 3-dimensional individual stereo model based on mirror images of the unaffected orbit was obtained to fabricate an anatomically adapted titanium mesh using computer-assisted design and manufacturing. The titanium mesh was inserted into the defect using computer navigation. The postoperative globe projection and orbital volume were measured and the incidence of postoperative complications was evaluated.

RESULTS

The average postoperative globe projection was 15.91 ± 1.80 mm on the affected side and 16.24 ± 2.24 mm on the unaffected side (P = .505), and the average postoperative orbital volume was 26.01 ± 1.28 and 25.57 ± 1.89 mL, respectively (P = .312). The mean mesh depth was 25.11 ± 2.13 mm. The mean follow-up period was 23.4 ± 7.7 months (12 to 34 months). Of the 10 patients, 9 did not develop diplopia or a decrease in visual acuity and ocular motility. Titanium mesh exposure was not observed in any patient. All patients were satisfied with their postoperative facial symmetry.

CONCLUSION

Orbital floor reconstruction after extensive maxillectomy with an individual titanium mesh fabricated using computer-assisted techniques can preserve globe projection and orbital volume, resulting in successful clinical outcomes.

Image-guided bone resection as a prospective alternative to cutting templates—A preliminary study

OBJECTIVE

To evaluate the accuracy of craniomaxillofacial resections performed with an image-guided surgical sagittal saw.

MATERIAL AND METHODS

Twenty-four craniomaxillofacial resections were performed using an image-guided sagittal saw. Surgical outcomes were compared with a preoperative virtual plan in terms of the resected bone volume, control point position and osteotomy trajectory angle. Each measurement was performed twice by two independent observers.

RESULTS

The best convergence between the planned and actual bone resection was observed for the orbital region (6.33 ± 4.04%). The smallest mean difference between the preoperative and postoperative control point positions (2.00 ± 0.66 mm) and the lowest mean angular deviation between the virtual and actual osteotomy (5.49 ± 3.17 degrees) were documented for the maxillary region. When all the performed procedures were analyzed together, mean difference between the planned and actual bone resection volumes was 9.48 ± 4.91%, mean difference between the preoperative and postoperative control point positions amounted to 2.59 ± 1.41 mm, and mean angular deviation between the planned and actual osteotomy trajectory equaled 8.21 ± 5.69 degrees.

CONCLUSION

The results of this study are encouraging but not fully satisfactory. If further improved, the hereby presented navigation technique may become a valuable supporting method for craniomaxillofacial resections.

Ultralow-dose computed tomography imaging for surgery of midfacial and orbital fractures using ASIR and MBIR

The influence of dose reductions on diagnostic quality using a series of high-resolution ultralow-dose computed tomography (CT) scans for computer-assisted planning and surgery including the most recent iterative reconstruction algorithms was evaluated and compared with the fracture detectability of a standard cranial emergency protocol. A human cadaver head including the mandible was artificially prepared with midfacial and orbital fractures and scanned using a 64-multislice CT scanner. The CT dose index volume (CTDIvol) and effective doses were calculated using application software. Noise was evaluated as the standard deviation in Hounsfield units within an identical region of interest in the posterior fossa. Diagnostic quality was assessed by consensus reading of a craniomaxillofacial surgeon and radiologist. Compared with the emergency protocol at CTDIvol 35.3 mGy and effective dose 3.6 mSv, low-dose protocols down to CTDIvol 1.0 mGy and 0.1 mSv (97% dose reduction) may be sufficient for the diagnosis of dislocated craniofacial fractures. Non-dislocated fractures may be detected at CTDIvol 2.6 mGy and 0.3 mSv (93% dose reduction). Adaptive statistical iterative reconstruction (ASIR) 50 and 100 reduced average noise by 30% and 56%, and model-based iterative reconstruction (MBIR) by 93%. However, the detection rate of fractures could not be improved due to smoothing effects.

Ratio of Simple versus Comminuted Lateral Wall Fractures of the Orbit

Reduction of a fracture may be relatively easy with a simple, noncomminuted fracture along the zygomaticofrontal suture, zygomaticomaxillary buttress, or the inferior rim of the orbit. When one or more of these key landmarks is comminuted, it becomes more important to confirm that the fracture commonly seen between the greater wing of the sphenoid and the zygoma is properly repositioned. The zygomaticosphenoidal suture is an excellent landmark with a simple lateral orbital wall fracture (LOWF), but it may not be reliable in patients with a comminuted fracture. The purpose of this study is to determine the frequency that the lateral orbital wall (LOW) is a reliable landmark in the reduction of a zygoma fracture by determining the ratio between simple versus comminuted LOWF. To identify 100 patients with a LOWF, the authors reviewed consecutive midface computed tomography images of 877 patients performed over a 25-month period from one of our city's primary Level I trauma and teaching hospitals. A total of 121 LOWF were identified in 100 patients. In 60.3% of cases the facture was a simple, noncomminuted LOWF. In 39.7% of cases the fracture was comminuted (p = 0.023). Simple LOWF are significantly more common than comminuted fractures. In 39.7% of fractures the LOW is comminuted. This suggests that there are many fractures in which other modalities may be much more important to use to confirm the proper reduction of the zygoma.

Use of a Three-Dimensional Model to Optimize a MEDPOR Implant for Delayed Reconstruction of a Suprastructure Maxillectomy Defect

The use of a three-dimensional (3-D) model has been well described for craniomaxillofacial reconstruction, especially with the preoperative planning of free fibula flaps. This article reports the application of an innovative 3-D model approach for the calculation of the exact contours, angles, length, and general morphology of a prefabricated MEDPOR 2/3 orbital implant for reconstruction of a suprastructure maxillectomy defect. The 3-D model allowed intraoperative modification of the MEDPOR implant which decreased the risk of iatrogenic harm, contamination while also improving aesthetic results and function. With the aid of preoperative 3-D models, porous polypropylene facial implants can be contoured efficiently intraoperatively to precisely reconstruct complex craniomaxillofacial defects.

Management of fractures of the zygomaticomaxillary complex

The zygomaticomaxillary complex (ZMC) has important aesthetic, structural, and functional roles that need to be preserved and/or restored during treatment of facial fractures. Surgical treatment of ZMC fractures is indicated when there is displacement of the bony fragments, and open reduction and internal fixation is the treatment of choice in cases of comminution or fracture instability. The surgical approaches used for fracture reduction as well as the type, number, and location of the fixation will be determined by the pattern of the fracture and the surgeon's preference. This article discusses the main points of the management of ZMC fractures.

Improved catheter navigation with 3D electromagnetic guidance

PURPOSE

To evaluate the in vitro performance of an electromagnetic navigation system (ENS) in aortic arch branch cannulation and describe its role for fenestrated endograft deployment.

METHODS

Reconstructed multidetector computed tomography images of silicone phantoms representing the aortic arch and a thoracoabdominal aortic aneurysm were uploaded onto the StealthStation workstation, which provided 3-dimensional visualization of a guidewire by tracking sensors on its tip. For the evaluation of aortic arch branch cannulation, 9 operators were asked to cannulate the phantom's common carotid and left subclavian arteries using the (1) ENS, (2) a 2-dimensional (2D) screen setting simulating fluoroscopy, and (3) both imaging modalities. Analysis included procedure times, number of wall hits, and the Imperial College Complex Cannulation Scoring Tool (IC3ST) qualitative performance score. To evaluate the ability of the ENS during positioning of a fenestrated stent-graft over the visceral segment, a custom-made 4-vessel fenestrated stent-graft with sensors on the fenestrations was deployed 5 consecutive times using the ENS as the exclusive imaging technique.

RESULTS

In the aortic arch model, cannulation times were significantly longer in the ENS group. However, compared with the 2D version, using both imaging modalities reduced fluoroscopic times [median 26.5 seconds (IQR 19.7-30.7) vs. 87 seconds (IQR 64-128), p<0.0001] and wall hits [median 8.5 (IQR 16-38) vs. 14 (IQR 11-160, p<0.05), while improving IC3ST performance scores [31/35 (IQR 30-31.2) vs. 25/35 (IQR 24-27), p<0.05]. Following deployment of the endograft with tracked fenestrations, the 4 visceral vessels were cannulated in all cases using only the ENS.

CONCLUSION

The use of the ENS as a complementary imaging modality might be beneficial in terms of radiation exposure, cannulation performance, and positioning of intravascular devices.

Traditional and contemporary surgical approaches to the orbit

Traditional orbital approaches are nearly a century old and still comprise the foundation of techniques used today. Computer-assisted planning and intraoperative navigation have recently been reported with more prevalence in the literature. The purpose of this article was to review commonly used approaches to the orbit: old and new.

Latest trends in craniomaxillofacial surgical instrumentation

PURPOSE OF REVIEW

To review the past year's literature regarding recent innovations in surgical instrumentation for craniomaxillofacial surgery.

RECENT FINDINGS

Current advances in surgical instrumentation have led to many improvements in the field, allowing greater visualization and precision both before and during procedures. One of the common goals is to achieve excellent outcomes with minimal complications, while at the same time minimizing invasiveness of surgery. Highlighted innovations include greater capacities for acquisition of data, leading to improved imaging modalities and expansion of computer-assisted surgical techniques; continued developments in biomaterials used in various reconstructions; and novel uses of bone cutting and bone fixation instrumentation.

SUMMARY

Technology in the field of craniomaxillofacial surgery is developing rapidly, leading to novel instrumentation being utilized across a broad spectrum of areas. Published data have been encouraging to date, indicating an ever increasing adaptation of these innovations in clinical practice. Future efforts need to focus on cost-benefit analysis and constructing larger-scale studies to better understand effectiveness and patient outcomes.

Validation of anatomical landmarks-based registration for image-guided surgery: an in-vitro study

INTRODUCTION

Perioperative navigation is a recent addition to orthognathic surgery. This study aimed to evaluate the accuracy of anatomical landmarks-based registration.

MATERIALS AND METHODS

Eighty-five holes (1.2 mm diameter) were drilled in the surface of a plastic skull model, which was then scanned using a SkyView cone beam computed tomography scanner. DICOM files were imported into BrainLab ENT 3.0.0 to make a surgical plan. Six anatomical points were selected for registration: the infraorbital foramena, the anterior nasal spine, the crown tips of the upper canines, and the mesial contact point of the upper incisors. Each registration was performed five times by two separate observers (10 times total).

RESULTS

The mean target registration error (TRE) in the anterior maxillary/zygomatic region was 0.93 ± 0.31 mm (p < 0.001 compared with other anatomical regions). The only statistically significant inter-observer difference of mean TRE was at the zygomatic arch, but was not clinically relevant.

CONCLUSION

With six anatomical landmarks used, the mean TRE was clinically acceptable in the maxillary/zygomatic region. This registration technique may be used to access occlusal changes during bimaxillary surgery, but should be used with caution in other anatomical regions of the skull because of the large TRE observed.

The mirroring technique: a navigation-based method for reconstructing a symmetrical orbit and cranial vault

BACKGROUND

The reconstruction of orbital structures and the cranial vault curvature can be challenging after trauma or wide resections for tumors. Sophisticated methods have been developed recently, but these are resource- and time-consuming.

OBJECTIVE

We report the mirroring technique, which is an effective and costless application for navigation-guided reconstruction procedures.

METHODS

At the time of the reconstruction, high-resolution images are reloaded while forcing a left-right axial flip. The pointer subsequently enables a virtual 3-dimensional projection of the position of the contralateral normal anatomy.

RESULTS

This method was applied successfully in 2 cases of en plaque sphenoid wing meningiomas with secondary exophthalmia.

CONCLUSION

The mirroring technique represents an accurate method of outlining the contralateral normal anatomy onto the pathological side based on navigation guidance.

Closed reduction of mandibular condyle fractures using C-arm fluoroscopy: a technical note

We describe a C-arm technique for mandibular condylar fractures in an anatomic study using a model skull and show its feasibility in a clinical case. The C-arm allowed posterior-anterior visualization of the condylar process. The X-ray axis was canted ∼15 degrees cranially to the Frankfort horizontal line. The skull's sagittal plane was rotated ∼15 degrees ipsilaterally to the X-ray axis. This technique facilitates clear visualization of the condylar neck with easy, flexible, and timely adjustments. In selected cases, this method would convert the clinical settings of the condylar fracture pattern to that which would not be amenable to an open approach, making possible minimally invasive surgical procedures.

C-arm-guided reduction of zygomatic fractures revisited

BACKGROUND

Anatomic reduction of the zygomatic arch, a key surgical landmark for midfacial width and projection, is essential for the treatment of combined fractures of the zygomaticomaxillary complex and zygomatic arch. Reduction control in surgery for this common facial fracture would be facilitated by intraoperative real-time assessment using widely available and reliable equipment. Although C-arm fluoroscopy is routinely used in the repair of orthopedic fractures, its use in the maxillofacial region, particularly for combined zygomatic fractures, has been scarcely reported.

METHODS

We prospectively evaluated C-arm-guided reduction in 38 patients of combined zygomatic fracture without concurrent craniofacial fractures. Patients were classified according to the presence or absence of bone contact in the displaced zygomatic arch, namely as conserved (C) and loss (L) types, respectively. Reduction status was determined by the degree of recovery of the malar prominence and arch shape.

RESULTS

In all cases, C-arm imaging clearly displayed the displaced zygomatic arch and body in a single image. Cumulative fluoroscopic time was a few minutes in all cases. Total reduction status was excellent in 21 patients and good in 17. No case was classified as fair or poor. Repair was significantly more favorable in type C than in type L cases (p = 0.0016).

CONCLUSIONS

In combined zygomatic fractures, the C-arm technique provides easy, flexible, and time-efficient adjustment. Its comprehensive imaging for zygomatic arch shape and body contour markedly facilitates the control of fracture reduction and protects against unexpected, unsatisfactory outcomes.

Contemporary management of orbitozygomatic complex trauma

Orbitozygomatic complex fractures are the second most common fractures of the maxillofacial skeleton. Interpersonal violence predominates as the cause in the United Kingdom. Treatment is directed at restoration of function of the eye and aesthetics.

Orbitozygomatic fractures with enophthalmos: analysis of 64 cases treated late

PURPOSE

To present our treatment experience in delayed orbitozygomatic fracture with enophthalmos and compare the results of traditional surgery, navigation-guided surgery, and 3-dimensional (3D) model-guided surgery in the Departments of Oral and Maxillofacial Surgery and Ophthalmology, Shanghai Ninth People's Hospital, Shanghai, China.

PATIENTS AND METHODS

This is a retrospective review of a consecutive clinical case series. From 2008 to 2010, 64 patients diagnosed with delayed orbitozygomatic fractures with enophthalmos were treated in the departments. Computed tomography (CT) scan and ophthalmologic examination were performed before surgery. Traditional surgery and computer-assisted treatment (navigation and 3D model) were used for zygoma reduction. Three materials were applied for orbital reconstruction: hydroxyapatite (HA), porous polyethylene (Medpor; Porex Surgical Inc, Newnan, GA), and titanium mesh. Zygomatic reduction and globe projection of different treatment methods were evaluated by postoperative CT scan and clinical follow-up visits.

RESULTS

Thirty-nine cases with enophthalmos (mean, 4.96 mm) had traditional surgery for fracture reduction and orbital reconstruction, whereas the other twenty-five cases with enophthalmos (mean, 5.71 mm) had computer-assisted surgery consisting of 3D models to pre-bend the titanium mesh for orbital reconstruction and plates for fracture fixation (n = 25) and navigation-guided surgery (n = 11). Postoperative CT with 3D reconstruction showed good zygomatic reduction in 74.3% of the cases with traditional surgery, 85.7% with computer-assisted 3D models only, and 100% with navigation-guided surgery. In the traditional surgery group, 74.2% of the cases had good postoperative globe projection (≤2 mm), 19.4% had mild enophthalmos (≤3 mm), and 6.5% had moderate enophthalmos (≤4 mm). In the group undergoing computer-assisted 3D model surgery, 75% of the cases had good globe projection and 25% had mild enophthalmos. In the navigation-guided surgery group, 90.9% of the cases had good globe projection and 9.1% had mild enophthalmos. Titanium mesh was used for orbital reconstruction in 47 cases (among which, 12 combined with Medpor or HA), whereas 12 had Medpor only and 5 had HA only. Good globe projection was acquired in 74% of the cases with titanium mesh only, 83% with combined materials, 67% with Medpor only, and 20% with HA only.

CONCLUSIONS

Computer-assisted surgery can improve the treatment results of delayed orbitozygomatic fracture with enophthalmos. Navigation-guided surgery with a 3D model and titanium mesh with Medpor are the best ways to treat delayed orbitozygomatic fractures with severe enophthalmos.