|SYMPOSIUM - OCULAR FACIAL PLASTIC SURGERY
|Year : 2015 | Volume
| Issue : 4 | Page : 442-446
Virtual surgical planning for orbital reconstruction
Srinivas M Susarla1, Katherine Duncan2, Nicholas R Mahoney3, Shannath L Merbs3, Michael P Grant4
1 Department of Plastic and Reconstructive Surgery, Johns Hopkins Hospital, Baltimore, MD, USA
2 Department of Ophthalmology, University of Maryland Medical Center, Baltimore, MD, USA
3 Department of Ophthalmology, Division of Oculoplastic Surgery, Wilmer Eye Institute, Johns Hopkins Hospital, Baltimore, MD, USA
4 Department of Plastic and Reconstructive Surgery and Department of Ophthalmology, Division of Oculoplastic Surgery, Wilmer Eye Institute, Johns Hopkins Hospital, Baltimore, MD, USA
|Date of Web Publication||21-Oct-2015|
Srinivas M Susarla
Department of Plastic and Reconstructive Surgery, Johns Hopkins Hospital, 801 N. Caroline Street, JHOC 8, Baltimore, Maryland
Source of Support: None, Conflict of Interest: None
| Abstract|| |
The advent of computer-assisted technology has revolutionized planning for complex craniofacial operations, including orbital reconstruction. Orbital reconstruction is ideally suited for virtual planning, as it allows the surgeon to assess the bony anatomy and critical neurovascular structures within the orbit, and plan osteotomies, fracture reductions, and orbital implant placement with efficiency and predictability. In this article, we review the use of virtual surgical planning for orbital decompression, posttraumatic midface reconstruction, reconstruction of a two-wall orbital defect, and reconstruction of a large orbital floor defect with a custom implant. The surgeon managing orbital pathology and posttraumatic orbital deformities can benefit immensely from utilizing virtual planning for various types of orbital pathology.
Keywords: Orbital Decompression, Orbital Reconstruction, Orbital Trauma
|How to cite this article:|
Susarla SM, Duncan K, Mahoney NR, Merbs SL, Grant MP. Virtual surgical planning for orbital reconstruction. Middle East Afr J Ophthalmol 2015;22:442-6
|How to cite this URL:|
Susarla SM, Duncan K, Mahoney NR, Merbs SL, Grant MP. Virtual surgical planning for orbital reconstruction. Middle East Afr J Ophthalmol [serial online] 2015 [cited 2019 Aug 23];22:442-6. Available from: http://www.meajo.org/text.asp?2015/22/4/442/164626
| Introduction|| |
Over the past 20 years, advances in radiographic imaging and computer technology have allowed for application of image-guided surgery in orbital reconstruction. Conversely, volumetric analyses of anatomical structures have been utilized for the design of standardized anatomic implants for orbital reconstruction and custom patient-specific implants for complex orbital and midfacial defects. These advances have allowed for improved efficiency, accuracy, and safety in the surgical management of orbital pathology. The purpose of this review is to discuss the applications of computer-guidance and advanced computed tomography (CT)-imaging in the management of various conditions affecting the bony orbit. Four illustrative case examples are presented: Orbital decompression for thyroid-eye disease, midface reconstruction following a zygomaticomaxillary complex (ZMC) injury, reconstruction of a posttraumatic two-wall orbital defect, and reconstruction of a large orbital floor defect with a custom alloplastic implant.
| Thyroid Eye Disease|| |
Thyroid eye disease (TED) is an autoimmune inflammatory disorder of the orbit that results in proptosis, diplopia, eyelid retraction, exposure keratopathy and in severe cases, optic nerve compression. The pathogenesis of TED has not been entirely elucidated however it is most likely due to the activation of thyroid stimulating receptors by circulating thyrotropin receptor antibodies. Activation of these receptors in the orbit results in deposition of hyaluronan and resulting extraocular muscle enlargement as well as hypertrophy of orbital adipose tissue.,, As the orbital contents enlarge, the patient is at risk for sight-threatening compressive optic neuropathy. Various treatment methodologies including steroids, orbital radiation, immunomodulators, and selenium have been used. However, refractory or sight-threatening cases of TED usually require surgical decompression.
Orbital decompression has been a mainstay of TED treatment since the 1950s. The variability in outcomes particularly in terms of proptosis and ocular alignment has resulted in the development of numerous surgical techniques for decompression with no clear consensus on which is most effective. The recent development of computer-assisted surgical planning and execution has the potential to result in more efficacious, consistent and predictable decompressions. Multiplanar CT scans with three-dimensional (3D) reconstruction allow the surgeon to carefully evaluate the individual anatomy and identify specific bone segments for resection. Intraoperatively, the CT images and the patient's anatomy are virtually overlapped allowing for stereotactic navigation throughout the case. This allows the surgeon to check his/her distance from important anatomical landmarks and to measure the extent of bony resection in order to carefully match preoperative planning. Postoperative imaging and assessment may be used to objectively quantify the magnitude of decompression and correlate this with clinical outcomes. The objective data provided by computer-assisted orbital decompression has the potential to result in safer, more efficacious and consistent decompressions. In the clinical example shown [Figure 1] and [Figure 2], real-time image guidance was utilized to allow for extensive, asymmetric decompression of the bilateral orbits (left: Lateral orbital wall, right: Medial and lateral walls).
|Figure 1: Preoperative (top panels) and postoperative (bottom panels) frontal and submentovertex views of a male patient with thyroid orbitopathy who underwent computer-assisted orbital decompression|
Click here to view
|Figure 2: Preoperative (left panels) and postoperative (right panels) demonstrating the three-dimensional computer planning for orbital decompression and superimposition of the expected result over the postoperative images (right middle and right bottom panels)|
Click here to view
| Periorbital Trauma|| |
Injuries to the bony orbit are common among patients sustaining craniomaxillofacial trauma.,,,,, The external orbital framework is disrupted in several different types of facial fractures (e.g. ZMC, frontal bone, Le Fort III). The integrity of the internal orbit can likewise be disrupted, either in isolation or as a component of complex midfacial or upper facial injury. The orbital skeleton provides support for the globe and ocular adnexa and houses neurovascular structures critical to normal visual sensory function. While disruption of the orbital framework can compromise these structures, such injuries are, fortunately, rare. Conversely, surgical management of orbital skeletal injuries is fraught with potential peril, as dissection, bony mobilization, or placement of intra-orbital hardware may damage the globe or critical neurovascular structures. In this regard, advances in computer imaging have enhanced the surgeon's ability to safely dissect the internal orbit, have allowed for the design and manufacture of standard implants for orbital reconstruction, planning for correction of secondary deformities, quantitative assessment of fracture reduction and volume restoration, and have improved the ability to visualize, in real-time, the orbital anatomy during dissection.,,,,,,,,,,,,,,,,,,
| Zygomaticomaxillary Complex Fractures|| |
ZMC fractures sometimes termed zygoma fractures or orbitozygomatic fractures, are among the most common type of facial fracture.,,, High-or low-energy mechanisms can disrupt the articulations of the zygomatic bone with the frontal bone (frontozygomatic suture), temporal bone (zygomatic arch), sphenoid bone (sphenozygomatic suture), and maxilla (zygomaticomaxillary buttress). The 3D relationship between these articulations was not initially understood in the management of these injuries, which were commonly referred to as "tripod" fractures. Advances in CT have improved the understanding of these injuries and the complex 3D anatomy that needs to be restored for successful management.,,,,,, Restoration of the sphenozygomatic articulation in the lateral orbit remains the most reliable predictor of a successful reduction but is difficult to assess without surgical access to the internal orbit.,,,, Furthermore, management of the orbital floor remains controversial among patients with ZMC fractures., The use of real-time imaging (mini C-arm, CT) has allowed for assessment of anatomic alignment and orbital floor integrity following reduction, improving operating times and decreasing patient morbidity from unnecessary orbital exploration.,,, In the case presented, an orbitozygomatic fracture was repaired utilizing virtual planning to establish the appropriate position of the right zygoma. To accomplish this, the left zygoma complex was digitally rendered from a 3D CT reconstruction and subsequently mirrored and placed onto the right midface [Figure 3]. The reconstituted virtual position of the zygoma served as a template and was then used to guide intra-operative positioning of the displaced fracture. Virtual planning also allowed for visualization of the sizable orbital floor defect, which required orbital exploration and reconstruction using an anatomical plate.
|Figure 3: Three-dimensional and axial computed tomography, as used for operative planning for a displaced orbitozygomatic fracture. In the preoperative images (top panels), the displaced zygoma (top left) was repositioned by mirroring the left zygoma and virtually positioning the mirrored bone (top middle and top right panels). The postoperative images (bottom panels) demonstrate anatomic alignment of the zygomatic articulations and reconstruction of the orbital floor|
Click here to view
| Isolated Orbital Fractures|| |
Injuries to the orbital floor are commonly encountered among surgeons affiliated with trauma centers that treat facial injuries. Orbital floor injuries may occur in isolation or in conjunction with higher level Le Fort injuries, ZMC fractures, naso-orbital-ethmoid fractures, panfacial trauma, and often occur with fractures of the medial orbital wall. The primary goal for orbital reconstruction is to restore the premorbid orbital volume. In this regard, image-guidance technology has been useful for the design of anatomic orbital implants, particularly for two-walled defects involving the floor and medial wall.,,,,,, Custom implants can also be utilized for reconstruction of irregular defects or when there is a significant bone loss. Real-time intra-operative image guidance is a useful to aid in dissection of the orbital floor and medial wall, allowing the surgeon to assess accurately position relative to the superior orbital fissure, optic canal, and the anterior and posterior ethmoidal foramina, thereby decreasing the risk of damage to critical arterial, venous, and nervous structures in these areas. In the first clinical example, virtual planning was used to assess the size and position of the orbital implant required for reconstruction of a posttraumatic defect involving the right medial orbital wall and floor [Figure 4] and [Figure 5]. The unaffected orbit was used for comparison to allow for adequate reconstitution of orbital volume. The preoperative enophthalmos was predictably corrected; the postoperative image fusion demonstrates appropriate positioning of the implant along the orbital floor and medial wall, with a stable landing on the posterior ledge. In the second clinical example, a patient with a large, posttraumatic orbital floor defect with significant volume change and marked enophthalmos underwent presurgical planning and design of a custom titanium/polyethylene implant for orbital reconstruction [Figure 6] and [Figure 7]. The postoperative result demonstrates marked improvement in globe position, with excellent positioning of the implant along the fracture margins.
|Figure 4: Preoperative (top panels) frontal and submentovertex views of a male patient with an orbital floor and medial wall fracture who underwent computer-assisted planning for orbital reconstruction. In the postoperative (bottom panels) photos, the enophthalmos has been corrected and the globe position is symmetric|
Click here to view
|Figure 5: Preoperative (left panels) and postoperative (right panels) demonstrating the three-dimensional computer planning for orbital reconstruction with an anatomic implant. The implant is rendered within the software and virtually placed within the defect. This allows the surgeon to position the implant and compute the orbital volume relative to the unaffected side. Intra-operatively, placement of the implant in the appropriate position can be ensured with the use of real-time navigation|
Click here to view
|Figure 6: Preoperative (top panels) frontal and submentovertex views of a female patient with a large right orbital floor fracture with significant enophthalmos. Computer-assisted planning was utilized to design a custom implant for reconstitution of orbital volume for enophthalmos correction. Postoperatively (bottom panels), the patient has has no orbital dystopia or enophthalmos|
Click here to view
|Figure 7: Preoperative (left panels) and postoperative (right panels) images, demonstrating the three-dimensional computer planning and subsequent reconstruction of a large orbital floor defect with an anatomic titanium-alloplastic hybrid implant. The preoperative images are utilized to compute the volume of the defect relative to the unaffected side. The custom implant is then designed to restore the orbital volume and correct the globe position|
Click here to view
| Conclusions|| |
Advances in computer technology and imaging have improved the accessibility and efficacy of orbital reconstruction for defects involving the bony orbit. Due to the complex shape of the internal orbit, proximity of critical soft tissue structures, and small margins of error, the orbital skeleton is an ideal anatomic region for virtual planning and real-time intra-operative navigation. Utilization of this technology has the potential to improve the surgical treatment of common problems, make challenging clinical cases more accessible and predictable, and has enormous utility as an adjunct for trainee instruction.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Stan MN, Garrity JA, Bahn RS. The evaluation and treatment of graves ophthalmopathy. Med Clin North Am 2012;96:311-28.
Garrity JA, Bahn RS. Pathogenesis of graves ophthalmopathy: Implications for prediction, prevention, and treatment. Am J Ophthalmol 2006;142:147-53.
Pillar AJ, Richa DC. Treatment options for thyroid eye disease. Curr Treat Options Neurol 2014;16:303.
Ezra DG, Rose GE. Old and new: Evidence-based evaluation of interventions for Graves' Orbitopathy. Br J Ophthalmol 2014;98:287-8.
Susarla SM, Grant MP, Merbs S, Mahoney NR. Computer-assisted three-dimensional planning for orbital decompression. Craniomaxillofac Traum Reconstr 2014. p. 14. [Epub ahead of print].
Tavassol F, Kokemüller H, Müller-Tavassol C, Schramm A, Rücker M, Gellrich NC. A quantitative approach to orbital decompression in Graves' disease using computer-assisted surgery: A compilation of different techniques and introduction of the "temporal cage". J Oral Maxillofac Surg 2012;70:1152-60.
Ellis E 3rd
. Orbital trauma. Oral Maxillofac Surg Clin North Am 2012;24:629-48.
Ellis E 3rd
, Kittidumkerng W. Analysis of treatment for isolated zygomaticomaxillary complex fractures. J Oral Maxillofac Surg 1996;54:386-400.
Uzelac A, Gean AD. Orbital and facial fractures. Neuroimaging Clin N
Am 2014;24:407-24, vii.
Kochhar A, Byrne PJ. Surgical management of complex midfacial fractures. Otolaryngol Clin North Am 2013;46:759-78.
Marinho RO, Freire-Maia B. Management of fractures of the zygomaticomaxillary complex. Oral Maxillofac Surg Clin North Am 2013;25:617-36.
Avery LL, Susarla SM, Novelline RA. Multidetector and three-dimensional CT evaluation of the patient with maxillofacial injury. Radiol Clin North Am 2011;49:183-203.
van Hout WM, Van Cann EM, Muradin MS, Frank MH, Koole R. Intraoperative imaging for the repair of zygomaticomaxillary complex fractures: A comprehensive review of the literature. J Craniomaxillofac Surg 2014;42:1918-23.
Gordon CR, Susarla SM, Yaremchuk MJ. Quantitative assessment of medial orbit fracture repair using computer-designed anatomical plates. Plast Reconstr Surg 2012;130:698e-705.
Scolozzi P, Momjian A, Heuberger J, Andersen E, Broome M, Terzic A, et al.
Accuracy and predictability in use of AO three-dimensionally preformed titanium mesh plates for posttraumatic orbital reconstruction: A pilot study. J Craniofac Surg 2009;20:1108-13.
Metzger MC, Schön R, Weyer N, Rafii A, Gellrich NC, Schmelzeisen R, et al.
Anatomical 3-dimensional pre-bent titanium implant for orbital floor fractures. Ophthalmology 2006;113:1863-8.
Bell RB, Markiewicz MR. Computer-assisted planning, stereolithographic modeling, and intraoperative navigation for complex orbital reconstruction: A descriptive study in a preliminary cohort. J Oral Maxillofac Surg 2009;67:2559-70.
Scolozzi P, Momjian A, Heuberger J. Computer-aided volumetric comparison of reconstructed orbits for blow-out fractures with nonpreformed versus 3-dimensionally preformed titanium mesh plates: A preliminary study. J Comput Assist Tomogr 2010;34:98-104.
Scolozzi P, Jaques B. Computer-aided volume measurement of posttraumatic orbits reconstructed with AO titanium mesh plates: Accuracy and reliability. Ophthal Plast Reconstr Surg 2008;24:383-9.
Liu XZ, Shu DL, Ran W, Guo B, Liao X. Digital surgical templates for managing high-energy zygomaticomaxillary complex injuries associated with orbital volume change: A quantitative assessment. J Oral Maxillofac Surg 2013;71:1712-23.
Lu W, Zhou H, Xiao C, Shen Q, Lin M, Fan X. Late correction of orbital-zygomatic-maxillary fractures combined with orbital wall fractures. J Craniofac Surg 2012;23:1672-6.
Strong EB, Fuller SC, Wiley DF, Zumbansen J, Wilson MD, Metzger MC. Preformed vs intraoperative bending of titanium mesh for orbital reconstruction. Otolaryngol Head Neck Surg 2013;149:60-6.
Stuck BA, Hülse R, Barth TJ. Intraoperative cone beam computed tomography in the management of facial fractures. Int J Oral Maxillofac Surg 2012;41:1171-5.
Mustafa SF, Evans PL, Bocca A, Patton DW, Sugar AW, Baxter PW. Customized titanium reconstruction of post-traumatic orbital wall defects: A review of 22 cases. Int J Oral Maxillofac Surg 2011;40:1357-62.
Metzger MC, Hohlweg-Majert B, Schön R, Teschner M, Gellrich NC, Schmelzeisen R, et al.
Verification of clinical precision after computer-aided reconstruction in craniomaxillofacial surgery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:e1-10.
Markiewicz MR, Dierks EJ, Potter BE, Bell RB. Reliability of intraoperative navigation in restoring normal orbital dimensions. J Oral Maxillofac Surg 2011;69:2833-40.
Zhang Y, He Y, Zhang ZY, An JG. Evaluation of the application of computer-aided shape-adapted fabricated titanium mesh for mirroring-reconstructing orbital walls in cases of late post-traumatic enophthalmos. J Oral Maxillofac Surg 2010;68:2070-5.
Ellis E 3rd
, Reddy L. Status of the internal orbit after reduction of zygomaticomaxillary complex fractures. J Oral Maxillofac Surg 2004;62:275-83.
Ellis E 3rd
, Perez D. An algorithm for the treatment of isolated zygomatico-orbital fractures. J Oral Maxillofac Surg 2014;72:1975-83.
Park DJ, Garibaldi DC, Iliff NT, Grant MP, Merbs SL. Smooth nylon foil (SupraFOIL) orbital implants in orbital fractures: A case series of 181 patients. Ophthal Plast Reconstr Surg 2008;24:266-70.
Garibaldi DC, Iliff NT, Grant MP, Merbs SL. Use of porous polyethylene with embedded titanium in orbital reconstruction: A review of 106 patients. Ophthal Plast Reconstr Surg 2007;23:439-44.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]