Efficacy of computer-assisted surgery in secondary orbital reconstruction

Orbital reconstruction: a systematic review and meta-analysis evaluating the role of patient-specific implants

The purpose of this study is to execute an evidence-based review answering the following question (PICO): "Do patient-specific implants (PSI), manufactured or designed using computer-assisted technology, improve outcomes (orbital volume change, enophthalmos, diplopia, and operative duration) compared to conventional methods in orbital reconstruction following traumatic orbital injury in the adult patient population?" We performed a systematic review and meta-analysis in accordance with PRISMA guidelines. Inclusion criteria included any comparative paper whereby computer-assisted technology was used in the prefabrication or design process of implants for use in post-traumatic orbital reconstruction. Paediatric patient populations were excluded. Eight databases were systematically searched for relevant studies. Risk of bias was assessed through the NOS and RoB2 tools. Random-effects models were used to identify differences in outcomes between groups where possible. Analysis was performed using R 4.0.0. Eleven of 4784 identified studies were included, comprising 628 adult patients, with 302 and 326 patients in the patient-specific and conventional groups, respectively. Weighted mean difference between unaffected and post-operative orbital volume was 0.32 ml (SD 0.75) and 0.95 ml (SD 1.03) for patient-specific and conventional groups, respectively. Significant improvement was identified in post-operative orbital volume reconstitution with the use of PSI, compared to conventional implants, in 3 of the 5 reporting studies. Equally, post-operative enophthalmos trended towards lower severity in the patient-specific group, with 11.2% of patients affected in the patient-specific group and 19.2% in the conventional group, and operative duration was significantly reduced with the use of PSI in 3 of the 6 reporting studies. Despite a tendency to favour PSI, no statistically significant differences in key outcomes were identified on meta-analysis. Although there is some encouraging data to support improved outcomes with the use of patient-specific orbital implants in post-traumatic reconstruction, there is, at present, no statistically significant evidence to objectively support their use over conventional implants based on the currently available comparative studies. Based on the results of this study, the choice of implant used should, thus, be left to the discretion of the surgeon.

Use of computer-assisted surgery in the orbit

PURPOSE

To present the application of computer-assisted surgery (CAS) in pre-operative planning, intra-operative navigation, and post-operative assessment as an adjunct tool in orbital surgery.

METHODS

An IRB-approved, retrospective review was performed to identify patients who had undergone orbital surgery by a single surgeon from July 2013 to December 2019 with attention to pre-operative virtual surgical planning, intra-operative navigation, and post-operative assessment. The reasons and methods of CAS use were classified.

RESULTS

The use of computer-assisted technologies was identified in 91 cases out of 464 orbital surgeries (19.6%). This included 23 (25.3%) orbital decompression surgeries, 39 (42.9%) fracture repairs, and 25 (27.5%) orbital tumors. In all cases, pre-, intra-, and post-operative CAS allowed for increased operative efficiency and safety with good outcomes.

CONCLUSIONS

Use of CAS in orbital surgery can allow for complex radiographic analysis and in select cases is a great tool to add to the orbital surgeon's armamentarium.

Computer-assisted navigation in orbitofacial surgery

The purpose of this systematic review is to investigate the most common indications, treatment, and outcomes of computer-assisted surgery (CAS) in ophthalmological practice. CAS has evolved over the years from a neurosurgical tool to maxillofacial as well as an instrument to orbitofacial surgeries. A detailed and organized scrutiny in relevant electronic databases, journals, and bibliographies of the cited articles was carried out. Clinical studies with a minimum of two study cases were included. Navigation surgery, posttraumatic orbital reconstruction, computer-assisted orbital surgery, image-guided orbital decompression, and optic canal decompression (OCD) were the areas of interest. The search generated 42 articles describing the use of navigation in facial surgery: 22 on orbital reconstructions, 5 related to lacrimal sac surgery, 4 on orbital decompression, 2 articles each on intraorbital foreign body and intraorbital tumors, 2 on faciomaxillary surgeries, 3 on cranial surgery, and 2 articles on navigation-guided OCD in traumatic optic neuropathy. In general, CAS is reported to be a useful tool for surgical planning, execution, evaluation, and research. The largest numbers of studies and patients were related to trauma. Treatment of complex orbital fractures was greatly improved by the use of CAS compared with empirically treated control groups. CAS seems to add a favourable potential to the surgical armamentarium. Planning details of the surgical approach in a three-dimensional virtual environment and execution with real-time guidance can help in considerable enhancement of precision. Financial investments and steep learning curve are the main hindrances to its popularity.

Evaluating the impact of image guidance in the surgical setting: a systematic review

Background

Image guidance has been clinically available for over a period of 20 years. Although research increasingly has a translational emphasis, overall the clinical uptake of image guidance systems in surgery remains low. The objective of this review was to establish the metrics used to report on the impact of surgical image guidance systems used in a clinical setting.

Methods

A systematic review of the literature was carried out on all relevant publications between January 2000 and April 2016. Ovid MEDLINE and Embase databases were searched using a title strategy. Reported outcome metrics were grouped into clinically relevant domains and subsequent sub-categories for analysis.

Results

In total, 232 publications were eligible for inclusion. Analysis showed that clinical outcomes and system interaction were consistently reported. However, metrics focusing on surgeon, patient and economic impact were reported less often. No increase in the quality of reporting was observed during the study time period, associated with study design, or when the clinical setting involved a surgical specialty that had been using image guidance for longer.

Conclusions

Publications reporting on the clinical use of image guidance systems are evaluating traditional surgical outcomes and neglecting important human and economic factors, which are pertinent to the uptake, diffusion and sustainability of image-guided surgery. A framework is proposed to assist researchers in providing comprehensive evaluation metrics, which should also be considered in the design phase. Use of these would help demonstrate the impact in the clinical setting leading to increased clinical integration of image guidance systems.

Electronic supplementary material

The online version of this article (10.1007/s00464-019-06876-x) contains supplementary material, which is available to authorized users.

New and emerging patient-centered CT imaging and image-guided treatment paradigms for maxillofacial trauma

This article reviews the conceptual framework, available evidence, and practical considerations pertaining to nascent and emerging advances in patient-centered CT-imaging and CT-guided surgery for maxillofacial trauma. These include cinematic rendering-a novel method for advanced 3D visualization, incorporation of quantitative CT imaging into the assessment of orbital fractures, low-dose CT imaging protocols made possible with contemporary scanners and reconstruction techniques, the rapidly growing use of cone-beam CT, virtual fracture reduction with design software for surgical pre-planning, the use of 3D printing for fabricating models and implants, and new avenues in CT-guided computer-aided surgery.

Application of Computer-Aided Designing and Rapid Prototyping Technologies in Reconstruction of Blowout Fractures of the Orbital Floor

INTRODUCTION

Traumatology of the maxillofacial region represents a wide range of different types of facial skeletal injuries and encompasses numerous treatment methods. Application of computer-aided design (CAD) in combination with rapid prototyping (RP) technologies and three-dimensional computed tomography techniques facilitates surgical therapy planning for efficient treatment.

OBJECTIVE

The purpose of this study is to determine the efficiency of individually designed implants of poly-DL-lactide (PDLLA) in the reconstruction of blowout fractures of the orbital floor.

METHODS

In the course of a surgical treatment, individually designed implants manufactured by CAD/RP technologies were used. Preoperative analysis and postoperative monitoring were conducted to evaluate the successfulness of orbital floor reconstruction using customized PDLLA implants, based on: presence of diplopia, paresthesia of infraorbital nerve, and presence of enophthalmos.

RESULTS

In 6 of the 10 patients, diplopia completely disappeared immediately after surgical procedure. Diplopia gradually disappeared after 1 month in 3 patients, whereas in 1, it remained even after 6 months. In 7 patients, paresthesia disappeared within a month after surgery and in 3 patients within 2 months. Postoperative average Orbital volume (OV) of the injured side (13.333 ± 3.177) was significantly reduced in comparison with preoperative OV (15.847 ± 3.361) after reconstruction of the orbital floor with customized PDLLA implant (P < 0.001). Thus, average OV of corrected orbit was not different compared with the OV of the uninjured orbit (P = 0.981).

CONCLUSIONS

Reconstruction of blowout fractures of the orbital floor by an individually designed PDLLA implant combined with virtual preoperative modeling allows easier preoperative preparation and yields satisfactory functional and esthetic outcomes.

Evaluation of the Accuracy of Computer-Guided Mandibular Fracture Reduction

The aim of the current study was to evaluate the accuracy of computer-guided mandibular fracture reduction. A total of 24 patients with fractured mandible were included in the current study. A preoperative cone beam computed tomography (CBCT) scan was performed on all of the patients. Based on CBCT, three-dimensional reconstruction and virtual reduction of the mandibular fracture segments were done and a virtual bone borne surgical guide was designed and exported as Standard Tessellation Language file. A physical guide was then fabricated using a three-dimensional printing machine. Open reduction and internal fixation was done for all of the patients and the fracture segments were anatomically reduced with the aid of the custom-fabricated surgical guide. Postoperative CBCT was performed after 7 days and results of which were compared with the virtually reduced preoperative mandibular models. Comparison of values of lingula-sagittal plane, inferior border-sagittal plane, and anteroposterior measurements revealed no statistically significant differences between the virtual and the clinically reduced CBCT models. Based on the results of the current study, computer-based surgical guide aid in obtaining accurate anatomical reduction of the displaced mandibular fractured segments. Moreover, the computer-based surgical guides were found to be beneficial in reducing fractures of completely and partially edentulous mandibles.

The Role of Computer-Assisted Technology in Post-Traumatic Orbital Reconstruction: A PRISMA-driven Systematic Review

Post-traumatic orbital reconstruction remains a surgical challenge and requires careful preoperative planning, sound anatomical knowledge and good intraoperative judgment. Computer-assisted technology has the potential to reduce error and subjectivity in the management of these complex injuries. A systematic review of the literature was conducted to explore the emerging role of computer-assisted technologies in post-traumatic orbital reconstruction, in terms of functional and safety outcomes. We searched for articles comparing computer-assisted procedures with conventional surgery and studied outcomes on diplopia, enophthalmos, or procedure-related complications. Six observational studies with 273 orbits at a mean follow-up of 13 months were included. Three out of 4 studies reported significantly fewer patients with residual diplopia in the computer-assisted group, while only 1 of the 5 studies reported better improvement in enophthalmos in the assisted group. Types and incidence of complications were comparable. Study heterogeneities limiting statistical comparison by meta-analysis will be discussed. This review highlights the scarcity of data on computer-assisted technology in orbital reconstruction. The result suggests that computer-assisted technology may offer potential advantage in treating diplopia while its role remains to be confirmed in enophthalmos. Additional well-designed and powered randomized controlled trials are much needed.

Mirror-Imaged Rapid Prototype Skull Model and Pre-Molded Synthetic Scaffold to Achieve Optimal Orbital Cavity Reconstruction

PURPOSE

Reconstruction of traumatic orbital wall defects has evolved to restore the original complex anatomy with the rapidly growing use of computer-aided design and prototyping. This study evaluated a mirror-imaged rapid prototype skull model and a pre-molded synthetic scaffold for traumatic orbital wall reconstruction.

PATIENTS AND METHODS

A single-center retrospective review was performed of patients who underwent orbital wall reconstruction after trauma from 2012 to 2014. Patients were included by admission through the emergency department after facial trauma or by a tertiary referral for post-traumatic orbital deformity. Three-dimensional (3D) computed tomogram-based mirror-imaged reconstruction images of the orbit and an individually manufactured rapid prototype skull model by a 3D printing technique were obtained for each case. Synthetic scaffolds were anatomically pre-molded using the skull model as guide and inserted at the individual orbital defect. Postoperative complications were assessed and 3D volumetric measurements of the orbital cavity were performed. Paired samples t test was used for statistical analysis.

RESULTS

One hundred four patients with immediate orbital defect reconstructions and 23 post-traumatic orbital deformity reconstructions were included in this study. All reconstructions were successful without immediate postoperative complications, although there were 10 cases with mild enophthalmos and 2 cases with persistent diplopia. Reoperations were performed for 2 cases of persistent diplopia and secondary touchup procedures were performed to contour soft tissue in 4 cases. Postoperative volumetric measurement of the orbital cavity showed nonsignificant volume differences between the damaged orbit and the reconstructed orbit (21.35 ± 1.93 vs 20.93 ± 2.07 cm(2); P = .98). This protocol was extended to severe cases in which more than 40% of the orbital frame was lost and combined with extensive soft tissue defects.

CONCLUSION

Traumatic orbital reconstruction can be optimized and successful using an individually manufactured rapid prototype skull model and a pre-molded synthetic scaffold by computer-aid design and manufacturing.

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.

Evaluation of the application of computer-aided shape-adapted fabricated titanium mesh for mirroring-reconstructing orbital walls in cases of late post-traumatic enophthalmos

PURPOSE

Computer-aided individually shape-adapted fabricated titanium mesh for the mirroring-reconstruction of the orbit is a promising method for the correction of post-traumatic enophthalmos. The purpose of this study was to evaluate the application of this technique and assess the treatment outcomes.

PATIENTS AND METHODS

Twenty-one patients with delayed treatment of unilateral impure orbital fracture and post-traumatic enophthalmos were included in this study. Computed tomography-based mirroring-reconstruction images of the orbit were obtained for each individual to fabricate anatomically adaptive titanium mesh by computer-aided design and computer-aided manufacturing techniques. After exposing the areas of orbital defect and reducing the herniated soft tissue, the titanium mesh was inserted to reconstruct the internal orbit with a mean deep extension of 29.33 mm. Measurements were performed to assess the change in the degree of enophthalmos and orbital volume before and after surgery. Paired samples t test and Pearson correlation coefficient were employed for statistical analysis.

RESULTS

Follow-up examinations revealed that the degree of enophthalmos decreased to less than 2 mm in 11 patients, 2 to 4 mm in 9 patients, and remained greater than 7 mm in 1 patient. Statistical analysis revealed that post-traumatic enophthalmos in this series was 4.05 +/- 2.02 mm, which was associated with an orbital volume increment of 6.61 +/- 3.63 cm(3), with a regression formula of enophthalmos = 0.446 x orbital volume increment + 2.406. Orbital reconstruction effected a orbital volume decrease of 4.24 +/- 2.41 cm(3) and enophthalmos correction of 2.01 +/- 1.46 mm, the regression formula being enophthalmos = 0.586 x orbital volume decrease + 0.508. After surgery, the degree of unresolved enophthalmos was 2.03 +/- 1.52 mm, and the retained orbital volume expansion was 2.23 +/- 2.86 cm(3), and the regression formula was enophthalmos = 0.494 x orbital volume expansion + 1.415.

CONCLUSION

Application of the individual fabricated titanium mesh for orbital reconstruction reduced the trauma-induced orbital volume increment by 65% and corrected 50% of severe late enophthalmos. Additional augmentation of orbital contents was required for further correction. The related treatment parameters were suggested.

Rapid prototyping in craniofacial surgery: using a positioning guide after zygomatic osteotomy - A case report

INTRODUCTION

The management of post-traumatic deformity in the midface region poses challenges for the maxillofacial surgeon. Ensuring symmetry after zygomatic osteotomy can be difficult and precise positioning of the osteotomised bony fragments requires careful treatment planning. It may be necessary to use a coronal flap to allow the surgeon to compare the contralateral zygomatic bone to allow symmetrical reduction. The authors present a new technique for the positioning of osteotomised zygomatic bones using a combination of computer assisted surgical simulation and rapid prototyping.

METHOD

A patient presented to our unit with a post-traumatic zygomatic deformity. Using surgical simulation software the displaced zygomatic bone was osteotomised and placed in the idéal position on a three-dimensional computed tomography scan (3D CT). The position was determined by reference to the contralateral zygoma. In addition the repositioning of the soft tissues was simulated. A surgical guide which allowed intraoperative positioning of the osteotomised zygoma was manufactured by a rapid prototyping process. Use of the guide allowed a minimally invasive approach to the affected zygoma. The post-operative results were compared to the predicted outcome.

RESULTS

The post-operative appearance was satisfactory and corresponded well with the predicted result. There was a significant reduction in operative time compared to the previous management of similar cases.

Treatment with individual orbital wall implants in humans - 1-Year ophthalmologic evaluation

BACKGROUND

In 2009 a method of creating individual, patient specific orbital wall implants using rapid prototyping (RP) was shown in a preliminary human study. That study showed that it is financially viable to produce anatomical models and that this technology could be used in the repair of orbital floor fractures.

MATERIALS AND METHODS

In this study, 24 consecutive subjects who had sustained orbital fractures (14 males, 6 females) without any coexisting central nervous system or globe injury were assessed post-operatively. The first series of 12 patients, recruited during the period 2005-2006, were treated with classical method (CM) of forming titanium mesh by manual manipulation, based on individual subjective assessment of the extent and shape of damaged orbital walls. The following 12 cases, recruited between 2007 and 2008, were treated with patient specific titanium mesh implants designed with an RP method. Early (2 weeks) and late (12 months) follow-up was performed. Patients were evaluated by binocular single vision (BSV) test and an assessment of eye globe motility.

RESULTS

The superiority of the RP treatment method over CM was shown on the basis of early results when BSV loss area and reduction of vertical visual disparity (VVD) in upgaze were considered. Better outcomes for the RP group were confirmed in the late follow-up results which showed a reduction of BSV loss area, correction of primary globe position and a very significant improvement in upgaze.

CONCLUSIONS

One-year post-operatively, functional assessment of pre-bent individual implants of the orbital wall has shown the technique to be a predictable reconstruction method. Nevertheless longer follow-up and an increase in the number of cases treated are required for the full evaluation of the technique.

Comparison of different registration methods for surgical navigation in cranio-maxillofacial surgery

BACKGROUND

Surgical navigation requires registration of the pre-operative image dataset with the patient in the operation theatre. Various marker and marker-free registration techniques are available, each bearing an individual level of precision and clinical practicability. In this study the precision of four different registration methods in a maxillofacial surgical setting is analyzed.

MATERIALS AND METHODS

A synthetic full size human skull model was registered with its computer tomography-dataset using (a) a dentally mounted occlusal splint, (b) the laser surface scanning, (c) five facial bone implants and (d) a combination of dental splint and two orbital bone implants. The target registration error was computed for 170 landmarks spread over the entire viscero- and neurocranium in 10 repeats using the VectorVision2 (BrainLAB AG, Heimstetten, Germany) navigation system. Statistical and graphical analyses were performed by anatomical region.

RESULTS

An average precision of 1mm was found for the periorbital region irrespective of registration method (range 0.6-1.1mm). Beyond the mid-face, precision linearly decreases with the distance from the reference markers. The combination of splint with two orbital bone markers significantly improved precision from 1.3 to 0.8mm (p<0.001) on the viscerocranium and 2.3-1.2mm (p<0.001) on the neurocranium.

CONCLUSIONS

An occlusal splint alone yields poor precision for navigation beyond the mid-face. The precision can be increased by combining an occlusal splint with just two bone implants inserted percutaneously on the lateral orbital rim of each side.