Increasing the accuracy of orbital reconstruction with selective laser-melted patient-specific implants combined with intraoperative navigation

Patient-specific implants for maxillofacial defects: challenges and solutions

Background

Reconstructing maxillofacial defects is quite challenging for most surgeons due to the region’s complex anatomy and cosmetic and functional effects on patients. The use of pre-made alloplastic implants and autogenous grafts is often associated with resorption, infection, and displacement. Recent technological advances have led to the use of custom computer-designed patient-specific implants (PSIs) in reconstructive surgery. This study describes our experience with PSI, details the complications we faced, how to overcome them, and finally, evaluates patient satisfaction.

Case presentation

Six patients underwent reconstruction of various maxillofacial defects arising due to different etiologies using PSI. A combined total of 10 implants was used. PEEK was used to fabricate 8, while titanium was used to fabricate 2. No complications were seen in any patient both immediately post-op and in subsequent follow-ups. All patients reported a high level of satisfaction with the final result both functionally and cosmetically.

Conclusion

The use of computer-designed PSI enables a more accurate reconstruction of maxillofacial defects, eliminating the usual complications seen in preformed implants and resulting in higher patient satisfaction. Its main drawback is its high cost.

Design, Modeling, Additive Manufacturing, and Polishing of Stiffness-Modulated Porous Nitinol Bone Fixation Plates Followed by Thermomechanical and Composition Analysis

The use of titanium bone fixation plates is considered the standard of care for skeletal reconstructive surgery. Highly stiff titanium bone fixation plates provide immobilization immediately after the surgery. However, after the bone healing stage, they may cause stress shielding and lead to bone resorption and failure of the surgery. Stiffness-modulated or stiffness-matched Nitinol bone fixation plates that are fabricated via additive manufacturing (AM) have been recently introduced by our group as a long-lasting solution for minimizing the stress shielding and the follow-on bone resorption. Up to this point, we have modeled the performance of Nitinol bone fixation plates in mandibular reconstruction surgery and investigated the possibility of fabricating these implants. In this study, for the first time the realistic design of stiffness-modulated Nitinol bone fixation plates is presented. Plates with different levels of stiffness were fabricated, mechanically tested, and used for verifying the design approach. Followed by the design verification, to achieve superelastic bone fixation plates we proposed the use of Ni-rich Nitinol powder for the AM process and updated the models based on that. Superelastic Nitinol bone fixation plates with the extreme level of porosity were fabricated, and a chemical polishing procedure used to remove the un-melted powder was developed using SEM analysis. Thermomechanical evaluation of the polished bone fixation plates verified the desired superelasticity based on finite element (FE) simulations, and the chemical analysis showed good agreement with the ASTM standard.

Implant-oriented navigation in orbital reconstruction part II: preclinical cadaver study

In orbital reconstruction, the acquired position of an orbital implant can be evaluated with the aid of intraoperative navigation. Feedback of the navigation system is only obtained after positioning of the implant: the implant's position is not tracked in real time during positioning. The surgeon has to interpret the navigation feedback and translate it to desired adjustments of the implant's position. In a previous study, a real-time implant-oriented navigation approach was introduced and the system's accuracy was evaluated. In this study, this real-time navigation approach was compared to a marker-based navigation approach in a preclinical set-up. Ten cadavers (20 orbital defects) were reconstructed twice, by two surgeons (total: 80 reconstructions). Implant positioning was significantly improved in the real-time implant-oriented approach in terms of roll (2.0° vs. 3.2°, P=0.03), yaw (2.2° vs. 3.4°, P=0.01) and translation (1.3mm vs. 1.8mm, P=0.005). Duration of the real-time navigation procedure was reduced (median 4.5 min vs. 7.5 min). Subjective appreciation of the navigation technique was higher for real-time implant-oriented navigation (mean 7.5 vs. 9.0). Real-time implant-oriented navigation feedback provides real-time, intuitive feedback to the surgeon, which leads to improved implant positioning and shortens duration of the navigation procedure.

Orbital floor symmetry after maxillectomy and orbital floor reconstruction with individual titanium mesh using computer-assisted navigation

PURPOSE

The present study aimed to evaluate the symmetry of the orbital floor after maxillectomy and orbital floor reconstruction with individual titanium mesh using a computer-assisted navigation system.

PATIENTS AND METHODS

Nineteen patients who underwent orbital floor reconstruction with individual titanium mesh were included in this study. Postoperative computed tomography scans recorded after three-dimensional (3D) reconstruction were used to evaluate the symmetry of the orbital floor, including orbital floor height, orbital floor eminence, globe projection, orbital volume, and surface deviation.

RESULTS

The average orbital floor height of the reconstructed and the unaffected side was 37.7 ± 2.3 and 37.8 ± 2.7 mm, respectively (P = .47). The average orbital floor eminence of the reconstructed and the unaffected side was 40.1 ± 5.5 and 39.6 ± 5.3 mm, respectively (P = .17). The average globe projection of the reconstructed and the unaffected side was 15.5 ± 3.2 and 15.3 ± 3.0 mm, respectively (P = .27). The average orbital volume of the reconstructed and the unaffected side was 25.9 ± 4.4 and 26.3 ± 4.4 cm³, respectively (P = .29). Repeatability between the reconstructed and the unaffected side was 88.3% ± 2.6% at within 1 mm and 98.6% ± 0.9% at within 2 mm. The average of maximum deviation was 2.4 ± 0.2 mm.

CONCLUSION

Individual titanium mesh is one of the best techniques for orbital floor reconstruction, as it can be placed precisely and helps achieve desirable esthetic outcomes through virtual surgical planning and using a computer-assisted navigation system.

Applications of three-dimensional printing in orbital diseases and disorders

PURPOSE OF REVIEW

To comprehensively review the applications of advanced three-dimensional printing technology in the management of orbital abnormalities.

RECENT FINDINGS

Three-dimensional printing has added value in the preoperative planning and manufacturing of patient-specific implants and surgical guides in the reconstruction of orbital trauma, congenital defects and tumor resection. In view of the costs and time, it is reserved as strategy for large and complex craniofacial cases, in particular those including the bony contour. There is anecdotal evidence of a benefit of three-dimensional printing in the manufacturing of prostheses for the exenterated and anophthalmic socket, and in the fabrication of patient-specific boluses, applicators and shielding devices for orbital radiation therapy. In addition, three-dimensional printed healthy and diseased orbits as phantom tangible models may augment the teaching and learning process of orbital surgery.

SUMMARY

Three-dimensional printing allows precision treatment tailored to the unique orbital anatomy of the patient. Advancement in technology and further research are required to support its wider use in orbital clinical practice.

Current Strategies in Post-traumatic Orbital Reconstruction

Posttraumatic orbital reconstruction is one of the most fascinating fields in reconstructive craniomaxillofacial surgery. Hardly any other field in craniomaxillofacial surgery has changed so much in terms of diagnostics, biomaterial selection for reconstruction, surgical techniques including approaches and quality control. In particular, in the field of reconstructive orbital surgery all advances in modern medical treatment are summarized and represented. Reconstructive orbital surgery thus became the medical field spearheading all reconstructive surgical specialties in terms of use of DICOM-data, computer assistance, change towards patient-specific solutions and establishing digital workflows for adequate quality control during all phases of treatment, i.e. pre-, intra- and postoperative. With this paper, this evolutionary process shall be demonstrated as well as display the spirit of change that was necessary to optimize reconstructive orbital surgery and to improve medical care in all areas of reconstruction. Finally, reconstructive orbital surgery could prove to be a highly foreseeable field nowadays, thus giving the next generation of CMF-surgeons a huge opportunity to drive this topic further into the future.

Navigation-Assisted Orbital Trauma Reconstruction Using a Bioactive Osteoconductive/Bioresorbable u-HA/PLLA System

Orbital fractures with orbital wall defects are common facial fractures encountered by oral-maxillofacial surgeons, because of the exposed position and thin bony walls of the midface. The primary goal of surgery is to restore the pre-injury anatomy and volume of hard tissue, and to free incarcerated or prolapsed orbital tissue from the fracture by bridging the bony defects with reconstructive implant material and restoring the maxillofacial-orbital skeleton. Numerous studies have reported orbital fracture repair with a wide variety of implant materials that offer various advantages and disadvantages. The ideal orbital implant material will allow conformation to individual patients' anatomical characteristics, remain stable over time, and are radiopaque, especially for the reconstruction of relatively large and/or complex bony walls. Based on these requirements, novel uncalcined and unsintered hydroxyapatite (u-HA) particles and poly-L-lactide (PLLA; u-HA/PLLA) composite sheets could be used as innovative, bioactive, and osteoconductive/bioresorbable implant materials for orbital reconstruction. In addition, intraoperative navigation is a powerful tool. Navigation- and computer-assisted surgeries have improved execution and predictability, allowing for greater precision, accuracy, and minimal invasiveness during orbital trauma reconstructive surgery of relatively complex and large orbital wall defects with ophthalmological malfunctions and deformities. This review presents an overview of navigation-assisted orbital trauma reconstruction using a bioactive, osteoconductive/bioresorbable u-HA/PLLA system.

[Frequency and management of complex facial fractures-an oral and maxillofacial surgical assessment]

INTRODUCTION

The treatment of facial fractures is an integral part of the oral and maxillofacial surgical treatment spectrum. In the case of complex fractures that involve multiple levels of the facial skeleton associated with severe concomitant injuries, an individual and interdisciplinary treatment approach is needed, which requires the infrastructure of a national trauma center.

OBJECTIVE

The aim of this study was to analyze the incidence and management of patients with complex facial fractures and considering the concomitant injury pattern.

MATERIAL AND METHODS

A retrospective analysis of patients with complex facial fractures during the years 2009-2015 admitted to the emergency surgical department of a national trauma center was carried out. The identification of appropriate patient cases was based on the International Statistical Classification of Diseases and Related Health Problems (ICD) coding of electronic patient data. Only patients with at least a combination of mandibular and midfacial fractures (2-level fractures) were considered. Patients with mainly dentoalveolar fractures and simple nasal bone fractures were not included. The evaluation of the electronic medical records included the etiology, fracture pattern, associated severe injuries on the basis of the injury severity score (ISS), treatment regimen as well as the length of the hospital stay.

RESULTS

In the 7‑year study period, 3382 patients were identified with facial fractures. Of these, 128 patients (3.78%) presented with a complex fracture pattern with a combination of mandibular fractures and fractures of the midface. The majority of these patients (n = 92) had less severe concomitant injuries (ISS ≤ 16), while 36 patients showed severe concomitant injuries (ISS > 16). The incidence of a 3-level fracture involving the mandible, midface and anterior skull base was only 0.47% and could be detected in 16 patients, of which 10 were classified as polytrauma (ISS > 16).

CONCLUSION

The incidence of complex fractures of the facial skeleton was comparatively low with almost 4%. More than one in four patients with complex injury patterns of the facial skeleton exhibited severe concomitant life-threatening injuries, necessitating an interdisciplinary management with the specialized infrastructure of a nationwide trauma center.

A novel approach to skull-base and orbital osteotomies through virtual planning and navigation

OBJECTIVE

Computer-assisted planning of osteotomy lines, coupled with navigation-guided performance of planned osteotomies, is a highly innovative approach to skull-base and orbital surgery. The aim of this pilot study is to provide an assessment of the accuracy of this novel approach in guiding the correct positioning of osteotomy lines in frontal, temporal, and orbital regions, defining the agreement between the spatial position of the planned and performed osteotomies.

METHODS

Fifteen patients with orbital, frontal sinus, and lateral skull-base diseases underwent virtual surgical planning. Osteotomies to access the orbit, frontal sinus, and lateral skull base were planned on computer tomography-based three-dimensional models. The planned osteotomies were reproduced on the operating field using a navigation system. The positions of the performed and planned osteotomies were compared. The results were described as the mean positional difference between planned and performed osteotomies and as Lin's concordance coefficient, and Bland-Altman limits of agreement were also defined.

RESULTS

The overall mean difference was 0.719 mm (95% confidence interval [CI]: 0.472 to 0.965 mm). Overall, Lin's concordance coefficient was 0.997 (95% CI: 0.996 to 0.998), and overall Bland-Altman limits of agreement ranged from -1.407 to 2.844 mm. The smallest mean difference (0.587 mm, 95% CI: 0.244 to 0.931 mm) was calculated in the orbit group, whereas the highest mean difference (0.904 mm, 95% CI: 0.428 to 1.379 mm) was described in the lateral skull-base group.

CONCLUSION

This study's results support the use of this novel planning and navigation protocol for guiding osteotomy in anterior and lateral skull-base surgery, providing a clinical validation of this technique.

LEVEL OF EVIDENCE

4 Laryngoscope, 00:1-9, 2018 Laryngoscope, 129:823-831, 2019.

Correction of Delayed Traumatic Enophthalmos Using Customized Orbital Implants

PURPOSE

To determine the relation between overcorrection of orbital volume and ocular projection in patients with orbital trauma.

MATERIALS AND METHODS

A prospective cohort study was performed of patients with enophthalmos as a side effect of orbital trauma. The sample included patients older than 18 years who required reconstruction using customized implants to treat enophthalmos with or without diplopia. The exclusion criteria were patients who had multiple or extended fractures and patients with amaurosis or a prosthetic eye. Orbital volumes were calculated and the position of the eyeball in the healthy and traumatized sockets was determined before and after installing the implant and the ratio between these variables was calculated. Two variables were identified: 1) orbital volume and 2) enophthalmos. Analysis of the estimator variables was performed, defining 3 groups: 1) healthy eye socket, 2) traumatized eye socket without implant, and 3) traumatized eye socket with implant. The Shapiro-Wilk test, paired t test, and linear regression analysis were performed. A P value less than .05 (95% confidence interval) indicated significant differences.

RESULTS

Of 294 patients who underwent orbital zygomatic complex reconstruction surgery, 13 required customized implants and only 5 met the inclusion criteria. The average volumetric variation in the groups of traumatized eye sockets with and without implants was statistically significant (P < .05), overcorrecting by an average of 4.2 cm³. The average enophthalmos variation in the groups of traumatized eye sockets with and without implants was statistically significant (P < .05), projecting the eyeball by an average 1.80 mm. The ratio between the average orbital volume and projection of the eyeball was determined to be 1:0.721 (correlation, 45.6%).

CONCLUSION

This study concluded that the eyeball is projected 0.7 mm for every 1 cm³ of volume added in customized orbital implants. However, additional clinical studies with larger samples should be conducted.

Patient-Specific Surgical Implants Made of 3D Printed PEEK: Material, Technology, and Scope of Surgical Application

Additive manufacturing (AM) is rapidly gaining acceptance in the healthcare sector. Three-dimensional (3D) virtual surgical planning, fabrication of anatomical models, and patient-specific implants (PSI) are well-established processes in the surgical fields. Polyetheretherketone (PEEK) has been used, mainly in the reconstructive surgeries as a reliable alternative to other alloplastic materials for the fabrication of PSI. Recently, it has become possible to fabricate PEEK PSI with Fused Filament Fabrication (FFF) technology. 3D printing of PEEK using FFF allows construction of almost any complex design geometry, which cannot be manufactured using other technologies. In this study, we fabricated various PEEK PSI by FFF 3D printer in an effort to check the feasibility of manufacturing PEEK with 3D printing. Based on these preliminary results, PEEK can be successfully used as an appropriate biomaterial to reconstruct the surgical defects in a “biomimetic” design.

Is there more to the clinical outcome in posttraumatic reconstruction of the inferior and medial orbital walls than accuracy of implant placement and implant surface contouring? A prospective multicenter study to identify predictors of clinical outcome

PURPOSE

Reconstruction of orbital wall fractures is demanding and has improved dramatically with the implementation of new technologies. True-to-original accuracy of reconstruction has been deemed essential for good clinical outcome, and reasons for unfavorable clinical outcome have been researched extensively. However, no detailed analysis on the influence of plate position and surface contour on clinical outcome has yet been published.

MATERIALS AND METHODS

Data from a previous study were used for an ad-hoc analysis to identify predictors for unfavorable outcome, defined as diplopia or differences in globe height and/or globe projection of >2 mm. Presumed predictors were implant surface contour, aberrant implant dimension or position, accuracy of reconstructed orbital volume, and anatomical fracture topography according to the current AO classification.

RESULTS

Neither in univariable nor in multivariable regression models were unfavorable clinical outcomes associated with any of the presumed radiological predictors, and no association of the type of implant, i.e., standard preformed, CAD-based individualized and non-CAD-based individualized with its surface contour could be shown.

CONCLUSION

These data suggest that the influence of accurate mechanical reconstruction on clinical outcomes may be less predictable than previously believed, while the role of soft-tissue-related factors may have been underestimated.

Should Virtual Mirroring Be Used in the Preoperative Planning of an Orbital Reconstruction?

PURPOSE

Mirroring has been used as a diagnostic tool in orbital wall fractures for many years, but limited research is available proving the assumed symmetry of orbits. The purpose of this study was to evaluate volume and contour differences between orbital cavities in healthy humans.

MATERIALS AND METHODS

In this cross-sectional study, the left and right orbital cavities of a consecutive sample of patients' computed tomograms were measured. Inclusion criteria were patients with no sign of orbital or sinus pathology or fracture. Outcome variables were differences in volume and contour. Descriptive statistics and Student paired t test were used for data analysis of orbital volume and distance maps were used for analysis of orbital contour.

RESULTS

The sample was composed of 100 patients with a mean age of 57; 50% were men. The total mean orbital volume was 27.53 ± 3.11 mL. Mean difference between cavities was 0.44 ± 0.31 mL or 1.59% (standard deviation [SD], 1.10%). The orbital contour showed high similarity, with an absolute mean left-versus-right difference of 0.82 mm (SD, 0.23 mm).

CONCLUSION

The authors hypothesize that the measured differences between right and left orbital volumes and contours are clinically minor. In consequence, the use of mirroring tools as part of preoperative planning in orbital reconstruction is legitimate with the aim of simulating the pre-traumatized anatomy.

A customised digitally engineered solution for fixed dental rehabilitation in severe bone deficiency: A new innovative line extension in implant dentistry

OBJECTIVES

Numerous procedures including soft and hard tissue reconstructions are necessary to allow for final implant-borne dental rehabilitation in patients with severe alveolar atrophy or resected jaws. In these cases, customised digitally engineered patient solutions for fixed or removable dental rehabilitation provide an innovative line extension to conventional implant dentistry.

MATERIAL AND METHODS

A wax-up was performed on plaster models that were scanned by 3D laser. The generated stereolithographic files were then fused with the preoperative 3D imaging data. The individualised "dental" patient solutions were designed digitally and comprised a skeletonised anchorage system and a suprastructure connection system. Insertion of the implants was performed on an outpatient basis. Conventional implant-supported prosthodontic rehabilitation was performed.

RESULTS

This digital planning algorithm can be applied to manufacture individualised patient solutions. Similar to conventional implant-supported dentures, these implants can be equipped with individual suprastructure connection systems for internal conical connection, ball-retained attachment, and external conical (telescopic) connection.

CONCLUSIONS

In patients with severe atrophy or resected jaws, particularly following ablative tumour surgery, customised digitally engineered solutions allow for an innovative, less invasive line extension to conventional implant dentistry. When conventional implant dentistry reaches its limits, they still offer a strategy for implant-borne dental rehabilitation.

Surgical Navigation: A Systematic Review of Indications, Treatments, and Outcomes in Oral and Maxillofacial Surgery

PURPOSE

This systematic review investigates the most common indications, treatments, and outcomes of surgical navigation (SN) published from 2010 to 2015. The evolution of SN and its application in oral and maxillofacial surgery have rapidly developed over recent years, and therapeutic indications are discussed.

MATERIALS AND METHODS

A systematic search in relevant electronic databases, journals, and bibliographies of the included articles was carried out. Clinical studies with 5 or more patients published between 2010 and 2015 were included. Traumatology, orthognathic surgery, cancer and reconstruction surgery, skull-base surgery, and foreign body removal were the areas of interests.

RESULTS

The search generated 13 articles dealing with traumatology; 5, 6, 2, and 0 studies were found that dealt with the topics of orthognathic surgery, cancer and reconstruction surgery, skull-base surgery, and foreign body removal, respectively. The average technical system accuracy and intraoperative precision reported were less than 1 mm and 1 to 2 mm, respectively. In general, SN is reported to be a useful tool for surgical planning, execution, evaluation, and research. The largest numbers of studies and patients were identified in the field of traumatology. Treatment of complex orbital fractures was considerably improved by the use of SN compared with traditionally treated control groups.

CONCLUSIONS

SN seems to be a very promising addition to the surgical toolkit. Planning details of the surgical procedure in a 3-dimensional virtual environment and execution with real-time guidance can significantly improve precision. Among factors to be considered are the financial investments necessary and the learning curve.

Evolution of design considerations in complex craniofacial reconstruction using patient-specific implants

Previously published evidence has established major clinical benefits from using computer-aided design, computer-aided manufacturing, and additive manufacturing to produce patient-specific devices. These include cutting guides, drilling guides, positioning guides, and implants. However, custom devices produced using these methods are still not in routine use, particularly by the UK National Health Service. Oft-cited reasons for this slow uptake include the following: a higher up-front cost than conventionally fabricated devices, material-choice uncertainty, and a lack of long-term follow-up due to their relatively recent introduction. This article identifies a further gap in current knowledge – that of design rules, or key specification considerations for complex computer-aided design/computer-aided manufacturing/additive manufacturing devices. This research begins to address the gap by combining a detailed review of the literature with first-hand experience of interdisciplinary collaboration on five craniofacial patient case studies. In each patient case, bony lesions in the orbito-temporal region were segmented, excised, and reconstructed in the virtual environment. Three cases translated these digital plans into theatre via polymer surgical guides. Four cases utilised additive manufacturing to fabricate titanium implants. One implant was machined from polyether ether ketone. From the literature, articles with relevant abstracts were analysed to extract design considerations. In all, 19 frequently recurring design considerations were extracted from previous publications. Nine new design considerations were extracted from the case studies – on the basis of subjective clinical evaluation. These were synthesised to produce a design considerations framework to assist clinicians with prescribing and design engineers with modelling. Promising avenues for further research are proposed.

Patient-specific biodegradable implant in pediatric craniofacial surgery

Surgical correction of premature fusion of calvarial sutures involving the fronto-orbital region can be challenging due to the demanding three-dimensional (3D) anatomy. If fronto-orbital advancement (FOA) is necessary, surgery is typically performed using resorbable plates and screws that are bent manually intraoperatively. A new approach using individually manufactured resorbable implants (KLS Martin Group, Tuttlingen, Germany) is presented in the current paper. Preoperative CT scan data were processed in iPlan (ver. 3.0.5; Brainlab, Feldkirchen, Germany) to generate a 3D reconstruction. Virtual osteotomies and simulation of the ideal outer contour with reassembled bony segments were performed. Digital planning was transferred with a cutting guide, and an individually manufactured resorbable implant was used for rigid fixation. A resorbable patient-specific implant (Resorb X-PSI) allows precise surgery for FOA in craniosynostosis using a complete digital workflow and should be considered superior to manually bent resorbable plates.

3D-printing techniques in a medical setting: a systematic literature review

BACKGROUND

Three-dimensional (3D) printing has numerous applications and has gained much interest in the medical world. The constantly improving quality of 3D-printing applications has contributed to their increased use on patients. This paper summarizes the literature on surgical 3D-printing applications used on patients, with a focus on reported clinical and economic outcomes.

METHODS

Three major literature databases were screened for case series (more than three cases described in the same study) and trials of surgical applications of 3D printing in humans.

RESULTS

227 surgical papers were analyzed and summarized using an evidence table. The papers described the use of 3D printing for surgical guides, anatomical models, and custom implants. 3D printing is used in multiple surgical domains, such as orthopedics, maxillofacial surgery, cranial surgery, and spinal surgery. In general, the advantages of 3D-printed parts are said to include reduced surgical time, improved medical outcome, and decreased radiation exposure. The costs of printing and additional scans generally increase the overall cost of the procedure.

CONCLUSION

3D printing is well integrated in surgical practice and research. Applications vary from anatomical models mainly intended for surgical planning to surgical guides and implants. Our research suggests that there are several advantages to 3D-printed applications, but that further research is needed to determine whether the increased intervention costs can be balanced with the observable advantages of this new technology. There is a need for a formal cost-effectiveness analysis.

Quantitative Assessment of Orbital Implant Position--A Proof of Concept

Introduction

In orbital reconstruction, the optimal location of a predefined implant can be planned preoperatively. Surgical results can be assessed intraoperatively or postoperatively. A novel method for quantifying orbital implant position is introduced. The method measures predictability of implant placement: transformation parameters between planned and resulting implant position are quantified.

Methods

The method was tested on 3 human specimen heads. Computed Tomography scans were acquired at baseline with intact orbits (t0), after creation of the defect (t1) and postoperatively after reconstruction of the defect using a preformed implant (t2). Prior to reconstruction, the optimal implant position was planned on the t0 and t1 scans. Postoperatively, the planned and realized implant position were compared. The t0 and t2 scans were fused using iPlan software and the resulting implant was segmented in the fused t2 scan. An implant reference frame was created (Orbital Implant Positioning Frame); the planned implant was transformed to the reference position using an Iterative Closest Point approach. The segmentation of the resulting implant was also registered on the reference position, yielding rotational (pitch, yaw, roll) as well as translational parameters of implant position.

Results

Measurement with the Orbital Implant Positioning Frame proved feasible on all three specimen. The positional outcome provided more thorough and accurate insight in resulting implant position than could be gathered from distance measurements alone. Observer-related errors were abolished from the process, since the method is largely automatic.

Conclusion

A novel method of quantifying surgical outcome in orbital reconstructive surgery was presented. The presented Orbital Implant Positioning Frame assessed all parameters involved in implant displacement. The method proved to be viable on three human specimen heads. Clinically, the method could provide direct feedback intraoperatively and could improve postoperative evaluation of orbital reconstructive surgery.

Management of orbital fractures: challenges and solutions

Many specialists encounter and treat orbital fractures. The management of these fractures is often challenging due to the impact that they can have on vision. Acute treatment involves a thorough clinical examination and management of concomitant ocular injuries. The clinical and radiographic findings for each individual patient must then be analyzed for the need for surgical intervention. Deformity and vision impairment can occur from these injuries, and while surgery is intended to prevent these problems, it can also create them. Therefore, surgical approach and implant selection should be carefully considered. Accurate anatomic reconstruction requires complete assessment of fracture margins and proper implant contouring and positioning. The implementation of new technologies for implant shaping and intraoperative assessment of reconstruction will hopefully lead to improved patient outcomes.

Titanium-Based Hip Stems with Drug Delivery Functionality through Additive Manufacturing

Postoperative infections are a major concern in patients that receive implants. These infections generally occur in areas with poor blood flow and pathogens do not always respond to antibiotic treatment. With the latest developments in nanotechnology, the incorporation of antibiotics into prosthetic implants may soon become a standard procedure. The success will, however, depend on the ability to control the release of antibiotics at concentrations high enough to prevent the development of antibiotic-resistant strains. Through additive manufacturing, antibiotics can be incorporated into cementless femoral stems to produce prosthetic devices with antimicrobial properties. With the emerging increase in resistance to antibiotics, the incorporation of antimicrobial compounds other than antibiotics, preferably drugs with a broader spectrum of antimicrobial activity, will have to be explored. This review highlights the microorganisms associated with total hip arthroplasty (THA), discusses the advantages and disadvantages of the latest materials used in hip implants, compares different antimicrobial agents that could be incorporated, and addresses novel ideas for future research.