Marcin Elgalal

Clinical application of 3D pre-bent titanium implants for orbital floor fractures

INTRODUCTION Orbital structures are affected in approximately 40% of all cases of craniofacial trauma. Changes in the bony orbital dimensions can alter the function of intraorbital contents and lead to serious complications. The unique anatomy of the orbit and the resulting surgical approaches make the process of fitting and aligning implants difficult, time consuming and operator dependent. It is now possible to make relatively inexpensive anatomical models on the basis of computed tomography images, using rapid prototyping. Such models can be used as templates to form titanium mesh implants, which are then used in the reconstruction of orbital floor defects. MATERIAL AND METHODS Six patients with facial trauma were included in this study. First, 3D virtual models and then physical models were created. These were used as templates to shape the titanium mesh and then intraoperatively as guides to aid correct implant placement in the orbit. RESULTS Significant improvement resulted in three cases and total recovery in three cases. CONCLUSION It is financially viable to build anatomical models, on the basis of CT studies, that can be used in the repair of orbital floor fractures.

Technical concept of patient-specific, ultrahigh molecular weight polyethylene orbital wall implant

INTRODUCTION The authors have been using patient-specific implants since 2006 and are constantly looking for new reconstructive materials, in order to create precise implants for orbital reconstruction. Such materials should be biocompatible and stable in the human body, as well as easy to machine and form into complex 3D shapes. Biocompatible ultrahigh molecular weight polyethylene (UHMW-PE) has several unique properties including high impact strength and a low friction coefficient that result in self-lubricating and thus non-sticking surfaces after processing. AIM To present the concept of a patient-specific, UHMW-PE orbital wall implant. MATERIALS AND METHODS The material used to manufacture the orbital implant was UHMW-PE converted into a solid block of medical polymer from a powder material. A delayed treatment unilateral orbital fracture case was chosen for reconstruction with patient-specific orbital wall implant. On the basis of computerized tomography, a virtual model of both orbits was prepared. The injured orbit was significantly enlarged due to dislocation of its walls. The 3D model of the facial skeleton was symmetrically divided into two parts. This resulted in two models - left and right orbit, then the uninjured orbit was superimposed onto the contralateral side. As a result two surfaces were created; the outer surface (taken from the injured orbit) was used to design the outer surface of the implant, and the inner (taken from the uninjured orbit) for the inner surface. By combining both these surfaces it was possible to determine the unique shape and thickness of the UHMW-PE implant that would allow for accurate reconstruction of the orbit. Following this, the CAD model was transferred to CAM software and a numerical code for a 5-axis milling machine was generated. The manufactured implant was sterilized in gas plasma and used to reconstruct three orbital walls. RESULTS The thickness of the manufactured implant ranged from 0.2 mm to 1.5 mm and was successfully inserted via transconjunctival approach. The lower, medial and lateral walls were reconstructed. The correct position of the right eyeball was re-established by moving it upward and medially, which resulted in enophthalmos and diplopia correction. The described method features several advantages: accurate reconstruction of the original shape of the orbit, precise modification of local implant thickness during design of the CAD model, structural globe support combined with a thin implant, the possibility of repairing large orbital floor defects, corrections using scissor/scalpel during surgery are relatively uncomplicated, low level of morbidity, smooth edges and gradual, controlled variations in implant thickness between different regions. Disadvantages: changes to the curvature of the implant cannot be made during surgery, implant may require fixing with screws to be stabilized during the early phase of healing, long time required to design and manufacture implants (pre-op) and also UHMW-PE implants are radiolucent and cannot be imaged using X-rays. CONCLUSION UHMW-PE appears to have numerous advantages as a material for precise reconstruction of the orbits. Such patient-specific implants are durable, can even be used to reconstruct very thin walls, do not exhibit the high degree of morbidity typical for autogenous bone grafts and result in restoration of vision function.

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.

The use of modern imaging techniques in the diagnosis and treatment planning of patients with orbital floor fractures

Summary Background Ocular motility impairment associated with orbital trauma may have several causes and manifest with various clinical symptoms. In some cases orbital reconstructive surgery can be very challenging and the results are often unsatisfactory. The use of modern imaging techniques aids proper diagnosis and surgical planning. Case Report The authors present the case of a 29-year-old male who sustained trauma to the left orbit. Orthoptic examination revealed limited supra- and infraduction of the left eye. The patient reported diplopia in upgaze and downgaze with primary position spared. Dynamic magnetic resonance imaging (dMRI) was performed, which revealed restriction of the left inferior rectus muscle in its central section. A patient-specific anatomical model was prepared on the basis of 3-dimensional computed tomography (CT) study of the intact orbit, which was used to prepare a custom pre-bent titanium mesh implant. The patient underwent reconstructive surgery of the orbital floor. Conclusions Modern imaging techniques such as dMRI and 3-dimensional CT reconstruction allow us to better understand the pathophysiology of orbital floor fractures and to precisely plan surgical treatment.

A Large Posttraumatic Subclavian Artery Aneurysm Complicated by Artery Occlusion and Arteriobronchial Fistula Successfully Treated Using a Covered Stent

The treatment of posttraumatic aneurysms of peripheral arteries using covered stents is increasingly commonplace. We present the case of a 10-year-old girl with a pseudoaneurysm of the subclavian artery complicated by an arteriobronchial fistula with hemorrhaging into the bronchial tree and distal subclavian artery occlusion. Despite the lack of artery patency, endovascular stent graft implantation was successful. Pseudoaneurysm exclusion and involution was achieved, together with a patent implant and maintained collateral circulation patency.

Pancreatitis-Related Abdominal Aortic Pseudoaneurysms Treated With Stent-Grafts

Endovascular treatment of pseudoaneurysms that develop as a complication of pancreatitis is increasingly more common. A case of a pseudoaneurysm of the abdominal aorta initially treated by implantation of a straight aortic stent-graft is presented. In the 4 months after the procedure, chronic inflammation of the retroperitoneal space caused a further perforation on the posterior wall of the aorta in the area of the bifurcation, distal to the graft. Implantation of a bifurcated stent-graft was subsequently performed. The aneurysm was excluded, with the implant and peripheral arteries remaining patent.

In vitro and in vivo imaging of ultra-high-molecular-weight polyethylene orbital implants.

The aim of this study is to compare magnetic resonance imaging (MRI) with computed tomography (CT) for visualization of an orbital alloplastic prosthesis made of ultra-high-molecular-weight polyethylene (UHMW-PE) both in vitro and in vivo. A study of 15 test implants from UHMW-PE visualized in vitro in CT and MRI and an in vivo visualization in a patient who suffered from orbital injury and underwent reconstructive surgery is presented. The postsurgery MRI showed the UHMW-PE material clearly, with no significant artifacts. The surrounding tissues could be satisfactorily evaluated. The CT scans did not present the graft material. Both techniques were sufficient tools for in vitro evaluation of the shape and measurement of the prosthesis.

Posterior Wall Capture and Femoral Artery Stenosis Following Use of StarClose Closing Device: Diagnosis and Therapy

A case of femoral artery obstruction following application of a StarClose type arterial puncture closing device (APCD) is presented. Ultrasonographic and angiographic imaging of this complication was obtained. The posterior wall of the vessel was accidentally caught in the anchoring element of the nitinol clip. This complication was successfully resolved by endovascular treatment and the implantation of a stent.

Simultaneous transcriptome and proteome analysis of EA.hy926 cells under stress conditions induced by nanomaterials: TRANSCRIPTOME AND PROTEOME ALTERATIONS

Today, the extensive and constantly growing number of applications in the field of nanotechnology poses a lot of questions about the potential toxicity of nanomaterials (NMs) toward cells of different origins. In our work we employed the tools of molecular biology to evaluate changes that occur in human endothelial cells at the transcriptomic and proteomic level, following 24 h of exposure to three different classes of NMs. Using microarray technology, we demonstrated that 24 h of exposure to silver nanoparticles (SNPs), multiwalled carbon nanotubes (MWCNTs) and polyamidoamine dendrimers (PAMAMs) leads to changes in 299, 1271, and 431 genes, respectively, influencing specific molecular pathways. The 2D-DIGE and mass spectrometry analysis revealed that differentially expressed proteins were involved in numerous cellular processes, for example, cytoskeletal reorganization, cell growth and proliferation, or response to stress. Both, transcriptome and proteome alterations indicate reorganization of mechanism regulating cell functioning.

On accuracy of personalized 3D-printed MRI-based models of brain arteries

Possibilities of constructing an anatomically correct and accurate geometric model of brain blood vessels basing on clinical 1.5T magnetic resonance images are explored. A high-resolution ToF MR image (0.49 mm3 voxel) was used to build a reference geometric model of selected real-brain arteries. This model was STL-described and 3D printed using a photopolymer material. The printed phantom was submerged in water and scanned using a low-resolution clinical MR system (0.33×0.33×2.2 mm). Level-set segmentation of the obtained T2 images showed significant staircase effect. After T2 image resampling to 0.33mm3 voxel size, the model walls become smoother, but thin branches were still missing. A Frangi filtering-based, smooth centerline-radius vessel branches description was then developed to achieve their correct reconstruction with subvoxel accuracy. Challenges of MRI acquisition of 3D printed models are discussed.