Marcin Kozakiewicz

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.

Accuracy of three-dimensional, paper-based models generated using a low-cost, three-dimensional printer

Our study aimed to determine the accuracy of a low-cost, paper-based 3D printer by comparing a dry human mandible to its corresponding three-dimensional (3D) model using a 3D measuring arm. One dry human mandible and its corresponding printed model were evaluated. The model was produced using DICOM data from cone beam computed tomography. The data were imported into Maxilim software, wherein automatic segmentation was performed, and the STL file was saved. These data were subsequently analysed, repaired, cut and prepared for printing with netfabb software. These prepared data were used to create a paper-based model of a mandible with an MCor Matrix 300 printer. Seventy-six anatomical landmarks were chosen and measured 20 times on the mandible and the model using a MicroScribe G2X 3D measuring arm. The distances between all the selected landmarks were measured and compared. Only landmarks with a point inaccuracy less than 30% were used in further analyses. The mean absolute difference for the selected 2016 measurements was 0.36 ± 0.29 mm. The mean relative difference was 1.87 ± 3.14%; however, the measurement length significantly influenced the relative difference. The accuracy of the 3D model printed using the paper-based, low-cost 3D Matrix 300 printer was acceptable. The average error was no greater than that measured with other types of 3D printers. The mean relative difference should not be considered the best way to compare studies. The point inaccuracy methodology proposed in this study may be helpful in future studies concerned with evaluating the accuracy of 3D rapid prototyping models.

Comparison of pre-bent titanium mesh versus polyethylene implants in patient specific orbital reconstructions

IntroductionComputerized tomography DICOM file can be relatively easily transformed to a virtual 3D model. With the help of additional software we are able to create the mirrored model of an undamaged orbit and on this basis produce an individual implant for the patient Authors decided to apply implants with any thickness, which are authors own invention to obtain volumetric support and more stable orbital wall reconstruction outcome. Material of choice was ultra-high molecular weight polyethylene (UHMWPE).ObjectiveThe aim of this study was to present and compare functional results of individual reconstructions of orbital wall using either titanium mesh or ultra-high molecular weight polyethylene.Materials and methods57 consecutive patients affected by orbital wall fracture (46 males, 11 females, mean age 34±14 year) were treated in Department of Maxillofacial Surgery from 2010 to 2012. In the first group we used patient specific treatment by titanium mesh shaped on a 3D printed model of a mirrored intact orbit (37 orbits) or by individually manufactured UHMW-PE implantby CAM milling in second group (20 orbits). All of these patients were subjected to preoperative helical computerized tomography and consultation of an ophthalmologist (including binocular single vision loss test - BSVL). Further on, patients were operated under general anaesthesia using transconjuctival approach. BSVL was again evaluated post-operationally in 1 month and 6 months later.ResultsFunctional treatment results (BSVL) for both groups were similar in 1 month as well as 6 months post operational time. There was no statistically significant difference between these two groups.ConclusionsThis study of 6 months functional result assessment of pre-bent individual implants and CNC milled ultra-high molecular weight polyethylene of the orbital wall has shown it to be a predictable reconstruction method. Individually shaped UHMWPE seems to be as good as pre-bent titanium mesh.

Management of persistent diplopia after surgical repair of orbital fractures

PURPOSE To present the results of management of patients with persistent diplopia after orbital reconstructive surgery with respect to the type of ocular motility impairment pattern. METHODS All patients referred during a 2-year period because of persistent diplopia after surgical repair of orbital fracture were categorized according to the degree and pattern of ocular motility impairment on the basis of orthoptic examination 3-4 weeks postoperatively. Patients were followed for a mean period of 10.5 months (range, 6-12 months), during which adequate treatment was implemented. RESULTS A total of 52 patients were included in the study (45 males; mean age, 41.8 ± 16.6 years). Most could be divided into 1 of 4 groups according to the type of ocular motility impairment. The follow-up orthoptic examination revealed resolution of diplopia in 9 patients (15%) and persistent but unbothersome diplopia in 26 (43.4%). Significant diplopia was treated conservatively in 3 patients (5%) and with strabismus surgery in 14 (23.3%) cases. CONCLUSIONS The results of this study indicate that in most cases of persistent diplopia after reconstructive surgery for orbital fractures, symptoms resolve over time without treatment; nevertheless, strabismus surgery is unavoidable in some cases.

Computer-aided orbital wall defects treatment by individual design ultrahigh molecular weight polyethylene implants

UNLABELLED Despite of well-known advantages of high molecular weight polyethylene (Medpor, Synpore) in orbital reconstructions, the thickness of those implants significantly exceeds 0.5 mm and precise modification of thickness is limited. The aim of this study was to present the application of a self-developed method of treatment orbital wall fracture by custom implant made of ultrahigh molecular weight polyethylene (UHMW-PE). MATERIAL AND METHOD First, the test of influence of sterilization process upon implant deformation was performed (autoclaving, ethylene oxide, gas plasma, irradiation). Next, ten cases for delayed surgical treatment of orbital fracture were included into this study (7 males, 3 females). Based on CT scan and mirrored technique, a CAD model of virtual implant for repairing orbital wall was made. Then, an implant was manufactured with a computer numerical controlled milling machine from UHMW-PE block, sterilized and used during a surgical procedure. Clinically used implants had thickness from 0.2 to 4.0 mm. RESULTS The best method of sterilization is ethylene oxide process, and the worst is autoclaving. In this series of delayed surgical cases, functional results of orbital surgery are worse than in simpler, early treated cases, but long-term subsidence of diplopia is noticeable [10% poor results]. The results of the treatment depend on the initial level of diplopia where severe initial diplopia to be corrected requires thicker implants (p < 0.01). It also leads to longer surgical procedures (p < 0.01), but prolongation of the surgery had no negative influence upon results of any investigated follow-up examinations. Obviously, the orbital destruction intensity is related to injury-evoked initial diplopia but it also influences whole results of treatment up to 12 months post-op. Interesting result is presented by the relation of maximal implant thickness to 12-month diplopia evaluation. Thicker implants used result in lower residual diplopia (p < 0.05). This is important because of the correlation between the higher orbital destruction intensity with a thicker UHMW-PE implant (p < 0.05) applied in this series. CONCLUSION Patient-specific ultrahigh molecular weight polyethylene implants enable precise reconstructions of orbital wall. One should not be afraid of a significant eye globe reposition caused by these thickness modulated implants, as such repositioning is essential for an efficient correction of enophthalmos.

Treatment strategy in Goldenhar syndrome.

AbstractGoldenhar syndrome is a rare congenital defect characterized by ocular symptoms including (epibulbar dermoids, microphthalmia, anophthalmia, eyes asymmetry/dysmorphy, cleft eyelid, exophthalmia, strabismus), auricular symptoms (dacryocystitis), preauricular appendages, preauricular fistulas, ear asymmetry, microtia, atresia of the external auditory canal), craniofacial deformities (cleft face, cleft lip, cleft palate, macrostomia, bifid tongue, hypoplasia of the mandible, hypoplasia of the maxilla, asymmetry of the mandible and maxilla, malocclusion, tooth discrepancies, agenesis of third molars and second premolars, supernumerary teeth, enamel and dentin malformations, delay in tooth development), and skeletal abnormalities (cleft spine, microcephaly, dolichocephaly, plagiocephaly, vertebral defects) or abnormalities of internal organs. The degree of abnormalities vary from severe to mild. In this article, we present a long-term observation of a patient with Goldenhar syndrome. During the patient’s life, the intensification of anomalies varied. We describe preoperative and postoperative orthodontic treatment and surgical correction procedures of maxillofacial deformation.

Efficacy assessment of the drainage with permanent airflow measurement in the treatment of pneumothorax with air leak.

AIM The aim of this study was to compare the efficacy of the treatment of patients with spontaneous pneumothorax with air leak (AL) using two different chest drainage systems. METHODS Patients were randomized into two groups: group A included 30 patients (23 males and 7 females, mean age 41.1 ± 16.29 y, range 17-71 y) in which digital drainage system was used, group B with 30 patients (22 males and 8 females, mean age 40.3 ± 15.74 y, range 18-72 y) in which traditional suction drainage system was applied.The following variables were evaluated: intensity of AL, duration of the chest tube drainage, delay in surgery, length of stay, and the overall hospitalization costs. RESULTS In group A the mean drainage duration was 47.63 hours, the hospitalization time was about 5.10 days, and the cost of hospitalization was €1,495. In group B the mean drainage duration was 84.93 hours, the hospitalization time was 6.97 days, and the hospitalization cost was €1,925. CONCLUSION The digital drainage system applied in the treatment of AL in patients with pneumothoraces reduced the duration of the drainage, the length of hospital stay, and overall hospitalization costs.

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.