Custom-made Implants Research Articles

A single centre's experience of managing spheno-orbital meningiomas: lessons for recurrent tumour surgery.

Spheno-orbital meningiomas are complex tumours involving the sphenoid wing and orbit. Various surgical strategies are available but treatment remains challenging and patients often require more than one surgical procedure. This study evaluated whether smaller surgical approaches and newer reconstructive methods impacted the surgical and clinical outcomes of patients undergoing repeat surgery. We retrospectively analysed the medical records of consecutive patients who underwent surgery for a spheno-orbital meningioma at a single tertiary centre between 2005 and 2016. We recorded procedural details and analysed complications, postoperative visual status and patient-reported cosmetic outcome. Thirty-four procedures were performed in 31 patients (M:F 12:22, median age 49years) including 19 (56%) primary operations and 15 (44%) repeat procedures. Seven patients (20.5%) had a pterional craniotomy, 19 (56%) had a standard orbitozygomatic craniotomy and 8 (23.5%) underwent a modified mini-orbitozygomatic craniotomy. Calvarial reconstruction was required in 19 cases with a variety of techniques used including titanium mesh (63%), PEEK (26%) and split calvarial bone graft (5%). Total tumour resection (Simpson grade I-II) was significantly higher in patients undergoing primary surgery compared with those having repeat surgery (41% and 0%, respectively; p = 0.0036). Complications occurred in 14 cases (41%). Proptosis improved in all patients and visual acuity improved or remained stable in 93% of patients. Cosmetic outcome measures were obtained for 18 patients (1 = very poor; 5 = excellent): 1-2, 0%; 3, 33%; 4, 28%; 5, 39%. Tumour recurrence requiring further surgery occurred in four patients (12%). There was no significant difference in clinical outcomes between patients undergoing primary or repeat surgery. Spheno-orbital meningiomas are highly complex tumours. Surgical approaches should be tailored to the patient but good clinical and cosmetic outcomes may be achieved with a smaller craniotomy and custom-made implants, irrespective of whether the operation is the patient's first procedure.

ПЛАСТИКА ГОЛЕНЕЙ ИМПЛАНТАТАМИ: ПОВТОРНЫЕ ОПЕРАЦИИ

Calf augmentation is a quite popular surgery in Russia. However, there is insufficient data on complications after the implants’ installation, its analysis is missing, and methods for correction and prevention of complications are not developed. The author has the experience of 53 re-surgeries after calf plasty with implants. The incorrect selection of implants was the cause of correction in 36 patients, the surgeon’s errors in their installation — in 7, the implant displacement — in 4, and its contouring — in 6 women. The analysis of each group of complications was performed. The author considers the installation of implants under the medial head of the gastrocnemius muscle as the method of choice for secondary surgery, which prevents implant displacement and isolates it from the previously formed cavity. The result of the correction directly depends on the proper selection of implants. The author recommends using his own method of implant selection, considering the length of the gastrocnemius muscle and the harmony of the leg contour. Sufficient knowledge of the anatomy of the lower leg is necessary to eliminate technical errors. Implant visualization after calf augmentation for aesthetic reasons was observed in 26 out of 561 cases, and in 3 of those cases an implant replacement surgery was required. To a large extent, contouring of the implant is observed due to its design. The advantage of custom-made implants of improved shape is shown.

Strength⁻Durability Correlation of Osteosynthesis Devices Made by 3D Layer Manufacturing.

To develop orthopedic implants that are optimized for each patient’s needs or skeletal structure (custom-made implants), evaluations of the bending strength, bending stiffness, and durability of various types of conventional osteosynthesis devices have become important. Four-point bending tests and compression bending tests of osteosynthesis devices (bone plates, intramedullary nail rods, spinal rods, compression hip screws (CHSs), short femoral nails, and metaphyseal plates) were carried out to measure their bending stiffness, bending strength, and durability. The bending stiffness of bone plates, intramedullary nails, spinal rods, CHSs, short femoral nails, and metaphyseal plates increased with increasing bending strength. The durability limit of various types of osteosynthesis devices linearly increased with increasing bending strength. The relationship (durability limit at 106 cycles) = 0.67 × (bending strength) (N·m) (R2 = 0.85) was obtained by regression. The relationship for the highly biocompatible Ti-15Zr-4Nb-4Ta alloy was also linear. The mechanical strength and ductility of specimens that were cut from various osteosynthesis devices were excellent and their microstructures consisted of fine structures, which were considered to be related to the excellent durability. These results are expected to be useful for the development of implants suitable for the skeletal structure of patients using three-dimensional (3D) layer manufacturing technologies.

New comprehensive procedure for custom-made total ankle replacements: Medical imaging, joint modeling, prosthesis design, and 3D printing.

Many failures in total joint replacement are associated to prosthesis-to-bone mismatch. With recent additive-manufacturing, that is, 3D-printing, custom-made prosthesis can be created by laser-melting metal powders layer-by-layer. Ankle replacement is particularly suitable for this progress because of the limited number of sizes and the poor bone stock. In this study a novel procedure is presented for subject-specific ankle replacements, including medical-imaging, joint modelling, prosthesis design, and 3D-printing. Three shank-foot specimens were CT-scanned, and corresponding 3D bone models of the tibia, fibula, talus, and calcaneus were obtained. From these models, specimen-specific implant sets were designed according to three different concepts, and 3D-printed from cobalt-chromium-molybdenum powder. Accuracy of the overall procedure was assessed via distance map comparisons between original anatomical and final metal implants. Restoration of natural ankle joint mechanics was check after implantation of each of the three sets. In a special rig, a manually-driven dorsi/plantar-flexion was applied throughout the passive arc. Additionally, at three different joint positions, joint torques were imposed in the frontal and axial anatomical planes. Mean manufacturing errors were found to be smaller than 0.08 mm. Consistent motion patterns were observed over repetitions, with the mean standard deviation smaller than 1.0 degree. In each ankle specimen, mobility, and stability at the replaced joints compared well with the original natural condition. For the first time, custom-made implants for total ankle replacements were designed, manufactured with additive technology and tested. This procedure is a first fundamental step toward the development of completely personalized prostheses. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Cranioplasty of Calvarial Skull Defects: A Comparative Study between Using Three Dimensional Custom-Made Cranioprostheses versus Hand-Made Bone Cement in Restoring Skull Configuration

Introduction: Cranioplasty is the surgical repair of a bony defect or deformity in the skull that is caused after cranial surgery or trauma. It carries cosmetic and protective benefits. Many types of materials are allowed. The subject of this study is to compare the outcome of two different manufacturing processes in reconstruction of calvarial skull defects by using 3D custom-made cranioprostheses versus hand-made bone cement implants. Patient and Methods: This is a prospective comparative study conducted on 20 patients of calvarial skull defects of different etiologies, sites and sizes, admitted in the neurosurgical departments of Cairo and Fayoum Universities in the period from August 2017 to February 2018. Patients are divided into two study groups: (group 1) 10 patients operated upon by 3D custom-made implant; (group 2) operated upon by hand-made bone cement implant. Statistical Analysis Used: Mann-Whitney test and Chi-square test. Results: Craniotomy using 3D custom-made implants gives better results than using bone cement in the functional restoration of skull shape and cranial protection with shorter operative time and less rate of postoperative complications. There is no statistically significant difference between the two study groups regarding cosmetic outcome. Conclusion: 3D custom-made implant is recommended for large and complex skull defects. Further and large studies might be needed.

Experimental investigation of rhombic dodecahedron micro-lattice structures manufactured by Electron Beam Melting

The aim of this scientific work is the analysis of rhombic dodecahedron micro-lattice structures under quasi-static and dynamic loading. The effect of unit cell size and strut diameter on mechanical properties was also considered. The specimens were designed by means of Materialise Magics® software and produced using Ti6Al4V ELI metal powder by Arcam Q10 electron beam melting (EBM) 3D printer, with the scientific collaboration of Mt Ortho Srl. The microstructure effect on the mechanical properties was analysed by optical and electron microscopy and Computed Tomography was used to analyse the morphology of unit cells. The experimental results show that these porous structures are very suitable for building custom-made implants in the field of orthopaedics and reconstructive neurosurgery. Moreover, by means of EBM additive manufacturing complex geometries, which are difficult to produce by conventional technologies, can be designed and produced.

Regulatory Concerns about Medical Device Manufacturing Using 3D Printing: Current State of the Issue

Custom-made implants, orthotics, orthoses, models for surgical planning and education, and much more are now created using 3D printers. In this article, the authors suiiunarized information on laws and regulations in the domain of legal support for 3D printing of medical devices in Russia and abroad. 3D printing is one of the promising avenues in developing new methods of treatment, so iiiunediate establishing of clear criteria for its legal regulation is necessary. As is, there are still many gaps in the legislative framework. The issues of the quality of 3D models, material standardization and manufacturing processes using 3D printing technologies remain unresolved. When using custom-made medical devices, respecting the rights of patients and preventing the use of prohibited or restricted materials are essential. Yet, legal barriers to this irmovative direction of medicine must be avoided.

Preliminary application of three-dimension printing technology in surgical management of bicondylar tibial plateau fractures

ObjectiveSurgical management of bicondylar tibial plateau fractures, which is frequently associate with high wound complication rates and functional impairment, remains a challenge for orthopedic surgeons. Recently, the emergence of three-dimension(3D) printing provided orthopedic surgeons with a new technology which has revolutionary impacts on surgical planning, operative guidance and custom-made implants manufacture. The aim of this study is to explore the clinical feasibility and application value of 3D printing in the surgical management of bicondylar tibial plateau fractures. MethodData of this retrospective study was collected from 11 patients suffering bicondylar tibial plateau fracture from October 2015 to August 2016. All of them underwent surgical treatment with the assistance of 3D printing technology. Real-size solid models and screw guide templates were printed for preoperative planning, surgical simulation and intraoperative guidance. Patients’ Demographics, surgery duration, intraoperative blood loss, the accuracy of preoperative planning were recorded and evaluated. ResultThe 3D printed models successfully provided the omni-directional exhibition of the fracture morphology. Model-based surgical simulation procedures and pre-selection of implants were generally consistent with the results of actual surgeries. There were no significant differences between the length of the osteosynthesis screws and that of actual surgeries (59.43 ± 11.13 mm vs 60.14 ± 12.05 mm). Beyond that, other parameters, such as surgical duration, intraoperative blood loss and HSS scores was satisfactory according to the surgical records and follow-up. ConclusionsAccording to our experience, the assistance of 3D printing technology in the surgical management of bicondylar tibial plateau fractures provides a comprehensive understanding of fracture features, an accurate patient-specific preoperative planning and an intraoperative guidance for real surgeries, thus leading to the optimization of clinical outcomes.

Postoperative Care in Facial Implants.

Facial augmentation is a growing field, secondary to the appreciation of the changes seen in the facial skeleton with aging and the growing acceptance/popularity of facial fat grafting and facial fillers. In addition, it plays a significant role in patients with congenital facial deficiencies as well as those interested in facial feminization/masculinization surgery. Several facial implants are discussed in this article including classic facial implants such as malar, submalar, chin, and prejowl implants as well as newer facial implants such as mandible, temporal, forehead, and skull implants. Special care is given to the postoperative care of these implants. Custom-made implants with three-dimensional computed tomography reconstruction are also discussed.

Feasibility of 3D-printed models of the proximal femur to real bone: a cadaveric study

3D technology has increased popularity during the past decade due to recent advancements and has been described as a useful tool in several fields of medicine including orthopaedic surgery. Applications include preoperative planning, custom-made implants, patient-specific guides, etc. The aim of this study was to evaluate the similarity between 3D-printed models and cadaveric femoral heads, based on CT scans. Cadaveric study of 12 male hips. Computed tomography (CT) was performed and through a semi-automatic segmentation process created the 3D model. Using a 3D printer, the model was printed in ABS plastic. 1 observer performed several measurements in the cadaver, and a 2nd observer performed the same measurements in the 3D-printed model. A 3rd observer compared both measurements and performed the statistical analysis. There were no significant differences in the measurements of bony structures between the cadaveric specimens and the 3D-printed model (p > 0.05 in all cases). We found significant differences when comparing measurements containing a soft tissue element, for example the dimensions of the cartilage covered femoral head (p < 0.0001). 3D-printed models of the hip are accurate and feasible to the real bone and can thus be reliable for preoperative planning or other uses that may arise in orthopaedic surgery. Presence of cartilage must be considered when creating the 3D model from CT that considers bone but not cartilage.

Customized implants for acetabular Paprosky III defects may be positioned with high accuracy in revision hip arthroplasty

In revision hip arthroplasty, custom-made implants are one option in patients with acetabular Paprosky III defects. In a retrospective analysis, we identified 11 patients undergoing cup revision using a custom-made implant. The accuracy of the intended position of the implant was assessed on post-operative 3D CT and compared to the pre-operative 3D planning in terms of inclination, anteversion, and centre of rotation. In addition, the accuracy of post-operative plain radiographs for measuring implant position was evaluated in relation to the 3D CT standard. We found a mean deviation between the planned and the final position of the custom-made acetabular implant on 3D CT of 3.6° ± 2.8° for inclination and of - 1.2° ± 7.0° for anteversion, respectively. Restoration of center of rotation succeeded with an accuracy of 0.3mm ± 3.9mm in the mediolateral (x) direction, - 1.1mm ± 3.8mm in the anteroposterior (y) direction, and 0.4mm ± 3.2mm in the craniocaudal (z) direction. The accuracy of the post-operative plain radiographs in measuring the position of the custom-made implant in relation to 3D CT was 1.1° ± 1.7° for implant inclination, - 2.6° ± 1.3° for anteversion and 1.3mm ± 3.5mm in the x-direction, and - 0.9mm ± 3.8mm in the z-direction for centre of rotation. Custom-made acetabular implants can be positioned with good accuracy in Paprosky III defects according to the pre-operative planning. Plain radiographs are adequate for assessing implant position in routine follow-up.

Modeling of 3D Implants via Personalized Contour Correction with Evaluation of Bone Tissue Density on the Hounsfield Scale

Increases in the numbers of surgical procedures for primary joint replacement inevitably lead to increases in the requirements for revision replacement of the hip joint. The number of patients with severe destruction of the acetabulum, in whom achievement of the implant stability is difficult or impossible, has increased. Manufacture of custom-made acetabular components is indicated in these cases. This article describes a method of filling defects in pelvic bones with custom-made implants 3D printed from medical titanium LPW-TI64-GD23-TYPE5 as specified by ASTM F136. The implant model is manufactured based on results of measurements of the density of the surrounding bone tissue using the Hounsfield scale.

Surgical Simulation and Custom-Made Implant for Cranial Fibrous Dysplasia.

The management of fronto-orbital fibrous dysplasia involves total excision of the dysplastic bone and bone reconstruction using implants. Custom-made implants are used to achieve good contouring. However, the remnant defect after excising the lesion often does not match the implant. To design the craniotomy line, a template was prepared by preoperative computed surgical simulation. The template was overlaid on the preoperative cranium, such that its inner surface fits exactly with the cranial surface. After excising the lesion by performing osteotomy, the implant was placed in the defect and fixed. Both template and implant were made of hydroxyapatite. The authors treated 4 patients, with fibrous dysplasia involving the fronto-facial region by using the template. Intraoperative trimming of the implant or bone defect was not required in 2 patients, while the third patient required mild trimming. They did not have any complications and obtained good contouring. The hydroxyapatite templates reduced the surgical time by determining the precise craniotomy line preoperatively, thus avoiding needless trimming of the implant and bone defect. Therefore, they can enhance the efficacy of treatment for fronto-orbital fibrous dysplasia lesion.

High Rate of Early Revision After Custom-Made Unicondylar Knee Arthroplasty

BackgroundThere has been a recent interest in custom-made partial knee arthroplasties to provide patient-specific instrumentation and better fit of the prosthesis. While unicondylar knee arthroplasties (UKAs) have demonstrated good outcomes and durable results in many studies, there is little evidence on outcomes of these custom-made implants. MethodsWe performed a retrospective review of all custom-made UKAs performed at our institution by one surgeon from 2008 to 2015. We analyzed preoperative demographics, clinical follow-up evaluations, and radiographs and performed an analysis of risk factors including age, gender, height, weight, body mass index, and tibial insert thickness. The incidence of revision surgery, radiographic failures indicating component loosening, and symptomatic clinically failed implants was calculated at an average of 54.0 months of follow-up. ResultsWe analyzed 115 consecutive custom-made medial UKAs from a single surgeon at our institution and found 29 (25.2%) UKAs had failed at an average of 33.1 months after surgery. Reasons for failure included aseptic femoral loosening (10), aseptic tibial loosening (8), loosening of both components (4), infection (3), progression of osteoarthritis (2), pain (1), and dislodged polyethylene insert (1). We found a significant relationship between implant failure and body mass index; no other study variables were statistically significant. ConclusionWe found a relatively high rate of aseptic loosening and particularly femoral component loosening in the short- to intermediate-term follow-up period. While further study of larger numbers of custom-made UKA from multiple institutions may help verify these findings, we recommend careful consideration of the use of this implant.

Evaluation of implant fit and frontal plane alignment after bi-compartmental knee arthroplasty using patient-specific instruments and implants.

IntroductionThe goals of successful bi-compartmental knee arthroplasty are to achieve correct fit and positioning of the implant, while appropriately correcting the mechanical alignment of the leg after surgery. As these requirements are not always reliably fulfilled using off-the-shelf implant systems, newer approaches for bi-compartmental resurfacing have been explored.Material and methodsIn this article we report the radiographic results of 30 patients with anteromedial osteoarthritis (OA) who were treated with a novel patient-specific fixed-bearing bi-compartmental knee resurfacing system using custom-made implants and instruments. Utilizing standardized pre- and postoperative radiographic analyses (based on anterior-posterior and lateral, anterior-posterior weight-bearing full-length radiographs, patella skyline views and preoperative computed tomography (CT) scanning) implant fit and positioning as well as correction of the mechanical axis (hip-knee-ankle angle, HKA) were determined.ResultsOn average, HKA was corrected from 173.4 ±3.47° preoperatively to 179.4 ±2.85° postoperatively. The coronal femoro-tibial angle was corrected on average 5.61°. The preoperative tibial slope measured on lateral views was 6.38 ±2.4°, while the average slope in the CT-based planning protocol (iView) was 6.14 ±2.40°. Postoperative lateral tibial slope was determined to be 5.77 ±1.97°. The thickness of the posterior femoral cuts was measured intraoperatively and, in all cases, corresponded well to the targeted thickness of the cuts provided by the iView. The joint line was preserved in all cases and the average Insall-Salvati index was 1.078 ±0.11 pre- and 1.072 ±0.11 postoperatively. The fit of the implant components measured by over- or underhang was excellent throughout (< 1.01 mm).ConclusionsCustom-made bicompartmental knee arthroplasty can ensure optimized fitting and positioning of the implant with restoration of the leg axis. These implants could be considered as an alternative primary solution for knee surgeons treating bi-compartmental disease.

Patient-specific design of a soft occluder for the left atrial appendage.

3D printing has been used to create a wide variety of anatomical models and tools for procedural planning and training. Yet, the printing of permanent, soft endocardial implants remains challenging because of the need for haemocompatibility and durability of the printed materials. Here, we describe an approach for the rapid prototyping of patient-specific cardiovascular occluders via 3D printing and static moulding of inflatable silicone/polyurethane balloons derived from volume-rendered computed tomography scans. We demonstrate the use of the approach, which provides custom-made implants made of high-quality, durable and haemocompatible elastomeric materials, in the fabrication of devices for occlusion of the left atrial appendage-a structure known to be highly variable in geometry and the primary source of stroke for patients with atrial fibrillation. We describe the design workflow, fabrication and deployment of patient-specific left atrial appendage occluders and, as a proof-of-concept, show their efficacy using 3D-printed anatomical models, in vitro flow loops and an in vivo large animal model.

Positioning of Custom-Made Acetabular Components at Revision Hip Arthroplasty: Do They Really Match as “a key and a lock”?

Purposes are to determine1) what frequency and what degree is of custom acetabular implants malposition in comparison with planned position, 2) what the reason of malposition is and 3) what the malposition consequences we can wait for.Patients and methods. The observation group included 20 patients (18 women and 2 men) with severe ac-etabular defects. Mean age of patients made up 53 (22-72) years. Position of the implants was compared with the parameters of preoperative planning using 5 postoperative CT indices (inclination, anteversion of semi-spherical part of the implant, spatial location of the rotation center in three axes). More than 10° deviation for inclination or anteversion and 5° dislocation of the rotation center in any axis was considered as a malposition of the component.Results. Only 5 of 20 constructions matched conditionally permissible limits by all the parameters. Most often excessive dislocation of the rotation center in lateral direction (10 cases) and excessive anteversion (9 cases) were observed. During 6 weeks follow up no complications related to the acetabular component position were recorded.Conclusion. It was shown that at revision arthroplasty with custom-made implants the probability of implant malposition as compared to the preoperative plan. The main reason could be the complexity of intraoperative orientation under conditions of abnormal hip anatomy. Malposition of the implants beyond the stated values did not result in complications within the early postoperative period. The longer follow up is required for the assessment of the long-term results.

Positioning of custommade acetabular components at revision hip arthroplasty: do they really match as “a key and a lock”?

Purposes are to determine 1) what frequency and what degree is of custom acetabular implants malposition in comparison with planned position, 2) what the reason of malposition is and 3) what the malposition consequences we can wait for. Patients and methods. The observation group included 20 patients (18 women and 2 men) with severe acetabular defects. Mean age of patients made up 53 (22-72) years. Position of the implants was compared with the parameters of preoperative planning using 5 postoperative CT indices (inclination, anteversion of semi- spherical part of the implant, spatial location of the rotation center in three axes). More than 10° deviation for inclination or anteversion and 5° dislocation of the rotation center in any axis was considered as a malposition of the component. Results. Only 5 of 20 constructions matched conditionally permissible limits by all the parameters. Most often excessive dislocation of the rotation center in lateral direction (10 cases) and excessive anteversion (9 cases) were observed. During 6 weeks follow up no complications related to the acetabular component position were recorded. Conclusion. It was shown that at revision arthroplasty with custom-made implants the probability of implant malposition as compared to the preoperative plan. The main reason could be the complexity of intraoperative orientation under conditions of abnormal hip anatomy. Malposition of the implants beyond the stated values did not result in complications within the early postoperative period. The longer follow up is required for the assessment of the long-term results.

3D digital geometry designs for Poland’s syndrome using Magics and Geomagic® Freeform®

PurposePoland’s syndrome patients often seek medical interventions to improve their aesthetic appearances. Design and manufacturing technologies make it possible to produce custom-made implants for such medical conditions. The purpose of this study was to compare the 3D digital geometries that were designed using Magics and Geomagic® Freeform® for two anonymous case studies of Poland’s syndrome patients.Design/methodology/approachComputed tomography data were acquired and processed in Mimics® to isolate the pectoralis muscles in STL file format. STL files were imported into Magics and Geomagic® Freeform® to design 3D digital geometries. Thereafter, comparative analyses were performed of the respective 3D digital geometries.FindingsThe angle between the vertical and oblique planes for both sides of the thorax was 6.5° for the female and 14° for the male. The surface areas and volumes of the geometries for the female were smaller than the male. Deviation analyses between the healthy side and reconstructed side of a thorax showed that 73 per cent of the test points for Magics and 78 per cent for Geomagic® Freeform® fell in the nominated tolerance region of >−5 and <+5 mm for the female. For the male, it was 83 per cent for Magics and 88 per cent for Geomagic® Freeform®.Practical implicationsGeomagic® Freeform® provides a more versatile design environment; however, the STL editor Magics may be an option to design 3D geometries for less intricate and less contoured implants.Originality/valueThis was a first attempt to compare the 3D geometries for Poland’s syndrome designed with an STL editor to those designed with a computer-aided design program.

Additive manufacturing of titanium alloys in the biomedical field: processes, properties and applications.

The mechanical properties and biocompatibility of titanium alloy medical devices and implants produced by additive manufacturing (AM) technologies - in particular, selective laser melting (SLM), electron beam melting (EBM) and laser metal deposition (LMD) - have been investigated by several researchers demonstrating how these innovative processes are able to fulfil medical requirements for clinical applications. This work reviews the advantages given by these technologies, which include the possibility to create porous complex structures to improve osseointegration and mechanical properties (best match with the modulus of elasticity of local bone), to lower processing costs, to produce custom-made implants according to the data for the patient acquired via computed tomography and to reduce waste.