Virtual Implantation Research Articles

The Ability of a Virtual Implantation Device to Evaluate Two Intraocular Lens Designs.

To evaluate the ability of a novel device using virtual implantation to compare the visual performance of two different types of intraocular lenses (IOLs). In this prospective, masked, and randomized clinical trial, the visual performance of monofocal and lowadd bifocal IOLs was compared using a device for virtual implantation called VirtIOL. Eighty patients (< 50 years old with healthy eyes and without cataract) were enrolled in this study. Defocus curve and contrast sensitivity were measured using the Freiburg Vision and Contrast Test (FrACT). Expected defocus curves for the monofocal IOL and the bifocal IOL confirm the utility of the method. The monofocal IOL provided a slightly higher mean visual acuity at 0.00 diopter (D) (mean ± standard deviation: -0.18 ± 0.07 D) compared to the bifocal IOL (-0.16 ± 0.08 D), but also a slightly lower visual acuity from -1.25 to -4.00 D. The mean contrast sensitivity was significantly higher for the monofocal IOL at 7, 11, and 15 cycles per degree. The investigators attest a high usability of the method due to simple communication with the test patient and quick and uncomplicated change of test objects. The visual performance of the monofocal and bifocal IOLs was as expected, with greater depth of focus but reduced contrast sensitivity for the bifocal IOL. The VirtIOL device represents a promising tool to predict the visual performance of IOLs before implantation in patients. [J Refract Surg. 2024;40(12):e911-e915.].

Prediction of visual outcomes using virtual implantation of a trifocal intraocular lens in presbyopic lens exchange patients.

To assess the reliability of a novel virtual IOL implantation device to predict the outcomes of a trifocal IOL. Clinical sites in Spain and Germany. Prospective multicenter study. Preoperative measurements obtained by the virtual implantation of AT LISA tri 839MP IOL (Carl Zeiss Meditec AG, Jena, Germany) with VirtIOL device (10Lens S.L.U., Terrassa, Spain) were compared to postoperative (month 3) outcomes following the IOL implantation. Evaluated metrics were defocus curve, contrast sensitivity (both in photopic conditions), and visual phenomena (visual angle size of burst and annular pattern) in mesopic conditions. The study included 45 presbyopic non-cataract patients (mean age 56.16±5.03 years). VirtIOL device reasonably predicted the shape of the defocus curve, especially in the intermediate vision range, but underestimated postoperative visual acuities mainly at the defocus range between +1.0D and -3.5D. The difference between predicted and achieved visual acuity was -0.11±0.13 logMAR (p<0.001) for 0.0D defocus and -0.16±0.15D logMAR (p<0.001) for -2.50D defocus. The shape of the contrast sensitivity curve was almost identical for predicted and achieved measurements, but the device underestimated the values by ≈0.3 logCS units for each spatial frequency. Visual phenomena were similar between the predicted and achieved outcome (predicted vs. achieved: burst pattern 2.65±0.97° vs. 2.74°±0.95°, p=0.63; annular pattern: 0.88±0.42° vs. 0.93±0.49°, p=0.59). The device reasonably predicted the pattern of measured variables. Visual acuity/contrast sensitivity reduction might be attributed to viewing the objects through a more complex optical system and would need to be accounted for in clinical studies.

Assessing the predictability of five intraocular lens calculation methods in eyes with prior myopic keratorefractive lenticule extraction.

To evaluate and compare the predictability of five methods of intraocular lens (IOL) calculation in eyes with prior keratorefractive lenticule extraction (KLEx) for the treatment of myopia. A retrospective case study included 100 eyes of 52 patients who underwent myopia and myopia with astigmatism treatment with small incision lenticule extraction (SMILE). Preoperative and 3-month postoperative measurements of optical biometry and corneal tomography were obtained. The spherical equivalent of the refractive change induced by surgery was converted to the corneal plane (SMILE-dif). A physically well-defined method was developed in which the same IOL model was implanted before and after SMILE. IOL power was calculated using ray-tracing (RT-Sirius), and several IOL power calculation formulas (Kane, EVO 2.0, Barrett Universal II Formula, Hoffer QST) before surgery. After surgery, IOL power was calculated with RT-Sirius, Kane using Mean Pupil Power at 5.5mm by ray tracing, EVO 2.0 Post Myopic LASIK/PRK, Barrett True K and Hoffer QST Post Myopic LASIK/PRK after surgery. The difference between the refractive error induced by the IOL before and after SMILE in the corneal plane (IOL-dif) was compared with SMILE-dif. The predicted error (PE) was calculated as the difference between SMILE-dif and IOL-dif. The PE obtained was 0.26 ± 0.55 diopters (D), 0.10 ± 0.45 D, 0.40 ± 0.37 D, -0.03 ± 0.36 D, 0.02 ± 0.51 D, with RT-Sirius, Kane, EVO 2.0, Barrett True K, and Hoffer QST respectively. PE was not statistically significantly different between Barrett True K and Hoffer QST, with differences being more homogeneous with Barrett, (variance σ2 = 0,13). The absolute EP obtained with Barrett True K achieved 84% of cases within ± 0.5 D, followed by Kane (72%), Hoffer QST (65%), EVO (61%) and RT-Sirius (59%). Barrett True K formula was the most accurate method for IOL calculation in eyes that had undergone SMILE for the correction of myopia. What is known The literature regarding IOL power calculation after SMILE is sparse, and the methods used to estimate corneal power following LASIK/PRK may not be applicable to SMILE procedures. The most common approach to investigating the predictability of IOL calculation formulas involves a theoretical model encompassing the virtual implantation of an IOL. What is new The Hoffer QST formula, Kane formula using Mean Pupil Power at 5.5mm, EVO 2.0, and Sirius' Ray Tracing software had not been previously evaluated using this approach. The Barrett True K formula was the most accurate method for IOL calculation in eyes that had undergone SMILE for myopia correction, outperforming Ray Tracing.

Anatomical compatibility of a novel total artificial heart-An in-silico study.

ShuttlePump is a novel total artificial heart (TAH) recently introduced to potentially overcome the limitations associated with the current state-of-the-art mechanical circulatory support devices intended for adults. In this study, we adapted the outflow cannulation of the previously established ShuttlePump TAH and evaluated the anatomical compatibility using the virtual implantation technique. We retrospectively assessed the anatomical compatibility of the ShuttlePump using virtual implantation techniques within 3D-reconstructed anatomies of adult heart failure patients. Additionally, we examined the impact of outflow cannula modification on the hemocompatibility of the ShuttlePump through computational fluid dynamic simulations. A successful virtual implantation in 9/11 patients was achieved. However, in 2 patients, pump interaction with the thoracic cage was observed and considered unsuccessful virtual implantation. A strong correlation (r <-0.78) observed between the measured anatomical parameters and the ShuttlePump volume exceeding pericardium highlights the importance of these measurements apart from body surface area. The numerical simulation revealed that the angled outflow cannulation resulted in a maximum pressure drop of 1.8 mmHg higher than that of the straight outflow cannulation. With comparable hemolysis index, the shear stress thresholds of angled outflow differ marginally (<5%) from the established pump model. Similar washout behavior between the pump models indicate that the curvature did not introduce stagnation zone. This study demonstrates the anatomic compatibility of the ShuttlePump in patients with biventricular failure, which was achieved by optimizing the outflow cannulation without compromising hemocompatibility. Nevertheless, clinical validation is critical to ensure the clinical applicability of these findings.

Placing the tibial component of an ankle prosthesis: results of a CT-based simulation in healthy adults.

To characterize the 3D geometry of the distal tibia resection area from healthy individuals using CT-based digital implantation for proper preoperative sizing of TAA tibia component placement. Standardized CT images of healthy ankle joints serving as intra-individual references for treatment of contralateral injuries were identified. The tibial cross section dedicated to virtually host the tibial component was digitally prepared, and the size of the virtual contact surface was calculated. Finally, out of five prototypes the one fitting best in terms of size and alignment was identified. CT scans taken from 319 subjects were used for the virtual implantation procedure. Body height and size of the distal tibia contact area correlated (r = 0.49 and 0.42 in females and males, each p < 0.001). Prosthesis sizes 2 and 3 fit well for the vast majority of patients, while the smallest and largest sizes are rarely required. Digital implantation of the tibial component should be considered a valuable tool for preoperative planning as well as for the development of new implant types.

Eccentricity and greater size of the glenosphere increase impingement-free range of motion in glenoid lateralized reverse shoulder arthroplasty: A computational study

IntroductionIncreasing the impingement-free Range Of Movement (ROM) is crucial for improving patient's functional outcome and reducing the rate of scapular notching. The purpose of this study was to compare, in a virtual model of Reverse Shoulder Arthroplasty with glenoid lateralization (L-RSA): 1) the impingement-free range of movement (ROM) between 155° Grammont-style inlay stem and 135° flushlay stem; 2) the effect of glenosphere size and type (centered vs eccentric) on impingement-free range of movement (ROM) using a 135° Neck Shaft Angle (NSA) flushlay stem. Materials and methods200 CT-scans of patients undergoing shoulder replacement for Cuff tear Arthropathy were analyzed in the present study. Virtual implantation of L-RSA was performed using the same glenoid implant and two stems, 155° inlay Grammont-style stem and 135° flushlay stem. For 135° stem, three different glenoid size (36 mm, 39 mm and 42 mm) were tried, as well as two glenoid type (centered and eccentric glenoid), while for 155° stem were tried two different glenoid size (36 mm and 42 mm), as well as two glenoid type (centered and eccentric glenoid). For both stems, two different baseplates (25 mm e 29 mm) were used. Finally, impingement-free ROM for each configuration and each stem was then calculated by the software and collected. ResultsIncreasing the glenosphere size demonstrated an increase in impingement-free ROM in both 25 mm and 29 mm baseplate groups (p < 0.01). Similarly, using eccentric glenoid type improved impingement-free ROM in the two subgroups (p < 0.01). When comparing inlay and flushlay designs, flushlay shows better total impingement-free ROM as well as better impingement-free ROM in all movements apart from abduction (p < 0.01). ConclusionsThis study demonstrated a correlation between glenoid size and glenoid type and impingement-free ROM using 135° flushlay stems. In particular, using a greater glenoid size and eccentric glenoid type allows for more mobility. When comparing 135° flushlay stem with 155° inlay stem, 135° stem allows greater mobility in all movements except for abduction.

Computer simulation help predict the frame deformation following a Venus-A transcatheter aortic valve implantation in patients with pure aortic regurgitation: a retrospective study.

Patient-specific computer simulation of transcatheter aortic valve implantation (TAVI) predicts the interaction between an implanted device and the surrounding anatomy. In this study, we validated the predictive value of computer simulation for the frame deformation following a Venus-A TAVI implant in patients with pure aortic regurgitation (AR). Furthermore, we used the validated computational model to evaluate the anchoring mechanism within the same cohort. This was a retrospective study. FEops HEARTguide technology was used to simulate the virtual implantation of a Venus-A valve model in a patient-specific geometry. The predicted frame deformation was quantitatively compared to the postoperative device deformation at multiple levels. The outward forces acting on the frame were extracted for each patient and the total outward force acting around the aortic annular (AA) and sinotubular junction (STJ) planes were recorded. Thirty patients were enrolled in the study with 10 in the migration group and 20 in the non-migration group. The dimensions of the simulated and observed frames had good correlations at Dmax (R2=0.88), Dmin (R2=0.91), perimeter (R2=0.92), and area (R2=0.92). The predicted outward force acting on the frame at the AA level was comparable between the migration and no-migration groups. The predicted outward force acting on the frame at the STJ level was always significantly higher in the migration group than the no migration group at different bandwidths: 3 mm (P=0.002), 5 mm (P=0.005), 10 mm (P=0.002). Patient-specific computer simulation of TAVI accurately predicted frame deformation in Chinese patients with pure AR. The forces at the STJ facilitated stabilization of the device within the aortic root, which might be used as a discriminator to identify patients at risk of device migration prior to intervention.

Risk Assessment of Nasal Cavity Perforation in the Maxilla: A Virtual Implant Placement Study Using Cone Beam Computed Tomography.

Implant surgery in individuals with atrophic maxilla presents challenges, particularly concerning nasal cavity complications such as perforations, implant migration, and airway obstruction. While panoramic radiographs offer diagnostic convenience, their two-dimensional nature limits the evaluation of anatomical structures. Cone beam computed tomography (CBCT) provides a three-dimensional assessment, enhancing surgical planning accuracy and potentially reducing complications. With the aim of understanding the measurement differences between panoramic radiographs and CBCT images, this retrospective study examined CBCT images of patients with severely atrophic maxilla taken between September 2021 and December 2023 at the Ahmet Keleşoğlu Faculty of Dentistry. Virtual implants were placed in various tooth regions using OnDemand3D software. The incidence of nasal cavity perforations and vertical bone height differences between panoramic radiographs and CBCT images were evaluated. For this purpose, vertical bone length measurements in panoramic and CBCT images were compared for the virtual implant placement areas. Statistical analyses, including t-tests and ANOVA, were performed to determine significant differences among quantitative measurements, and a chi square test with Bonferroni corrected z-tests were used for possible associations between ratios. CBCT data from 59 patients, totaling 1888 virtual implants, revealed significant differences in implant depths among tooth regions (F = 9.880, p < 0.001). Canine regions showed higher perforation risks, especially with 12 mm and 14 mm implants. Panoramic radiographs often overestimated vertical bone height in canine and first premolar regions compared to CBCT measurements, which could lead to increased perforation risks. Radiographic evaluations using CBCT prior to implant surgery in atrophic maxilla cases are crucial to prevent nasal cavity complications. Panoramic radiographs may inadequately represent three-dimensional anatomy, underscoring the importance of CBCT for accurate implant placement and surgical planning. Further studies should consider varying implant sizes and brands to generalize findings.

Objective measurement of intraocular lenses using the VirtIOL device

Purpose. The primary goal of this study was to evaluate the resolution of three different intraocular lenses using the VirtIOL device. The secondary objective was to determine the contrast achieved by these lenses. Material and Methods. An in-vitro assessment of three intraocular lenses (including a single vision IOL, a trifocal IOL and an EDOF IOL) was performed using the VirtIOL device. The key feature of this apparatus is a table-mounted device that allows the user to look through an IOL along the optical axis at a target at any distance. An industrial camera “UI-3040CP-C-HQ Rev.2 (AB02491)” (Co. Navitar, USA) was mounted on the chin rest of the VirtIOL. The USAF 1951 test chart was presented at the following distances: 6 m, 1 m and 0.4 m. The IOLs were each mounted in a model eye. The resolution capability, expressed as line pair per mm [lp/mm] and contrast values were measured under photopic conditions at a system aperture of 3 mm. The measurement of the contrast values was repeated ten times with each lens at each distance. Results. All IOLs (monofocal/trifocal/EDOF) achieved a resolution of 0.445 lp/mm at a distance of 6 m, as well as 1.00 / 2.82 / 2.52 lp/mm at 1 m. The measurement of resolution at the distance of 0.4 m resulted in 1.00 / 3.56 / 1.12 lp/mm. At various test distances, the following mean contrast values and standard deviations were obtained: 236 ± 8.1 / 115 ± 2.5 / 123 ± 3.9 (p &lt; 0.001) at 6 m, 96 ± 0.8 / 75 ± 0.7 / 81 ± 0.7 (p &lt; 0.001) at 1 m and 36 ± 0/ 42 ± 0.7 / 36 ± 0.4 (p &lt; 0.001) at 0.4 m. Conclusion. The VirtIOL device in combination with the measuring camera used provides a basis for objective measurements of IOLs. The resolution capability of the three IOLs increases with decreasing distance, whereas the contrast values decrease. This study confirms the usefulness of the setup and provides a basis for further evaluations of intraocular lenses with the VirtIOL device. Keywords intraocular lenses, VirtIOL, virtual implantation, resolution capability, contrast

Three-Dimensional Bowing Measurement of Distal Femur at Actual Size and Clinical Implications of Total Knee Arthroplasty.

Background and Objectives: To assess femoral shaft bowing (FSB) in coronal and sagittal planes and introduce the clinical implications of total knee arthroplasty (TKA) by analyzing a three-dimensional (3D) model with virtual implantation of the femoral component. Materials and Methods: Sixty-eight patients (average age: 69.1 years) underwent 3D model reconstruction of medullary canals using computed tomography (CT) data imported into Mimics® software (version 21.0). A mechanical axis (MA) line was drawn from the midportion of the femoral head to the center of the intercondylar notch. Proximal/distal straight centerlines (length, 60 mm; diameter, 1 mm) were placed in the medullary canal's center. Acute angles between these centerlines were measured to assess lateral and anterior bowing. The acute angle between the distal centerline and MA line was measured for distal coronal and sagittal alignment in both anteroposterior (AP) and lateral views. The diameter of curve (DOC) along the posterior border of the medulla was measured. Results: The mean lateral bowing in the AP view was 3.71°, and the mean anterior bowing in the lateral view was 11.82°. The average DOC of the medullary canal was 1501.68 mm. The average distal coronal alignment of all femurs was 6.40°, while the distal sagittal alignment was 2.66°. Overall, 22 femurs had coronal bowing, 42 had sagittal bowing, and 15 had both. Conclusions: In Asian populations, FSB can occur in coronal, sagittal, or both planes. Increased anterolateral FSB may lead to cortical abutment in the sagittal plane, despite limited space in the coronal plane. During TKA, distal coronal alignment guides the distal femoral valgus cut angle, whereas distal sagittal alignment aids in predicting femoral component positioning to avoid anterior notching. However, osteotomies along the anterior cortical bone intended to prevent notching may result in outliers due to differences between the distal sagittal alignment and the distal anterior cortical axis.

Avoiding Sinus Floor Elevation by Placing a Palatally Angled Implant: A Morphological Study Using Cross-Sectional Analysis Determined by CBCT.

Tooth loss in the posterior maxilla often necessitates dental implant placement, but the maxillary sinus anatomy poses challenges, especially during sinus floor elevation. Mesially angled implants are an alternative for total edentulism, but for single tooth deficiencies, palatally angled implants may offer a solution. This study evaluates the prevalence of avoiding sinus floor elevation by placing palatally angled implants in cases with a single missing tooth. A retrospective study at Ahmet Keleşoğlu Faculty of Dentistry involved 100 participants with a single missing tooth and prior CBCT scans. Virtual implants were placed using OnDemand3D (version 1.0.7462) software. On CBCT sections, implants were angled palatally to avoid sinus or nasal cavity perforation. Statistical analysis was conducted using R and MedCalc (version 4.3.2) software. Of the participants (60% female, average age 50.45), 76 edentulous regions required sinus elevation. The implant placeability rates varied across zones (second molar: 39.3%, first molar: 63.1%, second premolar: 78.5%). Implant placement at a palatal angle was significantly higher in the second premolar and first molar regions. Statistically significant differences were observed in the implant placeability between regions. This study supports the feasibility of avoiding sinus floor elevation through palatally angled implants in specific cases, reducing the associated complications.

Virtual Implant Planning and Surgical Guide for Single Implant Placement Fabricated from a Digital Diagnostic Cast, 2D Radiographic Imaging, and an Open-Source Program: A Dental Technique.

The following technique describes the virtual planning of a single implant by combining an intraoral digital scan, an open-source computer-aided design software program, bone sounding, and 2D radiographic imaging. The surgical implant guide is fabricated using additive manufacturing technologies. Further, the surgical implant guide positioned in the patient's mouth is used to radiographically verify the estimated mesiodistal implant angulation before proceeding with the surgical intervention and can be modified if necessary. When a CBCT scan is not available, this technique eases implant planning procedures and minimizes possible surgical complications.

Assessment of bone density in edentulous maxillae using cone beam computed tomography (CBCT)

IntroductionIn edentulous maxillae, the anterior maxilla is the region of interest for implant placement due to posterior bone resorption and sinus pneumatization. This study aimed to assess variations in bone density in different regions of the edentulous maxilla according to sex and age, using cone beam computed tomography (CBCT). Materials and methods69 CBCT from edentulous maxilla were analyzed. Six virtual implants were planned between the maxillary sinuses at incisor, canine, and premolar sites. Bone densities (in Hounsfield units HU) were recorded at six points on the neck, body, and apex of the buccal and lingual areas of each virtual implant. We used the two-sample t-test to compare male and female bone densities, and the Spearman correlation coefficient to analyze the correlation between mean bone density and age. One-way analysis of variance with post hoc pairwise t-tests was used to analyze the differences in density between three sites of the edentulous maxilla and the differences in density between three parts of the implant. The significance level was set at 5%. ResultsMean bone density in males was significantly higher than in females. There was a significant correlation between mean bone density and age in females. Incisor sites showed the highest mean bone density, followed by canine and premolar sites. There was a significant decline in bone density from the neck to the apex. ConclusionsBone density varied within and among edentulous maxillae. Bone density of the edentulous maxilla seemed to be influenced by age in women and by sex.

Increased Deltoid and Acromial Stress with Glenoid Lateralization and Onlay Humeral Stem Constructs in Reverse Shoulder Arthroplasty.

Reverse shoulder arthroplasty (RSA) designs include multiple options for glenoid component lateralization, and humeral component lateralization and distalization (inlay/onlay constructs). The influence of combined glenoid lateralization, and humeral distalization on acromial and deltoid stresses is not well understood. The purpose of this study was to evaluate changes in deltoid and acromial stresses with variations in glenoid lateralization, and with inlay versus onlay humeral components in RSA. Finite element analysis was performed using a RSA system with both inlay and onlay configurations. Variations in total glenoid lateralization from 3 to 9 mm were evaluated. Deltoid and acromial stresses were determined following virtual implantation and with 50° of external rotation. Increased glenoid lateralization resulted in greater stress of the deltoid and acromion. There was a modest increase in deltoid stress with glenoid lateralization alone (7% and 7.5% with progressive lateralization from 3 to 6 mm and 6 to 9 mm, respectively), but deltoid stress increased substantially with use of an onlay construct (60% at 9 mm of glenoid lateralization). Acromial stress correspondingly increased 37% with glenoid lateralization, and up to 117% with an onlay humeral construct. Increased lateralization of the glenoid component resulted in increased levels of deltoid and acromial stress. For a given amount of glenoid lateralization, utilization of an inlay stem decreased acromial and deltoid stresses compared to onlay constructs. These data allow surgeons to better understand the interactions of glenoid and humeral lateralization and distalization in the setting of contemporary RSA systems.Level of Evidence: Basic Science Study: Computer Modeling.

Interchangeability of bilateral anterior chamber depth in intraocular lens power calculation and its application in unilateral lens subluxation

Aims/Purpose: To assess the interchangeability of bilateral anterior chamber depth (ACD) in intraocular lens (IOL) power calculation, and to evaluate whether using the unaffected fellow eye's ACD can enhance refractive results in unilateral lens subluxation.Methods: Axial length (AL), keratometry (K) and ACD were obtained by IOLMaster 700. In cataract surgery candidates (Group 1), the virtual implantation of the same IOL model was used. The predictive results closest to the Plano of the Kane formula, using the right eye's biometry (AL, K and ACD), served as a benchmark. The results of the corresponding IOL power were further calculated by substituting the left eye's ACD for the right eye's one and compared with the benchmark. Eyes with unilateral lens subluxation (Group 2) underwent in‐the‐bag IOL placement after the capsular hook(s) implantation, with refraction conducted at least 1 month post‐operatively. Prediction errors (PE) of the Kane formula with or without the unaffected fellow eye's ACD were compared.Results: 392 eyes of 196 patients were analysed, including 173 candidates and 23 patients with unilateral subluxated lenses. In Group 1, there was no significant difference in bilateral ACD (p = 0.30). The predictive refraction using the right eye's ACD was −0.16 ± 0.10 diopter (D), and that obtained by the left eye's one was −0.16 ± 0.11 D (p = 0.64), with an absolute difference of 0.03 ± 0.03 D. In Group 2, the ACD was 2.89 ± 0.86 mm of the affected eye and 3.14 ± 0.37 mm of the fellow eye (p = 0.17). The median absolute PE, mean absolute PE and the percentage of PEs within ±0.50 D using the affected eye's ACD were 0.50 D, 0.59 D and 52.17%. Using the unaffected eye's ACD improved the outcomes to 0.45D, 0.52 D and 60.87%.Conclusions: Bilateral ACD values are interchangeable in routine IOL power calculation, and using the unaffected fellow eye's ACD can improve its accuracy in cases of unilateral lens subluxation undergoing in‐the‐bag IOL implantation.

Biomechanical analysis of peri-prosthetic bone response to hybrid threaded zirconia dental implants: An in silico model

The biomechanical response of mandibular bone determines primary stability and concomitant osseointegration of dental implants. This study explores the impact of nature of loading and bone conditions on biomechanical response of hybrid threaded single-piece zirconia dental implants. To develop such understanding, three implants (SQ_V, V_BUT, and V_V), with different combinations of threads, square (SQ), buttress (BUT), and triangular (V), have been investigated. Finite Element Analysis (FEA) was carried out to simulate implantation at the molar position of mandible of varying densities under axial (≤500 N) and oblique (118.2 N) loadings. Patient-specific bone conditions (for a wider population) were considered by scaling the density and the elastic modulus of mandible to represent, ‘weak’, ‘healthy’, and ‘strong’ bone conditions. FEA results revealed that SQ_V and V_BUT implants exhibited a better biomechanical response without significant variation (<0.5%) in von Mises stress, regardless of bone density and axial loadings. These implants are predicted to perform with clinically acceptable factor of safety under investigated implantation scenarios, whereas V_BUT implant showed a larger variation (∼±12%). FEA simulation with oblique loading further validated such results. The ‘weak’ bone conditions resulted in maximum peri-implant microstrain, whereas ‘strong and healthy' bone exhibited values close to the permissible range of physiological remodeling. The maximum micromotion (∼12.3 ± 6.2 μm for ‘weak’ bone) at bone-implant interface suggested that implant loosening and impaired osseointegration will not occur in any of selected virtual implantation cases. Both SQ_V and V_BUT implants will be considered further in implant development, involving manufacturing and product prototype validation. Taken together, the critical analysis of FEA results indicates a significant impact of bone density and distinct combinations of external threads on the biomechanical responses, in both the implant and the surrounding bone.

Virtual Implant Treatment Planning Using the Existing Denture With Metal Frameworks as a Radiographic Guide: A Technique Note.

A radiographic guide can provide adequate visualization of proposed tooth position and prosthetic space, which is essential for the guided implant surgery. Many existing methods for fabricating radiographic guides involve duplicating the patient's existing denture or fabricating a new diagnostic template especially when the existing denture has metal framework, which may lead to strong metallic artifacts. This article describes a convenient and cost-effective technique for fabricating radiographic guide and aiding the design of implant surgical guide by using an existing denture with a metal framework and radiopaque and flowable composite resin in a single visit.

Radiographic comparison of atelocollagen versus deproteinized bovine bone minerals covered with a collagen membrane in alveolar ridge preservation: a retrospective study

BackgroundAtelocollagen (AC) is a low-immunogenic collagen derivative with longer degradation time, which can be a suitable material for alveolar ridge preservation (ARP). However, there are few human studies on AC using for ARP. This research aims to radiographically evaluate the efficacy of AC in comparison to deproteinized bovine bone minerals covered with a collagen membrane (DBBM/CM) in ARP.MethodsMedical records in the Implantology Department of the Hospital of Stomatology of Wuhan University were screened for patients who received flapless ARP using either AC or DBBM/CM. A total of 58 patients were included in this retrospective study. 28 patients were treated with AC, while 30 patients were used DBBM/CM. Cone-beam computed tomography (CBCT) scans were taken before extraction and after 6 months of healing. To assess the dimensional change of the extraction sockets, the scanning data were output and transferred to the digital software to measure horizontal bone width change, vertical bone height change and bone volume change in region of interest. To evaluate the bone quality of healed sockets, the bone density of virtual implants was evaluated.ResultsThe horizontal bone width changes at all five different levels showed no significant difference between the two groups. The largest horizontal bone width decrement in both groups occurred at the crest of ridge, which decreased 3.71 ± 1.67 mm in AC group and 3.53 ± 1.51 mm in DBBM/CM group (p = 0.68). At the central buccal aspect, the ridge height reduced 0.10 ± 1.30 mm in AC group, while increased 0.77 ± 2.43 mm in DBBM/CM group (p = 0.10). The vertical bone height differences between two groups showed no statistical significance. The percentages of volume absorption in AC group and DBBM/CM group were 12.37%±6.09% and 14.54%±11.21%, respectively. No significant difference in volume absorption was found (p = 0.36). The average bone density around virtual implants in AC group (649.41 ± 184.71 HU) was significantly lower than that in DBBM/CM group (985.23 ± 207.85 HU) (p < 0.001).ConclusionsARP with AC had a similar effect on limiting the dimensional alteration of alveolar ridge, when radiographically compared with DBBM/CM.

Left Atrial Decompression With the HeartMate3 in Heart Failure With Preserved Ejection Fraction: Virtual Fitting and Hemodynamic Analysis.

Effective treatment of heart failure with preserved ejection fraction (HFpEF) remains an unmet medical need. Although left atrial decompression using mechanical circulatory support devices was previously suggested, the heterogeneous HFpEF population and the lack of tailored devices have prevented the translation into clinical practice. This study aimed to evaluate the feasibility of left atrial decompression in HFpEF patients with a HeartMate 3 (HM3, Abbott Inc, Chicago, USA) in silico and in vitro . Anatomic compatibility of the HM3 pump was assessed by virtual device implantation into the left atrium through the left atrial appendage (LAA) and left atrial posterior wall (LAPW) of 10 HFpEF patients. Further, the efficacy of left atrial decompression was investigated experimentally in a hybrid mock loop, replicating the hemodynamics of an HFpEF phenotype at rest and exercise conditions. Virtual implantation without substantial intersection with surrounding tissues was accomplished through the LAA in 90% and 100% through the LAPW. Hemodynamic analysis in resting conditions demonstrated normalization of left atrial pressures without backflow at a pump speed of around 5400 rpm, whereas a range of 6400-7400 rpm was required during exercise. Therefore, left atrial decompression with the HM3 may be feasible in terms of anatomic compatibility and hemodynamic efficacy.

An evolutionary perspective to intramedullary nail fit - comparing present-day data with a historical specimen collection.

Manufacturers aim to design implants fitting for the broadest possible population segment. Due to the scarcity of available morphological data of intact long bones, anatomical collections of historical bone specimens may represent valuable additional sources. Previous work on femoral morphology measurements suggests that historical specimens are widely consistent with data from present-day populations. This study aimed to investigate whether this also applies to the anatomical fitting of a clinically used femoral nail. Nail fit was computer-graphically quantified through virtual implantation into CT-based 3D models of 52 femora, comprising a subset representative of the present-day Caucasian population (n = 31), a subset from a historical medieval European bone collection (n = 20), and additionally, a dataset from a natural ice mummy from the Neolithic period. Nail fit was assessed by nail protrusion (area and distance) to the inner cortex surface and the distal nail tip's position in the medullary canal. Assessed measurements and parameters of the present-day Caucasian subset were mostly consistent with those of the medieval European subset. After adjusting for multiple testing, only the distance from lateral nail entry point to shaft axis remained significantly (p = 0.03) different when comparing our modern and medieval subsets. Subsequent bivariate (Spearman) correlation analyses for both subsets (modern and medieval) combined showed that of the three variables representing basic demographic parameters, individual age, biological sex, and femur length, most statistically significant associations to the examined nail fit measurements were found for age (six measurements at a level of p < 0.05), however, with a relatively weak monotonic correlation (rho values ranging between ±0.31 and ±0.37). The measurements for the Iceman's femur lie within the range of the modern and historical subgroups, but in some cases, differ by more than one standard deviation from the mean. Our results confirm previous findings, suggesting that more recent historical bone specimen collections may indeed be a convenient and easily accessible source of new 3D morphological data and complement existing data to be used for the development of femoral nails.