Cadaveric Bones Research Articles

DOUBLE-BARREL DRILL SLEEVE: A SURGICAL INNOVATION FOR PERCUTANEOUS OSTEOTOMY

IntroductionOsteotomy is a key step in distraction osteogenesis. Various techniques of osteotomy have been described with its own benefits and pitfalls. Percutaneous osteotomy using multiple drill holes is one of the most widely used osteotomy techniques. It still remains a challenge however to keep the drill holes aligned prior to the osteotomy. Moreover, the efficacy of percutaneous irrigation practice to keep the temperature low during drilling with this technique is also debatable. With an aim to overcome these challenges, we are introducing a device called the Double Barrel Drill Sleeve (DBDS) to perform percutaneous osteotomies. We attempted to compare this method to the conventional multiple drill holes technique using laboratory experiments and clinical data.Materials & MethodsDBDS has two adjacent parallel barrels that can fit 3.2 to 3.5 mm diameter drill bits. It has a guide member at the drilling end that can be inserted through a pre drilled hole at the near and far cortices of a bone. This provides a constant rotating point for drilling of holes through the barrels. An osteotomy simulation was performed to compare percutaneous drilling with DBDS vis-a-vis a conventional single drill sleeve (SDS) by qualified orthopaedic surgeons, mainly to assess the drilling patterns of both techniques. Percutaneous drilling was done on PVC pipes wrapped in thick sponge to simulate tubular bone with surrounding soft tissue. We also assessed the effect of indirect irrigation on temperature during drilling using the DBDS against a control group on a cadaveric bone model. Ultimately we reviewed our patients who had undergone osteotomy for distraction osteogenesis with DBDS and the conventional technique, and compared their outcomes.ResultsCompletion time for the osteotomy simulation in the DBDS group was significantly faster than the conventional drilling group; 74 seconds to 179 seconds. There was significantly less drilling deviation from the midpoint in the DBDS group as compared to the SDS group. Mean bone temperature during drilling with indirect irrigation using DBDS was significantly lower (32.6'C) compared to the control group (48.4'C). There was no significant difference in healing index between patients treated with DBDS and the conventional method. None of these patients developed non union.ConclusionsPercutaneous drilling with DBDS was quicker and more linear compared to the conventional method. Its double-barreled feature allows effective indirect irrigation during drilling. A comparable healing index in both of the techniques shows its clinical efficacy. These attributes make DBDS a usefull tool to overcome some of the pitfalls associated with the conventional multiple drill holes technique.

Immersive Virtual Reality and Cadaveric Bone are Equally Effective in Skeletal Anatomy Education: A Randomized Crossover Noninferiority Trial

Immersive virtual reality (IVR) technology is transforming medical education. Our aim was to compare the effectiveness of IVR with cadaveric bone models in teaching skeletal anatomy. A randomized crossover noninferiority trial was conducted. Anatomy laboratory of a large medical school. Incoming first-year medical students. Participants were randomized to IVR or cadaveric groups studying upper limb skeletal anatomy, and then were crossed over to use the opposite tool, to study lower limb skeletal anatomy. Participants in both groups completed a pre-and postintervention knowledge test. The primary endpoint of the study was change in performance from the pre-to postintervention knowledge test. Surveys were completed to assess participant's impressions on IVR as an educational tool. Fifty first-year medical students met inclusion criteria and were randomized. Among all students, the average score on the preintervention knowledge test was 14.6% (standard deviation (SD) = 18.2%) and 25.0% (SD = 17%) for upper and lower limbs, respectively. Percentage increase in scores between pre-and postintervention knowledge test, was 15.0% in the upper limb IVR group, and 16.7% for upper limb cadaveric bones (p = 0.286). For the lower limb, score increase was 22.6% in the IVR and 22.5% in the cadaveric bone group (p = 0.936). 79% of participants found that IVR was most valuable for teaching 3-dimensional orientation, anatomical relationships, and key landmarks. Majority of participants were favorable towards combination use of traditional methods and IVR technology for learning skeletal anatomy (LSM>3). In this randomized controlled trial, there was no significant difference in knowledge after using IVR or cadaveric bones for skeletal anatomy education. These findings have further implications for medical schools that face challenges in acquiring human cadavers and cadaveric parts.

Comparing the torsional resistance of different fixation techniques for spiral metacarpal fractures.

This study aimed to compare the torsional resistance of three fixation techniques for spiral metacarpal fractures: screw-only fixation, screw plus neutralization plate fixation, and a locking plate construct. A spiral fracture was created on 18 cadaveric metacarpal bones by applying an axial and torsional loading force using an Instron 3343 mechanical tester. The failure strength was defined as the native torque strength. The fractures were divided into three groups and fixed using each of the three techniques. The repaired bones were loaded to failure to determine the post-repair strength. The neutralization plate group conferred a post-repair torque (278.6 Nmm) that was similar to the native torque (292 Nmm) with a diminution of only 4.5% and appeared to provide the best resistance to torsion.

Are Simulated or 3D Printed Temporal Bones as Useful for Training as Cadaveric Bones.

The LaryngoscopeEarly View Triological Society Best Practice Are Simulated or 3D Printed Temporal Bones as Useful for Training as Cadaveric Bones Alan G. Micco MD, FACS, Corresponding Author Alan G. Micco MD, FACS [email protected] orcid.org/0000-0002-7513-5968 Northwestern Feinberg School of Medicine and Northwestern Medicine, Chicago, Illinois, U.S.A. Send correspondence to Alan G. Micco, Northwestern Feinberg School of Medicine and Northwestern Medicine, 676 N. St. Clair, Suite 1325, Chicago, IL 60611. Email: [email protected]Search for more papers by this author Alan G. Micco MD, FACS, Corresponding Author Alan G. Micco MD, FACS [email protected] orcid.org/0000-0002-7513-5968 Northwestern Feinberg School of Medicine and Northwestern Medicine, Chicago, Illinois, U.S.A. Send correspondence to Alan G. Micco, Northwestern Feinberg School of Medicine and Northwestern Medicine, 676 N. St. Clair, Suite 1325, Chicago, IL 60611. Email: [email protected]Search for more papers by this author First published: 17 April 2023 https://doi.org/10.1002/lary.30704 Editor's Note: This Manuscript was accepted for publication on March 26, 2023. No financial support was received or used to prepare this manuscript. I have no disclosures. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Early ViewOnline Version of Record before inclusion in an issue RelatedInformation

HELICAL VERSUS STRAIGHT PLATING OF PROXIMAL THIRD HUMERAL SHAFT FRACTURES - A BIOMECHANICAL STUDY

Proximal humeral shaft fractures are commonly treated with long straight locking plates endangering the radial nerve distally. The aim of this study was to investigate the biomechanical competence in a human cadaveric bone model of 90°-helical PHILOS plates versus conventional straight PHILOS plates in proximal third comminuted humeral shaft fractures.Eight pairs of humeral cadaveric humeri were instrumented using either a long 90°-helical plate (group1) or a straight long PHILOS plate (group2). An unstable proximal humeral shaft fracture was simulated by means of an osteotomy maintaining a gap of 5cm. All specimens were tested under quasi-static loading in axial compression, internal and external rotation as well as bending in 4 directions. Subsequently, progressively increasing internal rotational loading until failure was applied and interfragmentary movements were monitored by means of optical motion tracking.Flexion/extension deformation (°) in group1 was (2.00±1.77) and (0.88±1.12) in group2, p=0.003. Varus/valgus deformation (°) was (6.14±1.58) in group1 and (6.16±0.73) in group2, p=0.976. Shear (mm) and displacement (°) under torsional load were (1.40±0.63 and 8.96±0.46) in group1 and (1.12±0.61 and 9.02±0.48) in group2, p≥0.390. However, during cyclic testing shear and torsional displacements and torsion were both significantly higher in group 1, p≤0.038. Cycles to catastrophic failure were (9960±1967) in group1 and (9234±1566) in group2, p=0.24.Although 90°-helical plating was associated with improved resistance against varus/valgus deformation, it demonstrated lower resistance to flexion/extension and internal rotation as well as higher flexion/extension, torsional and shear movements compared to straight plates. From a biomechanical perspective, 90°-helical plates performed inferior compared to straight plates and alternative helical plate designs with lower twist should be investigated in future paired cadaveric studies.

Numerical model characterization of the sound transmission mechanism in the tympanic membrane from a high-speed digital holographic experiment in transient regime.

A methodology for the development of a finite element numerical model of the tympanic membrane (TM) based on experiments carried out in the time domain on a cadaveric human temporal bone is presented. Using a high-speed digital holographic (HDH) system, acoustically-induced transient displacements of the TM surface are obtained. The procedure is capable to generate and validate the finite element model of the TM by numerical and experimental data correlation. Reverse engineering approach is used to identify key material parameters that define the mechanical response of the TM. Finally, modal numerical simulations of the specimen are performed. Results show the feasibility of the methodology to obtain an accurate model of a specific specimen and to help interpret its behaviour with additional numerical simulations. STATEMENT OF SIGNIFICANCE: Improving knowledge of the dynamic behavior of the tympanic membrane is key to understanding the sound transmission system in human hearing and advance in the treatment of its pathologies. Recently we acquired a new tool to carry out experiments in transient regime by means of digital laser holography, capable of providing a large amount of information in a controlled transient test. In this work, these data are used to develop a methodology that generates a numerical model of the tympanic membrane based on numerical-experimental correlations. It is important to be able to develop models that fit specific patients. In this work, additional modal simulations are also presented that, in addition to validating the results, provide more information on the specimen.

An Injectable Calcium Phosphate Bone Graft Substitute Improves the Pullout Strength of Various Suture Anchor Designs in an Osteoporotic Bone Model

To compare various suture anchor designs with and without calcium phosphate (CaP) augmentation in an osteoporotic foam block model and decorticated proximal humerus cadaveric model. This was a controlled biomechanical study, consisting of 2 parts: (1) an osteoporotic foam block model (0.12 g/cc; n= 42) and (2) a matched pair cadaveric humeral model (n= 24). Suture anchors selected were an all-suture anchor, PEEK (polyether ether ketone)-threaded anchor, and a biocomposite-threaded anchor. For each study arm, one half the samples were first filled with injectable CaP and the other half were not augmented with CaP. For the cadaveric portion, the PEEK- and biocomposite-threaded anchors were assessed. Biomechanical testing consisted of a stepwise, increasing load protocol for a total of 40 cycles, followed by ramp to failure. For the foam block model, the average load to failure for anchors with CaP was significantly greater when compared with anchor fixation augmented without CaP; the all-suture anchor was 135.2 ± 20.2 N versus 83.3 ± 10.3 N (P= .0006); PEEK was 131 ± 34.3 N versus 58.5 ± 16.8 N (P= .001); and biocomposite was 182.2 ± 64.2 N versus 80.8 ± 17.4 N (P= .004). For the cadaveric model, the average load to failure for anchors augmented with CaP was again greater than anchor fixation without CaP; PEEK anchors went from 41.1 ± 21.1 N to 193.6 ± 63.9 N (P= .0034) and biocomposite anchors went from 70.9 ± 26.6 N to 143.2 ± 28.9 N (P= .004). Augmenting various suture anchors with CaP has shown to significantly increase pull-out strength and stiffness in an osteoporotic foam block and time zero cadaveric bone model. Rotator cuff tears are common in the elderly patients, in whom poor bone quality jeopardizes treatment success. Exploring methods that increase the strength of fixation in osteoporotic bone to improve outcomes in this patient population is important.

A cadaveric temporal bone study of the anatomical landmarks for middle turn cochleostomy.

This study aimed to determine anatomical landmarks for accurate and safe middle turn cochleostomy on cadaveric temporal bones. In 17 cadaveric wet adult temporal bones, cortical mastoidectomy was performed, followed by extended posterior tympanotomy through which a middle turn opening was created anterior to the stapes footplate. Micro-measurements of various lengths were taken from the cochleostomy to normal middle-ear anatomical landmarks using a digital microscope. The mean length from the middle turn cochleostomy to the processus cochleariformis was 1.8 ± 0.3 mm and to the tympanic segment of the facial nerve was 2.2 ± 0.3 mm. The mean shortest length from the oval window to the osseous spiral lamina was 2.4 ± 0.3 mm and to the internal carotid artery was 5.0 ± 0.6 mm. The mean shortest length from the round window to the internal carotid artery was 4.3 ± 0.6 mm. A middle turn cochleostomy can be safely drilled by using the measured lengths in difficult cases.

Development of a navigable 3D virtual model of temporal bone anatomy

Background Computed Tomography (CT) scanning offers an accurate structural definition of bones, blood vessels, and soft tissues; however, mental integration of cross-sectional 2D CT images for a 3D understanding of complex anatomical structures becomes difficult when the field of view is confined to the temporal bone. This project tried to provide a feasible solution to this problem by creating a navigable 3D virtual model which may aid in better comprehension of the temporal bone anatomy. Methods A helical-CT scan was used to obtain high-resolution cross-sectional slices of a cadaveric human temporal bone. Using the volume-rendering capabilities of 3D Slicer®, which involves volume data management, cropping of the data set, and threshold painting, detailed anatomical structures were segmented based on the intensity captured from different regions. This volumetric data was converted to an interactive virtual model using Blender®. Results The final product is a web page that allows interaction and navigation with a 3D annotated model of the temporal bone, which can be accessed from any device with a web browser. Conclusion This model can function as a training tool for students, teachers, and practitioners to understand and review the complex anatomy of the temporal bone.

Экспериментальное исследование нагрева костной ткани при воздействии на нее режущими фрезами с использованием бормашины

The article is devoted to modeling the situation of thermal damage to the facial nerve when working with cutting burrs during otosurgical interventions. Materials and methods. 12 cadaveric temporal bones were used, in which the average tissue density was previously measured using the densitometry method. In the work, we used a drill with a speed of 12,000 rpm and 2 spherical 5 mm diameter cutting burrs with 8 and 16 cutting edges. To cool the burr and the bone surface in the affected area, automatic and manual watering with 0,9% saline solution was used. To record the temperature in the bone depth, a system of two chromel-copel thermocouples was used with real-time data recording using a National Instruments analog-to-digital converter with a recording frequency of 100 Hz. A thermal imager Bosch GTC 400 C was used to record the final temperature of the bone surface. Results of the study. The index of the average bone density of the cadaveric temporal bones used in the study varied from 287 to 499 g/cm3. Data have been obtained indicating a direct correlation between bone density and temperature rise during milling. It was found that the rate of local temperature rise during milling of 9 bone samples with a density of 287–392 g/cm3 was statistically significantly (p < 0,05) greater in experiments using the burr with 16 cutting edges compared to experiments with the burr with 8 cutting edges. However, the rate of local temperature rise during milling of 3 bone samples with a density of 402–499 g/cm3 was statistically significantly (p < 0,05) greater in experiments using the burr with 8 cutting edges compared to experiments with the burr with 16 cutting edges. The use of an automatic saline system with preferential irrigation of the burr was less effective than manual delivery with primary irrigation of the bone surface (p = 0,000317). In 10 out of 12 observations with automatic irrigation, local heating of the bone was recorded at an average rate of 0,32 ± 0,15 °C per second, while with manual irrigation only in 1 case was an increase in temperature at a rate of 0,2 °С per second, and in the remaining 11 observations no increase in temperature was recorded. Conclusions. The developed model of the experiment on cadaveric bone tissue using chromel-copel thermocouples turned out to be a convenient tool for studying thermal phenomena. The heating rate of the bone during its burring depends on the bone tissue density, the characteristics of the burr and of irrigation.

Vacuum-Sealed Hot Water Bath Immersion for the Preparation of Anatomical and Surgical Cadaveric Bone Models

Bone models serve many purposes, including improving anatomical understanding, preoperative surgical planning, and intraoperative referencing. Several techniques for the maceration of soft tissues have been described, mainly for forensic analysis. For clinical research and medical use, these methods have been superseded by three-dimensional (3D) printed models, which require substantial equipment and expertise, and are costly. Here, cadaveric sheep vertebral bone was cleaned by vacuum sealing the specimen with commercial dishwashing detergent, immersing in a hot water bath, and subsequently manually removing the soft tissue. This eliminated the disadvantages of the previously existing maceration methods, such as the existence of foul odors, usage of hazardous chemicals, substantial equipment, and high costs. The described technique produced clean, dry samples while maintaining anatomical detail and structure to accurately model the osseous structures that can be useful for preoperative planning and intraoperative referencing. The method is simple, low-cost, and effective for bone model preparation for education and surgical planning in veterinary and human medicine.

C-CASE 2022: Competence to Excellence01. The Queen Bee phenomenon in Canadian surgical subspecialties: an evaluation of gender biases in the resident training environment02. Barriers to surgical peer coaching — What have we learned, and where do we go from here?03. Shared decision-making and evidence-based medicine: Pivotal or trivial to patient care in orthopedic trauma?04. Immersive virtual reality and cadaveric bone

# 01. The Queen Bee phenomenon in Canadian surgical subspecialties: an evaluation of gender biases in the resident training environment {#article-title-2} The Queen Bee phenomenon describes the behavioural response that occurs when women achieve success in a male-dominated environment, and in this

Transplantation of Hematopoietic Stem and Progenitor Cells from Cadaveric Organ Donors Leads to Long-Term Multilineage Engraftment in NSG Mice

Background Infusion of Hematopoietic Stem and Progenitor Cells (HSPC) from cadaveric organ donors (CD) has been used anecdotally in the setting of allogeneic Hematopoietic Stem Cell transplants (HSCT) most commonly with the intention for induction of mixed hematopoietic chimerism and subsequent immunological tolerance. No systematic study has addressed the functional capacity of these cells for inducing long-term multi-lineage engraftment. Since the introduction of post-transplant Cyclophosphamide (PTCy) it has been possible to reliably overcome HLA barriers and achieve stable engraftment across extensively HLA-mismatched donor and recipient pairs. Banked HSPC from cadaveric donors may provide a new approach to expand the number of donors for HSCT. Usage of HSPC from bone marrow (BM) of banked cadaveric donors is viewed as no different than live donor aspirated marrow by the FDA but is not yet available on the registry. This emerging source could be of high importance to allow rapid on-demand access to transplants for patients who lack HSPC donors or induce stable mixed chimerism and immune tolerance in patients undergoing combined organ and BM transplantation. The objective of our studies was to investigate whether hCD34⁺HSC selected from cadaveric BM retain their capacity for long-term multi-lineage engraftment. Methods and Results We compared CD34⁺-selected HSPC obtained from CD and living donors (LD) regarding their in vitro and in vivo function and with particular focus on their ability to achieve long-term multi-lineage engraftment following transplantation into NSG mice. Bone marrow was recovered from vertebral bodies of CD and CD34⁺ selected. 5x10⁵ hCD34⁺ cells from 24 different CD were transplanted i.v. in to NSG or SGM3 mice (n=5 per donor) following 1Gy total body irradiation (TBI). Blood was drawn every two weeks, starting week 4 and human CD45⁺ chimerism was analyzed via flow cytometry. All donors engrafted successfully and robust long-term multi-lineage engraftment >16 weeks was seen in 19 out of 22 donors. To further investigate the long-term repopulating capacity, we performed secondary transplants. BM of 15 primary engrafted donors was harvested, hCD45⁺ were selected with immunobeads and transplanted into 1Gy irradiated NSG mice. Successful multi-lineage engraftment after secondary transfer was observed in 12 out of 15 donors in the peripheral blood (PB). Results of tissue engraftment are still outstanding for most experiments. So far they showed mean engraftment of human CD45⁺ cells of 6.16%+/-2.4% for donor 1 and 8.48%+/-0.74% for donor 2 in the BM. To compare CD and LD we set up two side-by-side transplantation experiments and intra-mouse competitive engraftment studies using HLA-mismatched donors. Using side-by-side experiments no significant difference in human CD45⁺ chimerism was detected in blood measured at weeks 6, 12 and 16 pos-transplant. The tissues showed a mean engraftment of human CD45⁺ cells of 87% +/- 9.6% vs 71% +/- 9.5% in spleen and 76% +/- 5.3% vs 78% +/- 4% (NS) in BM upon takedown 20 weeks post-transplant. For our competitive assays, we transplanted 2.5x10⁵ hCD34⁺ i.v. from LD and CD simultaneously into NSG mice (n=5 per donor pair) following 1Gy TBI. In total 8 CD and 3 LD were used, out of whom 4 CD reached higher engraftment than the LD. Conclusion Our data suggest that CD34+HSPC from CD retain their long-term multi-lineage engraftment capacity, reaching at least equipotent levels as HSPC from living donors. Based on our findings cadaveric bone marrow should be considered as HSPC source for HSCT.

The accuracy of navigated versus freehand curettage in bone tumors: a cadaveric model study

PurposeNavigation has been suggested to guide complex benign bone tumor curettage procedures, but the contribution of navigation to the accuracy of curettage has never been quantified. We explored the accuracy of navigated curettage in a cadaveric observational pilot study, comparing navigated to freehand curettage, performed independently by an expert and a novice user.MethodsThe expert performed curettage on 20 cadaveric bones prepared with a paraffin wax mixture tumor, 10 freehand and 10 navigated. We re-used 12 bones for the novice experiments, 6 freehand and 6 navigated. Tumor and curettage cavity volumes were segmented on pre- and post-cone-beam CT scans. Accuracy was quantified using the Dice Similarity Coefficient (DSC), and with remaining tumor volume, bone curettage volume, maximal remaining width and procedure times compared between navigation and freehand groups for both users.ResultsThere were little differences in curettage accuracy between a navigated (DSC 0.59[0.17]) and freehand (DSC 0.64[0.10]) approach for an expert user, but there were for a novice user with DSC 0.67(0.14) and 0.83(0.06), respectively. All navigated and freehand procedures had some amount of remaining tumor, generally located in a few isolated spots with means of 2.2(2.6) cm3 (mean 20% of the tumor volume) and 1.5(1.4) cm3 (18%), respectively, for the expert and more diffusely spaced with means of 5.1(2.8) cm3 (33%) and 3.0(2.2) cm3 (17%), respectively, for the novice.ConclusionsIn an explorative study on 20 cadaveric bone tumor models, navigated curettage in its current setup was not more accurate than freehand curettage. The amount of remaining tumor, however, confirms that curettage could be further improved. The novice user was less accurate using navigation than freehand, which could be explained by the learning curve. Furthermore, the expert used a different surgical approach than the novice, focusing more on removing the entire tumor than sparing surrounding bone.

Ex vivo assessment of surgically repaired tibial plateau fracture displacement under axial load using large-volume micro-CT

Postoperative weight bearing has the potential to generate fragmental motion of surgically repaired tibial plateau fractures (TPFs), which may contribute to loss of fracture reduction. The effect of loading on the internal distribution of fragmentary displacements is currently unknown. The aim of this study was to determine the internal displacements of surgically repaired split TPFs due to a three-bodyweight load, using large-volume micro-CT imaging and image correlation. Fractures were generated and surgically repaired for two cadaveric specimens. Load was applied to the specimens inside a large-volume micro-CT system and scanned at 0.046 mm isotropic voxel size. Pre- and post-loading images were paired, co-registered, and internal fragmentary displacements quantified. Internal fragmental displacements of the cadaveric bones were compared to in vivo displacements measured in the lateral split fragments of TPFs in a clinical cohort of patients who had similar surgical repair and were prescribed pain tolerated postoperative weight bearing. The split fragments of cadaveric specimens displaced, on average, less than 0.3 mm, consistent with in vivo measurements. Specimen one rotated around the mediolateral axis, while specimen two displaced consistently caudally. Specimen two also had varying displacements along the mediolateral axis where, at the fracture site, the fragment displaced caudally and laterally, while the most lateral edge of the tibial plateau displaced caudally and medially. The methods applied in this study can be used to measure internal fragmental motion within TPFs.

Improvement of a commercial calcium phosphate bone cement by means of drug delivery and increased injectability

Calcium phosphate cements (CPCs) have been increasingly used as synthetic bone substitutes for repair and regeneration of bone defects given their biocompatibility, resemblance to bone and malleability. Moreover, their use as local antibiotic delivery systems is of main interest against bone infections, avoiding the adverse effects of high dosages of conventional therapy. The main goals of this work were to improve the properties of a commercial CPC (Neocement®), turning it injectable, and to provide it with a new functionality as a drug delivery system able to ensure a sustained release of an antibiotic commonly used in orthopaedics (gentamicin sulphate, GS). For this, the influence of the liquid phase amount (%LP) and type of polymer contained in the formulation (chitosan, Chi, or hydroxypropyl methylcellulose, HPMC) on the basic properties of the material was evaluated. It was found that the formulation containing 42%LP + HPMC+1.87% wt GS was the best one. It showed suitable setting and mechanical properties, and injectability around 87% (much superior to the original Neocement®, with 31%). It ensured a sustained release of GS for at least 14 days, at antibacterial levels. The antibiotic released is highly effective against S. epidermidis, but also presents some antibacterial activity against S. aureus. The CPC revealed to be non-cytotoxic. Moreover, it demonstrated good flowability and connectivity with human cadaveric trabecular bone.

Experimental testing of fracture fixation plates: A review.

Metal and its alloys have been predominantly used in fracture fixation for centuries, but new materials such as composites and polymers have begun to see clinical use for fracture fixation during the past couple of decades. Along with the emerging of new materials, tribological issues, especially debris, have become a growing concern for fracture fixation plates. This article for the first time systematically reviews the most recent biomechanical research, with a focus on experimental testing, of those plates within ScienceDirect and PubMed databases. Based on the search criteria, a total of 5449 papers were retrieved, which were then further filtered to exclude nonrelevant, duplicate or non-accessible full article papers. In the end, a total of 83 papers were reviewed. In experimental testing plates, screws and simulated bones or cadaver bones are employed to build a fixation construct in order to test the strength and stability of different plate and screw configurations. The test set-up conditions and conclusions are well documented and summarised here, including fracture gap size, types of bones deployed, as well as the applied load, test speed and test ending criteria. However, research on long term plate usage was very limited. It is also discovered that there is very limited experimental research around the tribological behaviour particularly on the debris’ generation, collection and characterisation. In addition, there is no identified standard studying debris of fracture fixation plate. Therefore, the authors suggested the generation of a suite of tribological testing standards on fracture fixation plate and screws in the aim to answer key questions around the debris from fracture fixation plate of new materials or new design and ultimately to provide an insight on how to reduce the risks of debris-related osteolysis, inflammation and aseptic loosening.

Predicting Cochlear Implant Electrode Placement Using Monopolar, Three-Point and Four-Point Impedance Measurements.

This study aimed to investigate the relationship between cochlear implant (CI) electrode distances to the cochlea's inner wall (the modiolus) and electrical impedance measurements made at the CI's electrode contacts. We introduced a protocol for "three-point impedances" in which we recorded bipolar impedances in response to monopolar stimulation at a neighboring electrode. We aimed to assess the usability of three-point impedances and two existing CI impedance measurement methods (monopolar and four-point impedances) for predicting electrode positioning during CI insertion. Impedances were recorded during stepwise CI electrode array insertions in cadaveric human temporal bones. The positioning of the electrodes with respect to the modiolus was assessed at each step using cone beam computed tomography. Linear mixed regression analysis was performed to assess the relationship between the impedances and electrode-modiolar distances. The experimental results were compared to clinical impedance data and to an existing lumped-element model of an implanted CI. Three-point and four-point impedances strongly correlated with electrode-modiolar distance. In contrast, monopolar impedances were only minimally affected by changes in electrode positioning with respect to the modiolus. An overall model specificity of 62% was achieved when incorporating all impedance parameters. This specificity could be increased beyond 73% when prior expectations of electrode positioning were incorporated in the model. Three-point and four-point impedances are promising measures to predict electrode-modiolar distance in real-time during CI insertion. This work shows how electrical impedance measurements can be used to predict the CI's electrode positioning in a biologically realistic model.

HR-pQCT parameters of the distal radius correlate with the bending strength of the radial diaphysis.

High resolution, peripheral quantitative computed tomography (HR-pQCT) scanners can now characterize an individual's trabecular architecture, cortical structure, and volumetric bone mineral density at a nominal resolution of 61μm. While predictions of failure load of the distal radius and tibial diaphysis in compression by finite element analysis (FEA) of HR-pQCT scans have been validated against mechanical tests of cadaveric bones in compression, namely for images with nominal resolutions of 82μm and 165μm, the HR-pQCT parameters that best predict bending strength of cortical bone remain unknown. Therefore, we scanned cadaveric forearms from 31 elderly donors (Female: 72.8±8.8years and Male: 72.1±6.3years), and then loaded the radial diaphysis to failure in three-point bending after denuding each bone (38 in total). The cortical parameters had stronger correlations with ultimate moment than the trabecular parameters such that cortical area and estimated failure load of the distal radius had the highest Spearman correlation coefficients (r=0.89 and r=0.81, respectively, p<0.0001). Despite being a known determinant of bone strength, cortical porosity of the distal radius did not correlate with ultimate moment (p=0.8537). In multivariate linear regressions with section modulus (SM) of the radial diaphysis as one of two predictors of bending strength, cortical area and cortical thickness were each significant contributors to the prediction of ultimate moment. Their contribution was one-half and one-third, respectively, of the contribution from SM. None of the HR-pQCT parameters were strongly correlated with post-yield displacement, an indicator of bone brittleness. In support of HR-pQCT imaging of the distal radius to identify individuals with osteoporosis, the present study found that parameters of the cortex and failure load predictions by linear FEA are strongly related to the bending strength of cortical bone.

Three-Dimensional Plastic Modeling on Bone Frames for Cost-Effective Neuroanatomy Teaching.

Cadaveric models remain an essential part of medical training across all specialties. Due to their scarcity, high costs, and possible health hazards, there is a need for more accessible and affordable alternatives, especially in low-resource settings. We introduce cost-effective and easily replicable three-dimensional (3D) printed models to help democratize access to hands-on neuroanatomy education.Silicone-based glue is applied on the surface of a 3D-printed or cadaveric bone frame. Using plastiline on a 3 mm 3D acrylonitrile butadiene styrene pen, the desired anatomical structure is printed on the bone frame. A heat gun is used to smoothen the plastic edges. The structure can then be painted according to its appearance in the real anatomy.Using this technique, we successfully generated a variety of anatomical models to study the cerebrovascular anatomy, the course of the cranial nerves in relation to the skull base, and extracranial structures including the spine.Procurement and conservation of cadaveric specimens can be cumbersome. Our model may be an affordable and easily replicable approach to bridging the gap in anatomy education between low- and high-resource facilities.