Cadaveric Bones Research Articles

The Evaluation of Mechanical Properties of Commercial Composite Bones and 3D-Printed Bones Produced Using the CJP Technology

Cadaver bones and artificial bones are utilized to perform preoperative studies and education purposes. Cadaver bones are hard to find, require ethical permissions, and have infection hazards. Therefore, commercial artificial bones are preferred in practice. Nonetheless, since these commercial alternatives are standardly produced in an average size and geometry, it is almost impossible to adapt them to a specific surgical simulation. In addition, these artificial bones have relatively high costs, which limits their accessibility. On the other hand, ColorJet printing (CJP), one of the three-dimensional printing technologies, offers a rapid and cost-effective alternative. However, whether the printed 3D-printed models can mechanically comply with artificial bones is unclear. In this study, 3D-printed bones and artificial commercial composite bones were compared in terms of mechanical properties. Compression tests were applied over 14 printed and 14 composite bones using the ISO 5833 standard. Mechanical properties including stress-strain, load to failure, and elastic modulus were calculated, and these results were compared using the two-sample independent t-test, which is one of the statistical analysis methods. Consequently, there was no significant difference between the bone models in terms of stress and failure load values (p

Inclusion of Glenoid Anteversion Provides a More Accurate Assessment of Glenoid Stability Using a Measuring Protocol for Modified Bony Shoulder Stability Ratio

PurposeThe objectives are to clarify whether there is a disparity between the conventional bony shoulder stability ratio (cBSSR) calculated using Moroder's method and satbility ratio (SR) obtained biomechanically, and whether the modified BSSR (mBSSR) calculated using the new method adjusted for glenoid anteversion shows good consistency with the biomechanically determined SR. MethodsForty-two glenoid models were successively constructed from seven cadaveric scapula bones, each with varying degrees of bone defects (intact/2 mm/4 mm/6 mm/8 mm/10 mm). The cBSSR and mBSSR were calculated by using the conventional and the modified radiological protocols, respectively. A biomechanical experiment was conducted to measure the biomechanical SR of the glenoid model for accuracy validation. Linear regression, ICC, Bland‒Altman plots, and repeated ANOVA were performed to compare these methods to ascertain the impact of including glenoid anteversion on the accuracy of the BSSR. ResultsThe mBSSR, which includes glenoid anteversion, showed a stronger correlation with biomechanical SRs compared to the cBSSR. Linear regression analysis showed R2 = 0.7727 and ICC = 0.726 for mBSSR vs. biomechanical SR, while R2 = 0.5507 and ICC = 0.363 for cBSSR vs. biomechanical SR. Bland‒Altman analysis revealed less bias between the mBSSR and biomechanical SR (bias = 0.0854, 95% CI [-0.0762, 0.2470]) than between the cBSSR and biomechanical SR (bias = 0.1899, 95% CI [0.0039, 0.3759]). Repeated measures ANOVA confirmed a significant difference between the cBSSR and biomechanical SR (p = 0.002). ConclusionThe inclusion of glenoid anteversion in the mBSSR calculations provides a more accurate assessment of glenoid stability. Our findings indicate the need to consider anteversion adjustments in BSSR estimation. Clinical RelevanceOur present research identified that conventional methods did not take glenoid anteversion into account. Through comprehensive biomechanical experiment, we have demonstrated that incorporating glenoid anteversion in the BSSR calculation yields a more precise assessment of glenoid stability, which can provide a crucial methodological foundation for clinical assessments.

A novel therapeutic pathway to the human cochlear nerve.

Traditional approaches to the human cochlear nerve have been impeded by its bony encasement deep inside the skull base. We present an innovative, minimally invasive, therapeutic pathway for direct access to the nerve to deliver novel regenerative therapies. Neuroanatomical studies on 10 cadaveric human temporal bones were undertaken to identify a potentially safe therapeutic pathway to the cochlear nerve. Simulations based on three-dimensional delineation of anatomical structures obtained from synchrotron phase-contrast imaging were analyzed. This enabled the identification of an approach to the nerve in the fundus of the internal auditory meatus by trephining the medial modiolar wall of the cochlea via the round window for a median depth of 1.48mm (range 1.21-1.91mm). The anatomical access was validated on 9 additional human temporal bones using radio-opaque markers and contrast injection with micro-computed tomography surveillance. We thus created an effective conduit for the delivery of therapeutic agents to the cochlear nerve.

Accuracy and precision of Volumetric Matching Micromotion Analysis (V3MA) is similar to RSA for tibial component migration in TKA.

Radiostereometric analysis (RSA) is the current gold standard to determine implant migration, but it requires bone markers and special equipment. Therefore, we developed VoluMetric Matching Micromotion Analysis (V3MA), a software program for Computed Tomography-based radiostereometric analysis (CT-RSA). This study aimed to determine the accuracy and precision of V3MA in vitro compared to RSA and provide a clinical proof of concept. The accuracy (RMSE (Root Mean Squared Error)) and precision (SD (standard deviation)) of V3MA were compared to RSA. A tibial component was placed in 21 different positions within a cadaveric bone to assess accuracy. For precision,a total of 20 repeated zero-migration examinations from 4 cadaveric bones with cemented tibial components were performed. In 6 total knee arthroplasty (TKA) patients 1 to 5 year migration was measured with V3MA and RSA. V3MA accuracy ranged between 0.02 and 0.09 mm for translations and was 0.01° for internal-external rotations. For RSA, the accuracy ranged between 0.03 and 0.09 mm for translations and was 0.09° for internal-external rotations. V3MA precision ranged between 0.01 and 0.06 mm for translations and 0.02 to 0.07° for rotations. RSA precision ranged between 0.00 and 0.06 mm for translations and 0.04 to 0.25° for rotations. V3MA was successful in 6 clinical cases and no systematic bias was present. In conclusion, the accuracy and precision of V3MA were similar to RSA. Therefore, V3MA is a promising alternative to RSA in migration measurements of tibial components in TKA.

Elastic properties of 3D printed clavicles are closer to cadaveric bones of elderly donors than commercial synthetic bones

Synthetic bone models have increasing utility in orthopaedic research due to their low cost and low variability and have been shown to be biomechanically equivalent to human bones in a variety of ways. The rise in additive manufacturing (AM) for orthopaedic applications presents an opportunity to construct synthetic whole-bone models for biomechanical testing applications, but there is a lack of research comparing these AM models to cadaveric or commercially available bone surrogates. This study compares the mechanical properties of 3D printed clavicle models to commercially available (4th generation Sawbones) and human cadaveric clavicles via nondestructive cyclic 4-point bending, axial compression, and torsion, and a final axial compression test to failure. Commercially available synthetic clavicles had 57.8–203% higher superior-inferior bending rigidity (p < 0.0001), 80.9–198% higher axial stiffness (p < 0.001), and 314–557% higher torsional rigidity (p < 0.05) on average than AM and cadaveric clavicles. Cadaveric and AM clavicles printed from a BoneMatrix/VeroWhite composite material had similar failure mechanisms under axial compression while AM VeroWhite clavicles experienced catastrophic failure, but these groups did not have significantly different ultimate failure loads. Together, these results demonstrate that current commercially available synthetic clavicles may be too rigid to emulate the mechanical properties of elderly cadaveric clavicles, and that AM bone models can closely mimic these cadaveric bones in a variety of biomechanical loading schemes. These results show promising applications for future work using 3D printed bone surrogates for biomechanical analysis of orthopaedic implants and other surgical repair techniques.

Bicortical Compression and Construct Stability With Variable Pitch Locking Screws in Cadaveric Specimens.

A variable pitch locking screw is intended to provide interfragmentary compression combined with fixed angle stability of locking plate constructs. The objective of this study was to compare variable pitch locking screws (3.5-mm KreuLock Ti locking compression screws, Arthrex Inc., Naples, FL) with standard locking screws (from the same manufacturer) in bicortical fixation scenarios in cadaver bone by assessing (1) interfragmentary compression and plate-bone compression and (2) construct biomechanical stability. Nine matched pairs of fresh-frozen cadaveric specimens with an average age of 67.2 years (range, 37-83) were used. Interfragmentary compression and plate-bone compression associated with insertion of single bicortical screws were compared between the variable pitch and standard locking screws at increasing levels of torque. The specimens tested were distal tibiae having a simulated longitudinal fracture. Additionally, fibulae were osteotomized to create a stable longitudinal fracture pattern and were fixed with a 5-screw plate construct with either all variable pitch or all standard locking screws. One of the 5 screws was placed across the osteotomy without lagging. Fibulae were tested cyclically with axial with torsional loading to compare displacements, rotation, and loads at failure or tested in 4-point bending to compare construct stiffness and maximum force to failure. Interfragmentary and plate-bone compression forces in the distal tibia model varied across specimens but were significantly higher with variable pitch locking screws compared with standard locking screws [512 N (SD = 324 N) vs. 79 N (SD = 64 N), P = 0.002, and 242 N (SD = 119 N) vs. 104 N (SD = 123 N), P = 0.028, respectively]. In cyclic loading of fibula constructs, no significant differences were detected in construct axial displacement or angular displacement (P > 0.05). In 4-point bending, no differences were detected in maximum force or bending stiffness (P > 0.05). Variable pitch locking screws produced interfragmentary compression between cortices and plate-bone compression that was greater than that produced by standard locking screws. In a stable bicortical fibula fixation scenario under external loading, the stability of variable pitch locking screw constructs was similar to constructs with standard locking screws.

Closed reduction by robot with different modes: Experimental study on tibial fracture specimen

PurposeThis paper evaluates the accuracy and safety of a long bone fracture reduction robot under different surgical modes. MethodsA long bone fracture reduction robot system was developed, which can be controlled via an autonomous surgical mode or a master-slave surgical mode. Reduction experiments were conducted on a long bone cadaver specimen. The accuracy and safety of the robotic reduction were compared across the different surgical modes. ResultsWhen the fracture reduction was completed by the robot, the translational deviation was less than 2 mm, and the angular deviation was less than 3° The autonomous reduction time was 140 s, while the master-slave reduction time was 200 s. ConclusionsBased on CT imaging verification, the accuracy of the robot in both autonomous and master-slave surgical modes meets clinical requirements. Future work will focus on further optimizing the robot system.

Frequency dependence and harmonic distortion of stapes displacement and intracochlear pressure in response to very high level sounds

Previous reports have suggested that intracochlear pressures (PIC) measured at the base of the cochlea increase directly proportionally with stapes displacement (DStap) in response to moderately high (<130 dB SPL) level sounds. Consistent with this assumption, we have reported that for low frequency sounds (<1 kHz), stapes displacement and intracochlear pressures increase linearly with sound pressure level (SPL) for moderately high levels (<130 dB SPL), but saturate at higher exposure levels (>130 dB SPL). However, the magnitudes of each response were found to be frequency dependent, thus the relationship between DStap and PIC may vary at higher frequencies or higher levels.In order to further examine this frequency and level dependence, measurements of DStap and PIC were made in cadaveric human temporal bones prepared with a mastoidectomy and extended facial recess to expose the ossicular chain. PIC was measured in scala vestibuli (PSV) and scala tympani (PST) simultaneously with SPL in the external auditory canal (PEAC) and laser Doppler vibrometry (LDV) measurements of stapes velocity (VStap). Consistent with prior reports, DStap and PSV increased proportionally with sound pressure level in the ear canal up to a frequency-dependent saturation point, above which both DStap and PSV showed a distinct deviation from proportionality with PEAC, suggesting that their relationship may remain constant at these high frequencies. Likewise, while the asymptotic value, and SPL at which saturation occurred were frequency dependent in both DStap and PSV, the reduction in gain with increasing SPL above this level was constant above this level at all frequencies, and the magnitude of responses at harmonics of the driving frequency increased with increasing level, consistent with harmonic distortion via peak clipping. Importantly, this nonlinear distortion shifts the energy arriving at the inner ear to higher frequencies than are present in incident stimulus, thus exposing the high frequency sensitive components of the auditory system to more noise than would be expected from measurement of that stimulus on its own. Overall, responses suggest that the cochlear representation of very high-level air conducted stimuli is limited by nonlinearities in the middle ear, and that this peak limiting leads to increased high frequency cochlear exposures than are present in the driving stimulus.

Nail–Plate Constructs for Treating Distal Femur Fractures: A Systematic Review of Biomechanical Studies

The biomechanical efficacy of nail–plate constructs (NPCs) used in the treatment of traumatic distal femur fractures (DFFs) remains understudied compared to traditional approaches. This systematic review examines the biomechanical efficacy of NPCs compared to alternative approaches for the surgical fixation of DFFs to guide surgical decision-making and improve patient outcomes. This systematic review searched the PubMed, CINAHL, MEDLINE, Web of Science, and SPORT Discus databases from inception until 24 January 2024. Inclusion criteria were biomechanical studies that involved nail–plate combination constructs for DFFs. Six observational studies were included. Of the included studies, five studies utilized synthetic bone models in testing, and one study used both synthetic and cadaveric bone models. All studies found NPCs to have significantly higher axial and torsional stiffness and resistance to loading than distal lateral femoral locking plate (DLFLP) constructs. The 11 mm NPCs were significantly stiffer than the 9 mm NPCs under torsional and axial loading. Only one of two studies found NPCs to have greater axial stiffness than dual-plate (DP) constructs. NPCs and DP constructs had greater torsional and axial stiffness than the plate-only or DP with medial distal tibial plate constructs. NPCs had less displacement and torque than the plate- or nail-only constructs under axial and torsional loads. NPCs demonstrate superior axial and torsional stiffness and resistance to mechanical loads compared to DLFLP. The varying performance between 11 mm and 9 mm NPCs suggests that construct diameter plays a role in mechanical stability. NPCs and DP constructs performed better than plate-only constructs. Future research should explore the impact of varying nail diameters and plate configurations on stability, as well as the clinical efficacy of NPCs across different patient populations, particularly those with varying bone densities, to better understand their performance in real-world scenarios.

The UmboMic: a PVDF cantilever microphone *

Objective. We present the ‘UmboMic,’ a prototype piezoelectric cantilever microphone designed for future use with totally-implantable cochlear implants. Methods. The UmboMic sensor is made from polyvinylidene difluoride (PVDF) because of its low Young’s modulus and biocompatibility. The sensor is designed to fit in the middle ear and measure the motion of the underside of the eardrum at the umbo. To maximize its performance, we developed a low noise charge amplifier in tandem with the UmboMic sensor. This paper presents the performance of the UmboMic sensor and amplifier in fresh cadaveric human temporal bones. Results. When tested in human temporal bones, the UmboMic apparatus achieves an equivalent input noise of 32.3 dB SPL over the frequency range 100 Hz–7 kHz, good linearity, and a flat frequency response to within 10 dB from about 100 Hz–6 kHz. Conclusion. These results demonstrate the feasibility of a PVDF-based microphone when paired with a low-noise amplifier. The reported UmboMic apparatus is comparable in performance to a conventional hearing aid microphone. Significance. The proof-of-concept UmboMic apparatus is a promising step towards creating a totally-implantable cochlear implant. A completely internal system would enhance the quality of life of cochlear implant users.

A Novel Bone-Screw-Fastener Demonstrates Greater Maximum Compression Force Before Failure Compared With a Traditional Buttress Screw.

This study compared the maximal compression force before thread stripping of the novel bone-screw-fastener (BSF) with the traditional buttress screw (TBS) in synthetic osteoporotic and cadaveric bone models. The maximum compression force of the plate-bone interface before loss of screw purchase during screw tightening was measured between self-tapping 3.5-mm BSF and 3.5-mm TBS using calibrated load cells. Three synthetic biomechanical models were used: a synthetic osteoporotic diaphysis (model 1), a 3-layer biomechanical polyurethane foam with 50-10-50 pounds-per-cubic-foot layering (model 2), and a 3-layer polyurethane foam with 50-15-50 pounds-per-cubic-foot layering (model 3). For the cadaveric metaphyseal model, 3 sets of cadaveric tibial plafonds and 3 sets of cadaveric tibial plateaus were used. A plate with sensors between the bone and plate interface was used to measure compression force during screw tightening in the synthetic bone models, while an annular load cell that measured screw compression as it slid through a guide was used to measure compression in the cadaver models. Across all synthetic osteoporotic bone models, the BSF demonstrated greater maximal compression force before stripping compared with the TBS [model 1, 155.51 N (SD = 7.77 N) versus 138.78 N (SD = 12.74 N), P = 0.036; model 2, 218.14 N (SD = 14.15 N) versus 110.23 N (SD = 8.00 N), P < 0.001; model 3, 382.72 N (SD = 20.15) versus 341.09 N (SD = 15.57 N), P = 0.003]. The BSF had greater maximal compression force for the overall cadaver trials, the tibial plafond trials, and the tibial plateau trials [overall, 111.27 N vs. 97.54 N (SD 32.32 N), P = 0.002; plafond, 149.6 N versus 132.92 N (SD 31.32 N), P = 0.006; plateau, 81.33 N versus 69.89 N (SD 33.38 N), P = 0.03]. The novel bone-screw-fastener generated 11%-65% greater maximal compression force than the TBS in synthetic osteoporotic and cadaveric metaphyseal bone models. A greater compression force may increase construct stability, facilitate early weight-bearing, and reduce construct failure.

A Comparative Analysis on the Histomorphometric Pattern of Various Segments of Adult Male Long Bones: Forensic Implication

Abstract Background: Human bone analysis is a useful tool in assessing and identifying skeletal remains. To make this easier, newer and modified approaches have often being documented. Aims and Objectives: The aim of this study is to analyze the histomorphometric features of various bone segments and its relevance in forensic case diagnosis. Materials and Methods: The human bones used were that of cadaveric bone samples harvested from three adult male Nigerians. The proximal, midshaft and distal segments of the femur, tibia, and humerus were utilized for the study. The bone sections were subjected to processing using Frost’s rapid manual preparation of ground sections techniques. Histomorphometric evaluation studied the number of primary osteons, secondary osteons, and osteon fragments, as well as the Haversian canal diameter (HCD). Results: The primary osteons, secondary osteons, osteon fragments, and HCD in each of the segments of the long bones show that the F values are less than the F critical for an alpha level of 0.05. This shows that there is no statistically significant (P &gt; 0.05) variation in the histomorphometric pattern for the various segments of the bones studied. Again differences in the haversian canal diameter of the various segments of the long bones shows statistically significant variation (P&lt; 0.05) among the long bones investigated. Conclusion: These findings have laid to rest the challenges with using the only available bone fragment for forensic case investigation as no notable variations exist across various segments.

Analysis of load distribution on the plate and lateral hinge of a valgus opening high tibial osteotomy during weight-bearing: a finite element analysis

IntroductionValgus high tibial osteotomy (HTO) is indicated for managing isolated medial knee osteoarthritis in a young patient with a metaphyseal deformity of the proximal tibia. In a medial opening HTO, maintaining the integrity of the lateral hinge is crucial for ensuring proper healing and correction retention. Using a locked plate to stabilize an HTO is common practice, allowing for earlier weight-bearing. The objective of this study was therefore to measure and track the mechanical load distribution on a locked fixation plate and the lateral hinge of an HTO using a finite element (FE) model simulating single-leg stance loading. HypothesisThe working hypothesis was that during weight-bearing, the plate and the lateral hinge absorb stress asymmetrically, predominantly on the plate. Material and methodsA numerical model of an HTO stabilized with a locked plate was developed based on the actual geometry of a healthy proximal tibia (using Autodesk Fusion 360 and Altair HyperWorks software). In this finite element simulation of loading, a mesh convergence study was conducted to optimize the accuracy of the numerical model results. The primary outcome measure was the maximum stress value in the affected areas (Von Mises stress, in MPa) of the plate and the lateral hinge. ResultsThe maximum stress intensity in the plate was approximately 20.29 MPa. The maximum stress intensity in the bony hinge was about 5.6 MPa. The results of the mesh convergence study for the hinge and the plate enabled defining the most suitable model for future FE studies: a 4 mm mesh for all model elements except for the high-stress area in the plate and the hinge, which were meshed with a 0.7 mm element size. This adaptation provided greater precision in the study. DiscussionThere is a distribution and allocation of stress both on the plate and the hinge, underlining the significance of the plate and the absolute necessity of preserving the hinge. Predictably, the plate absorbs the majority of the load, more than three times that of the hinge. ConclusionThe hypothesis is confirmed; however, additional studies would be necessary to validate these numerical results: an experimental component on instrumented cadaveric bones, as well as comparative studies of different fixation plates. Level of EvidenceV, expert opinion; controlled laboratory study.

Cochlear-Carotid Interval: Bridging Surgical Insights and Radiological Findings in Cadaveric Human Temporal Bones.

The temporal bone is a complex neurovascular structure. The procedure of cochlear implantation is performed with in few millimetres of area around which important structures like internal carotid artery, jugular bulb and facial nerve are present. Displacement of an electrode into the carotid canal although rare is considered as a major complication in cochlear implant surgery. The purpose of this study is to highlight the close anatomic relationship (radiologically as well as on cadaveric temporal bone dissection) between the cochlea and the carotid canal and its variations which will be helpful during cochlear implant (CI) surgery to prevent injury to internal carotid artery. This study was done in SMS Medical College and Hospital, Jaipur, India. High resolution computed tomography (HRCT) of cadaveric temporal bones was done after getting permission from ethical committee of the institute. 40 bones were studied. Cochlear carotid interval (CCI) was measured with the help of dicom reader and the same temporal bones were dissected under microscope and CCI was measured with help of millimetre scale. The CCI was found to be 2.08 ± 0.89mm and it was ranging from 0.48 to 4.25mm on HRCT temporal bone and on dissection 2.19 ± 0.85mm and it was ranging from 0.85 to 4.12mm. With the increasing popularity of CI surgeries, the importance of the CCI has become more pronounced, highlighting the need for meticulous surgical planning and technique. To the best of our knowledge this is the first study of CCI which is correlating radiological and dissection anatomy of CCI.

Locked plate constructs are not necessarily stiffer than nonlocked constructs: A biomechanical investigation of locked versus nonlocked diaphyseal fixation in a human cadaveric model of nonosteoporotic and osteoporotic distal femoral fractures.

The objective of this study was to compare the biomechanical properties of locked and nonlocked diaphyseal fixation in a model of distal femur fractures using osteoporotic and nonosteoporotic human cadaveric bone. A supracondylar osteotomy was created to mimic a fracture (OTA/AO 33A3) in osteoporotic (n = 4) and nonosteoporotic (n = 5) cadaveric distal femurs. The left and right femurs of each pair were instrumented with a distal femoral locking plate and randomly assigned to have diaphyseal fixation with either locked or nonlocked screws. The construct was cyclically axially loaded, and construct stiffness and load to failure were evaluated. In osteoporotic bone, locked constructs were more stiff than nonlocked constructs (mean 143 vs. 98 N/mm when all time points combined, P < 0.001). However, in nonosteoporotic bone, locked constructs were less stiff than nonlocked constructs (mean 155 N/mm vs. 185 N/mm when all time points combined, P < 0.001). In osteoporotic bone, the average load to failure was greater in the locked group than in the nonlocked group (mean 1159 vs. 991 N, P = 0.01). In nonosteoporotic bone, the average load to failure was greater for the nonlocked group (mean 1348 N vs. 1214 N, P = 0.02). Bone mineral density was highly correlated with maximal load to failure (R2 = 0.92, P = 0.001) and stiffness (R2 = 0.78, P = 0.002) in nonlocked constructs but not in locked constructs. Contrary to popular belief, locked plating constructs are not necessarily stiffer than nonlocked constructs. In healthy nonosteoporotic bone, locked diaphyseal fixation does not provide a stiffer construct than nonlocked fixation. Bone quality has a profound influence on the stiffness of nonlocked (but not locked) constructs in distal femur fractures.

Morphometric analysis of proximal femur in Indian population and its implications in Total Hip Arthroplasty

Geometric understanding of the proximal end of femur is significant for functional bipedal erect posture and in pre-operative planning of osteotomy as well as the design and development of implants for THA. Moreover, the anthropological parameters of any bone are determined by genetic and environmental factors such as age, race, gender and lifestyle and this leads to racial variations in the morphological parameters of proximal end of femur owing to lifestyle, physique, applied force and their distribution in India population.The current study was designed to study and compare the morphology of proximal end of femur in Indian population and was conducted on 94 dry human cadaveric bones of unknown age and sex to determine the morphology of the proximal end of femur. We observed the Femur Length as 426.6 ± 15.82 mm, Femur Neck Length as 3.455 ± 0.378 mm and Neck Shaft Angle as 125.27 ± 2.54° amongst other parameters.The findings also revealed significant variations in the morphological parameters among different populations, emphasizing the importance of considering racial diversity in the design and selection of implants for THA for improving the success and longevity of hip arthroplasty procedures.

The construction of canine distal limb models used in teaching sonography identification of vegetal foreign bodies.

Musculoskeletal ultrasonography is a useful tool to identify radiolucent vegetal foreign bodies (VFBs). However, limited ultrasound experience and unfamiliarity with the normal sonographic appearance of anatomical structures can decrease clinician confidence. This study aimed to design a reusable silicone model that can teach VFB identification within the canine distal limb. Four canine hindlimbs were used to design the silicone models, and 12 canine distal forelimbs were constructed. The model was constructed using cadaver bones, barley grass (Avena fatua) seeds, and silicone to mimic the anatomy of the canine distal limb with a grass seed VFB. Limbs were randomly grouped based on grass seed locations: (1) the interdigital webbing, (2) the palmar surface of the canine forelimb immediately proximal to the metacarpal pad, (3) the dorsal surface of the distal limb immediately proximal to the proximal phalange, or (4) no grass seed (control) placed. Each limb was systematically ultrasounded and compared with cadaver limbs and clinical VFB cases. A comparison of ultrasonographic images validated the construction, revealing that the simulation model replicates the anatomical and echotexture characteristics of the normal canine distal limb. Furthermore, these models also have a likeness to clinical canine distal limb VFB cases and can be utilized as a training tool.

Posterior atlantoaxial fixation of osteoporotic odontoid fracture: biomechanical analysis of the Magerl versus harms techniques in a cadaver model

BACKGROUND CONTEXTOdontoid fractures are among the most common cervical spine fractures in the elderly and are associated with increased morbidity and mortality. Clinical evidence suggests improved survival and quality of life after operative intervention compared to nonoperative treatment. PURPOSEThis study seeks to examine the stability of an osteoporotic Type II odontoid fracture following posterior atlantoaxial fixation with either the Magerl transarticular fixation technique or the Harms C1 lateral mass screws C2 pedicle screw rod fixation. STUDY DESIGNBiomechanical cadaveric study. METHODSEighteen cadaveric specimens extending from the cephalus to C7 were used in this study. Reflective marker arrays were attached to C1 and C2 and a single marker on the dens to measure movement of each during loading with C2–C3 and occiput-C1 being allowed to move freely. A biomechanical testing protocol imparted moments in flexion-extension, axial rotation, and lateral bending while a motion capture system recorded the motions of C1, C2, and the dens. The spines were instrumented with either the Harms fixation (n=9) or Magerl fixation (n=9) techniques, and a simulated Type II odontoid fracture was created. Motions of each instrumented spine were recorded for all moments, and then again after the instrumentation was removed to model the injured, noninstrumented state. RESULTSBoth Harms and Magerl posterior C1–C2 fixation allowed for C1, C2, and the dens to move as a relative unit. Without fixation the dens motion was coupled with C1. No significant differences were found in X, Y, Z translation motion of the dens, C1 or C2 during neutral zone motions between the Magerl and Harms fixation techniques. There were no significant differences found in Euler angle motion between the two techniques in either flexion-extension, axial rotation, or lateral bending motion. CONCLUSIONSOur findings suggest that both Harms and Magerl fixation can significantly reduce dens motion in Type II odontoid fractures in an osteoporotic cadaveric bone model. CLINICAL SIGNIFICANCEBoth Harms and Magerl posterior atlantoaxial fixation techniques allowed for C1, C2, and the dens to move as a relative unit following odontoid fracture, establishing more anatomic stability to the upper cervical spine.

Integration of 3D-printed middle ear models and middle ear prostheses in otosurgical training

BackgroundIn otosurgical training, cadaveric temporal bones are primarily used to provide a realistic tactile experience. However, using cadaveric temporal bones is challenging due to their limited availability, high cost, and potential for infection. Utilizing current three-dimensional (3D) technologies could overcome the limitations associated with cadaveric bones. This study focused on how a 3D-printed middle ear model can be used in otosurgical training.MethodsA cadaveric temporal bone was imaged using microcomputed tomography (micro-CT) to generate a 3D model of the middle ear. The final model was printed from transparent photopolymers using a laser-based 3D printer (vat photopolymerization), yielding a 3D-printed phantom of the external ear canal and middle ear. The feasibility of this phantom for otosurgical training was evaluated through an ossiculoplasty simulation involving ten otosurgeons and ten otolaryngology–head and neck surgery (ORL-HNS) residents. The participants were tasked with drilling, scooping, and placing a 3D-printed partial ossicular replacement prosthesis (PORP). Following the simulation, a questionnaire was used to collect the participants' opinions and feedback.ResultsA transparent photopolymer was deemed suitable for both the middle ear phantom and PORP. The printing procedure was precise, and the anatomical landmarks were recognizable. Based on the evaluations, the phantom had realistic maneuverability, although the haptic feedback during drilling and scooping received some criticism from ORL-HNS residents. Both otosurgeons and ORL-HNS residents were optimistic about the application of these 3D-printed models as training tools.ConclusionsThe 3D-printed middle ear phantom and PORP used in this study can be used for low-threshold training in the future. The integration of 3D-printed models in conventional otosurgical training holds significant promise.

Optical method to preserve residual hearing in patients receiving a cochlear implant

IntroductionWorldwide, thousands of patients with severe to profound hearing loss restore their hearing with cochlear implant (CI) devices. Newer developments in electrode design and manufacturing and a better understanding of cochlear mechanics allow for conserving critical structures, often translating into serviceable residual hearing and improving device performance. Monitoring insertion speed and intraluminal pressure helps mitigate some of these challenges. However, the information becomes available after irreparable damage has occurred.MethodsWe developed and tested a high-resolution optical system to navigate the intricate anatomy of the cochlea during electrode insertion. The miniaturized optical system was integrated in conventional cochlear implants electrode arrays and custom-made cochlear probes. Electrode insertion were conducted in eight cadaveric human temporal bones and video recordings were acquired. Micro-computed tomography (μCT) scans were performed to evaluate the position of the modified electrode arrays.ResultsFull insertions of the modified CI electrode were successfully conducted and verified by μCT scans. Video recordings of the cochlear structures visible in scala tympani were acquired, and no scala migration was detected.DiscussionSurgeons can now follow the CI electrode's path during its insertion and reduce cochlear damage through early interventions and steering of the CI electrode. Our device will be compatible with robotic platforms that are already available to insert these electrodes.