Cadaveric Specimens Research Articles

Compressive behavior of SLA open-cell lattices: A comparison between triply periodic minimal surface gyroid and stochastic structures for artificial bone

This study evaluates the compressive properties of stereolithography (SLA) fabricated open-cell lattices, specifically triply periodic minimal surface (TPMS) gyroid and stochastic structures, for artificial bone applications. Two resins, Standard White and BioMed Amber, were tested across four relative densities (0.2, 0.3, 0.4, 0.5). Mechanical characterization of horse tuber coxae trabecular bone used as a biological comparator showed an average elastic modulus of 0.05 GPa and a yield strength of 3.369 MPa. Gyroid structures exhibited higher elastic modulus and yield strengths, with BioMed Amber gyroid at a density of 0.5, achieving an elastic modulus of 0.623 GPa and yield strength of 14.149 MPa. Stochastic structures showed lower and more variable mechanical properties. The highest yield strength for stochastic structures was observed in BioMed Amber at a density of 0.5 (14.199 MPa). Comparative analysis indicated that high-performing synthetic structures approach the lower bounds of natural bone properties. Using a field-driven design approach, variable relative density structures were developed to emulate the mechanical properties of natural bone. SEM analysis provided insights into failure mechanisms, highlighting the impact of relative density on structural integrity and material ductility. This research supports the development of 3D-printed bone-like structures as viable substitutes for cadaveric specimens in preclinical tests, with implications for material science and orthopedic applications.

Choke Anastomosis: A Key Element Acting as a Shunt Converter Between Adjacent Angiosomes.

Choke anastomosis is commonly recognized as a resistance factor that detrimentally affects the hemodynamics of the skin flap; however, its additional potential physiological roles in normal skin function are currently not fully understood. Ten cadaveric forehead flap specimens pedicled with unilateral STAs were perfused with lead oxide-gelatin mixture, and then dissected into 3 layers, including the super temporal fascia-frontalis-galea aponeurotica layer, the subcutaneous adipose tissue layer, and the "super-thin flap" layer. The forehead flap and stratified specimens underwent molybdenum target x-ray and subsequent transparent processing to effectively visualize the microscopic spatial architecture of arterial vessels across all levels. Based on the different anastomoses near the midline area of the flap, 2 types of arterial perfusion were identified: choke anastomosis type (8/10) and true anastomosis type (2/10). The former formed multiple choke anastomoses near the midline. In the "super-thin flap" layer, arterial perfusion density on the ipsilateral side was significantly higher compared to that on the contralateral side. The arterioles on the ipsilateral side exhibited a dense and uninterrupted distribution, whereas those on the contralateral side appeared sparse and dispersed. The latter exhibited an alternative perfusion pattern; the bilateral arterial vessels were connected with 3 to 5 true anastomoses near the midline. Furthermore, the microscopic architecture confirmed a uniform distribution of arterioles that remained continuous from ipsilateral to contralateral sides in the "super-thin flap" layer. This study demonstrated that choke anastomosis not only impairs blood perfusion in the adjacent angiosomes but also acts as a shunt converter to impact the blood supply of distal skin flaps at different levels through the "trans-territory diversion phenomenon." This results in necrosis of the superficial dermis while preserving survival of the deep subcutaneous adipose tissue.

Nonspherical humeral arthroplasty increases internal rotation: a biomechanical comparison of the native humeral head to nonspherical and spherical humeral implants

BackgroundNonspherical humeral head implants more closely resemble native humeral anatomy than spherical components and may better replicate native shoulder range of motion (ROM) and kinematics. The purpose of this study was to compare shoulder ROM and kinematics of a commercially available nonspherical humeral head implant with the native humeral head and a height matched, custom manufactured spherical implant. MethodsSix fresh frozen cadaveric shoulder specimens were used with a custom shoulder testing system. The native shoulder was tested in multiple positions under anatomic muscle loading. Each specimen was tested for ROM and glenohumeral joint kinematics by measuring the humeral head apex and humeral head center (HHC) translation per degree of rotation using a MicroScribe digitizer. Measurements were then repeated after implantation of a spherical and, subsequently, a nonspherical humeral head prothesis. ResultsThe nonspherical implant had significantly more internal rotation (IR) compared to the spherical implant at 0° abduction (10.6 ± 6.2° more IR, P = .004, 95% confidence interval [CI]: −13.3, 34.5), 30° abduction (5.7 ± 2.8°, P = .009, 95% CI: −12.6, 24.0) and 60° abduction (6.8 ± 2.7°, P = .002, 95% CI: −8.3, 22.1) in the scapular plane, and 60° abduction (6.9 ± 2.0°, P = .031, 95% CI: −12, 25.6) in the coronal plane. The nonspherical implant had more IR than the native head at 60° of abduction in the scapular plane (7.0 ± 2.2° P = .002, 95% CI: −10.3, 24.3). The spherical head had less IR than the native head at 0° abduction (7.2 ± 4.8°, P = .031, 95% CI: 32.5, 18.1). There were no differences in humeral head apex translation per degree of rotation noted between the spherical implant or nonspherical implant and the native shoulder. The nonspherical head had less HHC translation than the native shoulder at 30° abduction in the forward flexion plane (P = .007); otherwise, there were no statistically significant differences in HHC translation between the native shoulder, the spherical head, and the nonspherical head. There was no significant difference observed between the average difference in anterior-posterior and superior-inferior radius of curvature of the nonspherical implants (2.0 ± 0.7 mm) and the native humeral heads (1.9 ± 1.3 mm) [P = .926]. ConclusionThe results of this biomechanical study suggest that the commercially available nonspherical humeral head has improved IR when compared to a custom, height controlled spherical implant and offers ROM and kinematics similar to the native humeral head in a cadaveric model.

Enhancing the coverage and rotation of anterior ethmoidal artery flap for septal perforation closure: Insights from a flap design study

Background and objectivesThe anterior ethmoidal artery flap (AEA) is a pedicle endonasal flap frequently used to repair septal perforations (SP). The posterior incision is the most complex to perform. The primary objective was to determine the minimum height of the posterior incision (PI) of an AEA completely cover an anterior septal perforation. Materials and methodsA cadaveric specimen was sectioned in the sagittal plane and a SP of 1 cm was created anteriorly. The PI of the AEA flap was made progressively at a height of 10, 20, 30, and 40 mm. The complete closure of the SP and the angle of rotation (AR) of the flap were assessed. ResultsAccording to the length of the PI the following results were obtained: PI = 10 mm: The SP was covered partially, and the AR was 45º. PI = 20 mm: The SP was fully covered, and the AR was 63º.PI = 30 mm and 40 mm: The SP was fully covered with redundant tissue.This study shows that an anterior ethmoidal artery flap that includes the nasal floor and the inferior meatus mucosa combined with a posterior incision of 20 mm could result in adequate coverage of all margins of an anterior SP up to area 1a of the septum.

Targeted Muscle Reinnervation in the Upper Arm: A Functional Anatomical Study

BackgroundThe aim of this study was to accurately locate the neural fascicle controlling hand movement in the upper arm, to enhance expression of motor intention after targeted muscle reinnervation. MethodsThe right sides of the median, ulnar and radial nerves were dissected from distal to proximal in 6 fresh cadaver specimens. The sectional location and diameter of the functional fascicle were measured at 10 and 20 cm below the acromion. The diameter of the main muscle branches of muscle reinnervation target muscles was measured. ResultsThe median nerve branch of finger and wrist flexion was mainly located between the 9 and 12 o’clock positions in the plane 10 and 20 cm below the acromion, where the diameter of the nerve fascicle was 2.07 and 2.04 mm, respectively. The ulnar nerve branch of finger and wrist flexion was mainly located between the 8 and 12 o’clock positions, with a diameter of respectively 1.80 and 1.99 mm. The radial branch of finger and wrist extension was mainly located between the 10 and 2 o’clock positions in the plane 10 cm below the acromion and between 6 and 12 o’clock in the plane 20 cm below the acromion, with a diameter of respectively 2.57 and 3.03 mm. ConclusionsThe nerve fascicles innervating the flexor and extensor fingers were distributed in relatively constant regions of the median, ulnar and radial nerve trunks, and their diameters closely matched the muscle branches of the target muscle.

Virtual Dissection Table Case Studies for Undergraduate Neuroanatomy Written Assignments.

Neuroanatomy education benefits from cadaveric specimens, yet challenges with access, cost, and health concerns exist. Virtual Dissection Tables (VDTs) offer digital alternatives to traditional cadaveric learning. This article evaluates the pedagogical value of VDTs in undergraduate neuroanatomy education. While VDTs, primarily Anatomage, offer interactive 3D cadaveric images and customization options, research on their impact on neuroanatomy learning outcomes remain limited. Existing studies suggest comparable knowledge retention between VDTs and cadaveric learning, with varying effects on student satisfaction. Investigations of non-exam-based neuroanatomy assessments, however, are scarce. This study presents a case study using VDTs as the basis for a neuroscience assignment report, exploring its construction, and evaluating its strengths, and weaknesses through a student survey. Implemented in an advanced neuroscience course, the assignment involves analyzing 3D reconstructed MRI scans of neuropathological conditions displayed on the VDT. The task requires students to collate, analyze, and predict symptoms based on the pathology observed, aligning their findings with neuroscience literature. This innovative approach aims to enhance research and academic writing skills while expanding the use of VDTs beyond traditional assessment formats in neuroscience education. We found that the case-study format benefited students' neuroanatomy learning and application ability. Further studies should be conducted, however, to understand the effect of VDT use on learning outcomes in case study contexts.

The classification of sacral foramina in a South African sample using cadaveric and osteological remains

Sacroiliac (SI) joint fixation is a technique used for SI joint fractures, SI joint dislocations and sacral fractures. Sacral screws can be placed either into the S1 or the S2 vertebrae if S1 is insufficient. Malpositioning of the screws is a common surgical complication as sacral variations exists amongst populations. Complications associated with the misposition of screws can lead to injury of the sacral venous plexus, iliac vessels, or sacral nerve roots. Therefore, this study aimed to evaluate sacral variations in a South African sample by determining distances between the first and second sacral foramina and classifying the common types of sacra found.A quantitative cross-sectional comparative study was conducted. One hundred and twenty (n = 120) dry human sacra and 11 formalin-fixed cadavers were measured to determine the linear distances between the first two anterior and posterior sacral foramina. Additionally, the dry human sacra were classified according to Mahato's classification system. A cadaver SI joint fixation simulation was performed by an orthopaedic surgeon.The mean sacral promontory height was found to be 31.81 mm and 37.52 mm in osteological and cadaver specimens, respectively. The mean anterior pedicle height was significantly different for the left (18.81 mm) and right (21.67 mm) side measurements. A statistically significant difference was found between cadavers and osteological samples for all measurements taken. In the osteological sample, ancestry and age mostly influenced the variations noted.Using Mahato's classification system, sacra with five sacral segments, auricular surfaces extending from the superior part of S1 to the middle of S3 and no accessory L5/S1 articulations had the highest prevalence of 59.17 %.The South African sample exhibited similarities but did not fully compare to other populations. The results in this study should be considered as a reference for surgeries involving the SI joint and sacral foramina. However, where possible, the exact anatomy with possible variations of the patient should be evaluated preoperatively using X-rays and angiograms.

Identification of an anatomical safe zone for humeral cerclage passage

BackgroundCerclage techniques have been utilized in the humerus in the setting of fractures and shoulder arthroplasty. Cerclage usage in the humerus has the potential to injure neurovascular structures. There is current literature describing deeper anatomic structures surrounding the humerus but not more superficial landmarks in reference to neurovascular structures. The purpose of this study was to determine safe zones for cerclage passage around the humerus. MethodsEight fresh-frozen cadaveric specimens with no history of deformity, prior surgery, or trauma to the shoulder or arm were utilized in this study. A standard extended deltopectoral approach was performed in all 8 specimens. Dissection was performed to identify the various musculotendinous and neurovascular structures surrounding the humerus. Cerclage sutures were placed around the humerus. Measurements were made from the radial and axillary nerve to anatomic structures and the cerclage sutures. ResultsThe radial nerve entered the spiral groove on average 45.8 mm distal (range: 30.4 to 63.3 mm) to the inferior aspect of the pectoralis major tendon. Cerclage suture passed just distal to the inferior aspect of the pectoralis major tendon did not violate the radial nerve. The axillary nerve was located on the humerus an average of 5.3 mm (range: 2.4-10 mm) proximal to the superior aspect of the latissimus dorsi tendon insertion. A safe zone for cerclage passage was not identified distal to the radial nerve entering the spiral groove. ConclusionThe radial nerve entered the spiral groove on the humerus distal to the pectoralis insertion in all specimens. The axillary nerve started to contact the humerus proximal to the latissimus dorsi in all specimens. In this study, we found that cerclage passage medial to lateral from the latissimus dorsi proximally to the area just distal to the inferior pectoralis major insertion distally is a safe zone for cerclage passage.

Crossing the Cervicothoracic Junction: A Biomechanical Investigation of C7 vs T1 Caudal Selection's Effect on Adjacent Segment Motion in Posterior Cervical Fusion.

Biomechanical Study. This study aims to evaluate the biomechanical adjacent segment effects of multi-level posterior cervical fusion constructs that terminate at C7 compared to those that terminate at T1 in cadaveric specimens. The cervicothoracic junction poses unique challenges for spine surgeons. Deciding to terminate multi-level posterior cervical fusion constructs at C7 or extend them across the cervicothoracic junction remains a controversial issue. Six cadaveric specimens underwent biomechanical testing in the intact state and after instrumentation with constructs from C3 and terminating at either C7 or T1. Range of motion (ROM) was assessed in flexion-extension, lateral bending, and axial rotation globally and at cranial and caudal adjacent segments. There was a significant decrease in overall flexion/extension by both C7 (-35.5°, P=0.002) and T1 (-39.8°, P=0.002) instrumentation compared to the intact spine. T1 instrumentation had significantly lower (-4.3°, P=0.008) flexion/extension ROM compared to C7 instrumentation. There were significant decreases in axial rotation by both C7 (-31.4°, P=0.009) and T1 (-36.8°, P=0.009) instrumentation compared to the intact spine, but no significant differences were observed between the two. There were also significant decreases in lateral bending by both C7 (-27.9°, P=0.022) and T1 (-33.7°, P=0.022) instrumentation compared to the intact spine, but no significant differences were observed between the two. No significant differences were observed in ROM at cranial or caudal adjacent segments between constructs terminating at C7 and those extending to T1. This biomechanical investigation demonstrates that constructs that cross the cervicothoracic junction experience less overall spinal motion in flexion-extension compared to those that terminate at C7. However, contrary to prior studies there is no difference in cranial and caudal adjacent segment motion. Surgeons should make clinical decisions regarding the caudal extent of fusion in multi-level posterior cervical fusions without major concerns about adjacent segment motion.

Carotid Plexus Sympathetic Nerves as a Landmark for the Abducens Nerve Within the Cavernous Sinus During Endoscopic Endonasal Surgery: Cadaveric Anatomic Study and Surgical Consideration.

The abducens nerve (CN VI) is vulnerable to injury during endoscopic endonasal transcavernous surgery. In this study, the authors aimed to develop the surgical anatomic landmark and explore the relationship between the sympathetic nerves (SNs) around the internal carotid artery (ICA) and CN VI within the cavernous sinus (CS). The relationship and patterns between the SNs and CN VI were investigated in 15 cadaveric specimens. The intraoperative examples of anatomic landmark were presented. There were SNs around the ICA running into the CN VI, classified into ascending SNs and accessory sympathetic branches. The ascending SNs were divided into 3 types: (1) Type I had a single ascending SN. There were 2 subtypes of Type I (Type IA [17/30, 56.7%] was defined as a single ascending branch that ran into the CN VI, and Type IB [4/30, 13.3%] was defined as a single ascending branch with a terminal bifurcation before merging into the CN VI or lateral CS wall), (2) Type II (7/30, 23.3%) was defined as 2 ascending branches that ran into the CN VI and the lateral CS wall, and (3) Type III (2/30, 6.7%) was defined as 3 ascending branches that ran into the CN VIs and the lateral wall of the CS. The accessory branches of the SNs were defined by sympathetic branches from the posterior genu or horizontal ICA and found in 6/30 sides (20%). The authors propose a classification of the relationship between paraclival ICA SNs and the CN VI within the CS, as approached during endoscopic endonasal surgery. The consistent relationship of the ascending SN and CN VI within the CS provides a reliable anatomic landmark during the endonasal approach to the CS.

Robot-assisted transosseous repair of triangular fibrocartilage complex: a cadaver study.

The feasibility and accuracy of robot-assisted bone tunnel construction in the transosseous repair of the triangular fibrocartilaginous complex (TFCC) were compared with those of freehand arthroscopic repair. A total of 20 cadaveric specimens were randomized into robotic-assisted and arthroscopy-guided groups. Three bone tunnels were constructed in the ulnar foveal region in each specimen. The discrepancy between the planned and actual tunnel exits was determined in the robot-assisted group by merging images. The success rate of tunnel construction, time consumption and number of drilling attempts were compared between groups. The median planned/actual exit discrepancy was 0.8 mm in the robot-assisted group, with 90% of tunnel exits successfully placed in the footprint region, compared to 63.3% in the arthroscopy-guided group. The robot-assisted group spent less time and required fewer drilling attempts to construct bone tunnels. These results indicated that the robot-assisted technique can accurately construct multiple bone tunnels in the foveal region and reduce the difficulty of TFCC transosseous repair.Level of evidence: III.

A reference framework for standardization and harmonization of CT radiomics features on cadaveric sample

Radiomics features (RFs) serve as quantitative metrics to characterize shape, density/intensity, and texture patterns in radiological images. Despite their promise, RFs exhibit reproducibility challenges across acquisition settings, thus limiting implementation into clinical practice. In this investigation, we evaluate the effects of different CT scanners and CT acquisition protocols (KV, mA, field-of-view, and reconstruction kernel settings) on RFs extracted from lumbar vertebrae of a cadaveric trunk. Employing univariate and multivariate Generalized Linear Models (GLM), we evaluated the impact of each acquisition parameter on RFs. Our findings indicate that variations in mA had negligible effects on RFs, while alterations in kV resulted in exponential changes in several RFs, notably First Order (94.4%), GLCM (87.5%), and NGTDM (100%). Moreover, we demonstrated that a tailored GLM model was superior to the ComBat algorithm in harmonizing CT images. GLM achieved R2 > 0.90 in 21 RFs (19.6%), contrasting ComBat's mean R2 above 0.90 in only 1 RF (0.9%). This pioneering study unveils the effects of CT acquisition parameters on bone RFs in cadaveric specimens, highlighting significant variations across parameters and scanner datasets. The proposed GLM model presents a robust solution for mitigating these differences, potentially advancing harmonization efforts in Radiomics-based studies across diverse CT protocols and vendors.

Applied anatomy study and preliminary clinical application of hyper selective neurectomy of triceps branches combined with partial neurotomy of S 2 nerve root to relieve spastic equinus foot

To observe the possibility of hyper selective neurectomy (HSN) of triceps branches combined with partial neurotomy of S 2 nerve root for relieving spastic equinus foot. Anatomical studies were performed on 12 adult cadaveric specimens. The S 2 nerve root and its branches were exposed through the posterior approach. Located the site where S 2 joined the sciatic nerve and measured the distance to the median line and the vertical distance to the posterior superior iliac spine plane, and the S 2 nerve root here was confirmed to have given off branches of the pelvic splanchnic nerve, the pudendal nerve, and the posterior femoral cutaneous nerve. Between February 2023 and November 2023, 4 patients with spastic equinus foot were treated with HSN of muscle branches of soleus, gastrocnemius medial head and lateral head, and cut the branch where S 2 joined the sciatic nerve. There were 3 males and 1 female, the age ranged from 5 to 46 years, with a median of 26 years. The causes included traumatic brain injury in 2 cases, cerebral hemorrhage in 1 case, and cerebral palsy in 1 case. The disease duration ranged from 15 to 84 months, with a median of 40 months. The triceps muscle tone measured by modified Ashworth scale (MAC) before operation was grade 3 in 2 cases and grade 4 in 2 cases. The muscle strength measured by Daniels-Worthingham manual muscle test (MMT) was grade 2 in 1 case, grade 3 in 1 case, and 2 cases could not be accurately measured due to grade 4 muscle tone. The Holden walking function grading was used to evaluate lower limb function and all 4 patients were grade 2. After operation, triceps muscle tone, muscle strength, and lower limb function were evaluated by the above grading. The distance between the location where S 2 joined the sciatic nerve and median line was (5.71±0.53) cm and the vertical distance between the location and posterior superior iliac spine plane was (6.66±0.86) cm. Before joining the sciatic nerve, the S 2 nerve root had given off branches of the pelvic splanchnic nerve, the pudendal nerve, and the posterior femoral cutaneous nerve. All the 4 patients successfully completed the operation, and the follow-up time was 4-13 months, with a median of 7.5 months. At last follow-up, the muscle tone of the patients decreased by 2-3 grades when compared with that before operation, and the muscle strength did not decrease when compared with that before operation. Holden walking function grading improved by 1-2 grades, and there was no postoperative hypoesthesia in the lower limbs. HSN of triceps branches combined with partial neurotomy of S 2 nerve root can relieve spastic equinus foot without damaging other sacral plexus nerves.

Is It Time for a Paradigm Shift in the Surgical Management of Trigeminal Schwannomas? Evaluating the Role of the Transorbital Approach: An Anatomo-Clinical Study and Systematic Literature Review

BackgroundEndoscopic transorbital approach emerged in recent years as an effective, minimally invasive route to access Meckel’s cave area. Several case series proved its effectiveness in the surgical treatment of trigeminal schwannomas. Nonetheless, this route provides the advantages of a minimally invasive approach associated with low morbidity rates. In this anatomo-clinical study we illustrate the usefulness of the superior eyelid transorbital approach for the surgical treatment of trigeminal schwannoma guiding the clinical applicability of the anatomical findings into the real surgical practice. MethodsSuperior eyelid transorbital endoscopic approach was performed on eight cadaveric specimens, and the surgical results were confirmed in a retrospective review of all the surgical cases of transorbital surgery performed by the senior authors providing an illustrative case. Finally, we performed a literature review of all the case series of trigeminal schwannomas operated through an endoscopic transorbital approach. ResultsStepwise dissection was divided in 3 phases: skin, endo-orbital and endocranial. The illustrative case provided demonstrate gross total resection of a cavernous sinus type trigeminal schwannomas treated through this route. Literature review revealed 68 cases of trigeminal schwannomas that were successfully treated using the transorbital approach. ConclusionsThe endoscopic transorbital approach may offer a valuable alternative for the surgical treatment of trigeminal schwannomas. This technique provides a minimally invasive, direct and natural “interdural” route to the lateral wall of the cavernous sinus and Meckel's cave.

Presoaking hamstring autograft with vancomycin does not jeopardize its biomechanical properties, including graft elongation, after cyclic loading.

Presoaking the graft with vancomycin before implantation has been shown to reduce the risk of postoperative infection after anterior cruciate ligament reconstruction (ACLR). However, the effects of presoaking on the graft biomechanical properties remain unclear. This study aimed to determine whether presoaking the graft with vancomycin affects the graft biomechanical properties and length after cyclic loading. Ten paired (20 specimens) gracilis and semitendinous tendons were harvested from fresh-frozen human cadaveric specimens. Two tendons were folded in half to make four strands, and the grafts were randomized into the vancomycin and control groups. The graft was exposed to the antibiotic solution for 15 min (5 mg/mL) and prepared by mixing 1 g of vancomycin with 200 mL of normal saline (NaCl 0.9%). The control group was soaked in normal saline for 15 min. The prepared grafts were attached to the actuator of a dynamic tensile-testing machine. All grafts were tested with 3000 cycles of cyclic loading followed by a pull-to-failure. The cyclic loading protocol consisted of position and load control blocks to simulate the graft in vivo in the postoperative phase after ACLR. Presoaking in vancomycin did not jeopardize the biomechanical properties of the graft. In addition, presoaking with vancomycin did not elongate the grafts. No significant differences were found in the mean Young's modulus and the mean total elongation of the graft of the specimen between the vancomycin group and the control group. Presoaking the graft with vancomycin jeopardized neither its biomechanical properties nor elongation even after cyclic loading in this in vitro study. It is suggested that vancomycin presoaking could be considered a safe and effective preventive measure for postoperative infections after ACLR. Not applicable.

Anatomical Trajectory of the Corrugator Supercilii Muscle in Koreans: Implications for Aesthetic and Clinical Practices.

Understanding the attachment patterns of the corrugator supercilii muscle (CS) is vital for treatments designed to improve facial symmetry and functionality. The aim of this research was to elucidate the anatomical trajectory and intricate relationships of the CS within the upper face and midface, specifically focusing on its connections with the frontalis (FT) and orbicularis oculi (OOc) muscles. The CS was examined in 41 specimens of embalmed adult Korean cadavers using microdissection, histological analyses, and microcomputed tomography, an in-depth exploration of its anatomical positioning and intricate interactions with adjacent muscles. Some lower fibers of the CS extended to the upper orbital part of the OOc in 59.5% of cases, while the CS interdigitated or blended exclusively with the FT in 40.5% of cases. The fibers of the CS demonstrated diverse extensions towards the upper face and midface, exhibiting varied trajectories and lengths. Additionally, lower fibers of the CS extended to significant anatomical landmarks such as the OOc, malaris muscle, and the superficial musculoaponeurotic system (SMAS). This study demonstrates that precise understanding of the CS and its relationship with the FT and OOc is crucial for optimizing invasive or non-invasive treatment like botulinum toxin injection, SMAS lifting and browplasty surgery. The extension of lower fibers of the CS to significant anatomical landmarks indicates complex interactions with adjacent facial structures, highlighting the necessity of detailed anatomical knowledge for clinical applications.

Development of a continuum-based, meshless, finite element modeling approach for representation of trabecular bone indentation

Implant subsidence into the underlying trabecular bone is a common problem in orthopaedic surgeries; however, the ability to pre-operatively predict implant subsidence remains limited. Current state-of-the-art computational models for predicting subsidence have issues addressing this clinical problem, often resulting from the size and complexity of existing subject-specific, image-based finite element (FE) models. The current study aimed to develop a simplified approach to FE modeling of subject-specific trabecular bone indentation resulting from implant penetration.Confined indentation experiments of human trabecular bone with flat- and sharp-tip indenters were simulated using FE analysis. A generalized continuum-level approach using a meshless smoothed particle hydrodynamics (SPH) approach and an isotropic crushable foam (CF) material model was developed for the trabecular bone specimens. Five FE models were generated with CF material parameters calibrated to cadaveric specimens spanning a range of bone mineral densities (BMD). Additionally, an alternative model configuration was developed that included consideration of bone marrow, with bone and marrow material parameters assigned to elements randomly according to bone volume (BV%) measurements of experimental specimens, owing to the non-uniform nature of trabecular bone tissue microstructure.Statistical analysis found significant correlation between the shapes of the numerical and experimental force-displacement curves. FE models accurately captured the bone densification patterns observed experimentally. Inclusion of marrow elements offered improved response prediction of the flat-tip indenter tests.Ultimately, the developed approach demonstrates the ability of a generalizable continuum-level SPH approach to capture bone variability using clinical bone imaging metrics without needing detailed image-based geometries, a significant step towards simplified subject-specific modeling of implant subsidence.

A comprehensive morphometric analysis of superior and inferior mesenteric arteries using cadaveric dissection and MDCT angiography

BackgroundSuperior mesenteric artery (SMA) and inferior mesenteric artery (IMA) are vital vascular structures supplying the majority of the intestinal tract. Despite their clinical significance, comprehensive morphometric studies combining traditional cadaveric dissection with modern imaging techniques are scarce in literature. This study aimed to provide a detailed morphometric analysis of the SMA and IMA using both cadaveric dissection and multi-detector computed tomography (MDCT) angiography. MethodsThe study utilized a dual approach, combining cadaveric dissection (30 formalin-fixed cadavers) and MDCT angiography (images from 50 patients). Measurements including stem lengths, diameters at origin, and distances from the aortic bifurcation were taken, along with assessment of vertebral levels of origin and branching patterns. Data from both components were analyzed using descriptive statistics. ResultsKey findings for SMA include: Mean stem length: 3.19 ± 0.72 cm (cadaveric) vs. 2.53 ± 0.53 cm (MDCT); Mean diameter at origin: 0.93 ± 0.22 cm (cadaveric) vs. 0.57 ± 0.10 cm (MDCT); Most common vertebral level of origin: Upper border of L1 (78 % of cases); Branching pattern variations observed in 23.3 % of cadaveric specimens, which included the origin of the inferior pancreaticoduodenal artery from the first jejunal artery, a common trunk for right colic and ileocolic arteries, and absence of middle colic artery. For IMA: Mean stem length: 3.61 ± 1.29 cm (cadaveric) vs. 3.41 ± 0.69 cm (MDCT); Mean diameter at origin: 0.50 ± 0.11 cm (cadaveric) vs. 0.26 ± 0.05 cm (MDCT); Most common vertebral level of origin: Upper border of L3 (40 % of cases). No variations observed in branching pattern. ConclusionsThe detailed measurements, frequency of variations, and comparison between traditional and modern assessment techniques offer a nuanced understanding of mesenteric vascular anatomy. This study bridges the gap between classical anatomical knowledge and contemporary imaging capabilities, potentially improving surgical planning, interventional procedures, and radiological interpretation.

The Effects of Unitizing Nail-Plate Constructs in Distal Femur Fractures: A Biomechanical Study.

To assess the biomechanical differences between linked and unlinked constructs in young and osteoporotic cadavers in addition to osteoporotic sawbones. Intraarticular distal femur fractures with comminuted metaphyseal regions were created in three young matched pair cadavers, three osteoporotic matched pair cadavers, and six osteoporotic sawbones. Precontoured distal femur locking plates were placed in addition to a standardized retrograde nail, with unitized constructs having one 4.5 mm locking screw placed distally through the nail. Nonunitized constructs had seven 4.5 mm locking screws placed through the plate around the nail, with one 5 mm distal interlock placed through the nail alone. Cadaveric specimens were subjected to axial fatigue loads between 150 and 1500 N (R Ratio = 10) with 1 Hx frequency for 10,000 cycles. Sawbones were axially loaded at 50% of the ultimate load for fatigue testing to achieve runout, with testing performed with 30 and 300 N (R Ratio = 10) loads with 1 Hz frequency for 10,000 cycles. In young cadavers, there was no difference in the mean cyclic displacement of the unitized constructs (1.51 ± 0.62mm) compared to the non-unitized constructs (1.34 ± 0.47mm) (Figure 4A), (p = 0.722). In osteoporotic cadavers, there was no difference in the mean cyclic displacement of the unitized constructs (2.46 ± 0.47mm) compared to the non-unitized constructs (2.91 ± 1.49mm) (p =0.639). There was statistically no significant difference in cyclic displacement between the unitized and non-unitized groups in osteoporotic sawbones(p = 0.181). Linked constructs did not demonstrate increased axial stiffness or decreased cyclical displacement in comparison to unlinked constructs in young cadaveric specimens, osteoporotic cadaveric specimens, or osteoporotic sawbones.

A Cadaveric Study: Does Ankle Positioning Affect the Quality of Anatomic Syndesmosis Reduction?

The objective of this study was to compare the quality of syndesmotic reduction with the ankle in maximal dorsiflexion versus neutral plantarflexion (normal resting position). Baseline computed tomography (CT) imaging of 10 cadaveric ankle specimens from 5 donors was obtained with the ankles placed in normal resting position. Two fellowship-trained orthopaedic surgeons disrupted the syndesmosis of each ankle specimen. All ankles were then placed in neutral plantarflexion and were subsequently reduced with thumb pressure under direct visualization through an anterolateral approach and stabilized with one 0.062-inch K-wire placed from lateral to medial in a quadricortical fashion across the syndesmosis. Postreduction CT scans were then obtained with the ankle in normal resting position. This process was repeated with the ankles placed in maximal dorsiflexion during reduction and stabilization. Postreduction CT scans were then obtained with the ankles placed in normal resting position. All postreduction CT scans were compared with baseline CT imaging using mixed-effects linear regression with significance set at P < 0.05. Syndesmotic reduction and stabilization in maximal dorsiflexion led to increased external rotation of the fibula compared with baseline scans [13.0 ± 5.4 degrees (mean ± SD) vs. 7.5 ± 2.4 degrees, P = 0.002]. There was a tendency toward lateral translation of the fibula with the ankle reduced in maximal dorsiflexion (3.3 ± 1.0 vs. 2.7 ± 0.7 mm, P = 0.096). No other statistically significant differences between measurements of reduction with the ankle placed in neutral plantarflexion or maximal dorsiflexion compared with baseline were present (P > 0.05). Reducing the syndesmosis with the ankle in maximal dorsiflexion may lead to malreduction with external rotation of the fibula. There was no statistically significant difference in reduction quality with the ankle placed in neutral plantarflexion compared with baseline. Future studies should assess the clinical implications of ankle positioning during syndesmotic fixation.