Dorsal Direction Research Articles

Failure of Universal 2 Wrist Joint Replacements: A Retrieval Study

Abstract Background The Universal 2 total wrist arthroplasty was one of the most common wrist replacements, but long-term results were disappointing, due to substantial damage to the polyethylene component and, in some cases, metallosis. The purpose of this research was to investigate the underlying reasons for this polyethylene damage. Methods From a single clinical center, retrieval analysis was undertaken on six Universal 2 wrists and two additional polyethylene components. All components were analyzed at the macroscale and dimensional measurements of polyethylene components were undertaken. These were compared against known component orientation in vivo to identify areas of greatest material loss. Results Of 62 Universal 2 wrists implanted, there was a tendency for smaller implants to be revised more frequently. Of the six explanted wrists, material loss was always noticeable on the ulnar side, and to a lesser extent in the dorsal direction. Five of eight polyethylene components had failed at the base of the ulnar-side blind hole. Smaller implants tended to have less thickness at the base of the blind holes, thus explaining the failure of smaller sizes. Discoloration and surface fatigue of explants indicated oxidation of components. Average time in vivo for the explants was 13.8 years which indicates the slow nature of polyethylene oxidation. All were revised due to loosening. All were implanted in rheumatoid patients with a mean age at surgery of 56.1 years. Three of the six Universal 2 wrists, all sized Extra Small, showed severe wear of the titanium alloy carpal component. Conclusion Failure of the polyethylene components was due to a combination of inappropriate sterilization technique plus a design issue where polyethylene was thinnest on the smallest size components. Continued surveillance of patients implanted with Universal 2 wrists is recommended.

Twisted cell flow facilitates three-dimensional somite morphogenesis in zebrafish

Tissue elongation is a fundamental morphogenetic process to construct complex embryonic structures. In zebrafish, somites rapidly elongate in both dorsal and ventral directions, transforming from a cuboidal to a V-shape within a few hours of development. Despite its significance, the cellular behaviors that directly lead to somite elongation have not been examined at single-cell resolution. Here, we describe the motion and shapes of all cells composing the dorsal half of the somite in three-dimensional space using lightsheet microscopy. We identified two types of cell movements—in horizontal and dorsal directions—that occur simultaneously within individual cells, creating a complex, twisted flow of cells during somite elongation. Chemical inhibition of Sdf1 signaling disrupted the collective movement in both directions and inhibited somite elongation, suggesting that Sdf1 signaling is crucial for this cell flow. Furthermore, three-dimensional computational modeling suggested that horizontal cell rotation accelerates the perpendicular elongation of the somite along the dorsoventral axis. Together, our study offers novel insights into the role of collective cell migration in tissue morphogenesis, which proceeds dynamically in the three-dimensional space of the embryo.

Association of dorsal malunion in distal radius fractures with wrist osteoarthritis: Alterations of bone density and stress-distribution patterns in relation to deformation angles

Distal radius fractures (DRFs) with dorsal malunion increase the risk of osteoarthritis (OA), although the cause of post-DRF OA is yet to be elucidated. To clarify the abnormal effects of a post-DRF dorsal radius deformity, we evaluated the bone density (BD) and stress-distribution patterns of the articular surface in dorsally malunited DRFs. In 36 cases of dorsally malunited DRFs following extra-articular fractures, we generated three-dimensional computerized models of the malunited distal radius from computed tomography data and extracted the subchondral bones of the radiocarpal joint (RCJ) and distal radioulnar joint (DRUJ). Both BD and stress distribution in the subchondral bones were quantitatively evaluated by comparing the affected and normal sides. Correlations of alterations in high-BD distribution and deformation angles were analyzed. The center of high-BD distribution from the center of the RCJ in the volar(-)-dorsal(+) direction was dorsal (0.56±0.72mm) on the affected side compared with the normal side (-0.15±0.63mm) [95% CI: 0.43, 1.00, P<0.0001]. The maximum stress distribution was also dorsal on the affected side (2.34±3.52mm) compared with the normal side (-2.49±1.62mm) [95% CI: 0.89, 1.79, P<0.0001]. The alterations in BD and stress distribution correlated with the dorsiflexion and radial deviation angles. In the DRUJ, there was no significant difference in BD between the affected and normal sides. In dorsally malunited DRFs, the alignment change of the RCJ resulted in high BD-concentration areas and stress distribution on the dorsal side of the radius, which may constitute a precursor for OA.

The multidirectional roles of the anterior oblique ligament and dorsoradial ligament of the thumb carpometacarpal joint.

The multidirectional biomechanics of the thumb carpometacarpal (CMC) joint underlie the remarkable power and precision of the thumb. Because of the unconfined nature of thumb CMC articulation, these biomechanics are largely dictated by ligaments, notably the anterior oblique ligament (AOL) and the dorsoradial ligament (DRL). However, the rotational and translational stabilizing roles of these ligaments remain unclear, as evidenced by the variety of interventions employed to treat altered pathological CMC biomechanics. The purpose of this study was to determine the effects of sectioning the AOL (n = 8) or DRL (n = 8) on thumb CMC joint biomechanics (rotational range-of-motion [ROM] and stiffness, translational ROM) in 26 rotational directions, including internal and external rotation, and in eight translational directions. Using a robotic musculoskeletal simulation system, the first metacarpal of each specimen (n = 16) was rotated and translated with respect to the trapezium to determine biomechanics before and after ligament sectioning. We observed the greatest increase in rotational ROM and decrease in rotational stiffness in flexion directions and internal rotation following DRL transection and in extension directions following AOL transection. The greatest increase in translational ROM was in dorsal and radial directions following DRL transection and in volar directions following AOL transection. These data suggest the AOL and DRL play complementary stabilizing roles, primarily restraining translations in the direction of and rotations away from the ligament insertion sites. These findings may inform future interventions or implant designs for pathological CMC joints.

Perineoplasty for anal incontinence after obstetric anal sphincter injury repair: a case report

BackgroundThe rectal and vaginal walls are typically sutured if severe perineal lacerations with rectal mucosal damage occur during vaginal delivery. In case of anal incontinence after the repair, re-suturing of the anal sphincter muscle is standard procedure. However, this procedure may not result in sufficient improvement of function.Case presentationA 41-year-old woman underwent suture repair of the vaginal and rectal walls for fourth-degree perineal laceration at delivery. She was referred to our department after complaining of flatus and fecal incontinence. Her Wexner score was 15 points. Examination revealed decreased anal tonus and weak contractions on the ventral side. We diagnosed anal incontinence due to sphincter dysfunction after repair of a perineal laceration at delivery. We subsequently performed sphincter re-suturing with perineoplasty to restructure the perineal body by suturing the fascia located lateral to the perineal body and running in a ventral–dorsal direction, which filled the space between the anus and vagina and increased anal tonus. One month after surgery, the symptoms of anal incontinence disappeared (the Wexner score lowered to 0 points), and the anorectal manometry values increased compared to the preoperative values. According to recent reports on the anatomy of the female perineal region, bulbospongiosus muscle in women does not move toward the midline to attach to the perineal body, as has been previously believed. Instead, it attaches to the ipsilateral surface of the external anal sphincter. We consider the fascia lateral to the perineal body to be the fascia of the bulbospongiosus muscle.ConclusionsIn a case of postpartum anal incontinence due to sphincter dysfunction after repair of severe perineal laceration, perineoplasty with re-suturing an anal sphincter muscle resulted in improvement in anal sphincter function. Compared to conventional simple suture repair of the rectal wall only, this surgical technique may improve sphincter function to a greater degree.

The Skull Shape Analysis of Wistar Albino Rats: A Geometric Morphometric Study

The aim of the study was to evaluate the skull shape of Wistar albino rats using the geometric morphometry method. For this purpose, a total of 52 adult rat skulls, 31 female and 21 male, were evaluated. Skulls were photographed from equal distance in dorsal and ventral directions. 13 and 18 landmarks were marked in dorsal and ventral images, respectively. Percentage variation values of principal components were calculated by performing principal component analysis in the MorphoJ program. Average shape graphs showing the positive and negative boundaries of the first three principal components were obtained. It was defined that scatter plot graphic showing the degree of grouping of male and female rats according to the first and second principal component. The study also examined the allometric effect with regression. Discriminant function analysis was performed to examine gender dimorphism. As a result of the study, it was determined that the most significant shape change was in the zygomatic arc and palate regions according to individuals, while it was also in the neurocranium acording to gender. We believe that the study will contribute to anatomy, biology and archeology studies on the shape of skull.

(387) Clinical Experience with Malleable Penile Implantation for Salvaging Inflatable Implant Infection

Abstract Introduction Antibiotic irrigation for treating prostheses is commonly believed to be a proper administration for those whose penile implant contracts with infection. However, there is no standard procedure for the irrigation period. Objective As a result, we encounter patients whose sinusoids were ruined from irrigation attempts for over three months. We sought to report an experience of salvaging penile implantation. Methods From 2010 to 2022, eight patients requested salvage penile implantation for treating unsuccessful inflatable implantation elsewhere. They report repeated antibiotic rescuing and wound debridement from 50 to 121 days of hospitalization. The diameter of the glans penis is measured and recorded in mm. Pelvic X-rays were made while the penis was downward and upward. One 44-year-old patient received no further salvaging penile implant because the corporeal sinusoid had too hardly fused to allow the contrast medium injection. The remaining seven received malleable types of penile implants ambulatory under acupuncture-assisted local anesthesia with which a cavernosal block must be performed in addition to a proximal dorsal nerve block, crural block, and peri penile infiltration. In addition, the novel method of glans enhancement was performed unexceptionally. The approach was longitudinal pubic (n=3) and circumferential (n=2). The pain level was assessed on the acupoint needle location or penis property. It was recorded on blood loss amount and operation times. A 32 to 35 ligation was performed at the retro-coronal venous plexus, which is readily identified by glans milking manipulation. A 5cm coroporotomy was made along the 11 or 1 o'clock position of the corpora cavernosa. To minimize the sinusoidal compression, corporal dilatation was made along the dorsal and medial directions distally and dorsolateral proximally. Neither electrocautery nor a suction apparatus was used because of minimal blood loss from manual compression. The water-tight suture was made to the tunic wound, closed continuously with 6-0 nylon with intermittent enhanced suture per centimeter. The overlying fascia layers and skin were finally closed with 6-zero chromic layer by layer. All patients received postoperative pelvic X-rays evidencing the appropriate housing of the cylinder. Sexual satisfaction was followed up yearly by the INTERNET. Results The operation time was 2.5 to 4.5 hours, and the blood loss was negligible. The pain level was more substantial at the arm acupoint at 71.4% (5/7). It was 11 to 61 months from the first and salvaging prosthesis implantation. The diameter of the glans increased from 26.0±2.3 mm to 35.3±2.2 mm. Four patients report couple satisfaction, whereas the remaining one feels male self-esteemed and female acceptable. All patients reported partial sinusoidal erection and no soft glans syndrome eventually. Conclusions A malleable penile prosthesis is beneficial for salvaging inflatable prosthesis infection. An anatomy-based corporeal dilation seems a proper way to minimize sinusoidal compression, although a larger sample size and longer follow-up are mandatory. The glans enhancement was unexceptionally attainable. Disclosure No.

(397) Investigating the Psychological Bother and Depression Among Gay Men with Peyronie's Disease

Abstract Introduction I: Peyronie's disease (PD) is associated with psychological bother, including depression and relationship dissatisfaction. Objective Our objective is to describe the prevalence of psychosocial issues using validated instruments, comparing gay and non-gay males. Methods We included patients diagnosed with PD who completed two validated questionnaires. The questionnaires were the Peyronie's Disease Questionnaire (PDQ) and the Center for Epidemiologic Studies Depression Scale (CES-D). The PDQ has 3 domains that evaluate psychological and physical symptoms, penile pain, and bother signs. Higher PDQ scores indicate a greater negative impact, and a score ≥ 9 on the bother domain indicates significant distress. A CES-D score ≥ 16/60 suggests clinical depression. All gay and non-gay patients were matched, and potential indicators of psychological distress were examined in both populations. Our multivariable analysis (MVA) models included age, sexual orientation, pain, and curvature. Additionally, we collected demographic information and PD-related characteristics. Results 74 individuals were matched based on age, curvature direction, and curvature degree: 37 gay and 37 non-gay. The median age was 57 (50, 62) years. Gay population characteristics: 60% were partnered; 54% had ≥ 2 comorbidities; median PD duration of 9 (4, 17) months; median curvature of 35 (29, 49) degrees; 66% had penile instability; 57% in a dorsal direction curvature, and 73% were located at the mid-shaft; 18% had multiplanar curvature. The PDQ scores in the gay vs. non-gay population: median score on psychological and physical domain of 10 (7, 18) vs. 11 (5, 16); median score on pain domain was 3 (0, 9) vs. 3 (0, 6), with 43% of the gay population with pain vs. 21% in non-gay; median score on bother domain was 8 (4, 10) vs. 8 (6, 11), with 65% of gay patients with significant bother (score ≥ 9) compared to 51% in non-gay. Regarding the CES-D scores, 38% of individuals in both populations demonstrated meaningful depression (score ≥ 16), with a median score of 12 (4, 19) in the gay population and a median of 12 (5, 23) in non-gay. In the MVA, sexual orientation was not a predictor for bother or depression (Table 1). Conclusions More than half of both groups had meaningful bother, and 1 in 3 had clinical depression; however, sexual orientation was not a predictor of bother or depression. Disclosure No.

Quantitative analysis of the skull in the Japanese wolf (Canis lupus hodophilax) using CT.

In this study using computed tomography (CT), the volumes of the internal cranial cavities, such as the braincase, frontal sinus and tympanic cavity, and the ratio of the volume of each cavity to the skull volume in Japanese wolves were quantified, and CT images of the frontal sinus were observed. The results were then compared with those of other wolf subspecies, including Akita, a dog breed, to clarify the characteristics of the internal cranial cavities in Japanese wolves. The present study revealed that the Japanese wolf had a relatively larger braincase volume and a relatively smaller frontal sinus volume than the wolf ssp. (a group of wild wolf subspecies except the Japanese wolf) and Akita. Moreover, the relative and absolute tympanic cavity volumes of the Japanese wolf and Akita were significantly smaller than those of the wolf ssp. In the CT image or macroscopic observations, the frontal sinuses of the wolf ssp. and Akita were relatively well developed to the caudal and dorsal directions, respectively, compared with that of the Japanese wolf, and the tympanic cavity of the wolf ssp. was more largely swelled ventrally and medially than that of other groups.

Anatomical cardiac and electrocardiographic axes correlate in both upright and supine positions: an upright/supine CT study

The correlation between the anatomical cardiac and electrocardiographic axes has been discussed for several years. Using upright computed tomography, this study aimed to reveal the relationship between the anatomical cardiac and electrocardiographic axes in both the supine and upright positions. Upright CT and standard supine CT were performed for healthy volunteers, following electrocardiography in both upright and supine position. On CT images, the coordinates of apex, the center of aortic valve (AV) and mitral valve (MV) were recorded, and the vectors and angles were calculated. Subcutaneous and visceral fat volume were semi-automatically calculated in a workstation. From a total 190 volunteers, 41 males were performed electrocardiography and included for this study. The QRS and anatomical axes (AV-apex and MV-apex axis) were significantly correlated in both supine and upright positions, while the angle of the AV-apex to Z axis was the most correlated (supine: r = − 0.54, p = 0.0002, upright: r = − 0.47, p = 0.0020). The anatomical axis moved in the dorsal and caudal directions from the supine to upright position. Multiple regression analysis revealed that the anatomical axis from the AV-apex to the Z-axis was determined according to age, body height, subcutaneous and visceral fat volumes.

Simulation of the Mechanical Behavior of the Degradation L4-L5 Lumbar Spine

Degenerative changes in the lumbar spine significantly reduce the quality of life of people. To fully understand the biomechanics of the affected spine, it is crucial to consider the biomechanical alterations caused by degeneration of the intervertebral disc (IVD). Therefore this study is aimed at the development of a discrete element model of the mechanical behavior of the L4-L5 spinal motion segment, which covers all the degeneration grades from healthy IVD to its severe degeneration, and numerical study of the influence of the IVD degeneration on stress state and biomechanics of the spine. To analyze the effects of IVD degeneration on spine biomechanics we simulated physiological loading conditions using compressive forces. The results of modeling showed that at the initial stages of degenerative changes, an increase in the amplitude and area of maximum compressive stresses in the disc is observed. At the late stages of disc degradation, a decrease in the value of intradiscal pressure and a shift in the maximum compressive stresses in the dorsal direction are observed. Such an influence of the degradation of the geometric and mechanical parameters of the tissues of the disc leads to the effect of bulging, which in turn will lead to the formation of an intervertebral hernia.

The RNF220 domain nuclear factor Teyrha-Meyrha (Tey) regulates the migration and differentiation of specific visceral and somatic muscles in Drosophila.

Development of the visceral musculature of the Drosophila midgut encompasses a closely coordinated sequence of migration events of cells from the trunk and caudal visceral mesoderm that underlies the formation of the stereotypic orthogonal pattern of circular and longitudinal midgut muscles. Our study focuses on the last step of migration and morphogenesis of longitudinal visceral muscle precursors and shows that these multinucleated precursors utilize dynamic filopodial extensions to migrate in dorsal and ventral directions over the forming midgut tube. The establishment of maximal dorsoventral distances from one another, and anteroposterior alignments, lead to the equidistant coverage of the midgut with longitudinal muscle fibers. We identify Teyrha-Meyhra (Tey), a tissue-specific nuclear factor related to the RNF220 domain protein family, as a crucial regulator of this process of muscle migration and morphogenesis that is further required for proper differentiation of longitudinal visceral muscles. In addition, Tey is expressed in a single somatic muscle founder cell in each hemisegment, regulates the migration of this founder cell, and is required for proper pathfinding of its developing myotube to specific myotendinous attachment sites.

Functional anatomy of shoulder muscles in the Pacific white-sided dolphin (Lagenorhynchus obliquidens).

Most intrinsic muscles of the forelimb in dolphins are either degenerated or lost; however, the muscles around the shoulder joint are well preserved. We dissected the forelimbs of Pacific white-sided dolphins and constructed a full-scale model of the flipper to compare and examine their movements following dissection. The humerus was oriented at approximately 45° ventrally from the horizontal plane of the dolphin and 45° caudally from the frontal plane. This maintains the neutral position of the flipper. The deltoideus and pectoralis major muscles were inserted into the body of the humerus, and the flipper was moved in the dorsal and ventral directions, respectively. A large tubercle, known as the common tubercle, was observed at the medial end of the humerus. Four muscles were inserted into the common tubercle: the brachiocephalicus, supraspinatus, and cranial part of the subscapularis, which laterally rotated the common tubercle. Subsequently, the flipper swung forward, and its radial edge was lifted. Conversely, the medial rotation of the common tubercle caused by the coracobrachialis and the caudal part of the subscapularis was accompanied by backward swinging of the flipper and lowering of the radial edge. These findings suggest the function of the flipper as a stabilizer or rudder is caused by the rotation of the humerus's common tubercle.

(424) A Contemporary Assessment of Patients Presenting to a Tertiary Medical Center with Peyronie’s Disease

Abstract Introduction Peyronie’s disease (PD) is a progressive wound-healing disorder resulting in plaque formation within the tunica albuginea. PD continues to be poorly understood and an area of investigation, with increased awareness by patients and clinicians. Most commonly, PD patients will have a singular plaque and uniplanar curvature in the dorsal or lateral direction. However, previous studies have categorized less common deformities as “atypical”, which includes ventral curvature, multiplanar curvatures, unilateral indentations, hourglass deformity, and severe loss of penile length. Objective We aim to characterize the presenting features of PD within a large cohort of patients presenting to a tertiary referral center. Furthermore, we seek to elucidate the pre-operative factors that correlate with subsequent surgical intervention. Methods 1483 consecutive patients presenting with PD from 2016 to 2021 were retrospectively identified. Patients were excluded if they only had virtual visits, refused penile duplex evaluation, or had PD surgical correction prior to presentation. Baseline demographics, prior treatments, physical exam findings, penile duplex assessment (PDDU), subsequent interventions, and clinical outcomes were documented. Univariate and multivariate analyses were performed to assess pre-operative predictors of subsequent surgical intervention. Results In total, 1263 patients met inclusion criteria. Mean age at presentation was 55.4 ± 11.1 years with a mean duration of PD at presentation of 33.2 ± 42.5 months. Mean primary curvature was 49.8 ± 20.8°. Primary ventral curvature was present in 11.4% and 36.5% of patients had a multiplanar curvature. Mean composite curvature was 60.4 ± 28.2°. Subjective penile shortening was reported by 64.8% of patients with a mean reported loss of 3.8 ± 2.1 cm. During PDDU, indentation/narrowing deformities was appreciated in 73.7%, hourglass deformity in 10.1%, and hinge effect in 33.0% of patients. Calcification was seen in 30.1% of patients. Operative intervention occurred in 35.3% of patients. Hypogonadism (1.56 OR, p=0.04), severity of primary curvature (1.03 OR, p&amp;lt;0.001), hourglass deformity (1.82 OR, p=0.01), decreased tunical elasticity (1.20 OR, p=0.03), and prior intralesional Xiaflex injections (2.94 OR, p &amp;lt;0.001) predicted subsequent surgical correction. Negative predictors of surgical intervention included use of any oral PD treatment (0.43 OR, &amp;lt;0.001) and ability to perform penetrative sex (0.72 OR, p=0.04). 446 (35.3%) patients underwent surgical intervention with 170 (38.1%) plaque incision/excision and grafting, 110 (24.7%) tunical plication, and 166 (37.2%) inflatable penile prosthesis cases. Conclusions Peyronie’s disease remains an incompletely understood disease and presenting features may be changing as a result of more sophisticated evaluation and physician experience. Ventral curvature, multiplanar curvatures, indentation deformity, hourglass deformity, and severe loss of penile length have been described as “atypical”, but these changes are not rare in our cohort of referred patients. Patients with worse erectile function and more severe PD characteristics were predictors of surgical intervention. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: Boston Scientific.

AN ACUTE COMPLEX PERILUNATE DISLOCATION WITH DEPRESSED DISTAL RADIUS FRACTURE - A CASE REPORT

Introduction Perilunate dislocations and fracture–dislocations are the most common forms of wrist dislocation and encompass a spectrum of injuries, which can include both ligamentous and osseous disruption. In clinical practice, the prex trans is commonly used to refer to associated fractures, whereas the prex peri- is used to describe a dislocation. Perilunate fracture–dislocations (greater arc injuries) are more frequently seen than perilunate dislocations (lesser arc injuries) with the ratio reported to be two to one, with displacement in a dorsal direction in 97% of cases. Here we present a case of 32 year old male with perilunate fracture dislocation with depressed distal radius fracture, which was managed by open dorsal approach with proper reduction, k wire xation and good functional outcome

The aortic arch of piglets

The morphology of the branches of the aortic arch is an important topic in car- diology. Vessels extending from the aortic arch may differ in number, place of departure in different species of animals, as well as have variations of branching within the same species. However, regardless of the existing variations, all of them are the main arterial highways for organs and tissues of the head, neck and thoracic extremities. Considering the above, we set a goal to study the branches of the aortic arch in piglets and give them a morphometric characteristic. The corpses of newborn piglets of the Landrace breed served as the material for the study. The research method was fine anatomical dissection and morphometry. For fine anatomical dissection, injection of the vascular bed with colored latex was performed. During the study, it was found that two arteries depart from the aortic arch in newborn pig- lets: the left subclavian and the brachiocephalic. When comparing the diameters of these arteries, it can be noted that the distribution of blood flow occurs asymmetrically. The bra- chiocephalic artery has a larger diameter. The brachiocephalic artery follows in the cranial direction and gives off the trunk of the common carotid arteries, after which it continues as the right subclavian artery. The diameter of the trunk of the common carotid arteries ex- ceeds that of the brachiocephalic artery. The diameter of the right subclavian artery did not significantly differ from that of the left subclavian artery. Branches of subclavian arteries include two groups: dorsal and ventral. Mainly the dorsal direction has the costal-cervical trunk, deep cervical and vertebral arteries, and the ventral direction has the brachial trunk, internal thoracic and superficial cervical arteries. The largest artery from the group of dor- sal branches is the costal-cervical trunk. Among the group of ventral branches, two arteries reach the maximum diameter: the internal thoracic and the brachial trunk.

Desenvolvimento de um protótipo de prótese de disco intervertebral para a coluna vertebral cervical de cães

ABSTRACT: Cervical arthroplasty with disc prosthesis has been proposed as a treatment option for dogs with Cervical Spondylomyelopathy. The present study developed a novel vertebral disc prosthesis for dogs. Sixteen Functional Spinal Units (C5-C6) were collected from dog cadavers with body weights ranging between 25 and 35 kg, and their vertebral measurements were used to design a prosthetic disc. The sizing of the prosthesis was performed based on the averages of the measurements of width, height, and length of the vertebral bodies from C5-C6 of all specimens. The prosthesis was developed using the Rhinoceros 3D® and SolidWorks® programs, and 3D prototyping was carried out to define the best design. The developed prosthesis consisted of two independent parts that are fixed to the cranial and caudal vertebral bodies, in the intervertebral space, and fitted together by metal-to-metal surfaces capable of moving in the lateral, ventral, and dorsal directions. Each part of the prosthesis is angled in two portions: vertically, in the intervertebral space, and horizontally, in contact with the ventral surface of the vertebral bodies, both of which are fixed by means of monocortical locking screws. The design of the developed prototype allowed a good fit in the intervertebral space between C4-C5, C5-C6, and C6-C7.

Phylogeny of the Ordovician and Silurian members of the order Atrypida

Brachiopods belonging to order Atrypida originated in the Middle Ordovician and went extinct in the Late Devonian. Few cladistic studies have been undertaken for this group. Here we investigate their early evolution through Silurian time. We present a parsimony-based phylogenetic analysis of 41 characters and 70 genera representing all the early taxonomic groups within the order. The stratigraphical record of the fossil genera analysed strongly aligns with the phylogeny recovered from our parsimony analysis. Most currently recognized subfamilies and families may be identified within clades, except for the Atrypinae, Idiospirinae, and the Septatrypidae. This warrants subdivision of the former and redefinition of the latter two. The subfamily Atrypinae is redefined, and a new subfamily of the Atrypidae, the Protatrypinae, is split off. Tracing character evolution across the tree indicates that the calcified spiralia and a jugum or jugal processes characterize all members of the Atrypida, except the most basal clade, the Cyclospiridae, which lacks a calcified jugum. Ribs are a homoplasious character, occurring in numerous clades throughout the tree. Darriwillian through Sandbian ages represent times with rapid evolution when most new autapomorphies seen in the atrypides evolved. This interval is the first major part of the Great Ordovician Biodiversification Event (GOBE). Solid teeth, dorsal direction of spiralia, elaborate ornamentation, and frills evolved in the latest Katian into early Silurian time. Solid teeth seen in distantly related clades from latest Katian onwards may be an analogous feature. The Late Ordovician Mass Extinction (LOME) is indicated in the stratigraphical tree together with a possible event at the end of the Aeronian. The tree supports the long-held assumptions that the Plectatrypinae evolved from the Spirigerininae. It further suggests that the genus Tuvaella may be included with the Davidsonioidea. Likewise, the redefined Atrypinae is a sister group of the Lissatrypidae and a derived group in the phylogenetic tree.

Human intracranial pulsatility during the cardiac cycle: a computational modelling framework

BackgroundToday’s availability of medical imaging and computational resources set the scene for high-fidelity computational modelling of brain biomechanics. The brain and its environment feature a dynamic and complex interplay between the tissue, blood, cerebrospinal fluid (CSF) and interstitial fluid (ISF). Here, we design a computational platform for modelling and simulation of intracranial dynamics, and assess the models’ validity in terms of clinically relevant indicators of brain pulsatility. Focusing on the dynamic interaction between tissue motion and ISF/CSF flow, we treat the pulsatile cerebral blood flow as a prescribed input of the model.MethodsWe develop finite element models of cardiac-induced fully coupled pulsatile CSF flow and tissue motion in the human brain environment. The three-dimensional model geometry is derived from magnetic resonance images (MRI) and features a high level of detail including the brain tissue, the ventricular system, and the cranial subarachnoid space (SAS). We model the brain parenchyma at the organ-scale as an elastic medium permeated by an extracellular fluid network and describe flow of CSF in the SAS and ventricles as viscous fluid movement. Representing vascular expansion during the cardiac cycle, a prescribed pulsatile net blood flow distributed over the brain parenchyma acts as the driver of motion. Additionally, we investigate the effect of model variations on a set of clinically relevant quantities of interest.ResultsOur model predicts a complex interplay between the CSF-filled spaces and poroelastic parenchyma in terms of ICP, CSF flow, and parenchymal displacements. Variations in the ICP are dominated by their temporal amplitude, but with small spatial variations in both the CSF-filled spaces and the parenchyma. Induced by ICP differences, we find substantial ventricular and cranial-spinal CSF flow, some flow in the cranial SAS, and small pulsatile ISF velocities in the brain parenchyma. Moreover, the model predicts a funnel-shaped deformation of parenchymal tissue in dorsal direction at the beginning of the cardiac cycle.ConclusionsOur model accurately depicts the complex interplay of ICP, CSF flow and brain tissue movement and is well-aligned with clinical observations. It offers a qualitative and quantitative platform for detailed investigation of coupled intracranial dynamics and interplay, both under physiological and pathophysiological conditions.

Setup error and residual error analysis of ExacTrac X-ray image guidance system in stereotactic radiotherapy for brain metastases

ObjectiveThis study aims to analyze the setup errors of the ExacTrac X-ray image guidance system in stereoscopic radiotherapy for brain metastases and discuss the necessity of setup error verification after bed angle movement. MethodsTwelve patients with brain metastases were treated with stereotactic radiotherapy. ExacTrac X-ray image guidance system was used to register and verify the image. Besides, the intra- and inter-fractional setup errors and residual errors were analyzed. ResultsTwelve patients received head stereotactic radiotherapy 56 times. The inter-fractional setup errors and residual errors were x (1.04 ± 0.16) and (0.15 ± 0.05) mm in left and right directions, y (1.25 ± 0.28) and (0.18 ± 0.07) mm in head and foot direction, and z (0.93 ± 0.81) and (0.14 ± 0.13) mm in abdominal and dorsal direction, respectively; Rx (0.81 ± 0.24) and (0.24 ± 0.09) degree in the sagittal plane, Ry (0.95 ± 0.19), (0.22 ± 0.06) degree in the cross-section, and Rz (1.03 ± 0.26), (0.22 ± 0.06) in the coronal plane. The difference was statistically significant (P < 0.05). Only 19.6% of the intra-fractional non-coplanar arc setup verification passed without correction for the first time, and the others were significantly improved after correction, presenting statistical significance (P < 0.05). The inter-fractional setup errors and residual errors were x (0.82 ± 0.25) and (0.13 ± 0.04) mm in left and right directions, y (0.67 ± 0.23) and (0.18 ± 0.08) mm in head and foot direction, and z (0.74 ± 0.21) and (0.19 ± 0.08) mm in abdominal and dorsal direction, respectively; Rx (0.67 ± 0.13) and (0.20 ± 0.08) degree in the sagittal plane, Ry (0.68 ± 0.13) and (0.17 ± 0.10) degree in the cross-section, and Rz (0.60 ± 0.28) and (0.19 ± 0.07) degree in the coronal plane. The difference was statistically significant (P < 0.05). ConclusionThe ExacTrac image guidance system enhanced the accuracy of setup in stereoscopic radiotherapy for brain metastases and satisfied the clinical requirements. It is necessary to verify the non-coplanar arc setup.