Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition

The teeth of sharks famously form a series of transversely organized files with a conveyor-belt replacement that are borne directly on the jaw cartilages, in contrast to the dermal plate-borne dentition of bony fishes that undergoes site-specific replacement. A major obstacle in understanding how this system evolved is the poorly understood relationships of the earliest chondrichthyans and the profusion of morphologically and terminologically diverse bones, cartilages, splints and whorls that they possess. Here, we use tomographic methods to investigate mandibular structures in several early branching ‘acanthodian’-grade stem-chondrichthyans. We show that the dentigerous jaw bones of disparate genera of ischnacanthids are united by a common construction, being growing bones with non-shedding dentition. Mandibular splints, which support the ventro-lateral edge of the Meckel's cartilage in some taxa, are formed from dermal bone and may be an acanthodid synapomorphy. We demonstrate that the teeth of Acanthodopsis are borne directly on the mandibular cartilage and that this taxon is deeply nested within an edentulous radiation, representing an unexpected independent origin of teeth. Many or even all of the range of unusual oral structures may be apomorphic, but they should nonetheless be considered when building hypotheses of tooth and jaw evolution, both in chondrichthyans and more broadly.

The Danger Zone for Iatrogenic Neurovascular Injury in All-Inside Lateral Meniscal Repair in Relation to the Popliteal Tendon: An MRI Study

Background: Lateral meniscal repair can endanger the nearby neurovascular structure (peroneal nerve or popliteal artery). To our knowledge, there have been no studies to evaluate the danger zone of all-inside meniscal repair through the anteromedial (AM) and anterolateral (AL) portals in relation to the medial and lateral edges of the popliteal tendon (PT). Purpose: To establish the risk of neurovascular injury and the danger zone in repairing the lateral meniscus in relation to the medial and lateral edges of the PT. Study Design: Descriptive laboratory study. Methods: Using axial magnetic resonance imaging (MRI) studies at the level of the lateral meniscus, lines were drawn to simulate a straight, all-inside meniscal repair device, drawn from the AM and AL portals to both the medial and lateral edges of the PT. In cases in which the line passed through the neurovascular structure, a risk of iatrogenic neurovascular injury was deemed, and measurements were made to determine the danger zones of neurovascular injury in relation to the medial or lateral edges of the PT. Results: Axial MRI images of 240 adult patients were reviewed retrospectively. Repairing the body of the lateral meniscus through the AM portal had a greater risk of neurovascular injury than repairs made through the AL portal in relation to the medial edge of the PT ( P = .006). The danger zone in repairing the lateral meniscus through the AM portal extended 1.82 ± 1.68 mm laterally from the lateral edge of the PT and 3.13 ± 2.45 mm medially from the medial edge of the PT. Through the AL portal, the danger zone extended 2.81 ± 1.94 mm laterally from the lateral edge of the PT and 1.39 ± 1.53 mm medially from the medial edge of the PT. Conclusion: Repairing the lateral meniscus through either the AM or the AL portals in relation to the PT can endanger the peroneal nerve or popliteal artery. Clinical Relevance: The surgeon can minimize the risk of iatrogenic neurovascular injury in lateral meniscal repair by avoiding using the all-inside meniscal device in the danger zone area as described in this study.

The Value of the Topography of the Inferior Epigastric Artery in Women in Breast Reconstructive Plastic Surgery

Currently, the most optimal option for breast reconstruction after mastectomy is the use of a pedicle DIEP flap from the inferior epigastric artery.The aim of the study was to study the features of the typical and variant anatomy of the inferior epigastric artery in women in the applied aspect.Material and methods. The study was carried out on 20 unfixed female bodies who died at the age of 54.6±4.7 years. We studied the level of intersection of the main trunk of the inferior epigastric artery with the lateral edge of the rectus abdominis muscle, the distance from this artery to the midline at different measurement levels, as well as the outer diameter of the studied vessel.Results. On the right, at different measurement levels, the distance from the main trunk of the inferior epigastric artery to the midline, the diameter of the artery, as well as the level of its intersection with the lateral edge of the rectus abdominis muscle in relation to the upper edge of the pubic bone, significantly exceed those on the left.Conclusion. It is necessary to take into account the peculiarities of the topographic anatomy of the inferior epigastric artery, planning and carrying out breast reconstruction with a DIEP flap, in order to prevent the development of necrosis in the postoperative period. For better reperfusion of the reconstruction area in the postoperative period, it is preferable to cut out the flap with the isolation of the right inferior epigastric artery (due to its larger diameter).

On the bandwidth and beam profile characteristics of a simple low frequency collimated ultrasound beam source

We numerically investigate the bandwidth and collimation characteristics of ultrasound beams generated by a simple collimated ultrasound beam source that consists of a piezoelectric disk operated near its radial mode resonances. We simulate the ultrasound beam generated in a fluid medium as a function of the excitation frequency for two cases: 1) free piezoelectric disk that corresponds to zero-traction along the lateral edge, and 2) fixed piezoelectric disk that corresponds to zero-displacement along the lateral edge. We present and discuss the physical mechanism underpinning the frequency-dependent collimation and bandwidth properties of the ultrasound beams. We observe that the collimated beam generated by the free disk repeatedly lengthens/shortens and also extends/retracts sidelobes with increasing frequency. Alternatively, fixing the piezoelectric disk results in a consistent beam profile shape across a broad range of frequencies. This facilitates generating broadband signals such as a Gaussian pulse or chirp, which are common in ultrasound imaging. Thus, the fixed piezoelectric disk finds application as a collimated ultrasound beam source in a wide range of applications including medical ultrasound imaging, scanning acoustic microscopy, sonar detection, and other nondestructive ultrasound inspection techniques.

New evaluation indices for rotational knee angles in standing anteroposterior knee radiographs

BACKGROUND: Identifying the time course of rotational knee alignment is crucial for elucidating the etiology in knee osteoarthritis. OBJECTIVE: The aim of this study was to propose new rotational indices for calculating the change in relative rotational angles between the femur and tibia in standing anteroposterior (AP) radiographs. METHODS: Forty healthy elderly volunteers (20 women and 20 men; mean age, 70 ± 6 years) were assessed. The evaluation parameters were as follows: (1) femoral rotational index: the distance between the sphere center of the medial posterior femoral condyle and the lateral edge of the patella, and (2) tibial rotational index: the distance between the medial eminence of the tibia and the lateral edge of the fibula head. The indices were standardized by the diameter of the sphere of the medial posterior femoral condyle. This study (1) identified the relationship between changes in rotational indices and the simulated rotational knee angles in the standing position, (2) proposed a regression equation for the change in relative rotational angles between the femur and tibia in standing AP radiographs, and (3) verified the accuracy of the regression equation. RESULTS: The rotational indices increased in direct proportion to simulated rotational knee angles (femoral index: r > 0.9,p < 0.0001; tibial index: r > 0.9, p < 0.0001). Based on the results, the regression equation with the accuracy of 0.45 ± 0.26° was determined. CONCLUSIONS: The proposed regression equations can potentially predict the change in relative rotational angles between the femur and tibia in a pair of standing AP radiographs taken at different dates in longitudinal studies.

The lateral edge and sourcil acetabular indices for surgical decision-making in developmental dysplasia of the hip

Purpose The acetabular index (AI) is a radiographic measure that guides surgical decision-making in developmental dysplasia of the hip (DDH). Two AI measurement methods are described; to the lateral edge of the acetabulum (AI-L) and to the lateral edge of the sourcil (AI-S). The purpose of this study was to determine the level of agreement between AI-L and AI-S on the diagnosis and degree of acetabular dysplasia in DDH. Methods A total of 35 patients treated for DDH with Pavlik harness were identified. The AI-L and AI-S were measured on radiographs (70 hips) at two and five years of age. AI-L and AI-S were then transformed relative to published normative data (tAI-L and tAI-S). Bland-Altman plots, linear regression and heat mapping were used to evaluate the agreement between tAI-L and tAI-S. Results There was poor agreement between tAI-S and tAI-L on the Bland-Altman plots with wide limits of agreement and no proportional bias. The two AI measurements were in agreement as to the presence and severity of dysplasia in only 63% of hips at two years of age and 81% at five years of age, leaving the remaining hips classified as various combinations of normal, mildly and severely dysplastic. Conclusion AI-L and AI-S have poor agreement on the presence or degree of acetabular dysplasia in DDH and cannot be used interchangeably. Clinicians are cautioned to prudently evaluate both measures of AI in surgical decision-making. Level of evidence I

The Shape of the First Metatarsal Head and its Association with its Pronation Angle and the Presence of Sesamoid-Metatarsal Joint Osteoarthritis

Category: Bunion Introduction/Purpose: The rounded shape of the first metatarsal head’s lateral edge on the dorsoplantar radiograph of the foot is used as a qualitative evaluation of the first metatarsal pronation in hallux valgus feet. However, the relationship between the rounded shape and the metatarsal pronation angle of the first metatarsal has not been examined in detail. Furthermore, hallux valgus often accompanies osteoarthritis in the sesamoid-metatarsal joint. Deformation of the metatarsal head by osteophytes on the lateral edge of the lateral sesamoid facet may affect the rounded shape. The purpose of this study was to evaluate the associations of the shape of the first metatarsal head with (1) the presence of osteoarthritis in the sesamoid-metatarsal joint and (2) the pronation angle of the first metatarsal head. Methods: Patients were prospectively recruited between December 2016 and March 2017. Patients with a history of previous foot and ankle surgery or destruction of the head due to rheumatoid arthritis were excluded. A total of 121 patients, with the mean age of 61 years, underwent weight-bearing dorsoplantar, lateral, and first metatarsal axial radiographs. The shape of the first metatarsal head’s lateral edge was classified as either rounded, intermediate, or angular in shape in the dorsoplantar view. The presence of osteoarthritis in the sesamoid-metatarsal joint and the pronation angle of the first metatarsal head were assessed in the first metatarsal axial view. Other variables that could affect the first metatarsal shape, including the lateral first metatarsal inclination angle, were also assessed. Univariate and multivariate analyses were performed to determine the associations of the rounded shape of the first metatarsal with the pronation angle and sesamoid-metatarsal joint osteoarthritis. Results: Of 121 feet, 31, 41, and 49 feet had rounded, intermediate, and angular metatarsal heads, respectively. Sesamoid- metatarsal joint osteoarthritis was evident in 49 (40%) feet. The mean hallux valgus and first metatarsal pronation angle was 23° and 9°, respectively. The prevalence of sesamoid-metatarsal osteoarthritis was significantly higher (24 (77%), 11 (27%), and 14 (29%) for rounded, intermediate, and angular, respectively, P < .001) in feet with a rounded metatarsal head. Furthermore, the metatarsal pronation angle was significantly larger (14°, 8°, and 4° for rounded, intermediate, and angular, respectively, P < .001). These associations were also significant in the multiple regression analysis. Conclusion: A rounded metatarsal head was associated with a higher prevalence of osteoarthritis within the sesamoid-metatarsal joint, as well as a larger first metatarsal head pronation angle. A negative round sign can be used as a simple indicator of an effective correction to the first metatarsal pronation angle during hallux valgus surgery. However, in feet with sesamoid-metatarsal osteoarthritis, surgeons will need to be cautious as overcorrection may occur.

Can the Apex of Tibial Tubercle Represent the Insertion of Patellar Tendon in Measurement of Quadriceps Angles? Imaging Verification

Background Clinical measurement of a quadriceps angle (Q-angle) has yet achieved consensus. The patellar stability is generally low despite that the tibial tubercle (TT) is fixed. The aim of this retrospective study was to verify whether the lower arm of a Q-angle (i.e. the patellar tendon [PT]) can be represented by the localization of TT. Methods The locations of the apex of TT and the center of PT in magnetic resonance imaging (MRI) were investigated in 100 consecutive young adult patients (50 men and 50 women; average, 27 years). The tibial width (TW), the distance from the apex of TT and the center of PT to the lateral edge of TW, and the PT width were measured. The ratios of the TT and PT to TW were compared statistically. Results The TW was 64 mm (62-66 mm). The apex of TT was 38% (37-39%) from the lateral edge of TW. The center of PT was 37% (36-38%) from the lateral edge of TW. Except the TW and PT width (both, p < 0.001), there was no statistical significance in all other comparisons between sexes ( p > 0.05). The correlation between the TT and PT in 100 patients was 0.84. There was statistical difference between the two parameters ( p = 0.02). Conclusion Although the center of PT is lateral to the apex of TT, the discrepancy is minimal (1% of TW, about 0.6 mm; or 3% of PT width). Clinically, using the TT to represent the insertion of PT may be reasonable.

Sex-Based Differences in Optimal Tunnel Placement for Acromioclavicular Joint Reconstruction

Background: Tunnel placement is important for outcomes after acromioclavicular (AC) joint reconstruction, yet little has been written on sex-based differences in optimal tunnel positioning. Hypothesis: No sex-based or anatomic differences will be found in ideal tunnel position based on radiographic measurements. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The records of 2382 patients were retrospectively examined for clavicle radiographs over a 20-year period. A random set of radiographs were reviewed until 200 radiographs from each sex met inclusion criteria per a priori power analysis. Anteroposterior clavicle radiographs were used to collect (1) length from lateral clavicle to lateral coracoid (LCLC), (2) length from lateral clavicle to medial coracoid (LCMC), (3) clavicle length (CL), and (4) clavicular depth at the midcoracoid (MCCD). The Student t test was used to compare differences between male and female patients. The Pearson correlation coefficient was used to measure linear correlations. Variables with a P < .1 were included in a multiple regression model. Results: The cohort included 200 men and 200 women. LCLC and LCMC were significantly greater for men than for women ( P < .0001). Clavicle length was significantly correlated with LCLC ( r = 0.63; P < .0001) and LCMC ( r = 0.74; P < .0001). MCCD was significantly correlated with LCLC ( r = 0.32; P < .0001) and LCMC ( r = 0.43; P < .0001). The approximate placement for the trapezoid tunnel was found to be 22.1 mm in women and 26.6 mm in men. The approximate placement for the conoid tunnel was found to be 40 mm in women and 46.6 mm in men. The ratios (LCLC:CL and LCMC:CL) were also significantly different between female and male patients. The LCLC:CL was 0.144 in women and 0.154 in men ( P < .0001). The LCMC:CL was 0.261 in women and 0.271 in men ( P < .0006). Conclusion: Significant sex-based differences are found in the position of the coracoid relative to the lateral edge of the clavicle. Coracoid position relative to the lateral edge of the clavicle is correlated with anatomic parameters, most strongly with clavicle length.