Developing a Technique for the Imaging-Based Measurement of ACL Elongation: A Proof of Principle

Towards the goal of obtaining non-invasive biomarkers reflecting the anterior cruciate ligament’s (ACL) loading capacity, this project aimed to develop a magnetic resonance imaging (MRI)-based method facilitating the measurement of ACL elongations during the execution of knee stress tests. An MRI-compatible, computer-controlled, and pneumatically driven knee loading device was designed to perform Lachman-like tests and induce ACL strain. A human cadaveric leg was used for test purposes. During the execution of the stress tests, a triggered real-time cine MRI sequence with a temporal resolution of 10 Hz was acquired in a parasagittal plane to capture the resultant ACL elongations. To test the accuracy of these measurements, the results were compared to in situ data of ACL elongation that were acquired by measuring the length changes of a surgical wire directly sutured to the ACL’s anteromedial bundle. The MRI-based ACL elongations ranged between 0.7 and 1.7 mm and agreed very well with in situ data (root mean square errors, RMSEs ≤ 0.25 mm), although peak elongation rates were underestimated by the MRI (RMSEs 0.19–0.36 mm/s). The high accuracy of elongation measurements underlines the potential of the technique to yield an imaging-based biomarker of the ACL’s loading capacity.

Diagnostic utility of parasagittal measurements of tonsillar herniation in Chiari I malformation

Background and purpose Although the cerebellar tonsils are parasagittal structures, the extent of tonsillar herniation (ETH) in Chiari I malformation (CMI) is currently measured in the midsagittal plane. We measured the ETH of each cerebellar tonsil in the parasagittal plane and assessed their diagnostic utility by comparing them to the midsagittal ETH measurements in predicting cough-associated headache (CAH), an indicator of clinically significant disease in CMI. Methods Eighty-five CMI patients with 3D-MPRAGE images were included. Neurosurgeons determined the presence of CAH. Sagittal images were used to measure ETH in the midsagittal (MS_ETH) and parasagittal planes (by locating tonsillar tips on each side on reformatted coronal images). Given the parasagittal ETH (PS_ETH) asymmetry in the majority of cases, they were considered Smaller_PS_ETH or Larger_PS_ETH. The accuracy of ETH measurements was assessed by the receiver operating characteristic (ROC) curve. Results Of 85 patients, 46 reported CAH. ROC analysis showed an area under the curve (AUC) of 0.78 for Smaller_PS_ETH significantly better than 0.65 for MS-ETH in predicting CAH ( p = 0.001). An AUC of 0.68 for Larger_PS_ETH was not significantly different from MS_ETH. The sensitivity and specificity of predicting CAH were 87% and 28% for MS_ETH >6 mm versus 90% and 46% for Smaller_PS_ETH >6 mm, and 52% and 67% for MS_ETH >9 mm versus 48% and 87% for Smaller_PS_ETH >9 mm. At ETH >15 mm, no differences were seen between the measurements. Conclusions Diagnostic utility of ETH measurements in detecting clinically significant CMI can be improved by parasagittal measurements of the cerebellar tonsillar herniation.

Reassessment of the Triassic archosauriform Scleromochlus taylori: neither runner nor biped, but hopper

The six known specimens of Scleromochlus taylori and casts made from their negative impressions were examined to reassess the osteological evidence that has been used to interpret Scleromochlus’s locomotion and phylogenetic relationships. It was found that the trunk was dorsoventrally compressed. The upper temporal fenestra was on the lateral surface of skull and two-thirds the size of the lower, the jaw joint posteriorly placed with short retroarticular process, and teeth short and subconical, but no evidence of external nares or antorbital fossae was found. The posterior trunk was covered with ~20 rows of closely spaced transversely elongate dorsal osteoderms. The coracoid was robust and elongate. The acetabulum was imperforate and the femoral head hemispherical and only weakly inturned such that the hip joint was unsuited to swinging in a parasagittal plane. The presence of four distal tarsals is confirmed. The marked disparity of tibial and fibular shaft diameters and of proximal tarsal dimensions indicates that the larger proximal tarsal is the astragalus and the significantly smaller tarsal is the calcaneum. The astragalus and calcaneum bear little resemblance to those of Lagosuchus, and the prominent calcaneal tuber confirms that the ankle was crurotarsal. There is no evidence that preserved body and limb postures are unnatural, and most specimens are preserved in what is interpreted as a typical sprawling resting pose. A principal component analysis of skeletal measurements of Scleromochlus and other vertebrates of known locomotor type found Scleromochlus to plot with frogs, and that finding combined with skeletal morphology suggests Scleromochlus was a sprawling quadrupedal hopper. Phylogenetic analyses found that Scleromochlus was not an ornithodiran, but was either within the Doswelliidae or outside the clade consisting of the most recent common ancestor of the Erythrosuchidae and Archosauria and all its descendants.

SPECIFIC MORPHOMETRIC FEATURES OF SUPERIOR SAGITTAL SINUS IN ADULTS

In order to determine the individual peculiarity of the shape, size, position and relations of the upper sagittal sinus, depending on the type of structure of the head in adults, craniometry and morphometry of the head sinuses were performed. The most significant venous collector of the brain is the upper sagittal sinus, which is located in the sagittal plane along the ridge of the lattice to the inner occipital projection. This formation is characterized by a triangular shape. The upper wall is formed by the leaves of the convex part of the solid membrane, and the two lateral walls by splitting the sickle of the cerebellum in the parasagittal plane. In adults, the upper wall contacts the inner surface of the parietal and occipital bones of the cranial vault. According to our data, the upper sagittal sinus has a specific range of variability depending on age, sex and head shape. The range of individual variability of the structure of the upper sagittal sinus was determined, which is characterized by the greatest values of length and height in adults, irrespective of gender with dolichomorphic head shape (narrow-headed) and increase in latitudinal parameters in people with meso- and brachymorphic head (middle and wide).

Ultrasound measurement of laryngeal structures in the parasagittal plane for the prediction of difficult laryngoscopies in Chinese adults

Abstract Background: Abnormal laryngeal structures are likely to be associated with a difficult laryngoscopy procedure. Currently, laryngeal structures can be measured by ultrasonography, however, little research has been performed on the potential role of ultrasound on the evaluation of a difficult laryngoscopy. The present study investigated the value of laryngeal structure measurements for predicting a difficult laryngoscopy. Objective: The main objective of this study was to explore the value of laryngeal structure measurements for predicting a difficult laryngoscopy. Methods: Two hundred and eleven adult patients (over 18 years old) were recruited to undergo elective surgery under general anesthesia via endotracheal intubation. Ultrasound was utilized to measure the distance between the skin and thyroid cartilage (DST), the distance between the thyroid cartilage and epiglottis (DTE), and the distance between the skin and epiglottis (DSE) in the parasagittal plane. These metrics were then investigated as predictors for classifying a laryngoscopy as difficult vs easy, as defined by the Cormack and Lehane grading scale. Results: Multivariate logistic regression showed that the DSE, but not DST or DTE, was significantly related to difficult laryngoscopies. Specifically, a DSE ≥ 2.36 cm predicted difficult laryngoscopies with a sensitivity and specificity of 0.818 (95% CI: 0.766-0.870) and 0.856 (95% CI: 0.809-0.904). Furthermore, when combining the best model constructed of other indicators (i.e. sex, body mass index, modified Mallampati test) to predict the difficult laryngoscopy, the AUC reached 93.28%. Conclusion: DSE is an independent predictor of a difficult laryngoscopy; a DSE cutoff value of 2.36 cm is a better predictor of a difficult laryngoscope than other ultrasound or physiological measurements for predicting a difficult laryngoscope. Nevertheless, it's more valuable to apply the best model of this study, composed of various physiological measurements, for this prediction purpose. Key words: difficult airway ;endotracheal intubation ; ultrasound

How moles walk; it's all thumbs

A recurring theme in the evolution of tetrapods is the shift from sprawling posture with laterally orientated limbs to erect posture with the limbs extending below the body. However, in order to invade particular locomotor niches, some tetrapods secondarily evolved a sprawled posture. This includes moles, some of the most specialized digging tetrapods. Although their forelimb anatomy and posture facilitates burrowing, moles also walk long distances to forage for and transport food. Here, we use X-ray Reconstruction Of Moving Morphology (XROMM) to determine if the mole humerus rotates around its long axis during walking, as it does when moles burrow and echidnas walk, or alternatively protracts and retracts at the shoulder in the horizontal plane as seen in sprawling reptiles. Our results reject both hypotheses and demonstrate that forelimb kinematics during mole walking are unusual among those described for tetrapods. The humerus is retracted and protracted in the parasagittal plane above, rather than below the shoulder joint and the ‘false thumb’, a sesamoid bone (os falciforme), supports body weight during the stance phase, which is relatively short. Our findings broaden our understanding of the diversity of tetrapod limb posture and locomotor evolution, demonstrate the importance of X-ray-based techniques for revealing hidden kinematics and highlight the importance of examining locomotor function at the level of individual joint mobility.

Intersegmental dynamics shape joint coordination during catching in typically developing children but not in children with developmental coordination disorder

Factors shaping joint coordination during multijoint movements were studied using a one-handed ball-catching task. Typically developing (TD) boys between 9 and 12 yr of age, at which catching becomes consistently successful, and boys with developmental coordination disorder (DCD) of the same age participated in the study. The arm was initially stretched down. Catching was performed by flexing the shoulder and elbow and extending the wrist in the parasagittal plane. Catching success rate was substantially lower in children with DCD. Amplitudes and directions of joint motions were similar in both groups. Group differences were found in shoulder and elbow coordination patterns. TD children performed the movement predominantly by actively accelerating into flexion, one joint at a time—first the elbow and then the shoulder—and allowing passive interaction torque (IT) to accelerate the other joint into extension. Children with DCD tended to accelerate both joints into flexion simultaneously, suppressing IT. The results suggest that the TD joint coordination was shaped by the tendency to minimize active control of IT despite the complexity of the emergent joint kinematics. The inefficient control of IT in children with DCD points to deficiency of the internal model of intersegmental dynamics. Together, the findings advocate that joint coordination throughout a multijoint movement is a by-product of the control strategy that benefits from movement dynamics by actively accelerating a single joint and using IT for rotation of the other joint. Reduction of control-dependent noise is discussed as a possible advantage of this control strategy.