Propagating spatiotemporal activity patterns across macaque motor cortex carry kinematic information.

Propagating spatiotemporal neural patterns are widely evident across sensory, motor, and association cortical areas. However, it remains unclear whether any characteristics of neural propagation carry information about specific behavioral details. Here, we provide the first evidence for a link between the direction of cortical propagation and specific behavioral features of an upcoming movement on a trial-by-trial basis. We recorded local field potentials (LFPs) from multielectrode arrays implanted in the primary motor cortex of two rhesus macaque monkeys while they performed a 2D reach task. Propagating patterns were extracted from the information-rich high-gamma band (200 to 400 Hz) envelopes in the LFP amplitude. We found that the exact direction of propagating patterns varied systematically according to initial movement direction, enabling kinematic predictions. Furthermore, characteristics of these propagation patterns provided additional predictive capability beyond the LFP amplitude themselves, which suggests the value of including mesoscopic spatiotemporal characteristics in refining brain-machine interfaces.

Thermomorphogenesis of the Arabidopsis thaliana root: Flexible cell division, constrained elongation, and the role of cryptochrome.

Understanding how plants respond to temperature is relevant for agriculture in a warming world. Responses to temperature of the shoot have been characterized more fully than those of the root. Previous work on thermomorphogenesis in roots established that for Arabidopsis thaliana (Columbia) seedlings grown continuously at a given temperature, the root meristem produces cells at the same rate at 15 as at 25ºC and the root's growth zone is the same length. To uncover the pathway(s) underlying this constancy, we screened 34 A. thaliana genotypes for parameters related to growth and division. No line failed to respond to temperature. Behavior was little affected by mutations in phytochrome or other genes that underly thermomorphogenesis in shoots. However, a mutant in cryptochrome2 was disrupted substantially in both cell division and elongation, specifically at 15ºC. Among the 34 lines, cell production rate varied extensively and was associated only weakly with root growth rate; in contrast, parameters relating to elongation were stable. Our data are consistent with models of root growth that invoke cell non-autonomous regulation for establishing boundaries between meristem, elongation zone, and mature zone.

Plant chromosome polytenization contributes to suppression of the root growth in high-polyploids.

Autopolyploidization, which refers to a polyploidization via genome duplication without a hybridization, promotes growth in autotetraploids, but suppresses growth in high-polyploids (autohexaploids or autooctoploids). The mechanism underlying this growth suppression (i.e., "high-ploidy syndrome") has not been comprehensively characterized. In this study, we conducted a kinematic analysis of the root apical meristem cells in Arabidopsis thaliana autopolyploids (diploid, tetraploid, hexaploid, and octoploid) to determine the effects of the progression of genome duplication on root growth. The results of the root growth analysis showed that tetraploidization increases the cell volume, but decreases cell proliferation. However, cell proliferation and volume growth are suppressed in high-polyploids. The whole-mount fluorescence in situ hybridization analysis revealed extensive chromosome polytenization in the region where cell proliferation does not usually occur in the high-polyploid roots, which is likely at least partly correlated with the suppression of endoreduplication. The study findings suggest that chromosome polytenization is important for the suppressed growth of high-polyploids.

The Role of Cerebellum and Basal Ganglia Functional Connectivity in Altered Voluntary Movement Execution in Essential Tremor.

Substantial evidence highlights the role of the cerebellum in the pathophysiology of tremor in essential tremor (ET), although its potential involvement in altered movement execution in this condition remains unclear. This study aims to explore potential correlations between the cerebellum and basal ganglia functional connectivity and voluntary movement execution abnormalities in ET, objectively assessed with kinematic techniques. A total of 20 patients diagnosed with ET and 18 healthy subjects were enrolled in this study. Tremor and repetitive finger tapping were recorded using an optoelectronic kinematic system. All participants underwent comprehensive 3T-MRI examinations, including 3D-T1 and blood-oxygen-level dependent (BOLD) sequences during resting state. Morphometric analysis was conducted on the 3D-T1 images, while a seed-based analysis was performed to investigate the resting-state functional connectivity (rsFC) of dorsal and ventral portions of the dentate nucleus and the external and internal segments of the globus pallidus. Finally, potential correlations between rsFC alterations in patients and clinical as well as kinematic scores were assessed. Finger tapping movements were slower in ET than in healthy subjects. Compared to healthy subjects, patients with ET exhibited altered FC of both dentate and globus pallidus with cerebellar, basal ganglia, and cortical areas. Interestingly, both dentate and pallidal FC exhibited positive correlations with movement velocity in patients, differently from that we observed in healthy subjects, indicating the higher the FC, the faster the finger tapping. The findings of this study indicate the possible role of both cerebellum and basal ganglia in the pathophysiology of altered voluntary movement execution in patients with ET.

Terrestrial locomotion characteristics of climbing perch (Anabas testudineus).

The evolution and utilization of limbs facilitated terrestrial vertebrate movement on land, but little is known about how other lateral structures enhance terrestrial locomotion in amphibian fishes without terrestrialized limb structures. Climbing perch (Anabas testudineus) exhibit sustained terrestrial locomotion using uniaxial rotating gill covers instead of appendages. To investigate the role of such simple lateral structures in terrestrial locomotion and the motion-generating mechanism of the corresponding locomotor structure configuration (gill covers and body undulation), we measured the terrestrial kinematics of climbing perch and quantitatively analysed its motion characteristics. The digitized locomotor kinematics showed a unique body postural adjustment ability that enables the regulation of the posture of the caudal peduncle for converting lateral bending force into propulsion. An analysis of the coordination characteristics demonstrated that the motion of the gill cover is kinematically independent of axial undulation, suggesting that the gill cover functions as an anchored simple support pole while axial undulation actively mediates body posture and produces propulsive force. The two identified feature shapes explained more than 87% of the complex lateral undulation in multistage locomotion. The kinematic characteristics enhance our understanding of the underlying coordinating mechanism corresponding to locomotor configurations. Our work provides quantitative insight into the terrestrial locomotor adaptation of climbing perch and sheds light on terrestrial motion potential of locomotor configurations containing a typical aquatic body and restricted lateral structure.

Modeling kinematic variability reveals displacement and velocity based dual control of saccadic eye movements.

Noise is a ubiquitous component of motor systems that leads to behavioral variability of all types of movements. Nonetheless, systems-based models investigating human movements are generally deterministic and explain only the central tendencies like mean trajectories. In this paper, a novel approach to modeling kinematic variability of movements is presented and tested on the oculomotor system. This approach reconciles the two prominent philosophies of saccade control: displacement-based control versus velocity-based control. This was achieved by quantifying the variability in saccadic eye movements and developing a stochastic model of its control. The proposed stochastic dual model generated significantly better fits of inter-trial variances of the saccade trajectories compared to existing models. These results suggest that the saccadic system can flexibly use the information of both desired displacement and velocity for its control. This study presents a potential framework for investigating computational principles of motor control in the presence of noise utilizing stochastic modeling of kinematic variability.

Muscle synergy and kinematic synergy analyses during sit-to-stand motions in hallux valgus patients before and after treatment with Kinesio taping.

OBJECTIVES: To explore the impact of hallux valgus (HV) on lower limb neuromuscular control strategies during the sit-to-stand (STS) movement, and to evaluate the effects of Kinesio taping (KT) intervention on these control strategies in HV patients. METHODS: We included 14 young healthy controls (HY), 13 patients in the HV group (HV), and 11 patients in the HV group (HVI) who underwent a Kinesio taping (KT) intervention during sit-to-stand (STS) motions. We extracted muscle and kinematic synergies from EMG and motion capture data using non-negative matrix factorization (NNMF). In addition, we calculated the center of pressure (COP) and ground reaction forces (GRF) to assess balance performance. RESULTS: There were no significant differences in the numbers of muscle and kinematic synergies between groups. In the HV group, knee flexors and ankle plantar flexors were abnormally activated, and muscle synergy D was differentiated. Muscle synergy D was not differentiated in the HVI group. CONCLUSION: Abnormal activation of knee flexors and plantar flexors led to the differentiation of module D in HV patients, which can be used as an indicator of the progress of HV rehabilitation. KT intervention improved motor control mechanisms in HV patients.

Abnormal interlimb coordination of motor developmental delay during infant crawling based on kinematic synergy analysis.

BACKGROUND: Previous studies have reported that abnormal interlimb coordination is a typical characteristic of motor developmental delay (MDD) during human movement, which can be visually manifested as abnormal motor postures. Clinically, the scale assessments are usually used to evaluate interlimb coordination, but they rely heavily on the subjective judgements of therapists and lack quantitative analysis. In addition, although abnormal interlimb coordination of MDD have been studied, it is still unclear how this abnormality is manifested in physiology-related kinematic features. OBJECTIVES: This study aimed to evaluate how abnormal interlimb coordination of MDD during infant crawling was manifested in the stability of joints and limbs, activation levels of synergies and intrasubject consistency from the kinematic synergies of tangential velocities of joints perspective. METHODS: Tangential velocities of bilateral shoulder, elbow, wrist, hip, knee and ankle over time were computed from recorded three-dimensional joint trajectories in 40 infants with MDD [16 infants at risk of developmental delay, 11 infants at high risk of developmental delay, 13 infants with confirmed developmental delay (CDD group)] and 20 typically developing infants during hands-and-knees crawling. Kinematic synergies and corresponding activation coefficients were derived from those joint velocities using the non-negative matrix factorization algorithm. The variability accounted for yielded by those synergies and activation coefficients, and the synergy weightings in those synergies were used to measure the stability of joints and limbs. To quantify the activation levels of those synergies, the full width at half maximum and center of activity of activation coefficients were calculated. In addition, the intrasubject consistency was measured by the cosine similarity of those synergies and activation coefficients. RESULTS: Interlimb coordination patterns during infant crawling were the combinations of four types of single-limb movements, which represent the dominance of each of the four limbs. MDD mainly reduced the stability of joints and limbs, and induced the abnormal activation levels of those synergies. Meanwhile, MDD generally reduced the intrasubject consistency, especially in CDD group. CONCLUSIONS: These features have the potential for quantitatively evaluating abnormal interlimb coordination in assisting the clinical diagnosis and motor rehabilitation of MDD.

Persistent avoidance of virtual food in anorexia nervosa-restrictive type: Results from motion tracking in a virtual stopping task.

OBJECTIVE: Food avoidance is central to patients with anorexia nervosa-restrictive type (AN-R). Competing accounts in experimental psychopathology research suggest that food avoidance may result from automatic, habitual responses or from elevated inhibitory control abilities. This study investigated behavioral trajectories of food avoidance in a novel virtual reality stopping task. METHOD: Sixty patients with AN-R and 29 healthy controls with normal weight were investigated using a novel, kinematic task in virtual reality. We recorded spatial displacement in stop- and go-trials to virtual food and control objects. Inhibitory control abilities were operationalized by the VR task in stopping performance (i.e., interrupted movement in stop-trials), whereas we also measured habitual avoidance of virtual food across both go- and stop-trials (i.e., delayed movement relative to nonfood objects). RESULTS: In patients with AN-R, hand displacements were shorter to food versus nonfood across stop- and go-trials, reflected in a Stimulus × Group interaction. Healthy controls showed no differences. Importantly, the food-specific effect in AN-R was identical across stop- and go-trials, indicating habitual food avoidance. Moreover, stop error rates (i.e., stop-trials with response) were lower in patients with AN-R. DISCUSSION: The findings suggest food-specific habitual avoidance and heightened generalized inhibitory control in AN-R. The continuously delayed displacements during active hand movements across stop- and go-trials indicated the persistence of patients' avoidance of food. PUBLIC SIGNIFICANCE: Experimental research investigates the mechanisms underlying mental disorders such as anorexia nervosa. In this study, we measured interrupted hand movements in response to food pictures or neutral pictures (shoes) in patients with anorexia nervosa and healthy controls. A virtual reality scenario was used. Findings indicated that patients were slower at approaching food, interrupted or not. Key mechanisms of food avoidance can be translated into habit-based treatment options in future research.

Cellular dynamics in the maize leaf growth zone during recovery from chilling depends on the leaf developmental stage.

KEY MESSAGE: A novel non-steady-state kinematic analysis shows differences in cell division and expansion determining a better recovery from a 3-day cold spell in emerged compared to non-emerged maize leaves. Zea mays is highly sensitive to chilling which frequently occurs during its seedling stage. Although the direct effect of chilling is well studied, the mechanisms determining the subsequent recovery are still unknown. Our goal is to determine the cellular basis of the leaf growth response to chilling and during recovery of leaves exposed before or after their emergence. We first studied the effect of a 3-day cold spell on leaf growth at the plant level. Then, we performed a kinematic analysis to analyse the dynamics of cell division and elongation during recovery of the 4th leaf after exposure to cold before or after emergence. Our results demonstrated cold more strongly reduced the final length of non-emerged than emerged leaves (- 13 vs. - 18%). This was not related to growth differences during cold, but a faster and more complete recovery of the growth of emerged leaves. This difference was due to a higher cell division rate on the 1st and a higher cell elongation rate on the 2nd day of recovery, respectively. The dynamics of cell division and expansion during recovery determines developmental stage-specific differences in cold tolerance of maize leaves.

Objective assessment of the effects of opicapone in Parkinson's disease through kinematic analysis.

BACKGROUND: Opicapone (OPC) is a third-generation, selective peripheral COMT inhibitor that improves peripheral L-DOPA bioavailability and reduces OFF time and end-of-dose motor fluctuations in Parkinson's disease (PD) patients. OBJECTIVES: In this study, we objectively assessed the effects of adding OPC to L-DOPA on bradykinesia in PD through kinematic analysis of finger movements. METHODS: We enrolled 20 treated patients with PD and motor fluctuations. Patients underwent two experimental sessions (L-DOPA, L-DOPA + OPC), separated by at least 1 week. In each session, patients were clinically evaluated and underwent kinematic movement analysis of repetitive finger movements at four time points: (i) before their usual morning dose of L-DOPA (T0), (ii) 30 min (T1), (iii) 1 h and 30 min (T2), and (iv) 3 h and 30 min after the L-DOPA intake (T3). RESULTS: Movement velocity and amplitude of finger movements were higher in PD patients during the session with OPC compared to the session without OPC at all the time points tested. Importantly, the variability of finger movement velocity and amplitude across T0-T3 was significantly lower in the L-DOPA + OPC than L-DOPA session. CONCLUSIONS: This study is the first objective assessment of the effects of adding OPC to L-DOPA on bradykinesia in patients with PD and motor fluctuations. OPC, in addition to the standard dopaminergic therapy, leads to significant improvements in bradykinesia during clinically relevant periods associated with peripheral L-DOPA dynamics, i.e., the OFF state in the morning, delayed-ON, and wearing-OFF periods.

Validity and Reliability of Upper Limb Kinematic Assessment Using a Markerless Motion Capture (MMC) System: A Pilot Study.

OBJECTIVE: To investigate the validity and test-retest reliability of a customized markerless motion capture (MMC) system that used iPad Pros with a Light Detection And Ranging scanner at two different viewing angles to measure the active range of motion (AROM) and the angular waveform of the upper-limb-joint angles of healthy adults performing functional tasks. DESIGN: Participants were asked to perform shoulder and elbow actions for the investigator to take AROM measurements, followed by four tasks that simulated daily functioning. Each participant attended 2 experimental sessions, which were held at least 2 days and at most 14 days apart. SETTING: A Vicon system and 2 iPad Pros installed with our MMC system were placed at 2 different angles to the participants and recorded their movements concurrently during each task. PARTICIPANTS: Thirty healthy adults (mean age: 28.9, M/F ratio: 40/60). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The AROM and the angular waveform of the upper-limb-joint angles. RESULTS: The iPad Pro MMC system underestimated the shoulder joint and elbow joint angles in all four simulated functional tasks. The MMC demonstrated good to excellent test-retest reliability for the shoulder joint AROM measurements in all 4 tasks. CONCLUSIONS: The maximal AROM measurements calculated by the MMC system had consistently smaller values than those measured by the goniometer. An MMC in iPad Pro system might not be able to replace conventional goniometry for clinical ROM measurements, but it is still suggested for use in home-based and telerehabilitation training for intra-subject measurements because of its good reliability, low cost, and portability. Further development to improve its performance in motion capture and analysis in disease populations is warranted.

From Novice to Expert: How Expertise Shapes Motor Variability in Sports Biomechanics-a Scoping Review.

With expertise, athletes develop motor strategies that enhance sports performance or reduce functional costs. Motor variability is known as a relevant way to characterize these strategies in athletes with different levels of expertise. The aim of this scoping review is to gather and discuss the latest advances in the impact of expertise on motor variability during sports-related tasks. A search encompassing three databases, Medline, SportDiscus, and Academic Search Complete, was performed. Our research methodology included three core themes: motor variability, laboratory instruments, and sports. Motor variability metrics (e.g., standard deviation and approximate entropy) and laboratory instruments (e.g., motion capture system, EMG, and force plate) were compiled. Athletes' expertise was defined by the time of deliberate practice, the performance results, or the level in which they performed. Overall, 48 of the 59 included studies determined that higher-skilled athletes had lesser motor variability than lower-skilled athletes. This difference in motor variability between skill levels was present within individual athletes (intra-individual) and between athletes (inter-individual). This result was independent of the criteria used to define expertise, the type of instrumentation used, and the metrics used to quantify motor variability.

The benefit of knowledge: postural response modulation by foreknowledge of equilibrium perturbation in an upper limb task.

For whole-body sway patterns, a compound motor response following an external stimulus may comprise reflexes, postural adjustments (anticipatory or compensatory), and voluntary muscular activity. Responses to equilibrium destabilization may depend on both motor set and a subject`s expectation of the disturbing stimulus. To disentangle these influences on lower limb responses, we studied a model in which subjects (n = 14) were suspended in the air, without foot support, and performed a fast unilateral wrist extension (WE) in response to a passive knee flexion (KF) delivered by a robot. To characterize the responses, electromyographic activity of rectus femoris and reactive leg torque was obtained bilaterally in a series of trials, with or without the requirement of WE (motor set), and/or beforehand information about the upcoming velocity of KF (subject`s expectation). Some fast-velocity trials resulted in StartReact responses, which were used to subclassify leg responses. When subjects were uninformed about the upcoming KF, large rectus femoris responses concurred with a postural reaction in conditions without motor task, and with both postural reaction and postural adjustment when WE was required. WE in response to a low-volume acoustic signal elicited no postural adjustments. When subjects were informed about KF velocity and had to perform WE, large rectus femoris responses corresponded to anticipatory postural adjustment rather than postural reaction. In conclusion, when subjects are suspended in the air and have to respond with WE, the prepared motor set includes anticipatory postural adjustments if KF velocity is known, and additional postural reactions if KF velocity is unknown.

Exploring the biomechanics and fatigue patterns of eccentric quasi-isometric muscle actions in the knee extensors and flexors.

PURPOSE: Eccentric quasi-isometric (EQI) resistance training is emerging as a promising option in sports medicine and rehabilitation. Despite prior research on EQI contractions in quadriceps and biceps brachii, their use in hamstring injury contexts is underexplored. Therefore, our study examines and contrasts the biomechanics and fatigue effects of EQI training on knee extensors and flexors. METHODS: Following familiarization, 16 healthy, active participants (9 men, 7 women; 23.5 ± 2.6 years, 72.1 ± 12.8 kg, 173.4 ± 10.7 cm) performed, in random order, four EQI contractions for knee extensions and flexions, respectively. EQI contractions were isotonically loaded to 70% of concentric (60°·s-1) maximal voluntary contraction. Rest between repetitions was set at three minutes, while four minutes separated each muscle group. Peak torque, mean torque, and optimal angle were evaluated pre- and post-bouts. Inter-repetition contraction time and angular velocity were also assessed. RESULTS: Average torque was 160.9 ± 44.2 and 71.5 ± 23.2 Nm for the extensors and flexors. Peak and mean torque significantly decreased for both extensors (p < 0.001, d = 0.70-0.71) and flexors (p ≤ 0.022, d = 0.36) after EQI contractions, respectively. However, the optimal angle increased for extensors (p < 0.001, d = 1.00) but not flexors (p = 0.811, d = 0.06). During EQI contractions, knee flexors exhibited greater intra-repetition velocity than extensors (p = 0.002; η2 = 0.50). Decreases in inter-repetition time and range of motion were more consistent for the extensors. CONCLUSIONS: Distinct responses exist when comparing EQI contractions of the knee extensors and flexors, particularly their effect on peak torque angles. These findings suggest knee flexors may require lower relative intensities to align more closely with extensor EQI contractions.

Critical Examination of Methods to Determine Tibiofemoral Kinematics and Tibial Contact Kinematics Based on Analysis of Fluoroscopic Images.

Goals of knee replacement surgery are to restore function and maximize implant longevity. To determine how well these goals are satisfied, tibial femoral kinematics and tibial contact kinematics are of interest. Tibiofemoral kinematics, which characterize function, is movement between the tibia and femur whereas tibial contact kinematics, which is relevant to implant wear, is movement of the location of contact by the femoral implant on the tibial articular surface. The purposes of this review article are to describe and critique relevant methods to guide correct implementation. For tibiofemoral kinematics, methods are categorized as those which determine (1) relative planar motions and (2) relative three-dimensional (3D) motions. Planar motions are determined by first finding anterior-posterior (A-P) positions of each femoral condyle relative to the tibia and tracking these positions during flexion. Of the lowest point (LP) and flexion facet center (FFC) methods, which are common, the lowest point method is preferred and the reasoning is explained. 3D motions are determined using the joint coordinate system (JCS) of Grood and Suntay. Previous applications of this JCS have resulted in motions which are largely in error due to "kinematic crosstalk." Requirements for minimizing kinematic crosstalk are outlined followed by an example, which demonstrates the method for identifying a JCS that minimizes kinematic crosstalk. Although kinematic crosstalk can be minimized, the need for a JCS to determine 3D motions is questionable based on anatomical constraints, which limit varus-valgus rotation and compression-distraction translation. Methods for analyzing tibial contact kinematics are summarized and validation of methods discussed.

Orientation of the Scapula in the Standing Position.

OBJECTIVES: A new ultrasound-based device is proposed to non-invasively measure the orientation of the scapula in the standing position to consider this parameter for Total Shoulder Arthroplasty. The aim of this study was to assess the accuracy and reliability of this device. METHODS: Accuracy was assessed by comparing measurements made with the ultrasound device to those acquired with a three-dimensional (3D) optical localization system (Northern Digital, Canada) on a dedicated mechanical phantom. Three users performed 10 measurements on three healthy volunteers with different body mass (BMI) indices to analyze the reliability of the device by measuring the intra and interobserver variabilities. RESULTS: The mean accuracy of the device was 0.9°± 0.7 (0.01-3.03), 1.3°± 0.8 (0.03-4.55), 1.9°± 1.5 (0.05-5.76), respectively, in the axial, coronal, and sagittal planes. The interobserver and intraobserver variabilities were excellent whatever the BMI and the users experience. CONCLUSIONS: The device is accurate and reliable enough for the measurement of the scapula orientation in the standing position.

Hip biomechanics in patients with low back pain, what do we know? A systematic review.

BACKGROUND: Biomechanical alterations in patients with low back pain (LBP), as reduced range of motion or strength, do not appear to be exclusively related to the trunk. Thus, studies have investigated biomechanical changes in the hip, due to the proximity of this joint to the low back region. However, the relationship between hip biomechanical changes in patients with LBP is still controversial and needs to be summarized. Therefore, the aim of this study was to systematically review observational studies that used biomechanical assessments in patients with non-specific LBP. METHODS: The search for observational studies that evaluated hip biomechanical variables (i.e., range of motion, kinematic, strength, and electromyography) in adults with non-specific acute, subacute, and chronic LBP was performed in the PubMed, Embase, Cinahl and Sportdiscus databases on February 22nd, 2024. Four blocks of descriptors were used: 1) type of study, 2) LBP, 3) hip and 4) biomechanical assessment. Two independent assessors selected eligible studies and extracted the following data: author, year of publication, country, study objective, participant characteristics, outcomes, and results. The methodological quality of the studies was assessed using the Epidemiological Appraisal Instrument and classified as low, moderate, and high. Due to the heterogeneity of the biomechanical assessment and, consequently, of the results among eligible studies, a descriptive analysis was performed. RESULTS: The search strategy returned 338 articles of which 54 were included: nine articles evaluating range of motion, 16 evaluating kinematic, four strength, seven electromyography and 18 evaluating more than one outcome. The studies presented moderate and high methodological quality. Patients with LBP, regardless of symptoms, showed a significant reduction in hip range of motion, especially hip internal rotation, reduction in the time to perform functional activities such as sit-to-stance-to-sit, sit-to-stand or walking, greater activation of the hamstrings and gluteus maximus muscles and weakness of the hip abductor and extensor muscles during specific tests and functional activities compared to healthy individuals. CONCLUSION: Patients with LBP present changes in range of motion, task execution, activation, and hip muscle strength when compared to healthy individuals. Therefore, clinicians must pay greater attention to the assessment and management of the hip during the treatment of these patients. SYSTEMATIC REVIEW REGISTRATION: International Prospective Register of Systematic Reviews (PROSPERO) (CRD42020213599).

Deep learning-based video-analysis of instrument motion in microvascular anastomosis training.

PURPOSE: Attaining sufficient microsurgical skills is paramount for neurosurgical trainees. Kinematic analysis of surgical instruments using video offers the potential for an objective assessment of microsurgical proficiency, thereby enhancing surgical training and patient safety. The purposes of this study were to develop a deep-learning-based automated instrument tip-detection algorithm, and to validate its performance in microvascular anastomosis training. METHODS: An automated instrument tip-tracking algorithm was developed and trained using YOLOv2, based on clinical microsurgical videos and microvascular anastomosis practice videos. With this model, we measured motion economy (procedural time and path distance) and motion smoothness (normalized jerk index) during the task of suturing artificial blood vessels for end-to-side anastomosis. These parameters were validated using traditional criteria-based rating scales and were compared across surgeons with varying microsurgical experience (novice, intermediate, and expert). The suturing task was deconstructed into four distinct phases, and parameters within each phase were compared between novice and expert surgeons. RESULTS: The high accuracy of the developed model was indicated by a mean Dice similarity coefficient of 0.87. Deep learning-based parameters (procedural time, path distance, and normalized jerk index) exhibited correlations with traditional criteria-based rating scales and surgeons' years of experience. Experts completed the suturing task faster than novices. The total path distance for the right (dominant) side instrument movement was shorter for experts compared to novices. However, for the left (non-dominant) side, differences between the two groups were observed only in specific phases. The normalized jerk index for both the right and left sides was significantly lower in the expert than in the novice groups, and receiver operating characteristic analysis showed strong discriminative ability. CONCLUSION: The deep learning-based kinematic analytic approach for surgical instruments proves beneficial in assessing performance in microvascular anastomosis. Moreover, this methodology can be adapted for use in clinical settings.

Neuromuscular fatigue and cognitive constraints independently modify lower extremity landing biomechanics in healthy and chronic ankle instability individuals.

The purpose was to determine the impact of both cognitive constraint and neuromuscular fatigue on landing biomechanics in healthy and chronic ankle instability (CAI) participants. Twenty-three male volunteers (13 Control and 10 CAI) performed a single-leg landing task before and immediately after a fatiguing exercise with and without cognitive constraints. Ground Reaction Force (GRF) and Time to Stabilization (TTS) were determined at landing in vertical, anteroposterior (ap) and mediolateral (ml) axes using a force plate. Three-dimensional movements of the hip, knee and ankle were recorded during landing using a motion capture system. Exercise-induced fatigue decreased ankle plantar flexion and inversion and increased knee flexion. Neuromuscular fatigue decreased vertical GRF and increased ml GRF and ap TTS. Cognitive constraint decreased ankle internal rotation and increased knee and hip flexion during the flight phase of landing. Cognitive constraint increased ml GRF and TTS in all three axes. No interaction between factors (group, fatigue, cognitive) were observed. Fatigue and cognitive constraint induced greater knee and hip flexion, revealing higher proximal control during landing. Ankle kinematic suggests a protective strategy in response to fatigue and cognitive constraints. Finally, these two constraints impair dynamic stability that could increase the risk of ankle sprain.