Three-dimensional Kinematic Analysis Research Articles

Analysis of the obstetrician's posture and movements during a simulated forceps delivery

BackgroundThe objective of this study was to identify and qualify, by means of a three-dimensional kinematic analysis, the postures and movements of obstetricians during a simulated forceps birth, and then to study the association of the obstetricians’ experience with the technique adopted.MethodFifty-seven volunteer obstetricians, 20 from the Limoges and 37 from the Poitiers University hospitals, were included in this multi-centric study. They were classified into 3 groups: beginners, intermediates, and experts, beginners having performed fewer than 10 forceps deliveries in real conditions, intermediates between 10 and 100, and experts more than 100. The posture and movements of the obstetricians were recorded between December 2020 and March 2021 using an optoelectronic motion capture system during simulated forceps births. Joint angles qualifying these postures and movements were analysed between the three phases of the foetal traction. These phases were defined by the passage of a virtual point associated with the forceps blade through two anatomical planes: the mid-pelvis and the pelvic outlet. Then, a consolidated ascending hierarchical classification (AHC) was applied to these data in order to objectify the existence of groups of similar behaviours.ResultsThe AHC distinguished four different postures adopted when crossing the first plane and three different traction techniques. 48% of the beginners adopted one of the two raised posture, 22% being raised without trunk flexion and 26% raised with trunk flexion. Conversely, 58% of the experts positioned themselves in a “chevalier servant” posture (going down on one knee) and 25% in a “squatting” posture before initiating traction. The results also show that the joint movement amplitude tends to reduce with the level of expertise.ConclusionForceps delivery was performed in different ways, with the experienced obstetricians favouring postures that enabled observation at the level of the maternal perineum and techniques reducing movement amplitude. The first perspective of this work is to relate these different techniques to the traction force generated. The results of these studies have the potential to contribute to the training of obstetricians in forceps delivery, and to improve the safety of women and newborns.

Professional skateboarding trousers design: according to the three-dimensional kinematic analysis for varied skateboarding manoeuvres

The popularity of skateboarding has caused an expansion of enthusiasts worldwide. Moreover, skateboarding is becoming increasingly professional at an international level. Professional skateboarding trousers are regarded as critical equipment and their design research should not be overlooked. This research aims to use motion capture to measure the angular changes characteristics of critical lower limb joints in skaters during sports activities, measure the length of the knee joint during actions, and establish a formula that describes the change characteristics between the angle and the length. The formula would allow for a data reference when designing the elasticity at the knee joints of skateboarding trousers. Thus, the initial step in this research methodology was to use a Vicon motion capture system to test and analyse the kinematic characteristics of seven skaters in the squat, jump, ollie, pop shove it, heel flip, kickflip, and 180° ollie. Based on the kinematic characteristics, the dynamic movements were broken down into static postures at 0°, 45°, 90°, 112.5°, and 135°. The body surface drawing method was then employed to measure changes in the knee joint body surface dimensions of the subjects. Next, the experimental data were analysed to explore the relationship between angle and length changes. Finally, the design was developed based on the data. Analysis and processing of the experimental data yielded the following conclusions: (1) The most significant knee joint change characteristics during skateboarding was the angle change observed during an ollie. (2) Knee joint skin stretch deformation is most evident in the anterior mid-leg line y2. (3) The relationship between kinematics and the structural design of skateboarding trousers was derived from the experimental data. Specifically, the equation for the relationship between angle change and length change is given by y2 = 0.0442x + 23.906. (4) The results show that the extreme range of skin stretching in the anterior midline is between –0.7 and 6.3 cm. Therefore, the loose design of the knee part of professional skateboarding trousers should not exceed 6.3 cm. This research approach can offer an effective design solution for professional skateboard trousers and can also be applied to other types of trousers.

3D kinematic analysis of salto backward in acrobatic rock and roll: a case study

Background and Study Aim. The aim of the study was to determine and compare basic kinematic characteristics in the key phases of the acrobatic element Salto backward tucked. Material and Methods. The research sample was created from two couples of the acrobatic rock and roll category Main class free style. The time, spatial, and time-spatial characteristics for both couples were determined based on a three-dimensional kinematic analysis. Measurements were carried out with Simi Motion 3D. The acrobatic element Salto backward tucked was chosen based on the fact that it is usually learned as the first overturn acrobatic element with the airborne phase. Results. In the time duration of the acrobatic element, a very similar duration was observed for both couples (CZ couple: 3.59 s and SK couple 3.55 s). The maximal height of the center of gravity the partner from the Czech Republic reach 3.54 m and partner from the Slovak Republic 3.35 m. The biggest difference noticed was between the male partners 14.59° in knee angle in the staff phase. Among the female partners, a difference was noted in the angle between the torso and the vertical plane at the moment of the end of the vertical displacement, when SK female partner has twice as much deviation of the torso, by exactly 19.49°. In the staff phase, differences in acceleration were also observed, when the male partner (16.56 m.s-2) and female partner (25.08 m.s-2) from the Slovak Republic achieved higher maximum acceleration. In the airborne phase was the biggest difference between female partners in the culmination point, namely in the angle in the knee joint (35.98°) and the angle between the torso in the vertical plane at the moment of opening the somersault (25.52°). Conclusions. The findings showed similarities and differences in various aspects of the performance, providing valuable insights into the kinematic structure of this acrobatic element in acrobatic rock and roll. Our study should contribute to the extension of knowledge of the kinematic structure of acrobatic element in acrobatic rock and roll.

Three-Dimensional Kinematic Analysis of the Lower Extremity in Ruesi Dat Ton Postures Performed by Healthy Volunteers

This study was conducted to investigate the three-dimensional (3D) joint angles and muscle activities of the lower extremities when performing the Ruesi Dat Ton: a form of traditional Thai medicine involving stretching and strengthening postures. Thirty healthy volunteers were recruited in order to let them perform five Ruesi Dat Ton postures, namely Tha Kae Khao Kae Kha, Tha Kae Lom Nai Ook Nai Eo, Tha Kae Klon Pattakhat, Tha Kae Siat Ook, and Tha Kae Lom Pat-Khat Kae Lom Nai Eo, by a random sequence of postures. The 3D joint angles and muscle activities during the performance of the Ruesi Dat Ton were analyzed at the 3D-motion analysis laboratory. Descriptive statistics were used for the analysis. All the Ruesi Dat Ton postures were in the normal range of motion of the back, hips, knees, and ankles. However, when compared to the joint angle values from the 3D motion analysis, a higher joint angle was found in the hip rotation of Tha Kae Khao Kae Kha (27.99±16.72 degrees), Tha Kae Lom Nai Ook Nai Eo (25.99±14.76 degrees), and Tha Kae Klon Pattakhat (20.99±12.59 degrees), knee flexion of Tha Kae Siat Ook (140.05±8.98 degrees), and trunk flexion of Tha Kae Lom Pat-Khat Kae Lom Nai Eo (52.10±14.83 degrees). All the postures produced more than 1% maximum voluntary isometric contraction of the muscle (MVIC). The muscle activities of Tha Kae Siat Ook were the most contracted, whereas Tha Kae Lom Pat-Khat Kae Lom Nai Eo were the least. Moreover, the study found that the rectus femoris muscle was the most active muscle in all postures. In conclusion, this research can help to select the most appropriate Ruesi Dat Ton posture to maximize the benefits for practitioners and to ensure safety while performing the postures.

'United we stand, divided we fall': intertwining as evidence of joint actions in pea plants.

In life, it is common for almost every kind of organism to interact with one another. In the human realm, such interactions are at the basis of joint actions, when two or more agents syntonize their actions to achieve a common goal. Shared intentionality is the theoretical construct referring to the suite of abilities that enable such coordinated and collaborative interactions. While shared intentionality has become an important concept in research on social cognition, there is controversy surrounding its evolutionary origins. An aspect still unexplored but promising to bring new insights into this open debate is the study of aneural organisms. To fill this gap, here we investigate whether climbing plants can act jointly to achieve a common goal, i.e. reaching the light. We examined Pisum Sativum plants growing intertwined when there is a need to climb but a potential support is not present in the environment. Three-dimensional kinematic analysis of their movement revealed a coordinated and complementary behaviour. They tend to coordinate their movement in time and space to achieve a joint climbing. By deliberately extending the context in which a joint action takes place, we pay tribute to the complex nature of this social phenomenon. The next challenge for the field of joint action is to generate a perspective that links coordination mechanisms to an evolutionary framework across taxa.

Three-dimensional discretization-based kinematic analyses of prestressed anchor cables reinforced rotational slopes subjected to earthquakes

Prestressed anchor cables are commonly utilized to reinforce slopes in earthquake-prone zones. The existing upper bound limit analyses of seismic slopes reinforced with prestressed anchor cables have the following limitations: (1) neglecting variable seismic excitations; (2) ignoring the three-dimensional spatial layout of cables because of using the plane-strain analysis. In this study, the time-space effects of seismic waves are analytically described by sin-cos functions incorporating wave amplification or soil damping. Based on the upper bound of plastic theory and a three-dimensional discretized failure mechanism, internal energy dissipation rate and work rates contributed by gravitational forces, variable seismic excitations, and prestressed anchor cables are computed. An energy-based function of dynamic factors of safety (DFS) is established, followed by a global optimization to identify the critical harmonic pattern of DFS. The accuracy is checked by numerical simulations where the seismic stability of an engineering slope adjacent to Yu-Huai railway is evaluated. Comparisons also show that the conventional simplified method not only cannot reflect the spatial layout of cables but also overestimate the mechanical contribution of cables. Finally, the dominant effects of the layout of cables, soil properties as well as physical parameters of seismic waves on the DFS and the critical failure mechanism are discussed.

The Orthotic Effects of Different Functional Electrical Stimulation Protocols on Walking Performance in Individuals with Incomplete Spinal Cord Injury: A Case Series.

Functional electrical stimulation (FES) of paralyzed muscles can facilitate walking after spinal cord injury (SCI). To test the orthotic effects of different FES walking protocols on lower joint kinematics and walking speed. Three adults with incomplete SCI participated in this study. Their lower extremity motor scores and 10-meter walk test results were as follows: subject A: 50, 1.05 m/s, subject B: 44, 0.29 m/s, and subject C: 32, 0.27 m/s. Participants completed four conditions of over-ground walking including no FES and three bilateral FES-walking protocols as follows: multi-muscle stimulation (stimulation of quadriceps and gastrocnemius in the stance phase, and hamstring and tibialis anterior in the swing phase), drop foot (tibialis anterior stimulation), and flexor withdrawal (common peroneal nerve stimulation). The FES system obtained gait phase information from foot switches located under the individuals' heels. Three-dimensional kinematic analysis was undertaken to measure minimum toe clearance (MTC); ankle, knee, and hip range of motion (ROM); stride length; and stride speed. Compared to no-FES walking, MTC increased during drop foot (all subjects), flexor withdrawal (subjects A and B), and multi-muscle stimulation (subjects B and C) protocols. A significant decrease in ankle ROM was seen with drop foot (all subjects), flexor withdrawal (subjects A), and multi-muscle stimulation (subjects A and C) protocols. Hip ROM increased with drop foot (subjects B and C), flexor withdrawal (subject B), and multi-muscle stimulation (subject C) protocols. Three FES walking protocols induced positive kinematic changes as indicated by increased MTC, decreased ankle ROM, and increased hip ROM during walking in subjects with incomplete SCI.

Three-Dimensional Kinematic Analysis and Research on the Strong Volleyball Spike Technique of Excellent Female Volleyball Spikers from China and Abroad

This paper uses three-dimensional camera and technical statistics to analyze and study the spiking technique of Chinese and foreign excellent female volleyball attackers. The results show that the speed of Chinese and foreign women�s volleyball spikers is close to 4m/s, the maximum ball speed is close to 30m/s and the hitting height is more than 2.9m; the air hitting action is with obvious forward movement. There is a gap between Chinese women�s volleyball spikers and excellent foreign attackers in terms of spiking success rate, hitting height and hitting speed.

Three-dimensional kinematic analysis of knee joint after anterior cruciate ligament reconstruction with personalized femoral positioner based on apex of deep cartilage

To investigate the changes of knee joint kinematics after anterior cruciate ligament (ACL) reconstruction assisted by personalized femoral positioner based on the apex of deep cartilage (ADC). Between January 2021 and January 2022, a total of 40 patients with initial ACL rupture who met the selection criteria were randomly divided into the study group (using the personalized femoral positioner based on ADC design to assist ACL reconstruction) and the control group (not using the personalized femoral positioner to assist ACL reconstruction), with 20 patients in each group. Another 20 volunteers with normal knee were collected as a healthy group. There was no significant difference in gender, age, body mass index, and affected side between groups ( P>0.05). Gait analysis was performed at 3, 6, and 12 months after operation using Opti _ Knee three-dimensional knee joint motion measurement and analysis system, and the 6 degrees of freedom (flexion and extension angle, varus and valgus angle, internal and external rotation angle, anteroposterior displacement, superior and inferior displacement, internal and external displacement) and motion cycle (maximum step length, minimum step length, and step frequency) of the knee joint were recorded. The patients' data was compared to the data of healthy group. In the healthy group, the flexion and extension angle was (57.80±3.45)°, the varus and valgus angle was (10.54±1.05)°, the internal and external rotation angle was (13.02±1.66)°, and the anteroposterior displacement was (1.44±0.39) cm, the superior and inferior displacement was (0.86±0.20) cm, and the internal and external displacement was (1.38±0.39) cm. The maximum step length was (51.24±1.29) cm, the minimum step length was (45.69±2.28) cm, and the step frequency was (12.45±0.47) step/minute. Compared with the healthy group, the flexion and extension angles and internal and external rotation angles of the patients in the study group and the control group decreased at 3 months after operation, and the flexion and extension angles of the patients in the control group decreased at 6 months after operation, and the differences were significant ( P<0.05); there was no significant difference in the other time points and other indicators when compared with healthy group ( P>0.05). In the study group, the flexion and extension angles and internal and external rotation angles at 6 and 12 months after operation were significantly greater than those at 3 months after operation ( P<0.05), while there was no significant difference in the other indicators at other time points ( P>0.05). There was a significant difference in flexion and extension angle between the study group and the control group at 6 months after operation ( P<0.05), but there was no significant difference of the indicators between the two groups at other time points ( P>0.05). Compared with conventional surgery, ACL reconstruction assisted by personalized femoral positioner based on ADC design can help patients achieve more satisfactory early postoperative kinematic results, and three-dimensional kinematic analysis can more objectively and dynamically evaluate the postoperative recovery of knee joint.

Effect of selective percutaneous myofascial lengthening and functional physiotherapy on walking in children with cerebral palsy: Three-dimensional gait analysis assessment

BackgroundWalking is the most affected motor function in children with cerebral palsy (CP). Orthopaedic surgery is regularly used to improve ambulation in children with CP. Selective Percutaneous Myofascial Lengthening (SPML) is considered the state-of-the art technique for surgical lengthening of spastic/contracted muscles in CP. The purpose of this study was to investigate the effect of combined SPML surgery and postoperative functional physiotherapy on gait function and characteristics of children with spastic cerebral palsy (CP). MethodsTwenty-six children with spastic CP, aged 5–7 years, Gross Motor Function Classification System (GMFCS) levels II (n = 6), III (n = 12) and IV (n = 8) participated in a quasi-experimental one-group pretest-posttest study with a 9-month follow-up. The Global Motion Graph Deviation Index (MGDI) (including MGDI sub-indices of each joint in each plane of motion) and spatiotemporal parameters of a three-dimensional kinematic gait analysis were used to assess the gait function and characteristics, respectively. ResultsNine months following SPML and functional physiotherapy, statistically significant improvements (p < 0.05) were noted in the Global MGDI, the MGDIs of sagittal plane knee and ankle motion analysis graphs, and the four most common spatiotemporal measures of gait: walking velocity, stride length, step length, and cadence. ConclusionChildren with spastic CP seem to gain better overall gait function following SPML procedure and functional physiotherapy, by achieving higher walking velocity, longer stride length and step length, and faster cadence. Further studies with control group and longer follow-up three-dimensional gait analyses are warranted to validate these positive results.

Effect of the Effortful Swallow on Pharyngeal Cavity Volume: Kinematic Analysis in Three Dimensions Using 320-Row Area Detector Computed Tomography.

This study evaluated the effects of the effortful swallow (ES) on pharyngeal cavity volume using three-dimensional kinematic analyses. Nine healthy volunteers (30.7 ± 7.8years old) underwent a CT scan while swallowing 10ml of honey thick liquid using no maneuvers (control) and during an ES. Upper and lower volumes (bordered by valleculae) of the pharyngeal air column and the bolus were measured at every frame and were compared between ES and control swallows. Duration of pharyngeal obliteration and the timing of swallowing events were also measured. Maximum volume and volume at the onset of hyoid anterosuperior movement using ES were significantly smaller than those in control swallows (p = 0.012, p = 0.015) in the upper pharynx but not significantly different in lower pharynx. Minimum pharyngeal volume was sustained for a longer time when ES was used compared to control swallows in both upper and lower pharynx (upper p = 0.016, lower p = 0.027). Onset of velopharyngeal closure was earlier when comparing ES and control swallows (p = 0.04). Termination of all events was significantly delayed when the ES was used (p < 0.05). Changes in the upper pharyngeal volume and in the onset of velopharyngeal closure suggest earlier pharyngeal constriction when using the ES. Longer pharyngeal obliteration and prolonged termination of velopharyngeal closure and epiglottis inversion suggest the prolonged pharyngeal constriction during the ES. These findings suggest the ES can be useful for improving the efficiency of swallowing.

Native knee kinematics is not reproduced after sensor guided cruciates substituting total knee arthroplasty

PurposeGait analysis was used to evaluate knee kinematics in patients who underwent successful primary total knee arthroplasty (TKA) using two modern bi-cruciate substituting designs. The knee joint was balanced intraoperatively using real-time sensor technology, developed to provide dynamic feedback regarding stability and tibiofemoral load. The authors hypothesized that major differences exist in gait parameters between healthy controls and post-TKA patients.MethodsTen patients who underwent successful TKA using bi-cruciate substituting designs were evaluated at a minimum of 9 months postoperatively using three-dimensional knee kinematic analysis; a multi-camera optoelectronic system and a force platform were used. Sensor-extracted kinematic data included knee flexion angle at heel-strike (KFH), peak midstance knee flexion angle (MSKFA), maximum and minimum knee adduction angle (KAA) and knee rotational angle at heel-strike. Multiple gait analysis data from the study group were compared to a group of ten healthy controls who were matched by age, sex and BMI. Clinical outcome in the TKA group was also measured using the Knee injury and Osteoarthritis Outcome Score (KOOS).ResultsClinically, at final follow-up, a statistically significant difference in pain, general symptoms, and activities of daily living was seen between the groups. From a gait analysis standpoint, TKA patients had significantly less rotation at heel strike (p = 0.04), lower late stance peak extension moments (p = 0.02), and less Knee Adduction Angle excursion during swing phase (p = 0.04) compared to the control group. No statistically significant difference was observed for knee flexion angle at heel strike, knee adduction moment, or peak knee flexion moment between the groups.ConclusionsModern bi-cruciate substituting TKA designs failed to reproduce normal knee kinematics. The lack of full knee extension during the stance phase, absence of the “screw-home mechanism” typical of an ACL functioning knee, and the reduced fluctuation in knee adduction angle during the swing phase still represent major proprioceptive and muscular recruitment differences between normal and replaced knees.

Mild-intensity running exercise recovered motor function by improvement of ankle mobility after unilateral brain injury of mice using three-dimensional kinematic analysis techniques

Motor dysfunction, such as gait impairment, is a major disability induced by traumatic brain injury or stroke. Treadmill running is often used as a physical exercise (Ex) clinically and experimentally for the recovery of patients. In animal experiments, although dynamic behavioral deficits can be evaluated using scoring systems, local and minor behaviors are difficult to determine. This study aims to evaluate motor dysfunction and recovery after brain damage (BD) with/without mild-intensity running Ex in mice using three-dimensional (3D) kinematic analysis. To determine exercise intensity, C57/BL6-strain male young adult mice were examined in an incremental running test while the pulmonary gas exchange of O2 and CO2 were measured. The animals were then subjected to left hemidecortication as BD, and some mice performed Ex (10 m/min for 30 min 5 times/wk) for 4 weeks. The BD with Ex and BD or sham-operated mice (sham) without (w/o) Ex had their gait recorded by four synchronized cameras, and gait was evaluated via 3D-kinematic analysis. The BD w/o Ex mice significantly differed in stride, step, and stride width for both limbs compared to the sham w/o Ex mice. The BD with Ex mice showed improvement. The BD w/o Ex mice had restricted ankle movements and impairment in dorsal/planter flexing using trajectory analysis. Consistent with these impairments, the nonaffected side also exhibited a different trajectory, suggesting compensatory movements. These results suggest that the appropriate Ex after BD recovered motor function. Furthermore, the present study suggested that 3D-kinematic analysis is a powerful tool for detecting minor behavioral alterations owing to the impairment of the affected side and the compensation of the unaffected side.

Three-dimensional Kinematic Analysis and Muscle Activation of the Upper Extremity in Ruesi Dutton Exercises

Objective: To investigate 3-D upper extremity joint angles and muscle activities in selected Ruesi-Dutton exercises.Material and Methods: Twenty-six healthy participants (mean age of 25.65, mean height of 165.08 cm, and mean weight of 56.69 Kg) volunteered to take part in this study. 3-D motion analysis consisted of eight cameras synchronized with a wireless electromyography (EMG) system to collect kinematic data and muscle activity. Participants performed five postures, including the Kae Lom Kho Mue posture, Kae Puat Thong Kae Kho Thao posture, Kae Kiat posture, Kae Puat Thong Sabak Chom posture, and Kae Lom Puat Sisa. The upper extremity joint angles and range of motion (ROM) and EMG were analyzed.Results: Most postures were in the normal range of motion. The percentage of MVIC was more than 1% and the Trapezius muscle is the most active in all postures.Conclusion: The data in this research is useful to help select the correct posture and exercise for a specific condition.

La réalité virtuelle, un outil pertinent pour la sensibilisation au métier de masseur-kinésithérapeute

The motor cortex plays a critical role in accurate visually guided movements such as reaching and target stepping. However, the manner in which vision influences the movement-related activity of neurons in the motor cortex is not well understood. In this study we have investigated how the locomotion-related activity of neurons in the motor cortex is modified when subjects switch between walking in the darkness and in light.Three adult cats were trained to walk through corridors of an experimental chamber for a food reward. On randomly selected trials, lights were extinguished for approximately 4 s when the cat was in a straight portion of the chamber's corridor. Discharges of 146 neurons from layer V of the motor cortex, including 51 pyramidal tract cells (PTNs), were recorded and compared between light and dark conditions. It was found that while cats’ movements during locomotion in light and darkness were similar (as judged from the analysis of three-dimensional limb kinematics and the activity of limb muscles), the firing behavior of 49% (71/146) of neurons was different between the two walking conditions. This included differences in the mean discharge rate (19%, 28/146 of neurons), depth of stride-related frequency modulation (24%, 32/131), duration of the period of elevated firing ([PEF], 19%, 25/131), and number of PEFs among stride-related neurons (26%, 34/131). 20% of responding neurons exhibited more than one type of change.We conclude that visual input plays a very significant role in determining neuronal activity in the motor cortex during locomotion by altering one, or occasionally multiple, parameters of locomotion-related discharges of its neurons.

Three-Dimensional Modeling and Kinematic Analysis of Human Elbow Joint Axis Based on Anatomy and Screw Theory

Ensuring the motion consistency of human and exoskeletons is the key to the research of wearable exoskeleton robots. However, as the complexity of the coupling of sliding and rolling motion in human joint tissue, it is hard to depict the dynamic states of the joint axis. Exploring the changed human joint axis can be significant in the process of studying the bionic joint of the exoskeleton robots. We proposed a method to build the biological joint model based on anatomy and used screw theory to explore the human biological joint axis on it. The humerus and ulna models were only reconstructed by scanning CT images of the elbow joint in any single position. According to anatomy, humerus trochlear and trochlear notch of models were tangent to build a movable elbow joint model. The screw theory was used to study the elbow joint axis based on the kinematic data of samples in the motion simulation of joint model. Comparing the motion between model and human experiment, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\boldsymbol{R}^{\boldsymbol{2}}}$</tex-math></inline-formula> of the Euler angles were above 0.97, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{RMSE}$</tex-math></inline-formula> were below 2.85, which showed the model following anatomical principles can reflect the human joints well. And the pattern that depicted joint axis travelled is similar to the shape of the Mobius Strip. This work provides a new method to study human joint axis, and the axis results provide references to the design of exoskeleton joints and bionic robots.

A method for full three-dimensional kinematic analysis of steep rock walls based on high-resolution point cloud data

The predisposition of a slope to generate rockfalls is related to the intensity of rock mass jointing and the geometric arrangement of discontinuities intersecting the rock face. With the increasing use of terrestrial laser scanner (TLS) in rock slope surveying, methods have been proposed to semi-automatically extract the spatial properties of outcropping discontinuities from high-resolution topographic data. The present paper builds upon one of such methods (named DiAna), and extends it to enhance the assessment of rockfall susceptibility over steep rock walls. In particular, a Matlab routine (named DiAna-K) that incorporates a full three-dimensional derivation of kinematic analysis principles is introduced. Kinematic tests for plane, wedge, block toppling, flexural toppling, and free fall failure are formulated by explicitly accounting for the presence of overhanging areas of the rock face as well as varying frictional strengths across different discontinuity sets, planes, or intersections between planes. Results from a test application at an abandoned quarry site highlight the ability of the proposed procedure to provide detailed insights into the kinematic feasibility of structurally controlled instabilities. They also demonstrate the importance of properly defining failure mechanisms over steep (and usually undersampled) topographies in order to derive realistic quantifications of rockfall hazards.

Investigating the biomechanical validity of the V-spine angle technique in cricket fast bowling

The effective utilisation of braking ground reaction forces is considered an essential biomechanical characteristic of fast bowling in cricket. The configuration of the trunk and legs during the delivery stride phase has been hypothesised to increase braking forces, causing the upper body segments to increase their angular momentum and thereby increase ball release speed. This study investigated the relationship between V-spine angle, front shank angle (plant angle) and front knee angle with braking ground reaction forces and ball release speed. Three-dimensional kinematic and kinetic analyses were performed for 17 male pace bowlers (17.2 ± 1.7 years) of New South Wales grade club level using data from a Cortex 2.0 motion analysis system (200 Hz) and Kistler force plates (1000 Hz). V-spine angle was strongly and significantly correlated with braking ground reaction force (r = −0.691), plant angle (r = −0.806) and front knee angle (r = −0.606). In addition, stepwise multiple linear regression analysis revealed that front shank angle was the strongest predictor of braking ground reaction force. The data suggests that V-spine angle and plant angle may play an important role in generating high braking ground reaction forces in bowling, with the front knee angle possibly playing a supporting role. Coaches may need to consider these findings when assessing the techniques of pace bowlers.

Angle-Angle Diagrams in the Assessment of Locomotion in Persons with Multiple Sclerosis: A Preliminary Study

Gait analysis is clinically relevant in persons with multiple sclerosis (PwMS) and consists of several joint angular displacement–time relationships and spatiotemporal parameters. However, it lacks representation by means of diagrams in which knee-angle/hip-angle and knee-angle/ankle-angle variations are plotted against each other at the same points of time. Three-dimensional kinematic analysis was performed on 20 subjects (10 PwMS/10 healthy controls, HCs), and the knee-angle/hip-angle and knee-angle/ankle-angle diagrams of both lower limbs were determined in the sagittal plane while walking on a motorized treadmill. The area (a quantifier of range of motion) and the perimeter (a quantifier of coordination) of angle-angle diagram loops were calculated. PwMS showed reduced knee-angle/ankle-angle loops compared to HCs (p &lt; 0.05), whereas the hip-angle/ankle-angle loops between the PwMS and HCs was not significant (p &gt; 0.05). Similarly, the activation of leg muscles showed significant differences between PwMS and HCs (p ranged from 0.05 to 0.001). The results indicate that the proposed knee-angle/hip-angle diagram is feasible and could be applied as a reliable tool in future studies aimed at assessing the acute and long-term effects of specific exercise programmes and/or pharmacological treatment in PwMS.

Feasibility of Markerless Motion Capture for Three-Dimensional Gait Assessment in Community Settings.

Three-dimensional (3D) kinematic analysis of gait holds potential as a digital biomarker to identify neuropathologies, monitor disease progression, and provide a high-resolution outcome measure to monitor neurorehabilitation efficacy by characterizing the mechanisms underlying gait impairments. There is a need for 3D motion capture technologies accessible to community, clinical, and rehabilitation settings. Image-based markerless motion capture (MLMC) using neural network-based deep learning algorithms shows promise as an accessible technology in these settings. In this study, we assessed the feasibility of implementing 3D MLMC technology outside the traditional laboratory environment to evaluate its potential as a tool for outcomes assessment in neurorehabilitation. A sample population of 166 individuals aged 9–87 years (mean 43.7, S.D. 20.4) of varied health history were evaluated at six different locations in the community over a 3-month period. Participants walked overground at self-selected (SS) and fastest comfortable (FC) speeds. Feasibility measures considered the expansion, implementation, and practicality of this MLMC system. A subset of the sample population (46 individuals) walked over a pressure-sensitive walkway (PSW) concurrently with MLMC to assess agreement of the spatiotemporal gait parameters measured between the two systems. Twelve spatiotemporal parameters were compared using mean differences, Bland-Altman analysis, and intraclass correlation coefficients for agreement (ICC2,1) and consistency (ICC3,1). All measures showed good to excellent agreement between MLMC and the PSW system with cadence, speed, step length, step time, stride length, and stride time showing strong similarity. Furthermore, this information can inform the development of rehabilitation strategies targeting gait dysfunction. These first experiments provide evidence for feasibility of using MLMC in community and clinical practice environments to acquire robust 3D kinematic data from a diverse population. This foundational work enables future investigation with MLMC especially its use as a digital biomarker of disease progression and rehabilitation outcome.