External Moment Research Articles

Bilateral Alterations in Isokinetic Strength and Knee Biomechanics During Side-Cutting 1 Year After Unilateral ACL Reconstruction

Background: Individuals with anterior cruciate ligament (ACL) reconstruction (ACLR) are a population that has a higher risk for ACL injury compared with the general population. To reduce the reinjury rate and improve the rehabilitation outcome after ACLR, risk factors for ACL injury have to be addressed. Purpose: To compare the knee biomechanics during side-cutting and isokinetic strength of the thigh muscle of the reconstructed leg with those of the contralateral leg and healthy controls and investigate the knee movement asymmetries in individuals with ACLR. Study Design: Controlled laboratory study. Methods: A total of 16 participants with ACLR (ACLR group; 11.8 ± 1.1 months after reconstruction) and 16 healthy controls (control group) were recruited. Landmark coordinates and ground-reaction forces during side-cutting and isokinetic strength of hamstring and quadriceps were collected. Two-way analysis of variance with the mixed design was performed to compare each dependent variable between groups and across legs. Results: The reconstructed leg had a significantly smaller knee flexion angle (P = .004) and less quadriceps strength (P = .003) than the contralateral leg. The knee extension moment and knee external rotation angle were decreased compared with both the contralateral leg (P = .001, P = .003, respectively) and the healthy control leg (P = .001, P = .001, respectively). The ACLR group showed greater knee abduction angles (P = .004) and smaller knee external rotation moments (P = .006) than the control group. The ACLR group also demonstrated greater asymmetries of knee flexion angle (P = .015), knee external rotation angle (P = .001), knee extension moment (P = .013), knee abduction moment (P = .001), and quadriceps strength (P = .046) than the control group. Conclusion: Knee biomechanics in the leg with ACLR were altered mainly in the sagittal plane during side-cutting compared with the contralateral leg. The altered movement patterns between the ACLR and control groups were primarily observed in the frontal and transverse planes. The ACLR group also demonstrated greater asymmetries of sagittal knee movement and concentric quadriceps strength than the control group. Clinical Relevance: Individuals with ACLR showed different alterations in the reconstructed and contralateral leg compared with healthy controls. These results suggest that rehabilitation programs after ACLR should further focus on restoring the knee flexion angle and quadriceps strength. Injury prevention programs need to be further targeted in the altered movement patterns observed between the ACLR and the healthy groups.

Centrifuge modelling of monotonic and cyclic lateral responses of a hybrid monopile-bucket foundation for offshore wind turbines

Various hybrid systems combined with several foundation elements have been proposed to improve the lateral performance of monopiles. Among them, the hybrid monopile-bucket foundation which consists of a traditional monopile and a wide-shallow bucket has received more and more attention and has been used in offshore wind pilot projects for supporting OWTs. However, deep insights into its monotonic and cyclic responses are still lacking. This study aims to understand the monotonic load-bearing, the evolution of cumulative displacement, stiffness and bending moment of the hybrid foundation in soft clay. A series of centrifuge model tests were conducted to simulate a hybrid monopile-bucket foundation and a monopile subjected to lateral monotonic and multi-stage cyclic loading. The monopile with the identical pile diameter and embedded length is used as a benchmark. The experimental results show that by the addition of the bucket, the hybrid foundation shows a 30.1% increase in ultimate capacity. Compared to the monopile, the cumulative displacement, unloading stiffness and the growth of bending moment of the hybrid foundation during cyclic can be reduced by up to 25%, 30% and 35.3%, respectively, implying the effectiveness and superiority of the hybrid foundation. Apart from the centrifuge tests, supplementary three-dimensional finite element analyses have also been performed to reveal the bearing mechanism and the sharing ratios of external load and moment carried by the single pile and the bucket of the hybrid foundation. The test and numerical results presented in this study are expected to provide design references for further practical applications of the hybrid foundations.

Examining the intrinsic foot muscles’ capacity to modulate plantar flexor gearing and ankle joint contributions to propulsion in vertical jumping

BackgroundDuring human locomotion, a sufficiently stiff foot allows the ankle plantar flexors to generate large propulsive powers. Increasing foot stiffness (e.g., via a carbon plate) increases the ankle's external moment arm in relation to the internal moment arm (i.e., increasing gear ratio), reduces plantar flexor muscles’ shortening velocity, and enhances muscle force production. In contrast, when activation of the foot's intrinsic muscles is impaired, there is a reduction in foot and ankle work and metatarsophalangeal joint stiffness. We speculated that the reduced capacity to actively control metatarsophalangeal joint stiffness may impair the gearing function of the foot at the ankle. MethodsWe used a tibial nerve block to examine the direct effects of the intrinsic foot muscles on ankle joint kinetics, in vivo medial gastrocnemius’ musculotendinous dynamics, and ankle gear ratio on 14 participants during maximal vertical jumping. ResultsUnder the nerve block, the internal ankle plantar flexion moment decreased (p = 0.004) alongside a reduction in external moment arm length (p = 0.021) and ankle joint gear ratio (p = 0.049) when compared to the non-blocked condition. Although medial gastrocnemius muscle–tendon unit and fascicle velocity were not different between conditions, the Achilles tendon was shorter during propulsion in the nerve block condition (p < 0.001). ConclusionIn addition to their known role of regulating the energetic function of the foot, our data indicate that the intrinsic foot muscles also act to optimize ankle joint torque production and leverage during the propulsion phase of vertical jumping.

Can Slight Variations to Lateral Wedge Insoles Induce Significant Biomechanical Changes in Patients with Knee Osteoarthritis?

Lateral wedge insoles are recommended in order to minimize the impacts of osteoarthritis of the knee. The amount of wedging required to induce a biomechanical response with clinical significance is still controversial. This study aimed to investigate the immediate biomechanical effects of different amounts of wedging in symptomatic medial knee OA. A 3D motion capture system and five force platforms were used to acquire walking kinematic and kinetic data along a 10 m walkway. Each participant was tested for six different lateral wedge insoles (0, 2, 4, 6, 8, and 10°) in a randomized order. Thirty-eight patients with medial osteoarthritis of the knee were recruited. The application of insoles resulted in an incremental reduction of the first peak of the external knee adduction moment under all experimental conditions in comparison with the control condition (0° insole). A significant increase (p &lt; 0.05) was observed in peak ankle eversion and in ankle eversion at the first peak of the external knee adduction moment with insoles higher than 8° and 6°, respectively. Slight variations to lateral wedge insoles, greater than 2°, appear to induce significant biomechanical changes in patients with knee osteoarthritis.

A novel hydraulic balanced turbine for stability control and application in drilling tools

ABSTRACT Most turbine designs are based on the continuous rotating turbine structure. In this paper, a novel hydraulic balanced turbine (HBT) with a symmetrical blade structure that can be used in a hydro-environment is proposed. The turbine, which uses the hydraulic impact of the nozzle jet and balanced turbine blade design in stability control, could be used to control stability in certain applications, e.g. in drilling engineering. This is a completely new way of thinking about turbine design. Because of the special blade design of the HBT, when the nozzle deviates from the balance position, the HBT will be restored to the balance position under the action of external moment. The follow-up performance of the HBT is directly related to the rotational speed of the nozzle. The theoretical and numerical solutions in this paper have good consistency. Modern computational resources allow computational fluid dynamics to be an integral part of turbine design. The simulation results proved that this innovative design is feasible and has potential application prospects. The HBT realizes the ‘soft’ connection between the controlled stable platform and the actuator in the vertical drilling tool, which can significantly improve the control precision of mechanical vertical drilling.

High tibial osteotomy effectively redistributes compressive knee loads during walking.

The objectives of this study were to estimate pre-and postoperative lower limb kinematics and kinetics and knee intra-articular forces during gait using musculoskeletal modeling in a cohort of patients with knee osteoarthritis (OA) undergoing high tibial osteotomy (HTO), compare these to controls, and determine correlations between changes in these parameters and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscores after HTO. Sixteen patients with isolated, symptomatic medial compartment knee OA completed pre-and postoperative gait analysis (mean follow-up time: 8.6 months). Sixteen age- and sex-matched asymptomatic volunteers participated as controls. Musculoskeletal modeling was used to evaluate lower limb joint moments and knee contact forces during gait. While HTO had limited influence on sagittal plane kinematics and moments, significant changes in the load distribution at the knee after HTO were observed with a lower postoperative compressive load on the medial compartment during midstance and a higher compressive load on the lateral compartment during early and late stance. Moreover, the lateral shear force in midstance was significantly lower after HTO. Changes in the external knee adduction moment (KAM) did not always coincide with reductions in the knee compressive force in the medial compartment. Biomechanical changes did not correlate with improvements in KOOS subscores. Hence, HTO effectively unloaded the medial compartment by redistributing part of the overall compressive force to the lateral compartment during gait with limited influence on gait function. The KAM may not adequately describe compartmental load magnitude or changes induced by interventions at the compartment level.Clinical trial registration: ClinicalTrials. gov Identifier-NCT02622204. Clinical significance: This study provides important evidence for changes in joint level loads after corrective osteotomy as joint preserving surgery and emphasizes the need for additional biomechanical outcomes of such interventions.

A Soft Exosuit Assisting Hip Abduction for Knee Adduction Moment Reduction During Walking

The knee joint experiences significant torques in the frontal plane to keep the body upright during walking. Excessive loading over time can lead to knee osteoarthritis (OA), the progression of which is correlated with external knee adduction moment (KAM). In this paper, we present a wearable soft robotic exosuit that applies a hip abduction torque and evaluate its ability to reduce KAM. The exosuit uses a portable cable actuation system to generate torque when desired while remaining unrestrictive when unpowered. We explored five different force profiles on healthy participants (N=8) walking on an instrumented treadmill at 1.25 m/s. For each force profile, we tested two peak force levels: 15% and 20% of bodyweight. We observed KAM reductions with two of the five profiles. With Force Profile 2 (FP2), peak KAM was reduced by 9.61% and impulse KAM by 12.76%. With Force Profile 5 (FP5), we saw reductions of peak KAM by 6.14% and impulse KAM by 21.09%. These initial findings show that the device has the ability to change walking biomechanics in a consistent and potentially beneficial way.

Gait Improvement in Patients with Knee Osteoarthritis after Proximal Fibular Osteotomy.

Proximal fibula osteotomy (PFO) is a relatively new surgery to treat medial compartment knee osteoarthritis (KOA), which can improve varum deformity and relieve knee joint pain. However, the gait alterations in KOA patients after PFO are still poorly understood. The purpose of this study was to evaluate the gait patterns change in patients of medial compartment KOA after PFO. Gait data were collected for 9 females with unilateral medial compartment KOA before and at 6 months after PFO and also for 9 healthy age-matched females. Paired t-test was used to determine the effect of PFO within the KOA group, and independent t-test were performed to compare between KOA and control groups for spatiotemporal, kinematic, and kinetic variables. The results showed that patients with KOA had significantly increased knee peak flexion angle, knee sagittal range of motion, and peak external hip adduction moment but decreased knee frontal range of motion in the affected limb after PFO. The gait symmetry was improved postoperatively confirmed by single support and swing phases, knee peak flexion angle and sagittal range of motion, peak external hip and knee adduction moments, and peak anterior and peak posterior ground reaction forces. These findings provided evidence of a biomechanical benefit and gait improvement following PFO to treat medial compartment KOA.

Entry angle during jump landing changes biomechanical risk factors for ACL injury

ABSTRACT ACL injuries are common among athletes. The injury usually occurs during sport movements involving sudden direction changes when landing and cutting. Twenty-one healthy females performed a series of jump-land-jump movements. They jumped from a 28 cm box onto two in-ground force platforms, followed by a maximal vertical jump. The direction of the first jump was tested with seven entry angles, jumping to the right (90 R, 60 R and 30 R), straight forward (0), and jumping to the left (90 L, 60 L and 30 L). Kinematic and kinetic data were recorded for data analysis. During the first 100 ms of landing, participants had significantly smaller peak knee flexion angles, larger initial knee valgus angles and larger peak knee joint external valgus moments when jumping to the right (90 R, 60 R and 30 R) compared to straight forward (0), and jumping to the left (90 L, 60 L and 30 L). Thus, entry angles to the right may increase the risk of ACL injury in the right knee. We suggest that these types of jumps should be used with caution during ACL rehabilitation, but may be useful for testing ACL risk factors in healthy individuals.

Individual muscle responses to mediolateral foot placement perturbations during walking

Walking requires active control of frontal plane balance through adjustments to mediolateral foot placement and ground reaction forces. Previous work on mediolateral balance perturbations and control of foot placement has often focused on the bilateral gluteus medius muscles. However, additional leg and trunk muscles can influence foot placement by transferring power to the foot and pelvis during swing. Thus, the purpose of this study was to determine individual muscle contributions to balance control following medial and lateral foot placement perturbations. Ten participants performed treadmill walking trials which included perturbations immediately before randomized heel strikes. Muscle contributions to foot placement, ground reaction forces, trunk power and frontal plane external moments during representative perturbed and unperturbed gait cycles were estimated using musculoskeletal modeling and simulation. Net muscle contributions to foot placement were 61 ± 50% more medial during the first recovery step following lateral perturbations and 28 ± 14% less medial in the second recovery step following medial perturbations. Following lateral perturbations, the swing gluteus medius performed 57 ± 50% more lateral work and the stance gluteus medius performed 61 ± 50% more medial work on the foot. Following medial perturbations, the erector spinae performed 39 ± 33% less lateral work on the foot. Changes in net muscle work on the foot were inconsistent with changes in step width, suggesting that changes in step width were not due to active muscle control but rather the mechanical effect of the perturbation. These outcomes provide a foundation for future studies analyzing balance control in populations at risk of falling.

Effects of barbell load on kinematics, kinetics, and myoelectric activity in back squats

ABSTRACT Shortly after beginning the upward phase of a free-weight barbell back squat there is often a deacceleration phase (sticking region) that may lead to repetition failure. The cause for this region is not well understood. Therefore, this study investigated the effects of 90%, 100%, and 102% of 1-RM barbell loads on kinematics, kinetics, and myoelectric activity in back squats. Twelve resistance-trained healthy males (body mass: 83.5 ± 7.8 kg, age: 27.3 ± 3.8 years, height: 180.3 ± 6.7 cm) participated in the study and lifted 134 ± 17 kg at 90% and 149 ± 19 kg at 100%, while they failed at 153 ± 19 kg with 102% load. The main findings were that barbell displacement and barbell velocity in the sticking region decreased with increasing loads. Moreover, the external hip extensor moment increased with heavier loads, whereas the knee extension and ankle plantarflexion moments were similar during the concentric phase. Also, reduced hip and knee extension together with lower myoelectric activity for all hip extensors and vastus lateralis were found for the 102% load compared to the others. Our finding suggests that the increased external hip extensor moment together with lower hip extensor myoelectric activity due to a reduced hip extension and thereby are responsible for lifting failure among resistance-trained males.

Immediate and six-week effects of wearing a knee sleeve following anterior cruciate ligament reconstruction on knee kinematics and kinetics: a cross-over laboratory and randomised clinical trial

BackgroundElastic knee sleeves are often worn following anterior cruciate ligament reconstruction (ACLR) but their effects on movement patterns are unclear.AimTo determine the immediate and six-week effects of wearing a knee sleeve on biomechanics of the knee during a step-down hop task.MethodsUsing a cross-over design, we estimated sagittal plane knee kinematics and kinetics and stance duration during a step-down hop for 31 participants (age 26.0 [SD 6.6] years, 15 women) after ACLR (median 16 months post-surgery) with and without wearing a knee sleeve. In a subsequent randomised clinical trial, participants in the ‘Sleeve Group’ (n = 9) then wore the sleeve for 6 weeks at least 1 h daily, while a ‘Control Group’ (n = 9) did not wear the sleeve. We used statistical parametric mapping to compare (1) knee flexion/extension angle and external flexion/extension moment trajectories between three conditions at baseline (uninjured side, unsleeved injured side and sleeved injured side); (2) within-participant changes for knee flexion angles and external flexion/extension moment trajectories from baseline to follow-up between groups. We compared discrete flexion angles and moments, and stance duration between conditions and between groups.ResultsWithout sleeves, knee flexion was lower for the injured than the uninjured sides during mid-stance phase. When wearing the sleeve on the injured side, knee flexion increased during the loading phase of the stance phase. Discrete initial and peak knee flexion angles increased by (mean difference, 95% CIs) 2.7° (1.3, 4.1) and 3.0° (1.2, 4.9), respectively, when wearing the knee sleeve. Knee external flexion moments for the unsleeved injured sides were lower than the uninjured sides for 80% of stance phase, with no change when sleeved. The groups differenced for within-group changes in knee flexion trajectories at follow-up. Knee flexion angles increased for the Control group only. Stance duration decreased by 22% for the Sleeve group from baseline to follow-up (-89 ms; -153, -24) but not for the Controls.ConclusionsApplication of knee sleeves following ACLR is associated with improved knee flexion angles during hop landing training. Longer term (daily) knee sleeve application may help improve hop stance duration, potentially indicating improved hop performance.Trial registrationThe trial was prospectively registered with the Australia New Zealand Clinical Trials Registry No: ACTRN12618001083280, 28/06/2018. ANZCTR

Effect of a valgus brace on medial tibiofemoral joint contact force in knee osteoarthritis with varus malalignment: A within-participant cross-over randomised study with an uncontrolled observational longitudinal follow-up.

BackgroundPrevious investigations on valgus knee bracing have mostly used the external knee adduction moment. This is a critical limitation, as the external knee adduction moment does not account for muscle forces that contribute substantially to the medial tibiofemoral contact force (MTCF) during walking. The aims of this pilot study were to: 1) determine the effect of a valgus knee brace on MTCF; 2) determine whether the effect is more pronounced after 8 weeks of brace use; 3) assess the feasibility of an 8-week brace intervention.MethodsParticipants with medial radiographic knee OA and varus malalignment were fitted with an Össur Unloader One© brace. Participants were instructed to wear the brace for 8 weeks. The MTCF was estimated via an electromyogram-assisted neuromuscular model with and without the knee brace at week 0 and week 8. Feasibility outcomes included change in symptoms, quality of life, confidence, acceptability, adherence and adverse events.ResultsOf the 30 (60% male) participants enrolled, 28 (93%) completed 8-week outcome assessments. There was a main effect of the brace (p<0.001) on peak MTCF and MTCF impulse, but no main effect for time (week 0 and week 8, p = 0.10), and no interaction between brace and time (p = 0.62). Wearing the brace during walking significantly reduced the peak MTCF (-0.05 BW 95%CI [-0.10, -0.01]) and MTCF impulse (-0.07 BW.s 95%CI [-0.09, -0.05]). Symptoms and quality of life improved by clinically relevant magnitudes over the 8-week intervention. Items relating to confidence and acceptability were rated relatively highly. Participants wore the brace on average 6 hrs per day. Seventeen participants reported 30 minor adverse events over an 8-week period.ConclusionAlthough significant, reductions in the peak MTCF and MTCF while wearing the knee brace were small. No effect of time on MTCF was observed. Although there were numerous minor adverse events, feasibility outcomes were generally favourable.Trial registrationAustralian and New Zealand Clinical Trials Registry (12619000622101).

Effects of Orthotic Correction of Hallux Valgus on Three-Dimensional Moments of Ankle Joint during Gait in Individuals with Hallux Valgus Deformity

Background Although many different types of foot-toe orthoses have known to correct hallux valgus deformity, most previous studies focused on the effects of a foot-toe orthosis as a clinical intervention for hallux valgus (HV) on simple gait function or alignment of the foot and ankle joints. Purpose To investigate effects of a hard and soft type foot orthoses on three-dimensional (3D) kinetic moments of ankle joints known to contribute to ankle arthrosis in individuals with HV using a force platform system based on motion analysis during gait. Study design This was a repeated-measures design. Methods Kinetic 3D moment data were obtained from 26 participants with HV. Two force platforms were used to collect kinetic data in three different foot-toe orthosis conditions during free walking. Repeated-measures analysis of variance was used to determine the effect of each foot-toe orthosis condition on ankle moment variables. Results There were significant differences in the maximal plantar flexion moment, second peak eversion moment, and maximal external rotation moment occurred at the terminal stance phase of the ankle joints between without foot orthosis and hard foot orthosis conditions (<italic>p</italic>&lt;0.05). In addition, there were significant differences in maximal plantar flexion moment occurred at the late stance phase during gait between without foot orthosis and soft foot orthosis conditions (<italic>p</italic>&lt; 0.05). Conclusions The results indicated the potential relationship between HV deformity and ankle osteoarthrosis through increasing ankle moments at the terminal stance under the without foot-toe orthosis condition. Particularly, the application of a hard foot-toe orthosis could contribute to treatment and prevention of ankle osteoarthrosis as well as HV correction.

Biomechanical comparison of 3 latissimus dorsi transfer sites for reverse total shoulder arthroplasty in the absence of teres minor.

Reverse total shoulder arthroplasty is often performed to treat rotator cuff tear arthropathy with irreparable rotator cuff tears. Patients with full-thickness tears involving the posterior cuff and teres minor specifically lose active external rotation of the humerus, limiting activities of daily living. A latissimus dorsi transfer has been described as one potential solution, but few studies have compared different latissimus dorsi transfer sites. This study assesses the biomechanics of 3 latissimus dorsi transfer sites, examining external rotation, deltoid muscle forces, and force across the glenoid for specific activities. The Newcastle Shoulder Model was modified to include a Delta III reverse shoulder arthroplasty and was used to model the effects of 3 latissimus dorsi transfer sites-anterior, posterolateral, and posterodistal-in the setting of teres minor deficiency. The latissimus dorsi was represented by 5 muscle elements approximating anatomic fascicle divisions. Kinematic data sets representing common activities were input into the model, allowing calculation of muscle forces and glenoid loads. Each of the 3 latissimus dorsi transfer sites demonstrated a change of moment arm from internal to external rotation with increased magnitude. Average maximum deltoid muscle forces and glenoid loading across all motions decreased for each of the 3 transfer sites, with the greatest decreased force noted for the posterior deltoid. This decrease in deltoid force and glenoid loading was significantly greater with the anterior and posterolateral transfer sites, relative to the posterodistal site. Latissimus dorsi transfer to all 3 sites in the setting of reverse total shoulder arthroplasty and posterior rotator cuff deficiency resulted in large external rotation moment arms. The transferred latissimus dorsi shared the external rotation load and resulted in decreased deltoid forces and glenoid loading with very small differences between the 3 transfer sites. The posterodistal location reduced deltoid force and glenoid loading to a lower degree compared with other sites, but it also showed that it did not alter the tendon length compared with the native shoulder.

Study on the correlation between early three-dimensional gait analysis and clinical efficacy after robot-assisted total knee arthroplasty

PurposeRobot-assisted technology is a forefront of surgical innovation that improves the accuracy of total knee arthroplasty (TKA). But whether the accuracy of surgery can improve the clinical efficacy still needs further research. The purpose of this study is to perform three-dimensional (3D) analysis in the early postoperative period of patients who received robot-assisted total knee arthroplasty (RATKA), and to study the trend of changes in gait parameters after RATKA and the correlation with the early clinical efficacy. MethodsPatients who received RATKA in the Center of Joint Surgery, the First Hospital Affiliated to Army Military Medical University from October 2020 to January 2021 were included. The imaging parameters, i.e., hip-knee-ankle angle, lateral distal femoral angle, medial proximal tibial angle, posterior condylar angle were measured 3 months post-TKA. The 3D gait analysis and clinical efficacy by Western Ontario Mac Master University Index (WOMAC) score were performed pre-TKA, 3 and 6 months post-TKA. The differences in spatiotemporal parameters of gait, kinetic parameters, and kinematic parameters of the operated limb and the contralateral limb were compared. The correlation between gait parameters and WOMAC scores was analyzed. Paired sample t-test and Wilcoxon rank-sum test were used to analyze the difference between groups, and Spearman correlation coefficient was used to analyze the correlation. ResultsThere were 31 patients included in this study, and the imaging indexes showed that all of them returned to normal post-TKA. The WOMAC score at 3 months post-TKA was significantly lower than that pre-TKA, and there was no significant difference between at 3 and 6 months. The 3D gait analysis results showed that the double support time of the operated limb reduced at 3 and 6 months (all p < 0.05), the maximum extension and maximum external rotation of the knee joint increased at stance phase, and the maximum flexion angle, the range of motion and the maximum external rotation increased at swing phase. Compared with the preoperative data, there were significant improvements (all p < 0.05). Compared with the contralateral knee joint, the maximum external rotation of the knee joint at swing phase was smaller than that of the contralateral side, and the maximum flexion and extension moment was greater than that of the contralateral knee. The maximum external rotation moment of the joint was greater than that of the contralateral knee joint (p < 0.05). There was a negative correlation between the single support time pre-TKA and the WOMAC score at 3 months (p = 0.017), and the single support time at 3 months was negatively correlated with the WOMAC score at 6 months (p = 0.043). The cadence at 6 months was negatively correlated with the WOMAC score at 6 months (p = 0.031). The maximum knee extension at stance phase at 6 months was negatively correlated with the WOMAC score at 6 month (p = 0.048). The maximum external rotation at stance phase at 6 months was negatively correlated with the WOMAC score at 6 months (p = 0.024). ConclusionThe 3D gait analysis of RATKA patients is more sensitive than WOMAC score in evaluating the clinical efficacy. Trend of changes in gait parameters shows that the knee joint support, flexion and extension function, range of motion, external rotation and varus deformity moment of the patient were significantly improved at 3 months after surgery, and continued to 6 months after surgery. Compared with the contralateral knee, the gait parameters of the operated limb still has significant gaps in functionality, such as the external rotation and flexion and extension. The single support time, cadence, knee extension, and knee external rotation of the operated limb have a greater correlation with the postoperative WOMAC score. Postoperative rehabilitation exercises should be emphasized, which is of great value for improving the early efficacy of RATKA.

CREATION OF OBJECT RECOGNITION AND TRACKING SYSTEM

In modern society, video recording systems have become widespread, allowing them to recognize objects, their absence, and changes in position. In the vast majority of intelligent systems for video monitoring and determining objects through their image, such objects as human faces, printed publications, and state registration numbers are taken into consideration. At the same time, the circumstances for accepting an image are quite strict, since there is a limit on illumination, background, location relative to the lens, and so on. All this significantly facilitates the joint work of a person with a computer, and creates the prerequisites for using all kinds of systems of artificial origin of the mind. The primary goal in the development of a method and software for the automatic design of a video surveillance system is the purpose of recognize an object whose image is transmitted through the camera. Since the image of any object depends on many moments of its direction about the video camera, illumination, characteristics of the recorder, static and dynamic characteristics of the object, it is rather difficult to arrange and present a picture in the guise of a specific mathematical model. As a result, the methods for implementing a computer representation are significantly dependent on the goals being solved and are occasionally inferior to generalization. As a result, the bulk of these methods is considered non-linear. This affects the need to accumulate the calculation of computer power and the difficulty of algorithms for work acquired through the technical channels of the resulting image. In addition to technical indicators that distort the quality of a digital image, several external moments are considered, and these are: lighting around the scene, moving objects within it, etc. As a result, to obtain the best accuracy of character recognition, it is necessary to take into account all the details. The aim of this work is to study the topic of object recognition in images and video, in order to further use the results of work in creating a system for object recognition in images and video.

The effects of foot orthosis and low-dye tape on lower limb joint angles and moments during running in individuals with pes planus

BackgroundPes Planus or Flat feet is one of the most common lower limb abnormalities. When runners with this abnormality participate in recreational running, interventional therapies could help in pain alleviation and enhance performance. To determine the most effective treatment, however, a biomechanical examination of the effects of each treatment modality is required. Research questionThe aim of the present study was to investigate the effects of Foot Orthoses (FOs) and Low-Dye Tape (LDT) on lower limb joint angles and moments during running in individuals with pes planus. Methodskinematic and kinetic data of 20 young people with pes planus were measured during running in three conditions: (1) SHOD (2) with shoes and FOs (3) with shoes and LDT. One-way repeated measure ANOVA was used to investigate the impacts of the FOs and LDT on the lower limb joint angles and moments throughout the stance phase of the running cycle. ResultsThe results showed that FOs reduced ankle eversion compared to SHOD and LDT (P < 0.001) and decreased the dorsiflexion angle (P = 0.005) and the plantarflexor moment compared to the SHOD (P < 0.001). FOs increased knee adduction angle (P = 0.021) and knee external rotator moment (P < 0.001) compared to both conditions and increased knee extensor and abductor moments compared to SHOD (P < 0.001). At the hip joint, FOs only increased hip external rotation compared with the LDT condition (P = 0.031); and LDT increased hip extensor moment compared to SHOD and FOs (P = 0.037) and also increased hip adduction angle compared to SHOD (P = 0.037). SignificanceFOs with a medial wedge appears to increase the external knee adduction moment and knee adduction angles, which are risk factors for the development and progression of knee osteoarthritis. Further, usage of FOs seems to reduce the ankle joint role in propulsion as it impacts the ankle sagittal angles and moments.

Study on the propulsion of the rigid-flexible composite plate driven on two points

The fish can be driven by the sarcomere at different locations of the body. To study the hydrodynamic performance of the fish in this process, the self-propulsion of a composite plate driving on two points was investigated. It is supposed that the forces were exerted on the junction point to maintain a given pitch motion of the rigid portion, and an additional external moment was exerted at a point on the flexible plate. The ratio between the lengths of the rigid portion and the flexible portion was fixed as 1/9, which was reasonable for a real fish. The acting point and phase angle of the additional external moment was varying to study the cooperation of the forces on different points. It was found that the additional external moment was not always promoting the propulsion velocity and efficiency of the composite plate. The additional external moment near the joint point was most suitable for improve the propulsive velocity and efficiency of the composite plate. The anti-phase additional external moment was prejudicing the propulsion of the plate. The additional external moment could change the vibration shape of the flexible plate and the flow structure around it. As ϕ = π, the amplitude and the gradient of the deformation was largely reduced, and the wake became long and narrow. The hydrodynamic forces at the head and tail portion of the flexible plate were hindering the propulsion of the plate, while the thrust was mainly produced on the intermediate portion. It was expected that our investigation can be helpful for the design of the soft robotic fish.

Submaximal electromyography-driven musculoskeletal modeling of the human trunk during static tasks: Equilibrium and stability analyses

Conventional electromyography-driven (EMG) musculoskeletal models are calibrated during maximum voluntary contraction (MVC) tasks, but individuals with low back pain cannot perform unbiased MVCs. To address this issue, EMG-driven models can be calibrated in submaximal tasks. However, the effects of maximal (when data points include the maximum contraction) and submaximal calibration techniques on model outputs (e.g., muscle forces, spinal loads) remain yet unknown. We calibrated a subject-specific EMG-driven model, using maximal/submaximal isometric contractions, and simulated different independent tasks. Both approaches satisfactorily predicted external moments (Pearson’s correlation ∼ 0.75; relative error = 44%), and removing calibration tasks under axial torques markedly improved the model performance (Pearson’s correlation ∼ 0.92; relative error ∼ 28%). Unlike individual muscle forces, gross (aggregate) model outputs (i.e., spinal loads, stability index, and sum of abdominal/back muscle forces) estimated from maximal and submaximal calibration techniques were highly correlated (r > 0.78). Submaximal calibration method overestimated spinal loads (6% in average) and abdominal muscle forces (11% in average). Individual muscle forces estimated from maximal and submaximal approaches were substantially different; however, gross model outputs (especially internal loads and stability index) remained highly correlated with small to moderate relative differences; therefore, the submaximal calibration technique can be considered as an alternative to the conventional maximal calibration approach.