Knee Joint Angle Research Articles

The Validity and Reliability of a New Intelligent Three-Dimensional Gait Analysis System in Healthy Subjects and Patients with Post-Stroke

Odonate is a new, intelligent three-dimensional gait analysis system based on binocular depth cameras and neural networks, but its accuracy has not been validated. Twenty-six healthy subjects and sixteen patients with post-stroke were recruited to investigate the validity and reliability of Odonate for gait analysis and examine its ability to discriminate abnormal gait patterns. The repeatability tests of different raters and different days showed great consistency. Compared with the results measured by Vicon, gait velocity, cadence, step length, cycle time, and sagittal hip and knee joint angles measured by Odonate showed high consistency, while the consistency of the gait phase division and the sagittal ankle joint angle was slightly lower. In addition, the stages with statistical differences between healthy subjects and patients during a gait cycle measured by the two systems were consistent. In conclusion, Odonate has excellent inter/intra-rater reliability, and has strong validity in measuring some spatiotemporal parameters and the sagittal joint angles, except the gait phase division and the ankle joint angle. Odonate is comparable to Vicon in its ability to identify abnormal gait patterns in patients with post-stroke. Therefore, Odonate has the potential to provide accessible and objective measurements for clinical gait assessment.

Biomechanical Characteristics and Metabolic Efficiency of Gait in Young-old and Old-old People

<h3>Research Objectives</h3> To investigate and compare the biomechanical characteristics and cardiopulmonary metabolic energy efficiency of gait between the young-old and the old-old community dwelling people. <h3>Design</h3> Cross-sectional study. <h3>Setting</h3> Clinical experimental study. <h3>Participants</h3> The elderly participants (N=78) were classified into the young-old (age range=65-74, mean age=70.2 ± 2.8 years, n=44) and the old-old (age range=75-84, mean age=77.9 ± 2.2 years, n=34) groups. <h3>Interventions</h3> Not applicable. <h3>Main Outcome Measures</h3> Spatiotemporal parameters (gait speed, cadence, step length, step width, and stride length), kinematics (angle of hip, knee, and ankle joint), kinetics (moment and power of hip, knee, and ankle joint), and cardiopulmonary metabolic energy efficiency during gait. <h3>Results</h3> Spatiotemporal gait parameters (gait speed, step length, and stride length) were significantly decreased in the old-old compared to the young-old group (p < 0.01). Peak ankle dorsiflexion angle, peak moment and peak power of knee and hip joints during gait were also significantly decreased in the old-old compared to the young-old group (p < 0.05, p < 0.01). On the other hand, net cardiopulmonary metabolic energy cost showed no significant difference between groups. <h3>Conclusions</h3> The old-old and young-old people showed significantly different gait characteristics, which suggested a need of customized intervention strategy in two elderly groups for preventing age-related hazardous condition such as fall. <h3>Author(s) Disclosures</h3> Eunhye Chung1,2, Su-Hyun Lee2, and Yun-Hee Kim1,2,3 1. Department of Medical Device Management & Research, SAIHST, Sungkyunkwan University, SAIHST, Seoul, Republic of Korea 2. Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea 3. Department of Health Sciences and Technology, Department of Digital Health, Sungkyunkwan University, SAIHST, Seoul, Republic of Korea

Potentiation of Stretch Shortening Cycle of Hip Moment and Power Only predict Jump Performance Enhancement

<h3>Research Objectives</h3> To investigate if lower-extremity joint specific potentiation of stretch shortening cycle (SSC) during the propulsive phase of jump test predicts jump height. <h3>Design</h3> Cross-sectional study. <h3>Setting</h3> University research laboratory. <h3>Participants</h3> Twenty-two young adults (12 females; mean age=25.75±3.03 years). <h3>Interventions</h3> Not applicable. <h3>Main Outcome Measures</h3> Participantsperformed three countermovement jump (CMJ) and static Jump (SJ) and bent their knees to the same flexion degree on two floor-embedded force platforms (AMTI). Using a 3-dimensional (3D) motion capture system (Vicon), jump height (JH) was measured using greater trochanters markers data of both lower extremities. Joint-based moment (Jmom) and power (Jpwr) of hip, knee, and ankle were calculated. Potentiation of SSC was calculated as CMJ/SJ ratios of JH, Jmom, and Jpwr for hip, knee, and ankle. The Vicon system contains 11 infrared cameras and two force platforms to synchronize kinetic and kinematic data. Linear regression models were used to examine if SSC potentiation predicts JH, controlling for knee joint angle and sex. <h3>Results</h3> JHPotentiation was 1.30±0.24. SSC Jmom potentiation was 1.33±0.40, 1.04±0.13, and 1.02±0.12 for hip, knee, and ankle, respectively. SSC Jpwr Potentiation was 1.39±0.53, 1.03±0.18, and 1.02±0.18 for hip, knee, and ankle, respectively. The regression models documented that SSC potentiation of hip Jpwr and Jmom predicted 77% and 87% of the variance in JH, respectively, after controlling for knee joint angle and sex. No other significant JH predictors were identified (p>0.05). <h3>Conclusions</h3> The findings show that hip Jmom and Jpwr SSC potentiation were associated with Jump test performance during the propulsive phase These findings provide an insight into understanding the mechanical function of the contribution of SSC potentiation of the lower extremities to jump tests performance. <h3>Author(s) Disclosures</h3> All authors declare no conflicts.

Wearable knee joint fatigue estimating system based on curvature and pressure sensing.

The injury of the knee joint is found to be directly related to the fatigue caused by excessive exercise. Many previous studies used wearable devices to measure the angle of knee joint during activities, but did not pay enough attention to the load of knee joint related to the fatigue degree of it. A wearable embedded system was designed to sense the motion state and load of knee joint and uses the sensoring data to estimate and predict the fatigue degree of knee joint during exercise in real time, so as to prevent it from being injured. An economical wearable system is designed to measure the parameters of the knee joint during exercises. Then the warning message and recommended healthy lasting time are able to be sent to users to avoid excessive exercise. 24 healthy volunteers aged 20-25 years were involved in the experiments. Two famous evaluation scales for knee joint from Department of Orthopedics (Lysholm score and IKDC score) were adopted to evaluate the protective effect. After 14 days of the first stage testing, all the participants with wearable devices reported healthy knee joint state to verify the effectiveness of the system. For the second stage, the testing group equipped with wearable warning devices did not receive obvious change in the two scales. However, Lysholm score of control group dropped by at least 7.4 and IKDC score dropped by at least 11.1 which were significantly reduced. Only using human perception to prevent knee joint fatigue had a risk of failure while the designed wearable system could protect the knee successfully from injuries during exercises, such as running, badminton, table tennis and basketball. Moreover, female gender and a high BMI value may be two factors that increase the risk of knee injuries during sports.

Semitendinosus muscle morphology in relation to surface electrode placement in anterior cruciate ligament reconstructed and contralateral legs.

The semitendinosus tendon is commonly harvested as graft tissue for anterior cruciate ligament reconstruction (ACLR). Although the semitendinosus tendon can regenerate following harvesting, ACLR results in substantial reductions in semitendinosus muscle size and length, potentially complicating electrode placement for electromyography. The purpose of this study was to assess whether the most commonly used electrode placement [recommended by the "Surface Electromyography for Non-Invasive Assessment of Muscles" (SENIAM) project] is appropriate for measuring semitendinosus electromyograms after ACLR. In nine participants (unilateral ACLR with a semitendinosus graft), B-mode ultrasonography was used to bilaterally determine (i) the semitendinosus muscle-tendon junction position and the state of tendon regeneration (latter for the ACLR leg only) and (ii) the anatomical cross-sectional area (ACSA) of the semitendinosus muscle at the SENIAM-recommended electrode placement site at rest and during isometric maximal voluntary contraction (MVC) at two knee joint angles. Depending on the contraction state and joint angle, the semitendinosus muscle had retracted past the recommended placement site in 33-78% of ACLR legs, but not in any contralateral legs. The ACSA of semitendinosus was smaller both at rest and MVC in the ACLR compared to contralateral leg. The ACSA for both legs decreased at MVC compared to rest and at deep compared to shallow knee flexion angles, likely due to sliding of the muscle under the skin. These results suggest SENIAM guidelines are likely unsuitable for recording surface electromyograms from the semitendinosus muscle after tendon harvesting for ACLR as the muscle of interest may not be within the electrode detection volume.

Females with hip-related pain display altered lower limb mechanics compared to their healthy counterparts in a drop jump task

BackgroundHip-related pain describes femoroacetabular impingement syndrome, acetabular dysplasia, and other hip pain conditions without clear morphological features. Movement strategies in this population, notably sex-related patterns, are poorly understood and may provide insights into why females report more pain and worse function. This study examined the sex-related differences during a drop vertical jump task between those with hip-related pain and healthy controls. MethodsPatients with hip-related pain and healthy controls completed five repetitions of a drop jump while their kinematics and kinetics were recorded using a motion capture system and force plates. Hip, knee, and ankle joint angles and external joint moments during landing were used in general estimating equations for comparison of group by sex by limb interactions. Time series data were further investigated using statistical parametric mapping. Findings: Females with hip-related pain had 9.1° less hip flexion (P = .041) and 9.2° less knee flexion (P = .024) than healthy females, and 8.3° less knee flexion than male counterparts with hip-related pain (P = .039). Males demonstrated 1.4° less hip flexion on the affected side compared to their uninvolved side (P = .004). Statistical parametric mapping results showed significant differences in knee flexion angle for females with hip-related pain compared to healthy females (P = .042). There were no significant differences in hip, knee, or ankle moments. InterpretationFemales with hip-related pain showed kinematic patterns distinct from healthy controls. Sex may be an important variable of interest in characterizing movement impairments in this population and movement impairments may be an appropriate target for intervention for these patients.

Properties of the iliotibial band and their relationships with gait parameters among patients with knee osteoarthritis.

This study aimed to determine the thickness and stiffness of the iliotibial band(ITB) in patients with knee osteoarthritis (KOA) and to identify the gait parameters that are associated with ITB properties. Eighteen female patients with radiographically diagnosed medial KOA and knee pain (age: 69.7 ± 5.9 years, body mass index: 23.0 ± 3.1 kg/m2 ) and 22 age-matched female individuals without knee pain (age: 69.1 ± 7.0 years, body mass index: 21.6 ± 3.6 kg/m2 ) were included. Shear wave elastography images were obtained at the height of the proximal pole of the patella with the participants in the supine position, and the ITB thickness and shear wave velocity, which is a surrogate measure of stiffness, were calculated. In patients with KOA, the knee and hip joint angles and moments during walking were calculated using a motion analysis system. The shear wave velocity was significantly higher in patients with KOA than in asymptomatic adults (11.3 ± 1.0 vs. 10.0 ± 1.8 m/s, respectively; p = 0.010); however, the thickness did not differ between them (2.1 ± 0.3 vs. 2.0 ± 0.3 mm, respectively; p = 0.705). The time-integral value of the knee adduction moment (β = 0.507, p = 0.032) and maximum value of the hip flexion moment (β = 0.498, p = 0.036) were associated with the shear wave velocity. Meanwhile, no parameters were associated with the thickness. The ITB was stiffer in patients with KOA than in asymptomatic adults; such a stiffer ITB was associated with greater knee adduction and hip flexion moments during walking. Clinical Significance: Greater mechanical loading was associated with a stifferITBin patients with KOA.

Effect of different landing actions on knee joint biomechanics of female college athletes: Based on opensim simulation.

Background: The anterior cruciate ligament (ACL) is one of the most injurious parts of the knee in the biomechanical environment during landing actions. The purpose of this study was to compare the lower limb differences in movement patterns, muscle forces and ACL forces during drop landing (DL), drop vertical jump (DVJ) and forward vertical jump (FVJ). Methods: Eleven basketball and volleyball female college athletes (Division II and I) were recruited. Landing actions of DL, DVJ and FVJ, kinematics and dynamics data were collected synchronously using a motion capture system. OpenSim was used to calculate the ACL load, knee joint angle and moment, and muscle force. Results: At initial contact, different landing movements influenced knee flexion angle; DL action was significantly less than FVJ action (p = 0.046). Different landing actions affected quadriceps femoris forces; FVJ was significantly greater than DL and DVJ actions (p = 0.002 and p = 0.037, respectively). However, different landing movements had no significant effects on other variables (knee extension moment, knee valgus angle and moment, hamstring and gastrocnemius muscle forces, and ACL forces) (p > 0.050). Conclusion: There was no significant difference in the knee valgus, knee valgus moment, and the ACL forces between the three landing actions. However, knee flexion angle, knee extension moments sagittal factors, and quadriceps and gastrocnemius forces are critical factors for ACL injury. The DL action had a significantly smaller knee flexion angle, which may increase the risk of ACL injury, and not recommended to assess the risk of ACL injuries. The FVJ action had a larger knee flexion angle and higher quadriceps femoris forces that were more in line with daily training and competition needs. Therefore, it is recommended to use FVJ action in future studies on risk assessment of ACL injuries and injury prevention in female college athletes.

Motor unit firing patterns of lower leg muscles during isometric plantar flexion with flexed knee joint position

The ankle flexor and extensor muscles are essential for pedal movements associated with car driving. Neuromuscular activation of lower leg muscles is influenced by the posture during a given task, such as the flexed knee joint angle during car driving. This study aimed to investigate the influence of flexion of the knee joint on recruitment threshold-dependent motor unit activity in lower leg muscles during isometric contraction. Twenty healthy participants performed plantar flexor and dorsiflexor isometric ramp contractions at 30 % of the maximal voluntary contraction (MVC) with extended (0°) and flexed (130°) knee joint angles. High-density surface electromyograms were recorded from medial gastrocnemius (MG), soleus (SOL), and tibialis anterior (TA) muscles and decomposed to extract individual motor units. The torque-dependent change (Δpps /Δ%MVC) of the motor unit activity of MG (recruited at 15 %MVC) and SOL (recruited at 5 %MVC) muscles was higher with a flexed compared with an extended knee joint (p < 0.05). The torque-dependent change of TA MU did not different between the knee joint angles. The motor units within certain limited recruitment thresholds recruited to exert plantar flexion torque can be excited to compensate for the loss of MG muscle torque output with a flexed knee joint.

Does the number of steps needed for UCM gait analysis differs between healthy and stroke?

The basis for the uncontrolled manifold (UCM) approach is the variability among repetitions of a motor task. Thus, reliable results might be influenced by the number of trials. This study estimated the number of steps needed for UCM analysis of stroke gait and if it is the same for healthy subjects. Twenty-five volunteers participated, sixteen in the stroke group (age 59.0 ± 7.5 years, ten hemiparesis at right), and nine in the healthy group (age 59.2 ± 4.9 years). We applied the UCM analysis over each lower limb's single support phase (SSP). The center of mass in the sagittal plane was the task variable, and the ankle, knee and hip joint angles, the elemental variables. The results obtained with 40 steps were used as a reference and compared with those obtained separately from 10, 20, and 30 steps. The mean values of the curves along the SSP were compared between the sets of steps. Further, for each volunteer, we calculated the Pearson correlation between the 40 steps curve and those obtained with other numbers of steps. Our results indicate that (1) the number of steps necessary to perform UCM analysis of stroke gait is larger than those necessary in healthy condition, (2) the synergy index is less sensitive to the number of steps than the UCM components (V_UCM and V_ORT), and (3) the analysis of the UCM over time requires a more significant number of steps than the mean values.

Effects of Knee Extension Joint Angle on Quadriceps Femoris Muscle Activation and Exerted Torque in Maximal Voluntary Isometric Contraction.

Simple SummaryFor human movement to occur, the neural system needs to activate muscles. Muscles then pull the bones that rotate around the joints. As the joint angle for the movement initiation changes, the mechanical conditions for the muscle force production also change, as does the exerted torque (i.e., maximal endpoint force). However, it is unclear whether different joint angles produce different muscle activation in maximal voluntary isometric contraction. This study investigated the effects of knee joint angle on muscle activation, produced torque, and whether the knee angle affects the muscle activation–torque ratio. Participants were instructed to produce maximal isometric knee extension in joint angles of 80, 90, 100, 110, 120, and 130°, while their muscle activation and torque output were assessed. The results confirmed the dependence of torque on knee angle, while muscle activation remained unaffected. While the trend could be observed, significant effects did not occur in muscle activation–torque ratio for lateral and medial quadriceps heads. The investigated range of knee joint angles seems to provide optimal conditions for maximal muscle activation but not for the torque output, hence for the ligament loading and joint contact forces. Therefore, clinicians and sports coaches should carefully set the training goals and choose the knee joint angles accordingly.This study investigated the effects of knee joint angle on muscle activation, exerted torque, and whether the knee angle affects the muscle activation–torque ratio. Nine healthy adult male participants participated in the study. They performed maximal voluntary isometric contraction (MVIC) at six (80°, 90°, 100°, 110°, 120°, and 130°) different knee joint angles (i.e., angles between the thigh and shin bones). Their maximal torque was assessed utilizing an isokinetic chair, while their muscle activation (root mean square [RMS]) was assessed using an eight-channel single differential surface EMG sensor. For the purposes of the torque–knee angle relationship and muscle activation–knee angle relationship, the torque and RMS were normalized relative to the maximal value obtained by each participant. To evaluate the muscle activation–torque ratio in function of knee angle, RMS was normalized relative to the corresponding torque obtained at each knee angle. Repeated measure analysis of variance was used to investigate the effects of knee angle on muscle activation, torque, and muscle activation–torque ratio. There was a significant effect of knee joint angle on normalized torque (F = 27.521, p < 0.001), while the activation of vastus lateralis and vastus medialis remained unchanged. The changes in knee angle affected the muscle activation–torque ratio of vastus lateralis (Chi-square = 16.246, p = 0.006) but not the vastus medialis. These results suggest that knee joint angles from 80° to 130° provide a stable milieu for muscle electrification, while mechanical factor such as knee joint angle (i.e., lever arm length) affect the torque output when one needs to contract quadriceps maximally during the isometric contraction.

Human-Robot Cooperative Strength Training Based on Robust Admittance Control Strategy.

A stroke is a common disease that can easily lead to lower limb motor dysfunction in the elderly. Stroke survivors can effectively train muscle strength through leg flexion and extension training. However, available lower limb rehabilitation robots ignore the knee soft tissue protection of the elderly in training. This paper proposes a human–robot cooperative lower limb active strength training based on a robust admittance control strategy. The stiffness change law of the admittance model is designed based on the biomechanics of knee joints, and it can guide the user to make force correctly and reduce the stress on the joint soft tissue. The controller will adjust the model stiffness in real-time according to the knee joint angle and then indirectly control the exertion force of users. This control strategy not only can avoid excessive compressive force on the joint soft tissue but also can enhance the stimulation of quadriceps femoris muscles. Moreover, a dual input robust control is proposed to improve the tracking performance under the disturbance caused by model uncertainty, interaction force and external noise. Experiments about the controller performance and the training feasibility were conducted with eight stroke survivors. Results show that the designed controller can effectively influence the interaction force; it can reduce the possibility of joint soft tissue injury. The robot also has a good tracking performance under disturbances. This control strategy also can enhance the stimulation of quadriceps femoris muscles, which is proved by measuring the muscle electrical signal and interaction force. Human–robot cooperative strength training is a feasible method for training lower limb muscles with the knee soft tissue protection mechanism.

Positive influence of neuromuscular training on knee injury risk factors during cutting and landing tasks in elite youth female handball players

Anterior cruciate ligament (ACL) ruptures are frequent in the age group of 15–19 years, particularly for female athletes. Although injury-prevention programs effectively reduce severe knee injuries, little is known about the underlying mechanisms and changes of biomechanical risk factors. Thus, this study analyzes the effects of a neuromuscular injury-prevention program on biomechanical parameters associated with ACL injuries in elite youth female handball players. In a nonrandomized, controlled intervention study, 19 players allocated to control (n = 12) and intervention (n = 7) group were investigated for single- and double-leg landings as well as unanticipated side-cutting maneuvers before and after a 12-week study period. The lower-extremity motion of the athletes was captured using a three-dimensional motion capture system consisting of 12 infrared cameras. A lower-body marker set of 40 markers together with a rigid body model, including a forefoot, rearfoot, shank, thigh, and pelvis segment in combination with two force plates was used to determine knee joint angles, resultant external joint moments, and vertical ground reaction forces. The two groups did not differ significantly during pretesting. Only the intervention group showed significant improvements in the initial knee abduction angle during single leg landing (p = 0.038: d = 0.518), knee flexion moment during double-leg landings (p = 0.011; d = −1.086), knee abduction moment during single (p = 0.036; d = 0.585) and double-leg landing (p = 0.006; d = 0.944) and side-cutting (p = 0.015;d = 0.561) as well as vertical ground reaction force during double-leg landing (p = 0.004; d = 1.482). Control group demonstrated no significant changes in kinematics and kinetics. However, at postintervention both groups were not significantly different in any of the biomechanical outcomes except for the normalized knee flexion moment of the dominant leg during single-leg landing. This study provides first indications that the implementation of a training intervention with specific neuromuscular exercises has positive impacts on biomechanical risk factors associated with ACL injury risk and, therefore, may help prevent severe knee injuries in elite youth female handball players.

Joint Angle Variability Is Altered in Patients with Peripheral Artery Disease after Six Months of Exercise Intervention.

Supervised exercise therapy (SET) is a conservative non-operative treatment strategy for improving walking performance in patients with peripheral artery disease (PAD). Gait variability is altered in patients with PAD, but the effect of SET on gait variability is unknown. Forty-three claudicating patients with PAD underwent gait analysis before and immediately after a 6-month SET program. Nonlinear gait variability was assessed using sample entropy, and the largest Lyapunov exponent of the ankle, knee, and hip joint angle time series. Linear mean and variability of the range of motion time series for these three joint angles were also calculated. Two-factor repeated measure analysis of variance determined the effect of the intervention and joint location on linear and nonlinear dependent variables. After SET, walking regularity decreased, while the stability remained unaffected. Ankle nonlinear variability had increased values compared with the knee and hip joints. Linear measures did not change following SET, except for knee angle, in which the magnitude of variations increased after the intervention. A six-month SET program produced changes in gait variability toward the direction of healthy controls, which indicates that in general, SET improved walking performance in individuals with PAD.

A non-immersive virtual reality-based intervention to enhance lower-extremity motor function and gait in patients with subacute cerebral infarction: A pilot randomized controlled trial with 1-year follow-up.

IntroductionThis study was conducted to evaluate whether a non-immersive virtual reality (VR)-based intervention can enhance lower extremity movement in patients with cerebral infarction and whether it has greater short-term and long-term effectiveness than conventional therapies (CTs).Materials and methodsThis was a single-blinded, randomized clinical controlled trial. Forty-four patients with subacute cerebral infarction were randomly allocated to the VR or CT group. All intervention sessions were delivered in the inpatient unit for 3 weeks. Outcomes were measured before (baseline) and after the interventions and at 3-month, 6-month and 1-year follow-ups. The outcomes included clinical assessments of movement and balance function using the Fugl–Meyer Assessment of Lower Extremity (FMA-LE) and Berg Balance Scale (BBS), and gait parameters in the sagittal plane.ResultsIn the VR group, the walking speed after intervention, at 3-month, 6-month, and 1-year follow-ups were significantly greater than baseline (p = 0.01, <0.001, 0.007, and <0.001, respectively). Compared with baseline, BBS scores after intervention, at 3-month, 6-month, and 1-year follow-ups were significantly greater in both the VR group (p = 0.006, 0.002, <0.001, and <0.001, respectively) and CT group (p = <0.001, 0.002, 0.001, and <0.001, respectively), while FMA-LE scores after intervention, at 3-month, 6-month, and 1-year follow-ups were significant increased in the VR group (p = 0.03, <0.001, 0.003, and <0.001, respectively), and at 3-month, 6-month, and 1-year follow-ups in the CT group (p = 0.02, 0.004 and <0.001, respectively). In the VR group, the maximum knee joint angle in the sagittal plane enhanced significantly at 6-month follow-up from that at baseline (p = 0.04).ConclusionThe effectiveness of the non-immersive VR-based intervention in our study was observed after the intervention and at the follow-ups, but it was not significantly different from that of CTs. In sum, our results suggest that non-immersive VR-based interventions may thus be a valuable addition to conventional physical therapies to enhance treatment efficacy.Clinical trial registrationhttp://www.chictr.org.cn/showproj.aspx?proj=10541, ChiCTR-IOC-15006064.

Feasibility of interleaved stimulation in peroneal stimulators: the effect of surface electrode configuration on foot kinematics

A peroneal stimulator is a neuroprosthetic device based on functional electrical stimulation (FES). It induces ankle dorsiflexion in the swing phase in patients affected by foot drop [1]. A well-known limitation of FES is the increased muscle fatigability due to the non-physiological motor unit (MU) activation. A possible approach to limit this issue is to interleave electrical pulses delivered to the muscle ( mstim ) and to the nerve ( nstim ) to distribute the stimulation among different MU groups [2], thus reducing the activation frequency of each group (interleaved stimulation). The practical applicability of this approach to peroneal stimulators requires that both mstim and nstim induce foot dorsiflexions (DFs) with minimal in-/eversion and ab-/adduction for all the knee angles within the swing phase. While for mstim knee rotations are not critical, changes in knee angle may modify the relative position between nstim electrodes and peroneal nerve, resulting in foot rotations outside the sagittal plane. Here we investigate the effect of nstim electrode positioning on induced foot rotations to identify the configuration leading to foot DF maximally similar to the voluntary ones for the entire knee ROM. We compared the electrically-induced foot movement for five nstim electrode positioning and four knee joint angles (0°, 20°, 40° and 60°, being 0° full knee extension) in ten healthy subjects. A grid of five cathodes was placed between fibular head and the tibial tuberosity (Fig. 1A) while a large anode (56 cm 2 ) was located on the patella. For each knee angle, electrical stimulation was delivered at the five stimulation sites (pulse duration: 200 µs, frequency: 20 Hz) and foot rotations were quantified with an IMU positioned under the foot. Foot in-/eversion and ab-/adduction were compared with those measured during voluntary DFs at each angle Fig. 1 B shows the ab-/adduction (Y-axes) and in-/eversion (X-axes) angles for each stimulation site (color-coded) and for the four knee angles in a representative subject. Red-dotted line delimits the acceptability area confining the angles obtained during voluntary DFs from all participants. All the points (stimulations) inside this area were regarded as producing a foot kinematic comparable to a voluntary DF. Figure c shows the number of subjects inside the acceptability area for all the stimulation configurations and knee angles. Collectively, configurations A and C included 7 out of 9 subjects, whilst for configurations D and E no subjects were inside the acceptability area for all knee angles. We identified a common nstim electrode configuration that induced, in the majority of the participants, foot (DF) with minimal eversion and inversion for the knee angles within the swing phase. This is a necessary condition to ensure the applicability of stimulation strategies based on distributed nerve/muscle stimulation (interleaved stimulation) aimed at reducing muscle fatigue in FES-based foot drop treatments.

Machine Learning-Based Peripheral Artery Disease Identification Using Laboratory-Based Gait Data.

Peripheral artery disease (PAD) manifests from atherosclerosis, which limits blood flow to the legs and causes changes in muscle structure and function, and in gait performance. PAD is underdiagnosed, which delays treatment and worsens clinical outcomes. To overcome this challenge, the purpose of this study is to develop machine learning (ML) models that distinguish individuals with and without PAD. This is the first step to using ML to identify those with PAD risk early. We built ML models based on previously acquired overground walking biomechanics data from patients with PAD and healthy controls. Gait signatures were characterized using ankle, knee, and hip joint angles, torques, and powers, as well as ground reaction forces (GRF). ML was able to classify those with and without PAD using Neural Networks or Random Forest algorithms with 89% accuracy (0.64 Matthew’s Correlation Coefficient) using all laboratory-based gait variables. Moreover, models using only GRF variables provided up to 87% accuracy (0.64 Matthew’s Correlation Coefficient). These results indicate that ML models can classify those with and without PAD using gait signatures with acceptable performance. Results also show that an ML gait signature model that uses GRF features delivers the most informative data for PAD classification.

KNEE ALIGNMENT IN ADOLESCENT FOOTBALL TRAINEES

Genu varum and valgum can trigger for osteoarthritis and happened between 16-18 years old. The study aimed to find out the relationship between knee joint alignment and footballers activities. This was a cross-sectional study, with 64 participants from two groups and only participants whom were meet all inclusion criteria were joined. It showed the knee joint angle in comparison to the norm was very significant with p- value 0.000 and there was a connection to practicing football against knee joint alignment, more specifically varum. In conclusion, there is a significant relationship between practicing football and the knee joint as measured by degree og genu varum and vagum as differences were found in year and duration of training.

Hip and knee joint angle patterns and kicking velocity in female and male professional soccer players: A principal component analysis of waveforms approach

ABSTRACT This study used principal component analysis (PCA) of waveforms to extract movement patterns from hip and knee angle time-series data; and determined if the extracted movement patterns were predictors of ball velocity during a soccer kick. Twenty-three female and nineteen male professional soccer players performed maximal effort instep kicks while motion capture and post-impact ball velocities data were recorded. Three-dimensional hip and knee joint angle time-series data were calculated from the beginning of the kicking leg’s backswing phase until the end of the follow-through phase and entered into separate PCAs for females and males. Three principal components (PC) (i.e., movement patterns) were extracted and PC scores were calculated. Pearson correlation coefficients were calculated to establish correlations between hip and knee PC scores and kicking velocity. Results showed better kicking performance in male players was associated with a greater difference between the hip extension at the end of the backswing/beginning of the leg cocking phases and hip flexion at the end of the follow-through phase (r = −0.519, p = 0.023) and a delayed internal rotation of the hip (r = 0.475, p = 0.040). No significant correlations between ball velocity and hip and knee kinematics were found for female players.

Breast Support Alters Trunk And Knee Joint Biomechanics During Double Limb Landing

Female athletes have a greater prevalence of traumatic knee injury than male athletes. Sex-based differences in injury rates emerge with maturation and the development of sex-specific traits including breast development. Breast support is known to alter trunk biomechanics during running tasks while in landing trunk orientation has been shown to mediate ACL strain. However, the effect of breast support on knee joint biomechanics has not been previously investigated. PURPOSE: To examine the effects of breast support on trunk and knee joint biomechanics during double limb landing. METHODS: Fourteen female collegiate athletes performed five double-limb landing trials in each of three sports bra conditions: no support, low support, and high support. Three-dimensional kinematics (240 Hz, Qualisys) and ground reaction forces (1200 Hz, AMTI Inc.) were recorded simultaneously. Visual 3D (C-Motion Inc.) was used to calculate peak trunk segment angles as well as peak knee joint angles and extension moments. A repeated measures ANCOVA with post-hoc pairwise comparisons were used to evaluate the effect of breast support on knee biomechanics. RESULTS: Increasing levels of breast support were associated with reductions in peak knee flexion (p = 0.008), peak knee valgus angles (p = 0.011) and peak knee valgus moments (p = 0.033) while there were no changes in peak knee moments (p = 0.216). Trunk flexion at initial contact (p = 0.024) and peak trunk flexion (p = 0.002) increased in response to greater breast support. CONCLUSIONS: The current data revealed a multi-joint mechanical adaptation in response to lower levels of breast support. These altered biomechanical patterns are consistent with a greater risk of traumatic knee injury including ACL rupture.