Lower Extremity Joint Research Articles

Validity of IMU measurements on running kinematics in non-rearfoot strike runners across different speeds

ABSTRACT This study aims to determine the validity of the lower extremity joint kinematics measured by inertial measurement units (IMUs) in non-rearfoot strike pattern (NRFS) runners across different speeds. Fifteen NRFS runners completed three 2-min running tests on a treadmill in random order at 8, 10 and 12 km/h, whilst data were synchronously collected using the IMU system and an optical motion capture system. Before the offset was corrected, the validity of the knee angle waveform was higher than that of the hip and ankle; after the offset was corrected, the validity increased in all three joints. The correlation between the touchdown angles in the sagittal plane measured by the two systems was relatively high after the offset was corrected. The running speed influenced the offset-corrected measurements, with higher error values at higher speeds. The IMU system was able to provide measurements of running kinematics in the sagittal plane of NRFS runners at different running speeds but was unable to reliably measure motion in the frontal and horizontal planes. Future research should analyse the 3D gait of NRFS runners under a larger range of speed conditions to provide evidentiary support for the use of IMUs in running analysis outside the laboratory.

A prophylactic lumbosacral brace and the biomechanics of parachute landing.

Lumbar injuries are common among paratroopers during landing maneuvers. Although bracing is widely advocated to increase spine stability, the effect of lumbar bracing on parachuting has yet to be quantified and the Chinese parachutist does not have a uniform prophylactic brace. The aim is to compare the effects of a novel, self-designed and self-manufactured lumbosacral brace with two ordinary lumbar braces based on biomechanical assessment of the lumbar and lower extremity joints during parachute landing. The study cohort consisted of 30 elite male paratroopers. Each participant was instructed to jump off a platform at two different heights (60 and 120 cm, respectively) and land on the force plate in a half-squat posture. Participants at each height were tested under four different conditions (no brace, elastic brace, semi-rigid brace, and lumbosacral brace). The Vicon 3D motion capture system and force plate were used to record and calculate biomechanical data, such as vertical ground reaction forces (vGRFs), joint angles, moments, and energy absorption. After the experiment, every participant completed the study questionnaires. The increase of the jumping height raised all the parameters significantly (P<0.01). The use of all three braces slightly decreased vGRF, and reduced the lumbar angle, moment, and angular velocity in the sagittal plane. The use of lumbosacral and semi-rigid braces restricted lumbar flexion more efficiently (P<0.05), and significantly increased the energy absorption of the hip joints (P<0.01) and hip flexion (P<0.01) at 120 cm. No significant effect of braces was found on the motion of knee and ankle joints. The subjective scores suggested that the lumbosacral brace was softer and more comfortable than the semi-rigid brace, and more effective than the elastic brace. The lumbosacral brace markedly restricted the lumbar motion in the sagittal plane than the elastic brace and was more comfortable than the semi-rigid brace. Therefore, the innovative design, high efficiency, and comfortable landing of the lumbosacral brace represent a reliable option for parachute jumping and training.

Joint Injury, Osteoarthritis, and Cardiovascular Disease Risk Factors in Former National Football League Athletes: An NFL-LONG Study.

Individuals with lower extremity osteoarthritis (OA) have a 25% greater risk of cardiovascular disease (CVD) than those without OA. The prevalence of traumatic joint injuries among National Football League (NFL) players exposes these athletes to an elevated risk for OA and potentially a greater risk of cardiovascular risk factors (CRFs) and CVD. To examine the associations between a history of lower extremity joint injury, lower extremity OA, and the prevalence of CRFs and CVD among former NFL athletes. Cross-sectional study. Former NFL players completed a comprehensive health questionnaire that was used in an ongoing study, the Neurologic Function Across the Lifespan: A Prospective, Longitudinal, and Translational Study for Former NFL Players (NFL-LONG). A subsample of 1738 former players reported lifetime medical diagnoses including CVD or CRFs. Crude and adjusted prevalence ratios (PRsadj) characterized the associations between CVD or CRFs and injury, OA diagnosis, or both among athletes who reported (1) no history of lower extremity joint injury or surgery and no diagnosed OA, (2) a history of lower extremity joint injury or surgery and no diagnosed OA, and (3) a history of lower extremity joint injury or surgery and diagnosed OA. Neither a history of lower extremity joint injury (PRadj = 1.34; 95% CI = 0.86, 2.07) nor a history of lower extremity joint injury and diagnosed OA (PRadj = 1.41; 95% CI = 0.89, 2.25) was significantly associated with CVD. However, CRFs were 30% and 53% more prevalent in former players with lower extremity joint injury and no diagnosed OA (PRadj = 1.30; 95% CI = 1.12, 1.50) and those with lower extremity joint injury and diagnosed OA (PRadj = 1.53; 95% CI = 1.31, 1.78), respectively, versus athletes with no history of either condition. The prevalence of CRFs was highest among former NFL athletes with a history of lower extremity joint injury and diagnosed OA. These findings provide insight regarding the potential pathways to chronic diseases that may be initiated by joint injury early in life.

Training interventions to reduce the risk of injury to the lower extremity joints during landing movements in adult athletes: a systematic review and meta-analysis

ObjectiveAim of this systematic review was to summarise training interventions designed to reduce biomechanical risk factors associated with increased risk of lower extremity landing injuries and to evaluate their practical...

Estimation of Lower Extremity Joint Moments and 3D Ground Reaction Forces Using IMU Sensors in Multiple Walking Conditions: A Deep Learning Approach.

Human kinetics, specifically joint moments and ground reaction forces (GRFs) can provide important clinical information and can be used to control assistive devices. Traditionally, collection of kinetics is mostly limited to the lab environment because it relies on data that are measured from a motion capture system and floor-embedded force plates to calculate the dynamics via musculoskeletal models. This spatially limited method makes it extremely challenging to measure kinetics outside the laboratory in a variety of walking conditions due to the expensive device setup and large space required. Recently, employing machine learning with IMU sensors are suggested as an alternative method for biomechanical analyses. Although these methods enable estimating human kinetic data outside the laboratory by linking IMU sensor data with kinetics dataset, they are limited to show inaccurate kinetic estimates even in highly repeatable single walking conditions due to the employment of generic deep learning algorithms. Thus, this paper proposes a novel deep learning model, Kinetics-FM-DLR-Ensemble-Net for single limb prediction of hip, knee, and ankle joint moments and 3 dimensional Ground Reaction Forces (GRFs) using three IMU sensors on the thigh, shank, and foot under several representatives walking conditions in daily living, such as treadmill, level-ground, stair, and ramp. This is the first study that implements both joint moments and GRFs in multiple walking conditions using IMU sensors via deep learning. Our deep learning model is versatile and accurate for identifying human kinetics across diverse subjects and walking conditions and our model outperforms state-of-the-art deep learning model for kinetics estimation by a large margin.

테니스 포핸드 스트로크 시 그립 형태에 따른 하지관절 움직임 및 상지근의 변화 차이 분석

The study was to examined the lower extremity movements of the semi-western and western grips during the forehand stroke in five male tennis players and determined the muscle activity of the upper extremities, with the following conclusions. First, the overall duration of each segment did not show significant differences, but the semi-western grip showed faster duration on average at P1 and the western grip at P2. Second, it was found that it is desirable to reduce the change in left-right width at the moment of impact to increase the rotational force and facilitate the weight transfer with anterior movement. Third, the lower extremity joint angles showed a statistically significant difference in the left hip joint E1 (p&lt;.05), and a significant difference in the right ancle joint. Fourth, the mobilization of the spinae muscles to generate trunk rotation for smooth transfer of lower extremity kinetic energy and the activity of the deltoid and hip flexor muscles for a strong swing were found to be important factors in transferring momentum to the ball.

Differences in lower extremity joint stiffness during drop jump between healthy males and females

The primary purpose of this study was to examine sex differences in lower extremity joint stiffness during vertical drop jump performance. A secondary purpose was to examine the potential influence of sex on the relationship between joint stiffness and jump performance. Thirty healthy and active individuals performed 15-drop jumps from 30 and 60 cm boxes. Hip, knee, and ankle joint stiffnesses were calculated for subphases of landing using a 2nd order polynomial regression model. Males had greater hip stiffness during the loading phase in drop jumps from both box heights than females’ drop jump from 60 cm box. Also, males had a greater ground reaction force at the end of eccentric phase, net jump impulse, and jump height regardless of box height. The 60 cm box height increased knee stiffness during the loading phase, but reduced hip stiffness during the loading phase and knee and ankle stiffness during the absorption phase regardless of sex. Joint stiffnesses significantly predicted drop jump height for females (p < .001, r2 = 0.579), but not for males (p = .609, r2 = −0.053). These results suggest that females may have different strategies to maximize drop jump height as compared to males.

Evaluation of the Accuracy of the Postural Stability Measurement with the Y-Balance Test Based on the Levels of the Biomechanical Parameters of 14-Year-Old Girls.

Dynamic balance monitoring involves the assessment of the muscular control during changes of the centre of gravity location in space above the supporting plane. We aimed to determine the structure of the Y-Balance Test and its accuracy based on measurements of strength and resistance to fatigue of muscles acting on the knee joint under static conditions, as well as joint motion ranges and static balance in girls aged 14 years. The study included 40 girls aged 14, who attended Gymnasium No. 2 in Cracow (Poland). The research was conducted in October 2020. Postural stability was examined with the use of the YBT. The measurements of muscle strength and knee joint extensor and flexor resistance to fatigue during an isometric contraction were performed in a standard position on the test bench. The measurements of lower extremity joint range of motion were performed in accordance with the SFTR methodology. Static balance was assessed with the use of the modified FBT. The factor structure obtained for both lower extremities has satisfactorily explained the common variance (about 70%) and showed slight differences between the left and right extremities. The factor structure in the group of examined girls suggests a highly hybrid nature of the Y-Balance Test with a wide spectrum of biomechanical variables that have little influence on the measurement results.

Differences in kick-leg kinematics in various side-kick heights

ABSTRACT This study aims to explore the variation of lower extremity kinematic characteristics when elite taekwondo athletes perform the side-kick on protective gear placed at various heights. Twenty distinguished male national athletes were recruited and were asked to kick targets at three different heights adjusted according to their body height. A three-dimensional (3D) motion capture system was used to collect kinematic data. Kinematic parameters differences in the side-kick at three different heights were analyzed by using a one-way ANOVA (p < .05). The results revealed significant differences in the peak linear velocities of the pelvis, hip, knee, ankle, and centre of gravity of the foot during the leg-lifting phase (p < .05). Significant differences between heights were noted in the maximum angle of pelvis left tilting and hip abduction in both phases. In addition, the maximum angular velocities of pelvis left tilting and hip internal rotation were only different in the leg-lifting phase. This study found that, to kick at a higher target, athletes increase the linear velocities of their pelvis and all lower extremity joints of attacking leg in the leg-lifting phase; however, they only increase rotational variables on the proximal segment at the peak angle of the pelvis (left tilting) and hip (abduction and internal rotation) in the same phase. As an application in actual competitions, according to the opponent’s body height, athletes can adjust both linear and rotational velocities of their proximal segements (pelvis and hip) and deliver into distal segements (knee, ankle, foot) linear velocity to perform accurate and rapid kicks.

Effect of load carriage on joint kinematics, vertical ground reaction force and muscle activity: Treadmill versus overground walking

BackgroundPrevious studies have investigated the effect of either different load or different surface conditions, such as overground or treadmill walking, on human biomechanics. However, studies combining these two aspects are scarce. Research questionThe purpose of this study was to quantify the difference in spatiotemporal parameters, lower extremity joint kinematics, vertical ground reaction forces (vGRF) and muscle activity between normal bodyweight (100 %BW) and 20 % increased bodyweight (120 %BW) during overground and treadmill walking. MethodsTen healthy young adults walked overground at self-selected speed and on an instrumented treadmill set to the overground speed. Spatiotemporal parameters, 3-dimensional lower extremity kinematics, vGRF and muscle activity were measured and compared between conditions. ResultsThe stance phase was longer for 120 %BW than 100 %BW in both overground and treadmill walking. Further, the stance phase was longer and cadence higher in treadmill than overground walking for both load conditions. Knee flexion angles were more than 3° greater in the second half of swing in treadmill than in overground walking. The vGRF was higher for 120 %BW compared to 100 %BW on both surfaces (treadmill, first peak: +18.6 %BW; second peak: +13.5 %BW; overground, first peak: +22.2 %BW; second peak: +19.8 %BW). Differences between conditions greater than 20 % were observed in short periods during the gait cycle for vastus medialis, vastus lateralis and semitendinosus. SignificanceResults regarding the effects of carrying additional load using a weight vest on joint kinematics during treadmill walking may be translated to overground walking but some changes in muscle activation can be expected.

Development and benchmarking of machine learning models to classify patients suitable for outpatient lower extremity joint arthroplasty

Study objectivePerforming hip or knee arthroplasty as an outpatient surgery has been shown to be operationally and financially beneficial for selected patients. By applying machine learning models to predict patients suitable for outpatient arthroplasty, health care systems can better utilize resources efficiently. The goal of this study was to develop predictive models for identifying patients likely to be discharged same-day following hip or knee arthroplasty. DesignModel performance was assessed with 10-fold stratified cross-validation, evaluated over baseline determined by the proportion of eligible outpatient arthroplasty over sample size. The models used for classification were logistic regression, support vector classifier, balanced random forest, balanced bagging XGBoost classifier, and balanced bagging LightGBM classifier. SettingThe patient records were sampled from arthroplasty procedures at a single institution from October 2013 to November 2021. PatientsThe electronic intake records of 7322 knee and hip arthroplasty patients were sampled for the dataset. After data processing, 5523 records were kept for model training and validation. InterventionsNone. MeasurementsThe primary measures for the models were the F1-score, area under the receiver operating characteristic curve (ROCAUC), and area under the precision-recall curve. To measure feature importance, the SHapley Additive exPlanations value (SHAP) were reported from the model with the highest F1-score. ResultsThe best performing classifier (balanced random forest classifier) achieved an F1-score of 0.347: an improvement of 0.174 over baseline and 0.031 over logistic regression. The ROCAUC for this model was 0.734. Using SHAP, the top determinant features of the model included patient sex, surgical approach, surgery type, and body mass index. ConclusionsMachine learning models may utilize electronic health records to screen arthroplasty procedures for outpatient eligibility. Tree-based models demonstrated superior performance in this study.

Drift in lower extremity joint angles measured with inertial measurement units during treadmill walking

Breaking the capacity barrier in intercalation-type anode materials for lithium-ion batteries while preserving other essential electrochemical properties remains a significant challenge. Here, using perovskite SrVO3 as a model, we demonstrate the feasibility of employing defect engineering to provide extra active sites for electrochemical reactions. Defective SrxVO3-δ samples with a unique amorphous-crystalline dual-phase structure are successfully prepared by regulating the nonstoichiometric Sr/V ratio and using a non-equilibrium solution combustion strategy to alleviate nucleation. The dual-phase SrxVO3-δ electrodes, which take advantage of both the high defect concentration advantage of amorphous and the high electrical/ionic conductivity of crystalline, give a high specific capacity of 508 mAh/g at a safe potential of 1.0 V vs. Li/Li+, showing a 40% increase over SrVO3 electrodes and outperforming most state-of-the-art intercalation-based anodes. In addition, when coupling with LiFePO4 cathode, the SrxVO3-δ electrodes can operate over 10,000 cycles with 91% capacity retention, overcoming the limited structural stability exhibited in typical defective electrodes. The study demonstrates the viability of modulating the crystallinity in intercalation-based anodes to enhance electrochemical performance and paves the way for the advancement of Li-ion battery technology.

Widespread localized areas of annular patches, plaques, and erythema.

Without prompt diagnosis and treatment, patients with Lyme disease may develop life threatening multi-organ system complications. As such, we discuss the key diagnostic features of the condition along with patient-specific suggested treatment protocols. Additionally, Lyme disease is reportedly expanding to regions that were previously not impacted, key epidemiological features are outlined. We discuss a patient with severe Lyme disease who presented with widespread cutaneous involvement and atypical pathologic findings within an uncharacteristic geographic region. Erythematous, annular patches and plaques with dusky-to-clear centers were initially observed on the right thigh and later extended to the trunk and bilateral lower extremities. The diagnosis of Lyme disease was made clinically and confirmed with western blot testing that was positive for IgM antibodies. The patient additionally had a history of rheumatoid arthritis, for which he discontinued treatment prior to the current presentation with Lyme disease. During follow up visits, the patient noted lower extremity joint pain. Due to the overlapping clinical features of post-Lyme arthritis and rheumatoid arthritis, key differences are outlined to prevent misdiagnosis. Data revealing trends in the geographic distribution of the disease and possible need for increased surveillance and prevention strategies within previously unaffected areas are discussed.

The Effect of Fatigue on Lower Extremity Joint Kinematics and Performance

ACL injuries are multifactorial in nature meaning they can be the result of faulty biomechanics, individual genetic predisposition, or environmental factors (Alentorn- Geli et al., 2009). A focus of most healthcare professionals including physical therapists and athletic trainers includes the screening for preventable risk factors for non- contact ACL injuries. Preventable risk factors include asymmetry between a person’s limbs, decreased hamstring strength, increased muscle fatigue, decreased landing angle of hip and knee Tlexion, increased valgus landing, and lack of Tlexibility in the hip internal rotators (Brophy, 2021). Given the short and long-term negative consequences of an ACL injury, it is important for healthcare providers to explore screening and prevention techniques to employ with at-risk athletic populations.

Effects of load increase on lower extremity kinetic and kinematic variables in the back squat exercise.

Squats are one of the most widely used weight training methods worldwide, and the single most ubiquitous with regard to multi-joint resistance training. The objective of the present study was to investigate kinematic and kinetic changes in the lower extremities as a result of load increases during a back squat exercise, and to propose an association between back squats and lower extremity injuries. Eight individuals with experience of back squat training were recruited. The subjects performed back squats with loads of 25%, 50%, 100%, and 125% of their body weight. During the performance, the center of pressure (COP) sway; vertical center of mass (COM) velocity; joint moment; joint range of motion (ROM) of flexion/extension and adduction/abduction; and rotation of the ankle, knee, and hip joints were measured. The participants' lower extremity joint ROM, vertical COM velocity, and COP variability did not change significantly with changes in weight loading. However, the moments applied to the lower extremity joints differed according to changes in barbell weight. The moments of plantar flexion (f= 54.362, p< 0.001), dorsiflexion (f= 8.475, p< 0.001), knee flexion (f= 12.013, p< 0.001), knee extension (f= 8.581, p< 0.001), hip flexion (f= 5.111, p< 0.001), and hip extension (f= 11.053, p< 0.001) increased in the sagittal plane (flexion/extension). There was also a significant increase in ankle eversion (f= 5.612, p= 0.004), hip abduction (f= 3.242, p= 0.037), and adduction (f= 5.846, p= 0.003) in the frontal plane (adduction/abduction). Among the moment variables in the transverse plane (rotation), there were significant differences in ankle internal rotation (f= 7.043, p= 0.001) and hip external rotation (f= 11.070, p< 0.001). As the barbell load increased, posture and performance were maintained, but rotational moments of the joints differed. It is expected that the joint directions that showed significant differences in this study are likely to be vulnerable to the risk of injury when an excessive load is applied to the body. Examples include the hip adduction moment, hip external rotation moment, and ankle internal rotation moment, and apply regardless of the increase in the rotational moments of joints from load increases.

External Focus Reduces Accuracy and Increases Antagonist Muscle Activation in Novice Adolescent Soccer Players.

Instep kick is one of the most effective kicking techniques in soccer. Lower extremity muscles and joints play a crucial role during instep kick. However, external (EF) and internal focus and their effect on the muscles are still ambiguous. In this study, 13 male adolescent soccer players were included and aimed to hit the targets in internal and EF conditions. Lower extremity muscle activations were measured with surface electromyography, and kinematics were measured with a high-speed video camera. Muscle activations and movement latencies were analyzed in four different phases (backswing, leg cocking, acceleration, and follow-through) of kicking. While 10 out of 13 participants kicked accurately in internal focus, only five out of 13 in EF kicked accurately. Gastrocnemius muscle activations increased significantly in EF in all phases except acceleration. Movement latencies were found 0.07 ± 0.002s for accurate and 0.05 ± 0.004s for inaccurate kicks in EF. A correlation has been found between accuracy and movement latency in EF (R = .67). Our results suggest that novices cannot yet coordinate their muscles in EF, cocontraction ratio increases. Therefore, training strategies that aim to reduce the cocontraction ratio can help the athlete increase performance through better motor coordination. Moreover, better motor coordination may be beneficial in preventing injuries (joint stiffness, etc.) caused by increased cocontraction ratio.

Comparison of Dynamic Postural Control in Youth Athletes with and without a History of Lateral Ankle Sprain : A Case-control Study

PURPOSE The purpose of this study was to compare the dynamic postural control of youth athletes with and without a history of lateral ankle sprains. METHODS Twenty-eight youth athletes (14 lateral ankle sprain, 14 healthy control) participated in this study. All participants answered the Foot and Ankle Ability Measure questionnaire and were subject to the Star Excursion Balance Test (SEBT) for dynamic postural control evaluation to collect the joint angles of the lower extremity, a center of pressure (COP) path, and COP velocity. Independent sample t-test or Mann-Whitney U-test were performed to analyze the difference between the groups. RESULTS The lateral ankle sprain group (LAS) was found to have a long experience in participating in sports, and low Foot and Ankle Ability Measure scores were identified when compared to the healthy control (CON; p&lt;0.05). LAS was observed with a short reach distance, less hip flexion, and dorsiflexion angles during the anterior direction of SEBT when compared to CON (p&lt;0.05). Furthermore, LAS showed a slower anteroposterior and mediolateral center of pressure velocities in the posteromedial aspect of SEBT and a slower anteroposterior COP velocity in the posterolateral aspect of SEBT when compared to that of CON (p&lt;0.05). There were no differences between the groups with respect to the other variables (p&gt;0.05). CONCLUSIONS Based on these results, decreased anterior reach distance of SEBT may be affected by changing the dynamic posture control strategy of the lower extremity joint on the sagittal plane in LAS.

Dynamics of lumbopelvic pain parameters in women with endoprosthetic hip joints who underwent caesarean section, under the influence of a physical therapy program

The purpose of the study was to evaluate the effectiveness of the developed physical therapy program based on the dynamics of indicators characterizing the limitation of life activities due to lumbopelvic pain in women with an endoprosthetic hip joint who underwent cesarean section. 9 women aged (28,5±1,6) years were examined 1 month after childbirth, which took place by caesarean section. The developed program of physical therapy lasted 1 month. Therapeutic exercises were applied; functional training, proprioceptive neuromuscular facilitation; massage of lower limbs, back. Movement limitations associated with an incompletely formed scar after cesarean section and the presence of an endoprosthesis were taken into account; safe strategies of movements related to child care were created. Determined The degree of restriction of vital activity according to the Oswestry Disability Index, Pelvic Girdle Questionnaire, Pregnancy Mobility Index was determined. During the initial examination, women were found to have a deterioration in their daily life activities and activities according to all the investigated indicators. During the re-examination, the improvement of vital activity in women according to the Oswestry Disability Index was 54.8 % compared to the initial result, according to the Pelvic Girdle Questionnaire – 58.6 % (р&lt;0.05). The dynamics of the Pregnancy Mobility Index results showed a statistically significant improvement in the condition of the examined women relative to the initial result in the subscales of daily home mobility (by 54.1 %), household activity (by 60.9%), and non-household activity (by 54.6 %). Based on the results of the study, it was concluded that physical therapy should be prescribed in the complex recovery of women with an endoprosthetic hip joint who underwent cesarean section to reduce the limitation of the degree of vital activity due to lumbopelvic pain. Keywords: rehabilitation, postpartum period, abdominal delivery, lower extremity joint endoprosthesis.

Changes in lower extremity joint moments one-year following osseointegration in individuals with Transfemoral lower-limb amputation: A case series

BackgroundDissatisfaction with socket prostheses has led to the development of bone-anchored prostheses through osseointegration for people with transfemoral amputation, eliminating the need for a prosthetic socket. Gait deviations of transfemoral prosthesis users may be linked to increased risk of osteoarthritis, and it remains unknown if gait biomechanics change following osseointegration. The purpose of this case series was to evaluate the longitudinal changes in joint kinetics one year post-osseointegration in patients with transfemoral amputation during walking. MethodsKnee, hip, and trunk internal moments were evaluated in the prosthetic and intact limbs during walking at a self-selected speed in four participants pre- and one-year post-osseointegration. Longitudinal changes were quantified using the percent change (%∆) in peak joint moments between the two time points and Cohen's d (d) effect size was used to determine the magnitude of effect on joint moments during walking one year following osseointegration. FindingsParticipants demonstrated increased peak knee extension moment (224 ± 308%∆, d = −1.31) in the prosthetic limb, while demonstrating reduced peak knee extension moment (−43 ± 34%∆, d = 1.82) in the intact limb post-osseointegration. Participants demonstrated bilateral reduction of peak hip extension moment (prosthetic: −22 ± 37%∆, d = 0.86; intact: −29 ± 10%∆, d = 1.27) and bilateral increase of peak hip abduction moment (prosthetic: 45 ± 40%∆, d = 1.20; intact: 23 ± 44%∆, d = 0.74) post-osseointegration. Participants demonstrated reduced peak trunk moments on both the prosthetic (extension: −31 ± 16%∆, d = 1.51; lateral flexion: −21 ± 20%∆, d = 0.63) and intact side (extension: −7 ± 22%∆, d = 0.38; lateral flexion: −22 ± 18%∆, d = 1.12) post-osseointegration. InterpretationThis case series suggests improved gait symmetry in individuals with transfemoral amputation one year following osseointegration, justifying future investigation.

Newly compiled Tai Chi (Bafa Wubu) promotes lower extremity exercise: a preliminary cross sectional study.

Tai Chi (Bafa Wubu) is a new type of simplified Tai Chi widely practiced by Tai Chi enthusiasts that has developed and perfected simplified Tai Chi movement and enriched Tai Chi practice methods. When practicing, Tai Chi athletes and enthusiasts can choose the Bafa Wubu movements to practice according to their physical conditions. The purpose of this article is to discuss the mechanism by which Bafa Wubu promotes lower extremity exercise from the perspective of exercise biomechanics. This article aims to explore the scientific training methods and technical characteristics of Bafa Wubu, and its contribution to comprehensive exercise of the lower extremities, by analyzing the biomechanical characteristics of the lower extremities of participants who practice Bafa Wubu at different levels and by comparing their ground reaction force, lower limb joints, and muscles during Bafa Wubu. A total of 16 male participants were recruited and divided into an amateur group (N = 8) and a professional group (N = 8). The data were collected by a BTS 3D infrared-based motion capture system, and Kistler 3D force plate. The lower extremity joint forces and muscle strength were calculated by anybody simulation software with inverse dynamics. During elbowing and leaning sideways with steps sideways (ELS), the ground reaction force of the professional group was significantly higher than that of the amateur group in the sagittal, vertical, and frontal axes (P < 0.01). While stepping forward, backward, and sideways, the professional group's joints loading at the hip, knee, and ankle was always higher in the vertical direction (P < 0.01). Furthermore, during warding off with steps forward (WOF), laying with steps forward (LF), and rolling back with steps backward (RBB), hip joint loading increased in the med-lat direction. During actions with steps backward and sideways, the professional group's ankle flexion/extension torque and hip abduction/rotation torque were significantly larger than those of the amateur group (P < 0.01). Different actions in Bafa Wubu activate muscles to different degrees, whereas the iliacus is mainly responsible for stabilizing postures when practitioners perform standing knee lifting motions. Professional groups who have been practicing Tai Chi (Bafa Wubu) for a long time have higher ground reaction force, and the force on the three joints of the lower extremities is different for various movements, which has positive significance for exercising the joints of the lower extremities. In addition, various motions activate muscles of different types at different levels. For amateurs to practice different movements to stimulate the muscles, targeted areas of practice promote the lower extremity muscles' synergistic force. In summary, the muscles and joints of the lower extremity can obtain comprehensive and balanced exercise through Bafa Wubu.