Knee Joint Motion Research Articles

Mechatronic Design and Control of a Rigid-Soft Hybrid Knee Exoskeleton for Gait Intervention

Knee exoskeletons have gained increasing attention for gait training and intervention. The effectiveness of conventional rigid exoskeletons is degraded by bulkiness, high inertia, and joint misalignment. The soft configurations relax the constraints on the knee joint, thus circumvent the misalignment issue, and reduce the system size and weight. However, the soft exoskeletons sacrifice the load sharing capability from rigid support, and also the mechanical stop for constraining joint working range to avoid unsafe knee hyperextension. This article presents a novel rigid-soft hybrid exoskeleton to provide bidirectional interventions safely for knee joint motion. The design is lightweight (1.2 kg to wear), avoids the rigid rotation center that induces knee joint misalignment, has minimal impact on normal walking kinematics, and is able to provide support to the human body. A gait intervention strategy is designed under the hybrid model of human and exoskeleton. Comprehensive experiments are conducted to demonstrate the capability of the presented exoskeleton on gait intervention.

Functional electrical stimulation for foot drop syndrome in patients with cerebral stroke

BACKGROUND: The deterioration of walking function as a result of acute cerebrovascular accident manifested by the foot drop syndrome, leading to difficulties in maintaining balance in the standing position and increased substitution strategies, is the most important limiting factor that affects autonomy and independence. The results of short time training with functional electrical stimulation in patients with cerebral stroke in the early and late recovery periods remain unknown.
 AIM: to study the functional and clinical results of a short course of functional electrical stimulation in patients with cerebral stroke and foot drop syndrome.
 MATERIALS AND METHODS: The study involved 20 patients with early and late hemispheric acute cerebrovascular accident who received a course of single-channel 30-minute functional electrical stimulation training of the m. tibialis anterior in conjunction with the main program of motor rehabilitation (60 minutes), consisting of 12 sessions. The biomechanics of walking at a random pace before and after training was investigated. Spatial and temporal parameters of walking, movements in hip, knee and ankle joints and maximum amplitudes of electromyography of the main muscle groups responsible for walking were recorded. Classical clinical scales were also used.
 RESULTS: No negative reaction to training with functional electrical stimulation was obtained. After treatment, there was a significant improvement in the following scales was observed: "Dynamic Gait Index", "Hauser Ambulation Index", "Timed Up and Go Test" test, muscle strength assessment, "Activity and Participation" domains. Spatial and temporal parameters demonstrate a complex syndrome characteristic of post-stroke walking. Walking speed and step cycle length increased significantly after training. The kinematics of movements in the hip and knee joints do not reveal significant dynamics. The difference from the control group of contralateral side indices in knee and hip joints, indicating bilateral functional involvement in the pathologic process, draws attention. Goniograms of the ankle joints of the paretic limb revealed the following parameters characteristic of the sagging foot: increase in the circumduction parameter on the paresis side, total amplitude of hip joint movements, knee joint flexion in the transfer period (Ka3), and ankle joint flexion amplitude in the transfer period (A3). Following functional electrical stimulation training, no changes were observed in these parameters.
 CONCLUSION: All clinical parameters have improved. Objective diagnostic results of the functional electrical stimulation training showed no significant effect on ankle joint function. Taking into account the limitations of this study, a follow-up study is planned.

Real-time tactile biofeedback device use for improving balance control of an adolescent with medulloblastoma

PurposeBiofeedback is used for regulating vestibular adaptation and balance by providing real-time stimulus to the individual during physical activities. This study aimed at (1) developing a wearable device, which tracks balance, counts the number and the direction of balance losses and provides haptic biofeedback through real-time vibration stimulus (2) investigating device efficacy on an adolescent medulloblastoma patient during static and dynamic tasks.Design/methodology/approachA 16-year-old medulloblastoma patient used the device during 10-m walking and single-leg stance tests. The knee joint kinematics and the number and direction of balance losses were recorded for “with” and “without” biofeedback conditions.FindingsThe device helped regulate the knee joint kinematics and reduce the number of balance losses of the medulloblastoma patient. The knee joint movement pattern similarity of the control subject was highly correlated (R2 = 0.997, RMSE = 1.232). Conversely, medulloblastoma patient knee joint movement pattern similarity was relatively weak (R2 = 0.359, RMSE = 18.6) when “with” and “without” biofeedback conditions were compared. The number of balance losses decreased when the medulloblastoma patient was guided with biofeedback.Research limitations/implicationsThe major limitation of this pilot study is the lack of a large and homogeneous number of participants. The medulloblastoma patient used the device while walking after she was given enough time to get used to the tactile biological feedback, so the long-term effect of the device and biofeedback guidance were not investigated. Additionally, the potential desensitization with prolonged use of the device was not evaluated.Practical implicationsBiofeedback reduced the number of balance losses; additionally, the knee joint movement pattern was regulated during static and dynamic tasks. This device can be integrated into the physical therapy of patients with balance, vestibular and postural control impairments.Social implicationsThis is compact and has an easy-to-wear design, patients, who have balance and postural control impairments, can practically use the device during their activities of daily living.Originality/valueThe device promotes physical activity adaptation and regulates gait through continuous and real-time balance control. Its design makes it simple for the user to wear it beneath clothing while using the sensor.

Friction and wear mechanism of artificial joint composite material PEEK/ZnO under different decomposition motion modes of knee joint

According to the standard of knee joint movement and actual working conditions, the complex movement of knee joint can be decomposed into three movement modes: sliding, swinging and twisting. The friction and wear mechanism of PEEK and PEEK/ZnO composites in sliding, swinging and twisting modes was studied on knee joint simulator. The result shows that the friction coefficient and wear of the PEEK/ZnO composite are lower than those of PEEK, and the addition of ZnO can effectively improve the wear resistance of the PEEK composite. The relevant data has deepened people's understanding of the tribological behavior and wear mechanism of artificial knee joints.

Improving Range of Motion through Leg Extension Exercise and Static Bike Exercise for Osteoarthritis Genu

Aging is identical with decreased functional abilities, such as prolonged standing, walking, squatting, running, or other activities. These decreases in functional ability can be caused by a degenerative disease, namely osteoarthritis (OA) genu resulting in a limited motion in the knee joint caused by a decrease in range of motion. Treatments for OA Genu cases include leg extension exercise and static bike exercise to maintain and to increase the range of motion (ROM) of knee joints. This study was a Quasi Experimental study. The study lasted for five weeks from May-June. The sample of this study were 24 people. The results of the study found that the ability to movement extension and knee flexion in both groups increased. Both groups obtained p value = 0.625 for extension and p value = 0.062 for flexion. The p value of extension and flexion is p0.05. Results showed that, after the intervention in both groups, the osteoarthritis patients at Siloam Hospitals Bali had improved flexion ROM and knee extension. Based on the difference value before and after treatment, the percentage increase in range of motion extension and flexion in the static bike group was slightly higher than the leg extension exercise group. It concludes that leg extension exercise and static bike exercise are equally good in increasing ROM of osteoarthritis patients. Leg extension exercises and static bike exercise can be used as alternative exercises to improve the ability to bend and to straighten knee joints experiencing limitations or stiffness.

A new passive transfemoral prosthesis mechanism based on 3R36 knee and ESAR foot providing walking and squatting

Researchers have proposed various linkage mechanisms to connect knee and ankle joints for above-knee prostheses, but most of them only offer natural walking. However, studies have shown that people assume a squatting posture during daily activities. This paper introduces a novel mechanism that connects the knee joint with the foot-ankle joint to enable both squatting and walking. The prosthetic knee used is the well-known 3R36, while the energy storing and return (ESAR) prosthetic foot is used for the ankle-foot joint. To coordinate knee and ankle joint movements, a six-bar linkage mechanism structure is proposed. Simulation results demonstrate that the proposed modular transfemoral prosthesis accurately mimics the motion patterns of a natural human leg during walking and squatting. For instance, the prosthesis allows a total knee flexion of more than 140° during squatting. The new prosthesis design also incorporates energy-storing mechanisms to reduce energy expenditure during walking for amputees.

Continuous Motion Estimation of Knee Joint Based on a Parameter Self-Updating Mechanism Model.

Estimation of continuous motion of human joints using surface electromyography (sEMG) signals has a critical part to play in intelligent rehabilitation. Traditional methods always use sEMG signals as inputs to build regression or biomechanical models to estimate continuous joint motion variables. However, it is challenging to accurately estimate continuous joint motion in new subjects due to the non-stationarity and individual differences in sEMG signals, which greatly limits the generalisability of the method. In this paper, a continuous motion estimation model for the human knee joint with a parameter self-updating mechanism based on the fusion of particle swarm optimization (PSO) and deep belief network (DBN) is proposed. According to the original sEMG signals of different subjects, the method adaptively optimized the parameters of the DBN model and completed the optimal reconstruction of signal feature structure in high-dimensional space to achieve the optimal estimation of continuous joint motion. Extensive experiments were conducted on knee joint motions. The results suggested that the average root mean square errors (RMSEs) of the proposed method were 9.42° and 7.36°, respectively, which was better than the results obtained by common neural networks. This finding lays a foundation for the human-robot interaction (HRI) of the exoskeleton robots based on the sEMG signals.

Hemilateral bone longitudinal transport technique for the treatment of hemilateral defects of long bones of lower limbs

To explore clinical efficacy of Ilizarov hemilateral bone longitudinal transport technique in treating hemilateral bone defects associated with chronic osteomyelitis of lower extremity long bones. Clinical data of 13 patients with hemilateral bone defects caused by chronic osteomyelitis of lower extremity long bones and treated by Ilizarov hemilateral bone longitudinal transport technique were retrospective analyzed, including 10 males and 3 female, aged from 14 to 55 years old;4 patients occurred femoral and 9 patients occurred tibial;10 patients were diagnosed as traumatic osteomyelitis and 3 patients as hematogenous osteomyelitis. The anatomical classification of Cierny-Mader in 13 patients was type Ⅲ. Bone and wound healing, postopertaive complication, and bony and functional results were observed by Paley evaluation standard. After removing external fixator, all patients were followed up from 6 to 70 months. Transporting time ranged from 54 to 158 d. And the time in external fixation ranged from 6.8 to 19.5 months. External fixation index (EFI) ranged from 1.23 to 1.6 months/cm. According to Paley's evaluation criteria, bony results were excellent in 13 patients;functional results showed excellent in 12 patients and good in 1 patient. Two patients occurred poor union on the docking sites and healed with autogenous iliac bone graft. The callus at the extended area was poorly mineralized and improved significantly when treated with low-intensity pulsed ultrasound in one patient. All patients had good wound healing without recurrence of osteomyelitis and refracture. There was no vascular and nerve injury and axial deviation in all patients and they were satisfied with the appearance and function of lower limbs. The range of motion of knee and ankle joint before operation was 120 ° to 150 ° and 35 °to 80 ° respectively, and at the latest follow-up was 110 ° to 140 ° and 30 ° to 75 ° . Ilizarov hemilateral bone longitudinal transport technique is effective in treating infective hemilateral bone defects of lower extremity long bones, which could not only simplify architecture of external fixation, but also reduce the number of fixation pins, shorten the time in external fixator and decrease the incidence of pin tract infection. However, this technique is highly demanding, and the growth of callus in extended region and healing of bone apposition should be noticed.

Using Dual-Orthogonal Fluoroscopy and CT to Assess the Relationship Between Knee Morphology and Patellar Kinematics in Patients With Patellofemoral Pain.

Patellofemoral pain (PFP) is one of the most common knee overuse injuries, with studies suggesting PFP as a precursor for early knee osteoarthritis. The etiology of PFP is multi-factorial; however, patellar mal-tracking has been regarded as a primary mechanism. Details of this multi-factorial mechanism have been unclear because of the limitations in evaluating in-vivo, three-dimensional (3D) patellofemoral joint movement during dynamic activities accurately. Alternatively, studies have demonstrated the high accuracy and repeatability of dual fluoroscopy and CT/MRI for measuring knee joint motion. This study uses dual fluoroscopy and CT to investigate the associations between joint morphology and patellar kinematics in healthy controls and subjects with PFP. Eight PFP females (29.7±10.6 years) and 10 healthy females (25.0±7.7 years) were recruited and screened by a sports medicine physician. CT imaging was performed on participants in a supine with the knee extended, and ankle and hip in neutral alignment. Dual-orthogonal fluoroscopy measured patellar movement while participants performed a lunge task. A calibration algorithm was used to register the 3D CT model to 2D fluoroscopy image to calculate the relative position and angles of the patella based on the clinical definition of patellar motion. Measures of patellar and trochlear morphology were generated and correlated to kinematic data. There was a significant difference in the patellar-to-trochlear width ratio; however, no other significant differences in CT morphology measurements were present between groups. For PFP patients in the weight-bearing extended position, there was a moderate positive correlation between the patellar-to-trochlear width ratio and medial-lateral patellar shift (τ = 0.643, p = 0.026). Healthy controls in this position demonstrated a moderate positive correlation between the lateral-trochlear inclination angle and medial-lateral patellar shift (τ = 0.600, p = 0.016) and moderate negative correlation between medial trochlear inclination angle and medial-lateral patellar shift (τ = -0.511, p = 0.040).The findings suggest that, for this cohort, there is correlation between morphology and patellar kinematics. Passive and active stabilizers likely have a role in mal-tracking.

A Fully Self-Powered Wearable Leg Movement Sensing System for Human Health Monitoring.

Energy-autonomous wearable human activity monitoring is imperative for daily healthcare, benefiting from long-term sustainable uses. Herein, a fully self-powered wearable system, enabling real-time monitoring and assessments of human multimodal health parameters including knee joint movement, metabolic energy, locomotion speed, and skin temperature, which are fully self-powered by highly-efficient flexible thermoelectric generators (f-TEGs) is proposed and developed. The wearable system is composed of f-TEGs, fabric strain sensors, ultra-low-power edge computing, and Bluetooth. The f-TEGs worn on the leg not only harvest energy from body heat and supply power sustainably for the whole monitoring system, but also serve as zero-power motion sensors to detect limb movement and skin temperature. The fabric strain sensor made by printing PEDOT: PSS on pre-stretched nylon fiber-wrapped rubber band enables high-fidelity and ultralow-power measurements on highly-dynamic knee movements. Edge computing is elaborately designed to estimate multimodal health parameters including time-varying metabolic energy in real-time, which are wirelessly transmitted via Bluetooth. The whole monitoring system is operated automatically and intelligently, works sustainably in both static and dynamic states, and is fully self-powered by the f-TEGs.

A transparent, self-adhesive and fully recyclable conductive PVA based hydrogel for wearable strain sensor

Hydrogel-based wearable sensors have attracted tremendous attention in the sensing electronics field due to their unique properties. However, integrating hydrogel sensors with transparency, biosafety, self-adhesiveness, recyclability and conductivity remains a great challenge. Here, we report an ionic conductive hydrogel prepared using poly (vinyl alcohol) (PVA) grafted with the 2,3-epoxypropyltrimethylammonium chloride (TMAC) through a facile freezing-thawing (F-T) process. The obtained PVA grafted with TMAC hydrogel (PVATH) exhibited relatively high transparency (∼87% transmittance) and strong self-adhesion to different substrates with high stretchability (544%) and good conductivity (0.038 S m−1). Most notably, the hydrogel can be fully recycled by a simple and green process on account of a fully physical cross-linking network. Even after three recycling cycles, the hydrogel sensor exhibited almost identical electromechanical performance with respect to the original sensor. The hydrogel was further assembled as a strain sensor for monitoring real-time human motions, including finger, wrist, elbow, knee joint and neck movement. This work provides an innovative design strategy to fabricate ionic conductive hydrogels and reduce electronic waste, which will broaden the applications of hydrogels in wearable devices.

Dual-Task Interference Slows Down Proprioception.

It is well-known that multitasking impairs the performance of one or both of the concomitant ongoing tasks. Previous studies have mainly focused on how a secondary task can compromise visual or auditory information processing. However, despite dual tasking being critical to motor performance, the effects of dual-task performance on proprioceptive information processing have not been studied yet. The purpose of the present study was, therefore, to investigate whether sensorimotor task performance would be affected by the dual task and if so, in which phase of the sensorimotor task performance would this negative effect occur. The kinematic variables of passive and active knee movements elicited by the leg drop test were analyzed. Thirteen young adults participated in the study. The dual task consisted of performing serial subtractions. The results showed that the dual task increased both the reaction time to counteract passive knee-joint movements in the leg drop test and the threshold to detect those movements. The dual task did not affect the speed and time during the active knee movement and the absolute angle error between the final and the target knee angles. Furthermore, the results showed that the time to complete the sensorimotor task was prolonged in dual tasking. Our findings suggest that dual tasking reduces motor performance due to slowing down proprioceptive information processing without affecting movement execution.

PENATALAKSANAAN FISIOTERAPI PADA KASUS OSTEOARTHRITIS GENUSINISTRA DENGAN MODALITASTRANSCUTANEUS ELECTRICAL NERVE STIMULATION, ULTRASOUND, DAN TERAPI LATIHAN DI RSUD KOTA BANDUNG

Background: Osteoarthritis is a chronic joint disease characterized by abnormalities in cartilage (cartilage), where abnormalities in the cartilage cause the bones to rub against each other resulting in stiffness, pain, limited movement, and disruption of daily activities.
 Objective: To determine the implementation of Physiotherapy in reducing pain, increasing muscle strength, increasing the scope of joint motion, and increasing functional abilities in cases of Osteoarthritihis Genu Sinistra by using tens modalities, ultrasound and exercise therapy. 
 Results: After 6 times of therapy, the results of pain assessment in the left knee from silent pain T1 = 7 to T6 = 4 motion pain T1 = 8 to T6 = 4 tenderness T1 = 4 to T6 = 2. Increased muscle strength of knee extensors T1 = 3 to T6 = 4 and knee flexors T1 = 3 to T6 = 4. As well as an increase in the scope of motion of the passive left knee joint, namely T1 = S 00-00-1200 to T6 = S 00-00-1300 and the scope of motion of the active left knee joint, namely T1 = S 00-00-1000 to T6 = S 00-00-1200.
 Conclusion: Ultrasound can help reduce pain, Tens can relax the muscles, and Exercise therapy can increase muscle strength, increase the joint motion, and can improve functional abilities.
 Keywords: Physiotherapy, Osteoarthritis Genu, Tens, Ultrasound, Exercise therapy.

Stair-Climbing Training System Using Visual VR Display for Total Knee Arthroplasty Patients

Total knee arthroplasty (TKA) is the primary treatment for knee osteoarthritis. However, TKA is highly likely to result in prolonged chronic postoperative pain. The one-foot-one-step walking style is likely to induce fear of movement because of pain, leading to catastrophic thinking about the actual activity and consequently limiting movement. The aim of this study is to develop a system to induce the sensation of stair climbing through the interaction of the visual and kinesthetic senses. By controlling the amount of movement of the foot and the point of view in virtual space, the system can present a visual image of stair climbing even when the patient steps in a fixed position. This system enables easy motor imagery intervention even for early postoperative patients who have difficulty with the actual stair climbing movement. The clinical intervention experiment confirmed that the smoothness of the knee joint motion during descent was improved by intervening with motor imagery during stair ascent and descent for TKA patients.

A chaotic bio-mechanics model of dairy cow leg

The real knee joint is very complex. When the knee joint performs the leg bending action, the relative motion between the lower surface of the femur and the upper surface of the tibia includes rolling and sliding. Therefore, a simple hinge pair model cannot correctly represents the real knee joint motion. In this work, we build a structure model of cow leg with both sliding and hinge pairs firstly; Then, according to the second kind of Lagrange equation of the structural model with the potential force and dissipative force, the system dynamics model is established. Third, the environmental noise, such as the elasticity of the ground which exerted on the cow’s feet directly, is taken into the nonlinear model, so, a more practical dynamic model of cow leg is constructed. Numerical simulation shows that the model has strong chaotic motion characteristics,and the model with noises is better than one without noises. For the chaotic model, small parameter changes will lead to large changes in the phase orbit diagram, which built a foundation for us to study and identify the pathology of dairy cows based on the dynamic weight time series signals during the process of dairy cows’ progress.

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

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

Comparison of accuracy for hip-knee-ankle (HKA) angle by X-ray and knee motion analysis system and the relationships between HKA and gait posture

BackgroundThe lower limb mechanical axis was used to assess the severity of knee osteoarthritis (KOA) with varus/valgus deformity and the accuracy of targeted lower limb alignment correction after operation by conventional X-rays. There are lots of parameters to assess the gait in elder patients such as velocity, stride length, step width and swing/stance ratio by knee joint movement analysis system. However, the correlation between the lower limb mechanical axis and gait parameters is not clear. This study is aimed at obtaining the accuracy of the lower limb mechanical axis by the knee joint movement analysis system and the correlation between the lower limb mechanical axis and gait parameters.MethodsWe analysed 3D knee kinematics during ground gait of 99 patients with KOA and 80 patients 6 months after the operations with the vivo infrared navigation 3D portable knee joint movement analysis system (Opti-Knee®, Innomotion Inc, Shanghai, China). The HKA (Hip-Knee-Ankle) value was calculated and compared to X-ray findings.ResultsHKA absolute variation after the operation was 0.83 ± 3.76°, which is lower than that before the operation (5.41 ± 6.20°, p = 0.001) and also lower than the entire cohort (3.36 ± 5.72). Throughout the cohort, a significant correlation with low coefficients (r = -0.19, p = 0.01) between HKA value and anterior-posterior displacement was found. In comparing the HKA values measured on the full-length alignment radiographs and 3D knee joint movement analysis system (Opti-Knee), there was a significant correlation with moderate to high coefficients (r = 0.784 to 0.976). The linear correlation analysis showed that there was a significant correlation between the values of HKA measured by X-ray and movement analysis system (R2 = 0.90, p < 0.01).ConclusionsData with equivalent results as HKA, the 6DOF of the knee and ground gait data could be provided by infrared navigation based 3D portable knee joint movement analysis system comparing with the conventional X-rays. There is no significant effect of HKA on the kinematics of the partial knee joint.

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.

Control system and kinematic analysis of lower limb prosthetic knee joint

AbstractIn order to study the motion characteristics of the prosthesis, a three‐dimensional model of the test platform was established, and the corresponding control scheme was designed according to this model. For the lower limb prosthesis test platform, a fuzzy proportion‐integration‐differentiation (PID) control model was created. Second, the matlab modules were used to construct the virtual model, and the goal function‘s control research was conducted. Finally, a virtual model was created, and the outcomes were studied, in order to assess the differences between the control results of proportional‐integral‐differential controller and fuzzy proportional‐integral‐differential controller. The results verify that the test platform using fuzzy proportional‐integral‐differential controller is capable of greater stability. The lower limb prosthetic knee joint test platform was built, and the corresponding experimental research was carried out on the motion of the lower limb prosthetic knee joint. The experimental data showed that the angle error of the hip joint was within 2° when the normal human gait was walking on the ground. The error of the joint angle does not exceed 3°. The prosthesis can clearly better mimic the angles of the hip and knee joints.

Reinforced technique of tension band wiring for tibial tuberosity fracture in adolescents: a case report for surgical technique.

We demonstrated the reinforced technique of tension band wiring and its surgical outcomes in the tibial tuberosity fracture of a 14-year-old male basketball player. For the modified technique, the wire was inserted between the patellar tendon and tibial tuberosity (insertion site of patellar tendon) and passed distally through the 2-mm-sized predrill cortical hole. Tightening the figure of the eight loops draws the fractured fragments together and anatomically reduces under appropriate compression. This technique can achieve the reduction and fixation of the fracture simultaneously. We confirmed the fixation stability with a range of knee joint motions. The patient was able to return back to the pre-injury level of sports activity at postoperative 2 months. The original technique of tension band wiring utilized the Kirschner wire to make a figure-of-eight loop. However, we used the patellar tendon and its insertion site of the tibial tuberosity for making a figure-of-eight loop. Moreover, the reduction and fixation of fracture were achieved simultaneously by tightening the tension band wire. This reinforced technique was firm enough for postoperative rehabilitation. The most certain advantage of this technique was to be able to reduce anatomically and fixate firmly with appropriate compression simultaneously. We recommend open reduction internal fixation with the reinforced technique of tension band wiring for displaced tibial tuberosity fracture in adolescent athletes.