Knee Joint Forces Research Articles

An expository analysis of biomechanical and subjective impacts induced by shoe inserts in asymptomatic subjects: A systematic review on functionality and mechanisms of action

AbstractThis systematic review explores the biomechanical and subjective effects of shoe inserts, including foot orthotics (FOs) and insoles, in asymptomatic subjects. Aimed at understanding their implications, the review poses two key research questions: (i) the influence of shoe inserts on lower extremity biomechanics and subjective perception and (ii) the effects of different design characteristics on these aspects. Following Preferred Reporting of Systematic Reviews and Meta‐Analysis guidelines, a meticulous search of Scopus and PubMed from August 2022 to March 2023 yielded 34 articles, with 26 focusing on biomechanical effects and eight on comfort effects. The studies, conducted during static and dynamic activities, such as standing, walking, jogging, running, jumping, and cycling, reveal significant reductions in rearfoot eversion, knee joint forces, and lower extremity muscle forces through postings and wedging in FOs. Changes in stiffness impact rearfoot kinematics, plantar pressure distribution, and ankle–foot power distribution. Conversely, surface texture and arch variations demonstrate limited significance. FOs and shoe inserts, characterized by geometric, material, location, size, and fabrication features, effectively regulate forces and moments on the lower extremity. This control promotes uniform plantar pressure distribution and enhances comfort during various activities. These insights benefit manufacturers, clinicians, and stakeholders, providing a deeper understanding of the positive benefits of FOs and shoe inserts. However, further well‐designed studies on clinical populations are necessary to validate these findings and establish their clinical efficacy, as the current focus remains on healthy subjects.

Myobolica: a stochastic approach to estimate physiological muscle control variability.

The inherent redundancy of the musculoskeletal systems is traditionally solved by optimizing a cost function. This approach may not be correct to model non-adult or pathological populations likely to adopt a "non-optimal" motor control strategy. Over the years, various methods have been developed to address this limitation, such as the stochastic approach. A well-known implementation of this approach, Metabolica, samples a wide number of plausible solutions instead of searching for a single one, leveraging Bayesian statistics and Markov Chain Monte Carlo algorithm, yet allowing muscles to abruptly change their activation levels. To overcome this and other limitations, we developed a new implementation of the stochastic approach (Myobolica), adding constraints and parameters to ensure the identification of physiological solutions. The aim of this study was to evaluate Myobolica, and quantify the differences in terms of width of the solution band (muscle control variability) compared to Metabolica. To this end, both muscle forces and knee joint force solutions bands estimated by the two approaches were compared to one another, and against (i) the solution identified by static optimization and (ii) experimentally measured knee joint forces. The use of Myobolica led to a marked narrowing of the solution band compared to Metabolica. Furthermore, the Myobolica solutions well correlated with the experimental data (R2 = 0.92, RMSE = 0.3 BW), but not as much with the optimal solution (R2 = 0.82, RMSE = 0.63 BW). Additional analyses are required to confirm the findings and further improve this implementation.

The effect of impaired unilateral ankle propulsion on contralateral knee joint loading

BackgroundImpairments in unilateral ankle propulsion may result from restriction by an external device or pathology such as lower limb amputation. Models of gait suggest this reduction may lead to increased collisional force on the contralateral side, potentially increasing force through the knee and increasing the risk of knee pain or osteoarthritis. Research questionHow do restrictions in unilateral ankle propulsive force affect contralateral knee joint loading in otherwise healthy individuals? Methods18 individuals without impairment walked on a treadmill at 1.5 m/s for two conditions: one free of restrictions, and one where a randomized limb’s ankle propulsive force was restricted using an off-the-shelf ankle-foot orthosis (AFO). Ankle propulsive power, lower extremity joint work, and ground reaction force variables were calculated for the final 3 gait cycles of each condition. Tibiofemoral joint contact force (TJCF) for the limb contralateral to the AFO was calculated through a standard OpenSim workflow utilizing the gait2392 model. Intra-limb pair-wise comparisons were made between conditions. ResultsCompared to walking unrestricted, the limb wearing the AFO demonstrated a significant reduction in peak ankle propulsive power and positive ankle work by approximately 50 % each (p<0.01). With ankle restriction, the ipsilateral knee significantly increased positive work (p<0.01). The overall propulsion produced by that limb did not change between conditions, demonstrated by a lack of change in anterior ground reaction force impulse (p=0.11). The knee of the limb contralateral to the AFO did not display differences in any TJCF variable between conditions (all p>0.07). SignificanceThese results suggest a unilateral deficit in ankle propulsion will not increase contralateral knee joint forces in individuals who are able to use other joints of the limb to compensate for the loss of ankle function. However, further research should investigate this relationship in those who display pathologies that may prevent more proximal compensations.

Design Aspects of Lower Limb Exoskeleton

Aim: This research work aimed at the design, simulation, and validation of a lower limb exoskeleton for rehabilitation. The device can provide regressive gait training for patients suffering from lower limb mobility disorders. Background: People suffering from mobility disorders, such as spinal cord injuries, and other related diseases are in high proportion. Exoskeletons play a vital role in enhancing the lifestyle of people with disorders. Devices that provide locomotion assistance and help in reducing the burden of therapists through effective and repetitive gait training are in high demand. Exoskeletons have further extended to the fields of the military to enhance the performance of physically abled persons. Prototype development of lower limb exoskeletons is too expensive and many of them are patented. The requirement for this system to perform human trials is subjective to several medical and ethical norms. Thus, there exists a need to evaluate and validate the exoskeleton designs. Methods: In this work, the design has been made inclusive of different body shapes and sizes. The device has been modeled in SOLIDWORKS and its structural integrity has been analyzed using the ANSYS software. Later, the model has been subjected to environmental assessment and then motion analysis using the ADAMS software. Results: The structural integrity analysis has revealed the design to be adequate to carry the applied load as the stresses induced were less than the yield strength of the material. The sustainability analysis showed that LLE made of aluminium alloy had less impact on the environment relative to the other two materials. Conclusion: The kinematic simulation revealed that the angular amplitudes, the reaction force of the right hip and knee joint, and the contact force between the shoe and the ground of the exoskeleton agreed well with the experimental findings of the literature.

Predicting Knee Joint Contact Forces During Normal Walking Using Kinematic Inputs With a Long-Short Term Neural Network.

Knee joint contact forces are commonly estimated via surrogate measures (i.e., external knee adduction moments or musculoskeletal modeling). Despite its capabilities, modeling is not optimal for clinicians or persons with limited experience. The purpose of this study was to design a novel prediction method for knee joint contact forces that is simplistic in terms of required inputs. This study included marker trajectories and instrumented knee forces during normal walking from the "Grand Challenge" (n = 6) and "CAMS" (n = 2) datasets. Inverse kinematics were used to derive stance phase hip (sagittal, frontal, transverse), knee (sagittal, frontal), ankle (sagittal), and trunk (frontal) kinematics. A long-short term memory network (LSTM) was created using matlab to predict medial and lateral knee force waveforms using combinations of the kinematics. The Grand Challenge and CAMS datasets trained and tested the network, respectively. Musculoskeletal modeling forces were derived using static optimization and joint reaction tools in OpenSim. Waveform accuracy was determined as the proportion of variance and root-mean-square error between network predictions and in vivo data. The LSTM network was highly accurate for medial forces (R2 = 0.77, RMSE = 0.27 BW) and required only frontal hip and knee and sagittal hip and ankle kinematics. Modeled medial force predictions were excellent (R2 = 0.77, RMSE = 0.33 BW). Lateral force predictions were poor for both methods (LSTM R2 = 0.18, RMSE = 0.08 BW; modeling R2 = 0.21, RMSE = 0.54 BW). The designed LSTM network outperformed most reports of musculoskeletal modeling, including those reached in this study, revealing knee joint forces can accurately be predicted by using only kinematic input variables.

Design and evaluation of a wedge-shaped adaptive knee orthosis for the human lower limbs.

The incidence of knee osteoarthritis (KOA) is moderately correlated with age and body weight and increases with life span and weight gain, associated with tearing and wearing the knee joints. KOA can adjust the force through the human lower limbs, redistribute the load of the knee joint, reduce the pain, and restore mobility when the arthritis changes are mild. However, most of the existing knee orthosis cannot be adjusted adaptively according to the needs of patients. This study establishes a biomechanical model of the knee joint to analyze the medial and lateral forces acting on the joint. The new adjustable knee orthosis is designed. It applies the principle of four-point bending to apply pressure to both sides of the knee joint, thereby adjusting the varus angle and modifying the medial and lateral forces on the knee joint. Through structural optimization, the prototype of the knee orthosis weighs only 324g. Utilizing three-dimensional scanning technology, discrete point cloud data of the leg surface is obtained, reconstructed, and processed to create a 3D model of the human leg surface. The design ensures a close fit to the human leg surface, offering comfortable wear. A pressure sensing film system is employed to build a pressure sensing test system, where the knee orthosis is worn on a prosthesis for pressure testing to evaluate its ability to adjust knee joint forces. The pressure test results demonstrate that the knee orthosis can stably provide an adjustment angle of 0-7° and sustain a maximum force of 10N on both sides of the knee joint over extended periods. A self-developed 8-channel plantar pressure sensing insole is calibrated against commercial plantar pressure sensors. Human wear tests on 15 subjects show that during the operation of the knee orthosis, it significantly adjusts plantar pressures, reducing lateral foot pressures by 22% overall, with more pronounced corrective effects observed in lighter participants. In this study, a wedge-shaped adaptive knee orthosis was provided for KOA patients. The four-point force principle was used to balance the force between femurs and tibia and adjust the meniscus contact gap. The orthotic appliance has the advantages of simple mechanical structure, adjustable correction Angle and good wearing comfort.

Evaluation of an Unloading Concept for Knee Osteoarthritis: A Pilot Study in a Small Patient Group.

Joint compressive forces have been identified as a risk factor for osteoarthritis disease progression. Therefore, unloader braces are a common treatment with the aim of relieving pain, but their effects are not clearly documented in the literature. A knee brace concept was tested with the aim of reducing joint loads and pain in knee osteoarthritis patients by applying an extension moment exclusively during the stance phase. The ideal effects were evaluated during gait based on musculoskeletal modeling of six patients, and experimental tests with a prototype brace were conducted on one patient. The effects were evaluated using electromyography measurements and musculoskeletal models to evaluate the muscle activation and knee compressive forces, respectively. The ideal brace simulations revealed a varying reduction of the first peak knee force between 3.5% and 33.8% across six patients whereas the second peak was unaffected. The prototype reduced the peak vasti muscle activation with 7.9% and musculoskeletal models showed a reduction of the first peak knee compressive force of up to 26.3%. However, the prototype brace increased the knee joint force impulse of up to 17.1% and no immediate pain reduction was observed. The reduction of the first peak knee compressive force, using a prototype on a single patient, indicates a promising effect from an applied knee extension moment for reducing knee joint loads during normal gait. However, further clinical experiments with this brace method are required to evaluate the long-term effects on both pain and disease progression in knee osteoarthritis patients.

Estimation of the knee joint load using plantar pressure data measured by smart socks: A feasibility study.

Unsupervised sports activities could cause traumas, about 70% of them are those of the low extremities. To avoid traumas, the athlete should be aware of dangerous forces acting within low extremity joints. Research in gait analysis indicated that plantar pressure alteration rate correlates with the gait pace. Thus, the changes in plantar pressure should correlate with the accelerations of extremities, and with the forces, acting in the joints. Smart socks provide a budget solution for the measurement of plantar pressure. To estimate the correlation between the plantar pressure, measured using smart socks, and forces, acting in the joints of the lower extremities. The research is case study based. The volunteer performed a set of squats. The arbitrary plantar pressure-related data were obtained using originally developed smart socks with embedded knitted pressure sensors. Simultaneously, the lower extremity motion data were recorded using two inertial measurement units, attached to the tight and the ankle, from which the forces acted in the knee joint were estimated. The simplest possible model of knee joint mechanics was used to estimate force. The estimates of the plantar pressure and knee joint forces demonstrate a strong correlation (r= 0.75, P< 0.001). The established linear regression equation enables the calculation of the knee joint force with an uncertainty of 22% using the plantar pressure estimate. The accuracy of the classification of the joint force as excessive, i.e., being more than 90% of the maximal force, was 82%. The results demonstrate the feasibility of the smart socks for the estimation of the forces in the knee joints. Smart socks therefore could be used to develop excessive joint force alert devices, that could replace less convenient inertial sensors.

Biomechanical effects of typical lower limb movements of Chen-style Tai Chi on knee joint.

The load and stress distribution on cartilage and meniscus of the knee joint in typical lower limb movements of Chen-style Tai Chi (TC) and deep squat (DS) were analyzed using finite element (FE) analysis. The loadings for this analysis consisted of muscle forces and ground reaction force (GRF), which were calculated through the inverse dynamic approach based on kinematics and force plate measurements obtained from motion capture experiments. Thirteen experienced practitioners performed four typical TC movements, namely, single whip (SW), brush knee and twist step (BKTS), stretch down (SD), and part the wild horse's mane (PWHM), which exhibit lower posture and greater lower limb force compared to other TC styles. The results indicated that TC required greater lower limb muscle strength than DS, resulting in greater knee joint forces. The stress on the medial cartilage in SW and BKTS fell within a range conductive to maintaining the balance between anabolism and catabolism of cartilage matrix. This was due to the fact that SW and BKTS reduce the medial to total tibiofemoral contact force ratios through knee abduction, which may effectively alleviate mild medial knee osteoarthritis (KOA). However, the greater medial contact force ratios observed in SD and PWHM resulted in great contact stresses that may aggravate the pain of patients with KOA. To mitigate these effects, practitioners should consider elevating their postures appropriately to reduce knee flexion angles, especially during the single-leg support phase. This adjustment can decrease the required muscle strength, load and stress on the knee joint.

Comparative validation of two patient-specific modelling pipelines for predicting knee joint forces during level walking

Over the past few years, the use of computer models and simulations tailored to the patient's physiology to assist clinical decision-making has increased enormously.While several pipelines to develop personalized models exist, their adoption on a large scale is still limited due to the required niche computational skillset and the lengthy operations required. Novel toolboxes, such as STAPLE, promise to streamline and expedite the development of image-based skeletal lower limb models. STAPLE-generated models can be rapidly generated, with minimal user input, and present similar joint kinematics and kinetics compared to models developed employing the established INSIGNEO pipeline. Yet, it is unclear how much the observed discrepancies scale up and affect joint contact force predictions. In this study, we compared image-based musculoskeletal models developed (i) with the INSIGNEO pipeline and (ii) with a semi-automated pipeline that combines STAPLE and nmsBuilder, and assessed their accuracy against experimental implant data.Our results showed that both pipelines predicted similar total knee joint contact forces between one another in terms of profiles and average values, characterized by a moderately high level of agreement with the experimental data. Nonetheless, the Student t-test revealed statistically significant differences between both pipelines. Of note, the STAPLE-based pipeline required considerably less time than the INSIGNEO pipeline to generate a musculoskeletal model (i.e., 60 vs 160 min). This is likely to open up opportunities for the use of personalized musculoskeletal models in clinical practice, where time is of the essence.

Optimization Reduces Knee-Joint Forces During Walking and Squatting: Validating the Inverse Dynamics Approach for Full Body Movements on Instrumented Knee Prostheses.

Because of the redundancy of our motor system, movements can be performed in many ways. While multiple motor control strategies can all lead to the desired behavior, they result in different joint and muscle forces. This creates opportunities to explore this redundancy, for example, for pain avoidance or reducing the risk of further injury. To assess the effect of different motor control optimization strategies, a direct measurement of muscle and joint forces is desirable, but problematic for medical and ethical reasons. Computational modeling might provide a solution by calculating approximations of these forces. In this study, we used a full-body computational musculoskeletal model to (a)predict forces measured in knee prostheses during walking and squatting and (b)study the effect of different motor control strategies (i.e.,minimizing joint force vs. muscle activation) on the joint load and prediction error. We found that musculoskeletal models can accurately predict knee joint forces with a root mean squared error of <0.5 body weight (BW) in the superior direction and about 0.1BW in the medial and anterior directions. Generally, minimization of joint forces produced the best predictions. Furthermore, minimizing muscle activation resulted in maximum knee forces of about 4BW for walking and 2.5BW for squatting. Minimizing joint forces resulted in maximum knee forces of 2.25BW and 2.12BW, that is, a reduction of 44% and 15%, respectively. Thus, changing the muscular coordination strategy can strongly affect knee joint forces. Patients with a knee prosthesis may adapt their neuromuscular activation to reduce joint forces during locomotion.

Tricompartment offloader knee brace reduces contact forces in adults with multicompartment knee osteoarthritis.

The levitation tricompartment offloader (TCO) brace is designed to unload all three knee compartments by reducing compressive forces caused by muscle contraction. This study aimed to determine the effect of the TCO on knee contact forces and quadriceps muscle activity in individuals with knee osteoarthritis. Lower limb kinematics, kinetics, and electromyography data were collected during a chair rise-and-lower task. A three-dimensionalinverse dynamics model of the lower leg and foot was used with a sagittal plane knee model to compute knee joint forces. TCO brace use significantly decreased forces in the tibiofemoral [p = 0.001; mean difference,MD (97.5% confidence interval,CI) -0.62 (-0.91, -0.33) body weight (BW)] and patellofemoral [p = 0.001; MD (97.5% CI) -0.88 (-1.36, -0.39) BW] compartments in high-power mode. Significant reductions in quadriceps tendon force [p = 0.002; MD (97.5% CI) -0.53 (-0.83, -0.23) BW] and electromyography intensity of the vastus medialis [p = 0.018, MD (97.5% CI) -30.7 (-59.1, -2.3)] and vastus lateralis [p = 0.012, MD (97.5% CI) -26.2 (-48.5, -3.9)] were also observed. The TCO significantly reduced tibiofemoral and patellofemoral contact forces throughout chair lower, and when knee flexion was greater than 50° during chair rise in high power. These results demonstrate that the TCO reduces contact forces in the tibiofemoral and patellofemoral joint compartments and confirms that the TCO unloads the joint by reducing compressive forces caused by the quadriceps. Clinical significance: The magnitude of knee joint unloading provided by the TCO is similar to that achieved by clinically recommended levels of bodyweight loss and is therefore expected to result in clinical benefits for knee osteoarthritis patients.

Training Path Optimization Method of a Moveable Multifunction Rehabilitation Robot

Passive path tracking training is usually used for robot assisted lower limb rehabilitation. The movement of robot will cause the fluctuation of joint force. This letter presents an optimal training path planning algorithm to reduce the patient's joint force caused by a moveable multifunction rehabilitation robot during passive pedaling training. The dynamics model of the human-robot system is established, and the joint forces of the patient are analysed. The planning process is divided into a series of motion steps based on the original training path, at which the optimal algorithm is applied to search the best path. Then, the optimal path is fitted by Bezier curve to get a closed training trajectory. Finally, a Bionic Experiment Platform (BEP) and Human-robot Interaction Platform (HIP) are established to verify the effectiveness of the optimal algorithm. The (BEP) experimental results show that the knee joint force drops by an average of 12.71%, and the maximum drops by 15.41%.The HIP experiment results show that the interaction force drops by an average of 8.5%.

Biomechanical Gender Differences in the Uninjured Extremity After Anterior Cruciate Ligament Reconstruction in Adolescent Athletes: A Retrospective Motion Analysis Study.

Introduction Subsequent anterior cruciate ligament (ACL) injury is more common in the pediatric population and encompasses graft failure and subsequent contralateral tears. Females are at a higher risk. The purpose of the present study was to compare the knee valgus angles at initial contact, knee extension moments, anterior and lateral knee joint forces, hip flexion angles, hip adduction moments, and ankle inversion during the drop vertical test in the uninjured extremity between adolescent males and females who had previously undergone an anterior cruciate ligament reconstruction (ACLR). Methods This IRB-approved retrospective chart review included patientsaged 8-18 years who were seen at the five to seven month postoperatively following ACL reconstruction. A total of 168 patients met our inclusion criteria (86 girls and 82 boys.) Using three-dimensional motion capture technology (CORTEX software, Motion Analysis Corp., Rohnert Park, CA), data were collected while the subject performed the drop vertical test over floor-mounted force plates (FP-Stairs, AMTI, Watertown, MA) under the direct supervision of a pediatric physical therapist. The Wilcoxon rank sum was used, and p < 0.05 was considered statistically significant. Results Females demonstrated a larger average knee joint extension moment (0.31 vs 0.28 N*m/kg, p = 0.0408), a larger anterior knee joint force at initial contact (3.51 vs. 2.79, N/kg, p = 0.0458), larger average hip flexion angle (41.50° vs. 35.99°, p = 0.0005), a smaller maximum hip adduction moment (0.92 vs. 1.16, N*m/kg, p = 0.0497), and a smaller average ankle inversion angle (5.08° vs. 6.41°, p = 0.03231). No significant differences were found regarding knee abduction angle or lateral knee joint force. Conclusions The biomechanical profile of the contralateral extremity varies significantly between the genders after ACLR. In the uninjured extremity, females may have larger hip flexion angles, smaller hip adduction moments, larger anterior knee joint forces, larger knee extension moments, and smaller ankle inversion angles as compared to males after ACLR. These findings may explain the higher incidence of subsequent contralateral injury in female adolescent athletes. Further work is required to develop a composite score that determines at-risk athletes.

An intelligent knee joint force tracking and balancing system using ANN

The knee joint is a complex joint in the body. It is one of the most active joints in the body. It also experiences some of the most extreme loads encountered during walking, running, jumping, etc. Damage due to arthritis or trauma or sports injuries can often result in Total Knee Replacement (TKR) surgery where implants are manufactured by a variety of implant manufacturers. Lima, Zimmer, Johnson &amp; Johnson, Stryker, etc areamong many of the companies supplying these implants. The initial tension in the joint is set by the surgeon using feel and touch which has always been controversial and subjective. It is heavily dependent on the skill and experience of the surgeons and is performed in an artisan fashion. In such cases, surgeons rely upon their natural haptic feedback to decide if the initial tension is adequate. Depending on the size of the patient’s limbs or the doctor, these settings can vary substantially. Currently, there is no unique tool that can tell surgeons what the actual tension in the tendons or contact force in the joint is in terms of Newton's force and if the compartmental forces are balanced or not. The intensity of this load plus the additional force during walking or running will dictate the ultimate load the new knee joint had to handle. Poor load balance during surgery can result in premature failure of the knee due to excess wear or fracture of the bones or dislocation. Surgeons are longing for a load transducer that can measure and track the joint surface contact point during the surgery and give real-time information about contact forces and their location at any position or orientation of the knee joint. This paper examines two of the existing sensors through publications and proposed one that appears to be the most suitable.

FINITE ELEMENT ANALYSIS OF A KNEE JOINT DURING JUMP

Athletes experience high levels of stress during sports activities. One of the most common activities is jumping. This is a very complex activity, which can lead to injuries and long recovery periods. In this research, professional athletes performed jumps in order to obtain ground force values from a force plate. A combination of ground force measurement and inverse dynamics was used to obtain knee joint force values during jumping. The obtained values were then used for the finite element analysis of a knee joint model in order to calculate stress values in the knee joint, with focus on femoral cartilage and menisci. The highest stress values were obtained at the anterior and posterior horn of the medial meniscus, with the highest stress value of 4.894 MPa. Femoral cartilage had lower value, with the maximum stress of 0.391 MPa.

Identification of Kinetic Abnormalities in Male Patients after Anterior Cruciate Ligament Deficiency Combined with Meniscal Injury: A Musculoskeletal Model Study of Lower Limbs during Jogging.

There is little known about kinetic changes in anterior cruciate ligament deficiency (ACLD) combined with meniscal tears during jogging. Therefore, 29 male patients with injured ACLs and 15 healthy male volunteers were recruited for this study to investigate kinetic abnormalities in male patients after ACL deficiency combined with a meniscal injury during jogging. Based on experimental data measured by an optical tracking system, a subject-specific musculoskeletal model was employed to estimate the tibiofemoral joint kinetics during jogging. Between-limb and interpatient differences were compared by the analysis of variance. The results showed that decreased knee joint forces and moments of both legs in ACLD patients were detected during the stance phase compared to the control group. Meanwhile, compared with ACLD knees, significantly fewer contact forces and flexion moments in ACLD combined with lateral and medial meniscal injury groups were found at the mid-stance, and ACLD with medial meniscal injury group showed a lower axial moment in the loading response (p < 0.05). In conclusion, ACLD knees exhibit reduced tibiofemoral joint forces and moments during jogging when compared with control knees. A combination of meniscus injuries in the ACLD-affected side exhibited abnormal kinetic alterations at the loading response and mid-stance phase.

Independently ambulatory children with spina bifida experience near-typical knee and ankle joint moments and forces during walking

BackgroundSpina bifida, a neurological defect, can result in lower-limb muscle weakness. Altered ambulation and reduced musculoskeletal loading can yield decreased bone strength in individuals with spina bifida, yet individuals who remain ambulatory can exhibit normal bone outcomes. Research questionDuring walking, how do lower-limb joint kinematics and moments and tibial forces in independently ambulatory children with spina bifida differ from those of children with typical development? MethodsWe retrospectively analyzed data from 16 independently ambulatory children with spina bifida and 16 children with typical development and confirmed that tibial bone strength was similar between the two groups. Plantar flexor muscle strength was measured by manual muscle testing, and 14 of the children with spina bifida wore activity monitors for an average of 5 days. We estimated tibial forces at the knee and ankle using motion capture data and musculoskeletal simulations. We used Statistical Parametric Mapping t-tests to compare lower-limb joint kinematic and kinetic waveforms between the groups with spina bifida and typical development. Within the group with spina bifida, we examined relationships between plantar flexor muscle strength and peak tibial forces by calculating Spearman correlations. ResultsActivity monitors from the children with spina bifida reported typical daily steps (9656 [SD 3095]). Despite slower walking speeds (p = 0.004) and altered lower-body kinematics (p < 0.001), children with spina bifida had knee and ankle joint moments and forces similar to those of children with typical development, with no detectable differences during stance. Plantar flexor muscle weakness was associated with increased compressive knee force (p = 0.002) and shear ankle force (p = 0.009). SignificanceHigh-functioning, independently ambulatory children with spina bifida exhibited near-typical tibial bone strength and near-typical step counts and tibial load magnitudes. Our results suggest that the tibial forces in this group are of sufficient magnitudes to support the development of normal tibial bone strength.

Finite element analysis on femur subjected to knee joint forces during incline-decline walking

Finite element analysis on femur subjected to knee joint forces during incline-decline walking

Techniques to determine knee joint contact forces during squatting: A systematic review.

This review article provides an overview of techniques used to determine human knee joint contact forces during squatting. The main two approaches are experimental and theoretical. Thigh calf contact has a significant effect on knee forces and should not be neglected. In this study, data were searched electronically and organized by techniques to find knee joint contact force during squatting theoretically and experimentally. There was a large variation in peak tibiofemoral (CV = 0.45) and patellofemoral (CV = 0.38) contact forces predicted theoretically. However, very little variation was observed between peak tibiofemoral contact forces (CV = 0.12) measured in vivo experimentally but measured knee joint force is available up to a limited knee flexion angle. There was a reduction in knee joint contact forces due to thigh calf contact. Literature of knee joint contact force prediction theoretically during squatting incorporating thigh calf contact force is very limited.