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Individuals with knee osteoarthritis (KOA) and flat feet are more likely to experience increased pain and cartilage damage. This study aimed to investigate the knee kinetics, kinematics, pain, and physical function in individuals with moderate symptomatic KOA, in comparison to asymptomatic control participants. Thirty volunteers with moderate KOA (with flat feet n = 15, with normal feet n = 15) and 30 asymptomatic people (with flat feet n = 15, with normal feet n = 15) were evaluated. The knee adduction angular impulse, knee flexion moment, knee flexion angular impulse, and knee flexion angle were measured during level walking. The pain was assessed in patients with KOA. The study found that individuals with KOA had a significant increase in the knee adduction angular impulse compared with the asymptomatic people (P <.05). The KOA with flat feet group had significantly lower knee flexion moment, knee flexion angular impulse, and knee flexion angle values than the KOA with normal feet group (P <.05). Furthermore, the KOA with flat feet group had a higher pain score than the KOA with normal feet group. Individuals with osteoarthritis and flat feet had lower knee flexion moments which may indicate reduced knee force exerted through compensatory mechanisms. Despite this reduction, they reported significantly higher levels of pain compared with those without flat feet, a finding that warrants further investigation in future studies. [ABSTRACT FROM AUTHOR]

Background: The knee adduction moment(KAM) of both lower limbs in patients with unilateral knee osteoarthritis(KOA) exhibits asymmetry during walking, but the factors influencing this asymmetry remain unclear. This study aimed to explore the influencing factors of KAM asymmetry in patients with unilateral KOA. Methods: A total of 148 patients with unilateral medial compartment KOA were selected for this retrospective study, and general data such as gender, age, and duration of disease were collected. The hip-knee-ankle (HKA) angle, degree of pain, and knee-extension muscle strength on the affected side were assessed through radiographic outcomes, the visual analog scale(VAS), and the Biodex isokinetic system. The peak KAM of both lower limbs was analyzed using a BTS motion-capture system and force platform. The asymmetry index(ASI) of KAM was calculated, and the patients were further categorized into the KAM symmetry group(ASI value ≤ 10%) and the KAM asymmetry group(ASI value>10%).Binary logistic regression analysis was employed to analyze the factors influencing the asymmetry of KAM. Results: 90 patients were categorized into the KAM asymmetry group, representing 60.8% of the cohort. A significant difference in the ASI value of KAM was observed between the two groups. Correlation analysis identified nine factors, including sex, age, and BMI, that were positively correlated with the ASI value of KAM. In contrast, knee-extension muscle strength and per-capita monthly household income were negatively correlated with the ASI value of KAM. Regression analysis revealed that being female(OR = 1.752), older age(OR = 2.472), increased BMI(OR = 1.535), larger varus angle(OR = 3.965), higher VAS score(OR = 2.617), Kellgren-Lawrence(K-L) grade IV(OR = 4.474), history of knee joint trauma(OR = 5.684), and living in a rural location(OR = 1.554) increased the risk of KAM asymmetry. Conversely, increased knee-extension muscle strength(OR = 0.758) and a per-capita monthly household income of 3000 ~ 6000 yuan(OR = 0.814) decreased the risk of KAM asymmetry. Conclusion: Female gender, older age, increased BMI, larger varus angle, higher VAS score, K-L grade IV, history of knee joint trauma, and living in a rural location are identified as risk factors for KAM asymmetry. Conversely, increased knee-extension muscle strength and a per-capita monthly household income of 3000 ~ 6000 yuan serve as protective factors against this asymmetry. [ABSTRACT FROM AUTHOR]

Quantitative three-dimensional gait analysis has been used to evaluate the loading at the knee (i.e. external knee adduction moment, EKAM) during level ground walking in individuals with knee osteoarthritis (OA). The magnitude of EKAM can be influenced by some factors, such as knee marker position and foot placement angles in static calibration trials, which may lead to inaccurate functional assessments and intervention planning. This study aimed to clarify the effects of knee position during static calibration trials on the evaluation of knee loading during gait in individuals with medial knee OA. Seventeen individuals with medial knee OA completed three different static standing trials; (1) knee flexed at 0 degrees, (2) knee flexed at 15 degrees, and (3) knee flexed at 30 degrees before walking at their self-selected speed. A sixteen-camera three-dimensional VICON gait analysis system with four AMTI force platforms was used to collect the EKAM, knee adduction angular impulse (KAAI), knee joint center (KJC), and other knee kinematic and kinetic variables during gait. A repeated measures ANOVA was used to investigate the differences between conditions. The 1st peak of EKAM, the 1st peak EKAM arm, KAAI, and knee extension moment were significantly increased at the 15-degree and 30-degree conditions in comparison with the 0-degree condition (P < 0.05). Additionally, the knee flexion moment and knee external rotation moment were significantly reduced at the 15-degree and 30-degree conditions in comparison with the 0-degree condition (P < 0.05). All biomechanical variables were influenced by the localization of the KJC during static calibration trials. The changes in knee position during static trials significantly affected the 1st peak EKAM, KAAI, and other knee kinematics and kinetics variables during gait. Therefore, future studies should consider keeping the participants’ knees in a consistent position during static trials between visits, as the variations in knee position could mask or exaggerate the differences between groups and interventions. [ABSTRACT FROM AUTHOR]

Knee osteoarthritis (KOA) is an age-dependent disease dominantly affected by mechanical loading. Balancing the forces acting on the medial knee compartment has been the focus of KOA interventions. This pilot study investigated the effects of functional electrical stimulation (FES) of the biceps femoris and lateral gastrocnemius on reducing peak knee adduction moment (pKAM) in healthy adults and individuals with medial KOA while stepping on an instrumented elliptical system. Sixteen healthy individuals and five individuals with medial KOA stepped on the robotic stepping system, which measured footplate-reaction forces/torques and ankle kinematics and calculated 3-D knee moments in real time using inverse dynamics. Participants performed four different tasks: regular stepping without FES as the baseline condition, stepping with continuous FES of the lateral gastrocnemius (FESLG), biceps femoris (FESBF), and simultaneous FES of both lateral gastrocnemius and biceps femoris (FESLGBF), throughout the elliptical cycle. The 3-D knee moments, tibia kinematics, and footplate-reaction forces were compared between the baseline and the three FES stepping conditions. Healthy participants demonstrated lower pKAM during each of the three FES conditions compared to baseline (FESLG (p = 0.041), FESBF (p = 0.049), FESLGBF (p = 0.048)). Participants with KOA showed a trend of lower pKAM during FES, which was not statistically significant given the small sample available. Incorporating elliptical + FES as a training strategy is feasible and may help to enhance selective force generation of the targeted muscles and reduce the medial knee compartment loading. [ABSTRACT FROM AUTHOR]

Purpose: Knee adduction, flexion moment, and adduction angle are often used as surrogate parameters of knee medial force. To verify whether these parameters are suitable as surrogates under different walking states, we investigated the correlation between knee medial loading with the surrogates during walking and turning. Methods: Sixteen healthy subjects were recruited to complete straight walk (SW), step turn (ST), and crossover turn (CT). Knee joint moments were obtained using inverse dynamics, and knee medial force was computed using a previously validated musculoskeletal model, Freebody. Linear regression was used to predict the peak of knee medial force with the peaks of the surrogate parameters and walking speed. Results: There was no significant difference in walking speed among these three tasks. The peak knee adduction moment (pKAM) was a significant predictor of the peak knee medial force (pKMF) for SW, ST, and CT (p < 0.001), while the peak knee flexion moment (pKFM) was only a significant predictor of the pKMF for SW (p = 0.034). The statistical analysis showed that the pKMF increased, while the pKFM and the peak knee adduction angle (pKAA) decreased significantly during CT compared to those of SW and ST (p < 0.001). The correlation analysis indicated that the knee parameters during SW and ST were quite similar. Conclusions: This study investigated the relationship between knee medial force and some surrogate parameters during walking and turning. KAM was still the best surrogate parameter for SW, ST, and CT. It is necessary to consider the type of movement when comparing the surrogate predictors of knee medial force, as the prediction equations differ significantly among movement types. [ABSTRACT FROM AUTHOR]

Abstract Background The knee adduction moment(KAM) of both lower limbs in patients with unilateral knee osteoarthritis(KOA) exhibits asymmetry during walking, but the factors influencing this asymmetry remain unclear. This study aimed to explore the influencing factors of KAM asymmetry in patients with unilateral KOA. Methods A total of 148 patients with unilateral medial compartment KOA were selected for this retrospective study, and general data such as gender, age, and duration of disease were collected. The hip-knee-ankle (HKA) angle, degree of pain, and knee-extension muscle strength on the affected side were assessed through radiographic outcomes, the visual analog scale(VAS), and the Biodex isokinetic system. The peak KAM of both lower limbs was analyzed using a BTS motion-capture system and force platform. The asymmetry index(ASI) of KAM was calculated, and the patients were further categorized into the KAM symmetry group(ASI value ≤ 10%) and the KAM asymmetry group(ASI value>10%).Binary logistic regression analysis was employed to analyze the factors influencing the asymmetry of KAM. Results 90 patients were categorized into the KAM asymmetry group, representing 60.8% of the cohort. A significant difference in the ASI value of KAM was observed between the two groups. Correlation analysis identified nine factors, including sex, age, and BMI, that were positively correlated with the ASI value of KAM. In contrast, knee-extension muscle strength and per-capita monthly household income were negatively correlated with the ASI value of KAM. Regression analysis revealed that being female(OR = 1.752), older age(OR = 2.472), increased BMI(OR = 1.535), larger varus angle(OR = 3.965), higher VAS score(OR = 2.617), Kellgren-Lawrence(K-L) grade IV(OR = 4.474), history of knee joint trauma(OR = 5.684), and living in a rural location(OR = 1.554) increased the risk of KAM asymmetry. Conversely, increased knee-extension muscle strength(OR = 0.758) and a per-capita monthly household income of 3000 ~ 6000 yuan(OR = 0.814) decreased the risk of KAM asymmetry. Conclusion Female gender, older age, increased BMI, larger varus angle, higher VAS score, K-L grade IV, history of knee joint trauma, and living in a rural location are identified as risk factors for KAM asymmetry. Conversely, increased knee-extension muscle strength and a per-capita monthly household income of 3000 ~ 6000 yuan serve as protective factors against this asymmetry.

Aims: This study aimed to analyze kinematics and kinetics of the tibiofemoral joint in healthy subjects with valgus, neutral, and varus limb alignment throughout multiple gait activities using dynamic videofluoroscopy. Methods: Five subjects with valgus, 12 with neutral, and ten with varus limb alignment were assessed during multiple complete cycles of level walking, downhill walking, and stair descent using a combination of dynamic videofluoroscopy, ground reaction force plates, and optical motion capture. Following 2D/3D registration, tibiofemoral kinematics and kinetics were compared between the three limb alignment groups. Results: No significant differences for the rotational or translational patterns between the different limb alignment groups were found for level walking, downhill walking, or stair descent. Neutral and varus aligned subjects showed a mean centre of rotation located on the medial condyle for the loaded stance phase of all three gait activities. Valgus alignment, however, resulted in a centrally located centre of rotation for level and downhill walking, but a more medial centre of rotation during stair descent. Knee adduction/abduction moments were significantly influenced by limb alignment, with an increasing knee adduction moment from valgus through neutral to varus. Conclusion: Limb alignment was not reflected in the condylar kinematics, but did significantly affect the knee adduction moment. Variations in frontal plane limb alignment seem not to be a main modulator of condylar kinematics. The presented data provide insights into the influence of anatomical parameters on tibiofemoral kinematics and kinetics towards enhancing clinical decision-making and surgical restoration of natural knee joint motion and loading. Cite this article: Bone Joint Res 2024;13(9):485–496.

Abstract Quantitative three-dimensional gait analysis has been used to evaluate the loading at the knee (i.e. external knee adduction moment, EKAM) during level ground walking in individuals with knee osteoarthritis (OA). The magnitude of EKAM can be influenced by some factors, such as knee marker position and foot placement angles in static calibration trials, which may lead to inaccurate functional assessments and intervention planning. This study aimed to clarify the effects of knee position during static calibration trials on the evaluation of knee loading during gait in individuals with medial knee OA. Seventeen individuals with medial knee OA completed three different static standing trials; (1) knee flexed at 0 degrees, (2) knee flexed at 15 degrees, and (3) knee flexed at 30 degrees before walking at their self-selected speed. A sixteen-camera three-dimensional VICON gait analysis system with four AMTI force platforms was used to collect the EKAM, knee adduction angular impulse (KAAI), knee joint center (KJC), and other knee kinematic and kinetic variables during gait. A repeated measures ANOVA was used to investigate the differences between conditions. The 1st peak of EKAM, the 1st peak EKAM arm, KAAI, and knee extension moment were significantly increased at the 15-degree and 30-degree conditions in comparison with the 0-degree condition (P

Abstract Background Knee Osteoarthritis (OA) is a highly prevalent age-related disease. The altered kinematic pattern of the knee joint as well as the adjacent joints affects to progression of knee OA. However, there is a lack of research on how asymmetry of the hip rotation angle affects the gait pattern in knee OA patients. Research question What are the impacts of asymmetric hip rotation range on gait biomechanical characteristics and do the gait patterns differ between patients with knee OA and healthy elderly people? Methods Twenty-nine female patients with knee OA and 15 healthy female elders as control group were enrolled in this study. The spatiotemporal parameters, kinematic and kinetic data during walking were measured using a three-dimensional motion capture system. The differences between knee OA and control group were analyzed using an independent t-test. Results The knee OA group exhibited a significant reduction in hip internal rotation range and internal/external rotation ratio on more affected side (p

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. [ABSTRACT FROM AUTHOR]

Background: Knee Osteoarthritis (OA) is a highly prevalent age-related disease. The altered kinematic pattern of the knee joint as well as the adjacent joints affects to progression of knee OA. However, there is a lack of research on how asymmetry of the hip rotation angle affects the gait pattern in knee OA patients. Research question: What are the impacts of asymmetric hip rotation range on gait biomechanical characteristics and do the gait patterns differ between patients with knee OA and healthy elderly people? Methods: Twenty-nine female patients with knee OA and 15 healthy female elders as control group were enrolled in this study. The spatiotemporal parameters, kinematic and kinetic data during walking were measured using a three-dimensional motion capture system. The differences between knee OA and control group were analyzed using an independent t-test. Results: The knee OA group exhibited a significant reduction in hip internal rotation range and internal/external rotation ratio on more affected side (p < 0.05). Significant differences were found in spatiotemporal parameters except to the step width. Significant reductions were also found in kinematic parameters (pelvic lateral tilt range, sagittal angle ranges in hip, knee and ankle, knee adduction mean angle). There were also significant differences in vertical ground reaction force and knee adduction moment (p < 0.05). Conclusions: Knee OA patients have asymmetric hip rotation ranges. Especially limited hip internal rotation could lead to the reduction of pelvic lateral tilt, which may cause greater knee joint loading. Therefore, it is necessary to pay attention to recovery of hip rotation after knee surgery. [ABSTRACT FROM AUTHOR]

To evaluate whether the knee adduction moment (KAM) could be reduced by a short instruction in the Draw-in (DI) maneuver in healthy adults, and whether knee joint function would improve with a longer DI gait intervention in patients with knee osteoarthritis (OA). In Study 1, healthy adults received 10 minutes supervised instruction in DI gait in and then practiced the gait independently for 10 minutes. Three-dimensional motion analysis measurement was performed in each phase. In Study 2, patients with OA performed a 20-minute DI gait intervention daily for 6 weeks. At baseline and after 6 weeks, knee pain, the Knee injury and Osteoarthritis Outcome Score, the MOS 8 item Short-Form Health Survey, thoracic kyphosis angle, knee joint range of motion, knee extension muscle strength, hip abduction muscle strength, and activity level were evaluated. In Study 1, the DI gait to decrease KAM could be learning following only 10 minutes of instruction and 10 minutes of self-practice in healthy adults. In Study 2, knee pain was reduced by 19 % and the thoracic kyphosis angle was reduced by 2.6° after 6 weeks. No significant changes in other parameters were detected, and the implementation rate was 86 ± 14 %. In healthy adults, DI gait instruction for 10 minutes of instruction and 10 minutes of self-practice reduced the KAM. In patients with knee OA, 20 minutes of DI gait per day for 6 weeks may reduce knee pain and thoracic kyphosis. • Using the draw-in maneuver while walking is an effective intervention for knee OA. • Gait retraining significantly improved knee pain and thoracic kyphosis. • Gait retraining had a high implementation rate. • Gate retraining using the draw-in maneuver can be mastered even by older adults. [ABSTRACT FROM AUTHOR]

Introduction: Osteoarthritis of the knee is a leading cause of disability and is a multi-factorial disease. Moreover, it is partly considered a mechanically driven disease in which higher abnormally disbursed forces play a prime role. With the progression of the disease, the gait function declines, so a comprehensive and objective evaluation of gait function would help in prognostic evaluation and management. Materials and Methods: This study included two groups: patients with primary knee osteoarthritis and a control group of healthy volunteers. Gait analysis and functional knee scores were evaluated for all the subjects. The KOOS score, temporal parameters excluding the step length, and spatial parameters excluding the stance phase percentage were evaluated for an individual as a whole. The KSS score, kinetic parameters, kinematic parameters, step length, and stance phase percentage were calculated for each knee separately. Each knee of the patient and controls was taken as 1 sample and categorized as per Kellgren–Lawrence score. An asymptomatic control group of subjects were included in group A. Symptomatic patients with KL grades 1, 2 were included in group M, and those with KL grades 3, 4 were included in group S. The kinetic and kinematic parameters and KSS score were compared among the three groups. Results: A total of 60 subjects were included of which 40 were patients and 20 were controls. In the control group, the age ranged from 22 to 48 years with a mean age of 28.6 years. In the patient group, the mean age was 60.3 years. Patients with knee osteoarthritis were significantly obese with slower walking speed, short stride length, longer stride time, and decreased cadence compared to the asymptomatic group. There was a significant difference in spatiotemporal parameters, functional scores, and kinetic and kinematic parameters among the groups. Conclusion: Various spatiotemporal, kinetic, and kinematic parameters like peak knee flexion angle, abduction/adduction angle, peak knee adduction moment, range of knee flexion, peak knee flexion, and gait deviation index along with functional scores varied significantly with the progression of the disease. [ABSTRACT FROM AUTHOR]

Objective: To determine the relationships among knee and patella alignments, BMI, quadriceps, and knee adduction moments, which are associated with knee osteoarthritis, in healthy people. Methods: In 60 young females, intercondylar distances normalized by body height, Q-angle, and BMI were assessed. The ratios of individual muscle:quadriceps thicknesses measured using ultrasonography were calculated. Correlations between these parameters were evaluated. Ten subjects were selected from the VALGUS, mild VARUS, or severe VARUS knee groups (

The study aim was to quantify the impact of a commercially available variable stiffness shoe (VSS) on 3-dimensional ankle, knee, and hip mechanics and estimated knee contact forces compared with a control shoe. Fourteen participants (10 females) with knee osteoarthritis completed gait analysis after providing informed consent. Shoe conditions tested were control shoe (New Balance MW411v2) and VSS (Abeo SMART3400). An OpenSim musculoskeletal model with static optimization was used to estimate knee contact forces. There were no differences in joint kinematics or in the knee adduction or flexion moments (P =.06; P =.2). There were increases in the knee internal and external rotation (P =.02; P =.03) and hip adduction and internal rotation moments for VSS versus control (P =.03; P =.02). The estimated contact forces were not different between shoes (total P =.3, medial P =.1, and lateral P =.8), but contact force changes were correlated with changes in the knee adduction moment (medial r2 =.61; P <.007). High variability in knee flexion moment changes and increases in the internal rotation moment combined with small decreases in the knee adduction moment did not lead to decreases in estimated contact forces. These results suggest that evaluation of VSS using only the knee adduction moment may not adequately capture its impact on osteoarthritis. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Knee adduction moment and knee adduction angular impulse enlargement is the main biomechanical risk factor of knee osteoarthritis. According to the survey, a change in the foot progression angle could effectively change the motion mode of patients with knee osteoarthritis. However, the impact of toe-in and toe-out on knee adduction moment and knee adduction angular impulse in young and elderly patients did not reach a consensus. Therefore, this study comprehensively discussed the effect of foot progression angle on knee adduction moment and knee adduction angular impulse in different populations through meta-analysis and provided a reference for the treatment of knee osteoarthritis. METHODS: By June 2022, searches were conducted on Web of Science, EBSCO, PubMed and CNKI databases using “foot progression angle, knee adduction moment, knee adduction angular impulse, gait” as Chinese and English search terms. Self-controlled randomized controlled studies analyzing the effects of toein and toe-out on knee adduction moment bimodality and knee adduction angular impulse were included. The cochrane bias risk assessment tool was utilized to make a quality evaluation of the literature. Stata 15.1 software was used for subgroup analysis to determine the effect of foot progression angle on knee adduction moment and knee adduction angular impulse. Meta-regression analysis was used to further determine characteristics of outcome indicators (knee adduction moment, knee adduction angular impulse) changing with foot progression angle. RESULTS: (1) A total of 15 self-control trials and 2 randomized controlled trials (455 subjects) were included in the meta-analysis. All of the included articles were of medium to high quality. (2) The meta-analysis results showed that the toe-in gait could reduce the first peak of knee adduction moment (SMD=-0.380, 95%CI:-0.710 to -0.060, P=0.022) and knee adduction angular impulse (SMD=-1.470, 95%CI:-2.160 to -0.770, P < 0.001) in young patients. The toe-out gait reduced the second peak of knee adduction moment (SMD=-0.720, 95%CI:-1.010 to -1.440, P < 0.001) in young patients. In addition, toe-in gait could reduce the first peak of knee adduction moment in elder patients (SMD=-0.550, 95%CI:-0.800 to -0.300, P < 0.001), but increase the second peak knee adduction moment of elderly (SMD=0.280, 95%CI:-0.010 to 0.560, P=0.047). The toe-out gait could decrease the second peak knee adduction moment in this population (SMD=-0.510, 95%CI:-0.830 to -0.190, P=0.002). (3) Meta-regression showed that the greater the toe-out in elderly patients, the lower the second peak knee adduction moment. CONCLUSION: (1) Toe-in reduced the first peak knee adduction moment and knee adduction angular impulse in young knee osteoarthritis patients aged 18 to 34 years. Since knee adduction moment and knee adduction angular impulse were associated with medial knee loading and knee osteoarthritis incidence, toe-in gait intervention may be a suitable rehabilitation strategy for young patients. (2) Toe-in increased the second peak of knee adduction moment in older knee osteoarthritis patients over 60 years of age, which may exacerbate knee osteoarthritis in this population. However, the second peak of knee adduction moment during walking in this population decreases as the toe-out increases, contributing to a reduction in medial knee loading, suggesting that older patients may consider using toe-out gait during walking. [ABSTRACT FROM AUTHOR]

The use of a contralateral cane has demonstrated a reduction in the external knee adduction moment (KAM) in patients with knee osteoarthritis. However, the underlying mechanism remains unclear. This study aimed to investigate the specific mechanism in healthy young subjects. Sixteen healthy young participants were included in this study. They walked on a floor under three loading conditions: no cane and with cane loads equivalent to 5% and 10% of body weight. Change in posture and kinetic features of ipsilateral leg were examined at two instants of ground reaction force (GRF) peaks. The results revealed a substantial decrease (40–55%) in both KAM and moment arm, whereas only 12% decrease was observed in GRF with 10% cane loading. Furthermore, KAM was strongly correlated with moment arm (r = 0.97, p < 0.01), but not with GRF (p > 0.05). The reduction in moment arm could be attributed to a medial shift of knee joint and/or a lateral shift of GRF. At the maximum cane loading, medial shift in the knee joint center was significant (p < 0.001), while any shift in GRF was insignificant (p > 0.80). The results suggest that the primary factor contributing to the reduction in KAM is the decrease in moment arm among healthy young subjects. Importantly, the reduction in moment arm was primarily induced by a medial shift of the knee joint center, emphasizing the significance of postural changes. [ABSTRACT FROM AUTHOR]

Knee osteoarthritis (KOA) is an age-dependent disease dominantly affected by mechanical loading. Balancing the forces acting on the medial knee compartment has been the focus of KOA interventions. This pilot study investigated the effects of functional electrical stimulation (FES) of the biceps femoris and lateral gastrocnemius on reducing peak knee adduction moment (pKAM) in healthy adults and individuals with medial KOA while stepping on an instrumented elliptical system. Sixteen healthy individuals and five individuals with medial KOA stepped on the robotic stepping system, which measured footplate-reaction forces/torques and ankle kinematics and calculated 3-D knee moments in real time using inverse dynamics. Participants performed four different tasks: regular stepping without FES as the baseline condition, stepping with continuous FES of the lateral gastrocnemius (FESLG), biceps femoris (FESBF), and simultaneous FES of both lateral gastrocnemius and biceps femoris (FESLGBF), throughout the elliptical cycle. The 3-D knee moments, tibia kinematics, and footplate-reaction forces were compared between the baseline and the three FES stepping conditions. Healthy participants demonstrated lower pKAM during each of the three FES conditions compared to baseline (FESLG (p = 0.041), FESBF (p = 0.049), FESLGBF (p = 0.048)). Participants with KOA showed a trend of lower pKAM during FES, which was not statistically significant given the small sample available. Incorporating elliptical + FES as a training strategy is feasible and may help to enhance selective force generation of the targeted muscles and reduce the medial knee compartment loading.

Purpose: Knee adduction, flexion moment, and adduction angle are often used as surrogate parameters of knee medial force. To verify whether these parameters are suitable as surrogates under different walking states, we investigated the correlation between knee medial loading with the surrogates during walking and turning. Methods: Sixteen healthy subjects were recruited to complete straight walk (SW), step turn (ST), and crossover turn (CT). Knee joint moments were obtained using inverse dynamics, and knee medial force was computed using a previously validated musculoskeletal model, Freebody. Linear regression was used to predict the peak of knee medial force with the peaks of the surrogate parameters and walking speed. Results: There was no significant difference in walking speed among these three tasks. The peak knee adduction moment (pKAM) was a significant predictor of the peak knee medial force (pKMF) for SW, ST, and CT (p < 0.001), while the peak knee flexion moment (pKFM) was only a significant predictor of the pKMF for SW (p = 0.034). The statistical analysis showed that the pKMF increased, while the pKFM and the peak knee adduction angle (pKAA) decreased significantly during CT compared to those of SW and ST (p < 0.001). The correlation analysis indicated that the knee parameters during SW and ST were quite similar. Conclusions: This study investigated the relationship between knee medial force and some surrogate parameters during walking and turning. KAM was still the best surrogate parameter for SW, ST, and CT. It is necessary to consider the type of movement when comparing the surrogate predictors of knee medial force, as the prediction equations differ significantly among movement types.

Background: A medial meniscus extrusion (MME) gradually expands during activities of daily living according to the mechanical stress on the medial compartment of the knee. Increase in MME occurs during the stance phase of the gait cycle, which is key for its expand. The knee adduction moment (KAM) represents the mechanical stress on the medial compartment; however, the relationship between the increase in MME and KAM is still unknown. Therefore, the present study aimed to investigate the relationship between MME during gait and KAM. Methods: Twenty-one patients with medial knee osteoarthritis and 11 healthy middle-aged adults were recruited. Three-dimensional motion analysis system and ultrasonography were used to measure the KAM and MME in the stance phase. The increase in MME was identified as the difference in MME between the maximum and minimum (ΔMME). Patients with knee osteoarthritis performed two conditions as normal and toe-out gait. The difference in KAM and ΔMME between conditions were evaluated. Results: ΔMME was correlated with the KAM second peak in normal gait of knee osteoarthritis patients (r = 0.51, p

Purpose: Patient-specific alignment in total knee arthroplasty (TKA) has shown promising patient-reported outcome measures; however, the clinical and biomechanical effects of restoring the native knee anatomy remain debated. The purpose of this study was to compare the gait pattern between a mechanically aligned TKA cohort (adjusted mechanical alignment—aMA) and a patient-specific alignment TKA cohort (inverse kinematic alignment—iKA). Methods: At two years postoperatively, the aMA and iKA groups, each with 15 patients, were analyzed in a retrospective case–control study. All patients underwent TKA with robotic assistance (Mako, Stryker) through an identical perioperative protocol. The patients' demographics were identical. The control group comprised 15 healthy participants matched for age and gender. Gait analysis was performed with a 3D motion capture system (VICON). Data collection was conducted by a blinded investigator. The primary outcomes were knee flexion during walking, knee adduction moment during walking and spatiotemporal parameters (STPs). The secondary outcomes were the Oxford Knee Score (OKS) and Forgotten Joint Score (FJS). Results: During walking, the maximum knee flexion did not differ between the iKA group (53.0°) and the control group (55.1°), whereas the aMA group showed lower amplitudes of sagittal motion (47.4°). In addition, the native limb alignment in the iKA group was better restored, and although more in varus, the knee adduction moments in the iKA group were not increased (225 N mm/kg) compared to aMA group (276 N mm/kg). No significant differences in STPs were observed between patients receiving iKA and healthy controls. Six of 7 STPs differed significantly between patients receiving aMA and healthy controls. The OKS was significantly better in patients receiving iKA than aMA: 45.4 vs. 40.9; p = 0.05. The FJS was significantly better in patients receiving iKA than aMA: 84.8 vs. 55.5; p = 0.002. Conclusion: At two years postoperatively, the gait pattern showed greater resemblance to that in healthy controls in patients receiving iKA rather than aMA. The restoration of the native coronal limb alignment does not lead to increased knee adduction moments due to the restoration of the native tibial joint line obliquity. Level of evidence: Level III. [ABSTRACT FROM AUTHOR]

An increase in medial meniscus extrusion during weight-bearing conditions is associated with the progression of medial knee osteoarthritis (OA). Toe-out gait modification has been known to reduce the knee adduction moment (KAM); however, its effect on reducing the increase in medial meniscus extrusion in patients with knee OA remains unclear. To (1) evaluate the effect of toe-out gait on the increase in medial meniscus extrusion and the KAM in patients with medial knee OA and (2) investigate the synergetic effect of lateral wedge insoles in combination with toe-out gait in determining the most effective intervention for reducing medial meniscus extrusion during gait. Twenty-five patients with medial knee OA were enrolled in this study. Participants walked under four conditions: normal gait, toe-out gait, normal gait with lateral wedge insoles, and toe-out gait with lateral wedge insoles. Medial meniscus extrusion and KAM peaks during gait were measured using ultrasound and a three-dimensional motion analysis system in each condition. These parameters were compared among the four conditions using repeated measures analysis of variance. The increase in medial meniscus extrusion and the second KAM peak were significantly lower in all interventions compared with those observed during normal gait. However, there was no significant difference among the interventions. This study suggested that toe-out gait reduces the increase in medial meniscus extrusion and is associated with the reduction of the second KAM peak. However, no synergistic effect of lateral wedge insoles and toe-out gait was observed. • Compared the effect of gait modifications on medial meniscus extrusion during gait. • Medial meniscus extrusion was inhibited by toe-out gait and lateral wedge insole. • Combined use of toe-out and lateral wedge insole reduced medial meniscus extrusion. • Gait modifications also reduced the second peak of knee adduction moment. • No difference between gait modifications when comparing medial meniscus extrusion. [ABSTRACT FROM AUTHOR]

The gait modification strategies Trunk Lean and Medial Thrust have been shown to reduce the external knee adduction moment (EKAM) in patients with knee osteoarthritis which could contribute to reduced progression of the disease. Which strategy is most optimal differs between individuals, but the underlying mechanism that causes this remains unknown. Which gait parameters determine the optimal gait modification strategy for individual patients with knee osteoarthritis? Forty-seven participants with symptomatic medial knee osteoarthritis underwent 3-dimensional motion analysis during comfortable gait and with two gait modification strategies: Medial Thrust and Trunk Lean. Kinematic and kinetic variables were calculated. Participants were then categorized into one of the two subgroups, based on the modification strategy that reduced the EKAM the most for them. Multiple logistic regression analysis with backward elimination was used to investigate the predictive nature of dynamic parameters obtained during comfortable walking on the optimal modification gait strategy. For 68.1 % of the participants, Trunk Lean was the optimal strategy in reducing the EKAM. Baseline characteristics, kinematics and kinetics did not differ significantly between subgroups during comfortable walking. Changes to frontal trunk and tibia angles correlated significantly with EKAM reduction during the Trunk Lean and Medial Thrust strategies, respectively. Regression analysis showed that MT is likely optimal when the frontal tibia angle range of motion and peak knee flexion angle in early stance during comfortable walking are high (R2 Nagelkerke = 0.12). Our regression model based solely on kinematic parameters from comfortable walking contained characteristics of the frontal tibia angle and knee flexion angle. As the model explains only 12.3 % of variance, clinical application does not seem feasible. Direct assessment of kinetics seems to be the most optimal strategy for selecting the most optimal gait modification strategy for individual patients with knee osteoarthritis. • Self-selected Trunk Lean modification reduces the EKAM more than Medial Thrust. • The degree of frontal tibia angle modifications may determine the optimal strategy. • Parameters during comfortable walking only moderately predict the optimal strategy. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the effect of walking cadence on knee flexion angular impulse and peak external flexion moment in patients with patellofemoral osteoarthritis (OA). Methods: Forty-eight patients with patellofemoral OA underwent repeated quantitative gait analyses on an instrumented treadmill using a randomized crossover design. Walking trials were conducted at a fixed gait speed, under three cadence conditions: (i) preferred cadence, (ii) +10% increased cadence, and (iii) −10% decreased cadence, completed in random order. Using a linear mixed model, we tested the association of cadence conditions with surrogate measures of patellofemoral load (primary outcome measure: knee flexion angular impulse) while controlling for body mass. We then repeated the analyses while sequentially replacing the dependent variable with secondary outcome measures. Results: Walking with increased cadence decreased (adjusted mean difference [95% confidence interval]) the knee flexion angular impulse (−0.85 N·m·s−1 [−1.52 to −0.18], d = 0.20) and peak knee flexion moment (−4.11 N·m [−7.35 to −0.86], d = 0.24), whereas walking with decreased cadence increased the knee flexion angular impulse (1.83 N·m·s−1 [1.15 to 2.49], d = 0.42) and peak knee flexion moment (3.55 N·m [0.30 to 6.78], d = 0.21). Similar decreases and increases were observed for secondary outcome measures. Conclusions: Walking with increased cadence, while maintaining a fixed gait speed, reduces knee flexion angular impulse as well as other surrogate measures of knee loading in patients with patellofemoral OA. [ABSTRACT FROM AUTHOR]

Purpose: The cumulative knee adduction moment (KAM) is a key parameter evaluated for the prevention of overload knee injuries on the medial compartment. Medial meniscus extrusion (MME), typical in hoop dysfunctions, is a measure for the cumulative mechanical stress in individual knees; however, its correlation with cumulative KAM is unknown. The aim of this study was to investigate the effect of temporary overload stress on MME and its correlation with cumulative KAM. Methods: Thirteen healthy asymptomatic volunteers (13 knees) were recruited for a cohort study (mean age, 23.1 ± 3.3 years; males: n = 8). The cumulative KAM was calculated using a three-dimensional motion analysis system, in addition to the number of steps taken while jogging uphill or downhill. MME was evaluated using ultrasound performed in the standing position. The evaluations were performed four times: at baseline (T0), before and after (T1 and T2, respectively) jogging uphill or downhill, and 1 day after (T3) jogging. Additionally, the Δ-value was calculated using the change of meniscus after efforts as the difference in MME between T1 and T2. Results: The MME in T2 was significantly greater than those in T0 and T1. Conversely, the MME in T3 was significantly lesser than that in T2. No significant difference was found between those in T0 and T1, and T3. ΔMME exhibited a significant positive correlation with the cumulative KAM (r = 0.68, p = 0.01), but not for peak KAM. Conclusion: The temporary reaction of MME observed in ultrasound correlates with the cumulative stress of KAM. [ABSTRACT FROM AUTHOR]

Background: High tibial osteotomy (HTO) reduces the load distribution of the medial compartment by modifying leg alignment. Knee adduction moment (KAM), a surrogate measure of dynamic loading in the knee joint, decreases after HTO. However, leg alignment does not fully account for KAM. Purpose: To assess the association between the pelvis-knee-ankle angle (PKA), a novel radiographic parameter reflecting leg alignment and pelvic width, and KAM and patient-reported outcomes after HTO. Study Design: Cross sectional study; Level of evidence, 3. Methods: PKA is the angle between the line from the midpoint of the anterior superior iliac spine to the center of the knee joint and the mechanical axis of the tibia. In this study, 54 patients with medial compartment knee osteoarthritis and varus alignment who underwent 3-dimensional gait analysis preoperatively and 2 years after medial open-wedge HTO were evaluated. The primary outcomes were hip-knee-ankle angle (HKA), PKA, KAM peaks, and Knee Society Score (KSS). Single and multivariate regression analysis including PKA and KAM peaks as well as other demographic and radiologic factors was performed. Results: HKA was weakly correlated with the first peak KAM (r = −0.33; P <.01) and second peak KAM (r = −0.27; P =.01) before HTO, but not significantly correlated after HTO. PKA was moderately correlated with the first peak KAM (r = 0.45; P <.01) and second peak KAM (r = 0.45; P <.01) before HTO and with the first peak KAM (r = 0.51; P <.01) and second peak KAM (r = 0.56; P <.01) after HTO. Multivariate linear regression revealed that postoperative PKA was still associated with the KAM peaks after HTO. Only postoperative PKA was correlated with the KSS satisfaction subscale (r = −0.30; P =.03). Conclusion: Although HKA was not correlated with KAM peaks after HTO, PKA was significantly correlated with KAM peaks in patients with varus knee osteoarthritis after HTO. [ABSTRACT FROM AUTHOR]

Objective: To characterize ambulatory knee moments with respect to medial knee osteoarthritis (OA) severity comprehensively and to assess the possibility of developing a severity index combining knee moment parameters.Methods: Nine parameters (peak amplitudes) commonly used to quantify three-dimensional knee moments during walking were analyzed for 98 individuals (58.7 ± 9.2 years old, 1.69 ± 0.09 m, 76.9 ± 14.5 kg, 56% female), corresponding to three medial knee osteoarthritis severity groups: non-osteoarthritis (n = 22), mild osteoarthritis (n = 38) and severe osteoarthritis (n = 38). Multinomial logistic regression was used to create a severity index. Comparison and regression analyses were performed with respect to disease severity.Results: Six of the nine moment parameters differed statistically significantly among severity groups (p ≤ 0.039) and five reported statistically significant correlation with disease severity (0.23 ≤ |r| ≤ 0.59). The proposed severity index was highly reliable (ICC = 0.96) and statistically significantly different between the three groups (p < 0.001) as well as correlated with disease severity (r = 0.70).Conclusion: While medial knee osteoarthritis research has mostly focused on a few knee moment parameters, this study showed that other parameters differ with disease severity. In particular, it shed light on three parameters frequently disregarded in prior works. Another important finding is the possibility of combining the parameters into a severity index, which opens promising perspectives based on a single figure assessing the knee moments in their entirety. Although the proposed index was shown to be reliable and associated with disease severity, further research will be necessary particularly to assess its validity.

To examine the relationship between anterior cruciate ligament injury risk factors in unanticipated cutting and decelerating. Three-dimensional kinematics and ground reaction forces were collected on 11 females (22 [2] y, 1.67 [0.08] m, and 68.5 [9.8] kg) during 2 unanticipated tasks. Paired samples t tests were performed to compare dependent variables between tasks. Spearman rank correlation coefficients were calculated to analyze the relationship between peak internal knee adduction moment and peak anterior tibial shear force (ASF) during 2 unanticipated tasks. Significantly greater knee abduction angles, peak knee adduction moments, and peak ASFs were observed during cutting (P ≤.05). A strong positive correlation existed between decelerating ASF and cutting ASF (ρ =.67), while correlations between decelerating knee adduction moment and cutting knee adduction moment and decelerating ASF and cutting knee adduction moment were not significant. In situations where time management is a necessity and only one task can be evaluated, it may be more appropriate to utilize an unanticipated cutting task rather than an unanticipated deceleration task because of the increased knee adduction moment and ASF. These data can help future clinicians in better designing more effective anterior cruciate ligament injury risk screening methods. [ABSTRACT FROM AUTHOR]

Background: Gait analysis has been used extensively for computing knee kinematics and kinetics, in particular, in healthy and impaired individuals. One variable assessed is the external knee adduction moment (EKAM). Variations in EKAM values between investigations may be caused by changes in static standing position, especially foot placement angles which may increase or reduce any differences seen.Purpose Of the Study: The current study aimed to explore the influence of static trial foot position on knee kinematic and kinetic variables during walking.Methods: Twelve healthy male participants completed three different static standing trials; 1) 20-degrees toe-in, 2) 0° and 3) 20-degrees toe-out before walking at their own pace during a lower limb kinematics and kinetics assessment. First and second peak EKAM was compared between static foot position trials, as well other knee kinematic and kinetic outcomes. Repeated measures ANOVA was used with post hoc pairwise comparison to determine the differences between static foot position trials.Results: The first peak of EKAM was significantly smaller in the 20o toe-out angle, than the 20o toe-in angle (p = 0.04-8.16% reduction). Furthermore, significant changes were found in peak knee kinematics and kinetics variables (adduction angle, external rotation angle, knee flexion moment external rotation moment, abduction angle and internal rotation angle) in the different positions.Conclusion: Modification in static foot position between study visits may result in changes especially in the 1st peak EKAM and other kinematics and kinetics variables during walking. Therefore, standardisation of static foot position should be utilised in longitudinal studies to ensure changes in EKAM are not masked or accentuated between assessments. [ABSTRACT FROM AUTHOR]

Background: Wearing unloader knee orthoses for the long term may have a side effect on knee adduction moment (KAM).Research Question: This study sought to determine whether equipping an unloader knee orthosis with vibrators improves its effectiveness in pain, stiffness, function, and reducing the KAM.Methods: The authors performed a clinical evaluation with the Western Ontario and McMaster Universities (WOMAC) questionnaire and instrumented gait analyses on 14 participants with medial compartment knee osteoarthritis in two testing sessions: before wearing the orthosis and after 6 weeks of use.Results and Significance: Wearing both orthoses for 6 weeks significantly improved (p < 0.05) pain, stiffness, and function compared to the baseline assessment. There was a significantly greater reduction in the first peak KAM (p = 0.016) and KAM impulse (p = 0.008) in the vibratory unloader knee orthosis than in the conventional knee orthosis in the second session. Equipping the unloader knee orthosis with vibrators can improve its effectiveness in reducing the KAM and can prevent the side effects of its use. Furthermore, equipping the unloader knee orthosis with the vibrators did not interfere with its effectiveness on pain, stiffness, and function. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to compare knee biomechanics of the replaced limb to the non-replaced limb of total knee replacement (TKR) patients and healthy controls during walking on level ground and on decline surfaces of 5°, 10°, and 15°. Methods: Twenty-five TKR patients and 10 healthy controls performed 5 walking trials on different decline slopes on a force platform and an instrumented ramp system. Two analyses of variance, 2 × 2 (limb × group) and 2 × 4 (limb × decline slope), were used to examine selected biomechanics variables. Results: The replaced limb of TKR patients had lower peak loading-response and push-off knee extension moment than the non-replaced and the matched limb of healthy controls. No differences were found in loading-response and push-off knee internal abduction moments among replaced, non-replaced, and matched limb of healthy controls. The knee flexion range of motion, peak loading-response vertical ground reaction force, and peak knee extension moment increased across all slope comparisons between 0° and 15° in both the replaced and non-replaced limb of TKR patients. Conclusion: Downhill walking may not be appropriate to include in early stage rehabilitation exercise protocols for TKR patients.

Purpose: Greater articular cartilage T1ρ magnetic resonance imaging relaxation times indicate less proteoglycan density and are linked to posttraumatic osteoarthritis development after anterior cruciate ligament reconstruction (ACLR). Although changes in T1ρ relaxation times are associated with gait biomechanics, it is unclear if excessive or insufficient knee joint loading is linked to greater T1ρ relaxation times 12 months post-ACLR. The purpose of this study was to compare external knee adduction (KAM) and flexion (KFM) moments in individuals after ACLR with high versus low tibiofemoral T1ρ relaxation profiles and uninjured controls. Methods: Gait biomechanics were collected in 26 uninjured controls (50% females; age, 22 ± 4 yr; body mass index, 23.9 ± 2.8 kg·m−2) and 26 individuals after ACLR (50% females; age, 22 ± 4 yr; body mass index, 24.2 ± 3.5 kg·m−2) at 6 and 12 months post-ACLR. ACLR-T1ρHigh (n = 9) and ACLR-T1ρLow (n = 17) groups were created based on 12-month post-ACLR T1ρ relaxation times using a k-means cluster analysis. Functional analyses of variance were used to compare KAM and KFM. Results: ACLR-T1ρHigh exhibited lesser KAM than ACLR-T1ρLow and uninjured controls 6 months post-ACLR. ACLR-T1ρLow exhibited greater KAM than uninjured controls 6 and 12 months post-ACLR. KAM increased in ACLR-T1ρHigh and decreased in ACLR-T1ρLow between 6 and 12 months, both groups becoming more similar to uninjured controls. There were scant differences in KFM between ACLR-T1ρHigh and ACLR-T1ρLow 6 or 12 months post-ACLR, but both groups demonstrated lesser KFM compared with uninjured controls. Conclusions: Associations between worse T1ρ profiles and increases in KAM may be driven by the normalization of KAM in individuals who initially exhibit insufficient KAM 6 months post-ACLR. [ABSTRACT FROM AUTHOR]

Introduction: The frontal plane knee moment (KAM1 and KAM2) derived from non-invasive three-dimensional gait analysis is a surrogate measure for knee joint load and of great interest in clinical and research settings. Many aspects can influence this measure either unintentionally or purposely in order to reduce the knee joint load to relieve symptoms and pain. All these aspects must be known when conducting a study or interpreting gait data for clinical decision-making.Methods: This systematic review was registered with PROSPERO (CRD42020187038). Pubmed and Web of Science were searched for peer-reviewed, original research articles in which unshod three-dimensional gait analysis was undertaken and KAM1 and KAM2 were included as an outcome variable. Two reviewers independently screened articles for inclusion, extracted data and performed a methodological quality assessment using Downs and Black checklist.Results: In total, 42 studies were included. Based on the independent variable investigated, these studies were divided into three groups: 1) gait modifications, 2) individual characteristics and 3) idiopathic orthopedic deformities. Among others, fast walking speeds (1) were found to increase KAM1; There were no sex-related differences (2) and genu valgum (3) reduces KAM1 and KAM2.Conclusion: While consistent use of terminology and reporting of KAM is required for meta-analysis, this review indicates that gait modifications (speed, trunk lean, step width), individual characteristics (body weight, age) and idiopathic orthopedic deformities (femoral or tibial torsion, genu valgum/varum) influence KAM magnitudes during walking. These factors should be considered by researchers when designing studies (especially of longitudinal design) or by clinicians when interpreting data for surgical and therapeutic decision-making. [ABSTRACT FROM AUTHOR]

As the modern golf swing has changed, the incidence of knee pain in professional golfers is increasing. For those with previous knee injuries, developing a golf-swing modification that reduces knee loading may be necessary to recover performance after injury. The purpose of this study was to test whether ball position modification reduces knee joint load in a golf swing. Thirteen male professional golfers participated in the study. Golf swings were captured using a three-dimensional motion capture system and two force platforms, with conditions for self-selected ball position and eight additional ball positions. Knee internal rotation and adduction moments were calculated. The length of one golf ball (4.27 cm) backward ball position (closer to the golfer) significantly reduced the peak internal rotation moment of the lead knee (-13.8%) (p < 0.001) and the length of one golf ball (4.27 cm) away from the target ball position significantly reduced the peak adduction moment of the lead knee (-11.5%) (p < 0.001) compared with that of the self-selected ball position. Based on these observations, we conclude that the backward ball position modification might be suggested for golfers with anterior cruciate ligament injuries, and the away from the target modification might be suggested for golfers with medial compartment knee osteoarthritis. [ABSTRACT FROM AUTHOR]

Knee adduction moment (KAM) is correlated with the progression of medial knee osteoarthritis (OA). Although a generic gait modification can reduce the KAM in some patients, it may have a reverse effect on other patients. We proposed the “decomposed ground reaction vector” (dGRV) model to 1) distinguish between the components of the KAM and their contribution to the first and second peaks and KAM impulse and 2) examine how medial knee OA, gait speed, and a brace influence these components. Using inverse dynamics as the reference, we calculated the KAM of 12 healthy participants and 12 patients with varus deformity and medial knee OA walking with/without a brace and at three speeds. The dGRV model divided the KAM into four components defined by the ground reaction force (GRF) and associated lever arms described with biomechanical factors related to gait modifications. The dGRV model predicted the KAM profile with a coefficient of multiple correlations of 0.98 ± 0.01. The main cause of increased KAM in the medial knee OA group, the second component (generated by the vertical GRF and mediolateral distance between the knee and ankle joint centers), was decreased by the brace in the healthy group. The first peak increased, and KAM impulse decreased with increasing velocity in both groups, while no significant change was observed in the second peak. The four-component dGRV model successfully estimated the KAM in all tested conditions. It explains why similar gait modifications produce different KAM reductions in subjects. Thus, more personalized gait rehabilitation, targeting elevated components, can be considered.

The relationship between knee moments and markers of knee osteoarthritis progression has not been examined in different knee osteoarthritis subtypes. The objective was to examine relationships between external knee moments during gait and tibiofemoral cartilage thickness in patients with nontraumatic and posttraumatic knee osteoarthritis. For this cross‐sectional study, participants with knee osteoarthritis were classified into two groups: nontraumatic (n = 22; mean age 60 years) and posttraumatic (n = 19; mean age 56 years, history of anterior cruciate ligament rupture). Gait data were collected with a three‐dimensional motion capture system sampled at 100 Hz and force plates sampled at 2000 Hz. External knee moments were calculated using inverse dynamics. Cartilage thickness was determined with magnetic resonance imaging (T1‐weighted, 3D sagittal gradient‐echo sequence). Linear regression analyses examined relationships between cartilage thickness with knee moments, group, and their interaction. A higher knee adduction moment impulse was negatively associated with medial to lateral cartilage thickness ratio (B = −1.97). This relationship differed between participants in the nontraumatic osteoarthritis group (r = −0.56) and posttraumatic osteoarthritis group (r = −0.30). A higher late stance knee extension moment was associated with greater medial femoral condyle cartilage thickness (B = −0.86) and medial to lateral cartilage thickness (B = −0.73). These relationships also differed between participants in the nontraumatic osteoarthritis group (r = −0.61 and r = −0.51, respectively) and posttraumatic osteoarthritis group (r = 0.10 and r = 0.25, respectively). Clinical Significance: The relationship between knee moments with tibiofemoral cartilage thickness differs between patients with nontraumatic and posttraumatic knee osteoarthritis. The potential influence of mechanical knee loading on articular cartilage may also differ between these subtypes. [ABSTRACT FROM AUTHOR]

Background: Previous literature suggests that patients treated with total ankle arthroplasty (TAA) versus ankle arthrodesis (AA) may have better function and lower risk for adjacent joint arthritis in the foot. Little is known on how these interventions affect proximal joints such as the knee. Questions: We sought to assess whether patients with TAA and AA exhibited altered biomechanics linked to the onset and progression of knee osteoarthritis (KOA). We used the knee adduction moment (KAM), a surrogate measure for the mechanical load experienced at the medial tibiofemoral compartment, because it is linked with the onset and progression of KOA. Methods: At a minimum of 2 years postoperatively, instrumented 3-dimensional walking gait was recorded in 10 TAA and 10 AA patients at self-selected walking speeds. TAA patients had either a Salto Talaris or INBONE prosthesis. Average first and second peak KAMs (Nm/kg), KAM impulse (Nm-s/kg), and range-of-motion (ROM, °) were calculated on both the affected and unaffected limbs for each patient. Results: There were no significant differences in the KAM's first and second peaks, impulse, or knee ROM in any plane between the unaffected and affected limbs, or between TAA and AA. Conclusion: TAA and AA may not meaningfully affect ipsilateral knee kinetics and KAMs in short-term follow-up. This study highlights the importance of continuing to study these parameters in larger cohorts of patients with longer follow-up to determine how our treatment of end-stage ankle arthritis may affect the incidence or progression of ipsilateral KOA. [ABSTRACT FROM AUTHOR]

Background: Knee braces and lateral wedge foot orthoses are two treatment options recommended for medial knee osteoarthritis, but the combination of both of them could further improve their effectiveness.Research Question: The aim was to evaluate whether the combination of lateral wedge foot orthoses with two types of knee brace enhances the biomechanical effects and pain relief during the stance phase of gait while maintaining comfort.Methods: Ten patients with medial knee osteoarthritis were fitted with a standard valgus brace, an unloader brace with valgus and external rotation functions, and 7° lateral wedge foot orthoses. The pain relief, comfort, kinematics and kinetics of the lower limb were measured during walking without orthotics, with the combined and with the isolated treatments.Results: The valgus and external rotation brace significantly reduced the knee adduction moment and allowed more knee flexion both in isolation and in combination to foot orthoses compared to the valgus brace or without treatment. Pain relief was not significant with the different orthotic treatment modalities. The valgus brace and combined treatment with either brace significantly increased the discomfort level, whereas the valgus and external rotation brace or foot orthoses in isolation did not induce significant discomfort.Significance: Amongst the tested orthotic treatment modalities, the valgus and external rotation brace obtained better biomechanical outcomes while maintaining comfort. The combined treatment with foot orthoses enhanced the effectiveness of the valgus brace, however foot orthoses may be unnecessary with the valgus and external rotation brace. [ABSTRACT FROM AUTHOR]

A high contact force between the medial femoral condyle and the tibial plateau is the primary cause of medial compartment knee osteoarthritis (OA). A high medial contact force (MCF) during gait has been shown to be correlated to both the knee adduction moment (KAM) and knee flexion/extension moment (KFM). In this study, we used OpenSim Moco to find gait kinematics that reduced the peaks of the KAM, without increasing the peaks of the KFM, which could potentially reduce the MCF and, hence, the progression of knee OA. We used gait data from four knee OA participants. Our simulations decreased both peaks of the KAM without increasing either peak of the KFM. We found that increasing the step width was the primary mechanism, followed by simulations of all participants to reduce the frontal plane lever arm of the ground reaction force vector about the knee, in turn reducing the KAM. Importantly, each participant simulation followed different patterns of kinematic changes to achieve this reduction, which highlighted the need for participant-specific gait modifications. Moreover, we were able to simulate emerging gait patterns within 15 min, enhancing the relevance and potential for the application of developed methods in clinical settings. [ABSTRACT FROM AUTHOR]

Altered gait could influence knee joint moment magnitudes and cumulative damage over time. Gait modifications have been shown to reduce knee loading in people with knee osteoarthritis during walking, although this has not been explored in multiple daily activities. Therefore, this study investigated the effect of different foot orientations on knee loading during multiple daily activities in people with and without knee osteoarthritis. Thirty people with knee osteoarthritis and twenty-nine without (control) performed walking, stair ambulation and sit-to-stand across a range of foot progression angles (neutral, toe-in, toe-out and preferred). Peak knee adduction moment, knee adduction moment impulse and knee pain were compared across a continuous range of foot orientations, between activities, and groups. Increased foot progression angle (more toe-in) reduced 1st peak knee adduction moment across all activities in both knee osteoarthritis and control (P < 0.001). There was a greater reduction in knee adduction moment in the control group during walking and stair ambulation (P ≤ 0.006), where the knee osteoarthritis group already walked preferably less toe-out than the control group. Under preferred condition, stair descent had the greatest knee loading and knee pain compared to other activities. Although increased foot progression angle (toward toe-in) appeared to be more effective in reducing knee loading for all activities, toe-in modification might not benefit stair ambulation. Future gait modification should likely be personalised to each patient considering the individual difference in preferred gait and knee alignment required to shift the loading medially or laterally. [ABSTRACT FROM AUTHOR]

This study aimed to identify the clinical and biomechanical factors of subjects with excessive foot pronation who are not responsive (i.e., "non-responders") to medially wedged insoles to increase knee adduction external moment. Ankle dorsiflexion range of motion, forefoot-shank alignment, passive hip stiffness, and midfoot passive resistance of 25 adults with excessive bilateral pronation were measured. Also, lower-limb angles and external moments were computed during walking with the participants using control (flat surface) and intervention insoles (arch support and 6° medial heel wedge). A comparison between "responders" (n = 34) and "non-responders" (n = 11) was conducted using discrete and continuous analyses. Compared with the responders, the non-responders had smaller forefoot varus (p = 0.014), larger midfoot passive internal torque peak (p = 0.005), and stiffness measured by the torsimeter (p = 0.022). During walking, non-responders had lower angle peaks for forefoot eversion (p = 0.001), external forefoot rotation (p = 0.037), rearfoot eversion (p = 0.022), knee adduction (p = 0.045), and external hip rotation (p = 0.022) and higher hip internal rotation angle peak (p = 0.026). Participants with small forefoot varus alignment, large midfoot passive internal torque, stiffness, small knee valgus, hip rotated internally, and foot-toed-in during walking did not modify the external knee adduction moment ("non-responders"). Clinicians are advised to interpret these findings with caution when considering the prescription of insoles. Further investigation is warranted to fully comprehend the response to insole interventions among individuals with specific pathologies, such as patellofemoral pain and knee osteoarthritis (OA). [ABSTRACT FROM AUTHOR]

Background: Using foot orthoses for managing medial knee osteoarthritis (MKOA) is common, although its effectiveness is in debate. Most orthoses are placed inside the shoe as a lateral wedged insole. Thus, most studies in this area have focused on the effect of insoles used with shoes. This study compared the effects of a lateral wedge with subtalar strap (combined insole) used while barefoot and lateral wedged insole fitted within sandal on pain, function and external knee adduction moment (EKAM) in patients with MKOA to consider which orthotic treatment is better. Methods: In this quasi-experimental pretest–posttest study, 29 participants with medial knee osteoarthritis were divided into two groups: (1) combined insole (n = 15) and (2) sandal (n = 14) groups. We recorded their gait while walking with and without orthoses using a motion analysis system. We evaluated their pain and performance with visual analog scale, Western Ontario and McMaster Universities Arthritis Index (WOMAC) questionnaire, 30 s chair stand, and Timed Up and Go functional tests. The pain and performance evaluations were repeated after one month. Results: The pain immediately decreased after walking with both orthoses (p < 0.001). There was no significant difference in EKAM results between the two orthoses. Pain and performance improved in both groups after a one month using the orthoses (p < 0.01). Conclusion: Both types of orthoses have similar effect and lead to better performance and less pain after 1 month. [ABSTRACT FROM AUTHOR]

• Replaced limb had lower knee extension moment than healthy limb in downhill walking. • Replaced limb had lower knee extension moment than non-replaced limb in downhill walking. • Knee extension moment increased across all slopes between 0° and 15° in total knee replacement patients. • Downhill walking may not be included in early stage rehabilitation after the surgery. The purpose of this study was to compare knee biomechanics of the replaced limb to the non-replaced limb of total knee replacement (TKR) patients and healthy controls during walking on level ground and on decline surfaces of 5°, 10°, and 15°. Twenty-five TKR patients and 10 healthy controls performed 5 walking trials on different decline slopes on a force platform and an instrumented ramp system. Two analyses of variance, 2 × 2 (limb × group) and 2 × 4 (limb × decline slope), were used to examine selected biomechanics variables. The replaced limb of TKR patients had lower peak loading-response and push-off knee extension moment than the non-replaced and the matched limb of healthy controls. No differences were found in loading-response and push-off knee internal abduction moments among replaced, non-replaced, and matched limb of healthy controls. The knee flexion range of motion, peak loading-response vertical ground reaction force, and peak knee extension moment increased across all slope comparisons between 0° and 15° in both the replaced and non-replaced limb of TKR patients. Downhill walking may not be appropriate to include in early stage rehabilitation exercise protocols for TKR patients. [Display omitted] [ABSTRACT FROM AUTHOR]

Background: Q-Factor (QF), or the inter-pedal width, in cycling is similar to step-width in gait. Although increased step-width has been shown to reduce peak knee abduction moment (KAbM), no studies have examined the biomechanical effects of increased QF in cycling at different workrates in healthy participants. Methods: A total of 16 healthy participants (8 males, 8 females, age: 22.4 ± 2.6 years, body mass index: 22.78 ± 1.43 kg/m2, mean ± SD) participated. A motion capture system and customized instrumented pedals were used to collect 3-dimensional kinematic (240 Hz) and pedal reaction force (PRF) (1200 Hz) data in 12 testing conditions: 4 QF conditions—Q1 (15.0 cm), Q2 (19.2 cm), Q3 (23.4 cm), and Q4 (27.6 cm)—under 3 workrate conditions—80 watts (W), 120 W, and 160 W. A 3 × 4 (QF × workrate) repeated measures of analysis of variance were performed to analyze differences among conditions (p < 0.05). Results: Increased QF increased peak KAbM by 47%, 56%, and 56% from Q1 to Q4 at each respective workrate. Mediolateral PRF increased from Q1 to Q4 at each respective workrate. Frontal-plane knee angle and range of motion decreased with increased QF. No changes were observed for peak vertical PRF, knee extension moment, sagittal plane peak knee joint angles, or range of motion. Conclusion: Increased QF increased peak KAbM, suggesting increased medial compartment loading of the knee. QF modulation may influence frontal-plane joint loading when using stationary cycling for exercise or rehabilitation purposes.

Background and Aim: The aim of this study was to investigate the effects of backward gait training protocol on knee adduction moment and impulse in male patients with medial knee osteoarthritis. Materials and Methods: This quasi-experimental study with a pretest-posttest design included two control groups (healthy and patient) and an experimental group (subjects with medial knee osteoarthritis). The subjects were 21 healthy men and 42 male patients with knee osteoarthritis who were divided into experimental and control groups according to the Kellgren and Lawrence radiologic scale and visual analogue scale. The experimental group performed backward gait training for six weeks. The dependent variables included 1st peak knee adduction moment, normalized 1st peak KAM, 2nd peak knee adduction moment and normalized 2nd peak KAM. A Vicon (130 Hz) motion analysis system with four T-Series cameras and two Kistler force plates (1000Hz) were used for data registration. Using Vicon Nexus 1.8.5 and polygon 4.1.2 softwares, data analysis was performed by paired sample t-test and one-way ANOVA (p0.05). However, before training significant differences were observe in knee adduction moment impulse between the healthy subjects and patients (P=0.014, P=0.004). After exercise we found decreased mean value for normalized knee adduction moment impulse in the experimental group compared to that in the healthy control group (p=0.067). Conclusion: Knee adduction moment impulse can be regarded as a predictive index with high sensitivity for evaluation of the severity of knee OA. Implementation of backward gait training protocol led to decreased knee adduction moment impulse in the experimental group.

Background and Aim:The aim of this study was to investigate the effects of backward gait training protocol on knee adduction moment and impulse in male patients with medial knee osteoarthritis.Materials and Methods:This quasi-experimental study with a pretest-posttest design included two control groups (healthy and patient) and an experimental group (subjects with medial knee osteoarthritis).The subjects were 21 healthy men and 42 male patients with knee osteoarthritis who were divided into experimental and control groups according to the Kellgren and Lawrence radiologic scale and visual analogue scale. The experimental group performed backward gait training for six weeks. The dependent variables included 1st peak knee adduction moment, normalized 1st peak KAM, 2nd peak knee adduction moment and normalized 2nd peak KAM. A Vicon (130 Hz) motion analysis system with four T-Series cameras and two Kistler force plates (1000Hz) were used for data registration. Using Vicon Nexus 1.8.5 and polygon 4.1.2 softwares, data analysis was performed by paired sample t-test and one-way ANOVA (p0.05).However, before training significant differences were observe in knee adduction moment impulse between the healthy subjects and patients (P=0.014, P=0.004). After exercise we found decreased mean value for normalized knee adduction moment impulse in the experimental group compared to that in the healthy control group (p=0.067).Conclusion:Knee adduction moment impulse can be regarded as a predictive index with high sensitivity for evaluation of the severity of knee OA. Implementation of backward gait training protocol led to decreased knee adduction moment impulse in the experimental group.

This study evaluated the effect of foot progression angle on the reduction in knee adduction moment caused by a lateral wedged insole during walking. Twenty healthy, young volunteers walked 10 m at their comfortable velocity wearing a lateral wedged insole or control flat insole in 3 foot progression angle conditions: natural, toe-out, and toe-in. A 3-dimensional rigid link model was used to calculate the external knee adduction moment, the moment arm of ground reaction force to knee joint center, and the reduction ratio of knee adduction moment and moment arm. The result indicated that the toe-out condition and lateral wedged insole decreased the knee adduction moment in the whole stance phase. The reduction ratio of the knee adduction moment and the moment arm exhibited a close relationship. Lateral wedged insoles decreased the knee adduction moment in various foot progression angle conditions due to decrease of the moment arm of the ground reaction force. Moreover, the knee adduction moment during the toe-out gait with lateral wedged insole was the smallest due to the synergistic effect of the lateral wedged insole and foot progression angle. Lateral wedged insoles may be a valid intervention for patients with knee osteoarthritis regardless of the foot progression angle. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine whether a lateral wedge insole reduces the external knee adduction moment during slope walking. Twenty young, healthy subjects participated in this study. Subjects walked up and down a slope using 2 different insoles: a control flat insole and a 7° lateral wedge insole. A three-dimensional motion analysis system and force plate were used to examine the knee adduction moment, the ankle valgus moment, and the moment arm of the ground reaction force to the knee joint center in the frontal plane. The lateral wedge insole significantly decreased the moment arm of the ground reaction force, resulting in a reduction of the knee adduction moment during slope walking, similar to level walking. The reduction ratio of knee adduction moment by the lateral wedge insole during the early stance of up-slope walking was larger than that of level walking. Conversely, the lateral wedge insole increased the ankle valgus moment during slope walking, especially during the early stance phase of up-slope walking. Clinicians should examine the utilization of a lateral wedge insole for knee osteoarthritis patients who perform inclined walking during daily activity, in consideration of the load on the ankle joint. [ABSTRACT FROM AUTHOR]

Featured Application: Knee osteoarthritis (OA) can be prevented using orthoses with actuators controlled using real-time biofeedback from wearable motion-sensors and multi-function exoskeletons and, incorporating integrated electro-magnetic stimulators may also enhance regenerative medicine treatments for knee OA. Knee osteoarthritis (OA) is a degenerative condition that critically affects locomotor ability and quality of life and, the condition is particularly prevalent in the senior population. The current review presents a gait biomechanics conceptual framework for designing active knee orthoses to prevent and remediate knee OA. Constant excessive loading diminishes knee joint articular cartilage and, therefore, measures to reduce kinetic stresses due to the fact of adduction moments and joint compression are an essential target for OA prevention. A powered orthosis enables torque generation to support knee joint motions and machine-learning-driven "smart systems" can optimise the magnitude and timing of joint actuator forces. Although further research is required, recent findings raise the possibility of exoskeleton-supported, non-surgical OA interventions, increasing the treatment options for this prevalent, painful and seriously debilitating disease. Combined with advances in regenerative medicine, such as stem cell implantation and manipulation of messenger ribonucleic acid (m-RNA) transcription, active knee orthoses can be designed to incorporate electro-magnetic stimulators to promote articular cartilage resynthesis. [ABSTRACT FROM AUTHOR]

• Radiographic measurements are significantly associated with gait kinetic data. • A knee adduction moment of 0.010 Nms/kg increases with 1° of mechanical tibiofemoral angle. • A knee adduction moment of 0.004 Nms/kg increases with 1° of ankle joint line orientation. • A mechanical tibiofemoral angle of 5.7° showed the highest discriminant validity. • An ankle joint line orientation of 7.5° showed the highest discriminant validity. Radiographic factors estimate the state of the static knee joint, and it is questionable how well these parameters reflect the dynamic knee condition. The external knee adduction moment (KAM) during gait is known to be a kinetic variable contributing to osteoarthritis progression. This study aims to investigate the effects of static radiographic parameters on the dynamic KAM during gait. Overall, 123 patients (mean age, 65.7 years; standard deviation, 8.1 years; 34 men and 89 women) were included. Seven radiographic parameters including the mechanical tibiofemoral angle (mTFA), Kellgren-Lawrence grade, and ankle joint line orientation (AJLO) were measured on radiographs, and the maximum KAM and KAM-time integral in the stance phase were obtained using three-dimensional gait analysis. The correlation and multiple regression analyses were performed for identifying significant radiographic measurements associated with the KAM. Most of the radiographic measurements correlated with the maximum KAM and KAM-time integral. As a result of multiple regression analysis, the mTFA (p < 0.001) and AJLO (p = 0.003) were identified as significant factors associated with the KAM-time integral (R2 = 0.450); the mTFA (p < 0.001) and AJLO (p = 0.003) were identified as a significant factor associated with the maximum KAM (R2 = 0.352) in multiple regression analysis. The discriminant validity of KAM was highest at varus 5.7 degree of the mTFA and 7.5 degree of the AJLO. The mTFA and AJLO were significantly associated with the KAM. However, to be used as a surgical indication for corrective osteotomy, a longitudinal study is needed to validate whether the mTFA and AJLO values directly cause osteoarthritis progression as we have suggested. III. [ABSTRACT FROM AUTHOR]