The knee adduction moment during gait in subjects with knee osteoarthritis is more closely correlated with static alignment than radiographic disease severity, toe out angle and pain.

This study tested whether the peak external knee adduction moments during walking in subjects with knee osteoarthritis (OA) were correlated with the mechanical axis of the leg, radiographic measures of OA severity, toe out angle or clinical assessments of pain, stiffness or function. Gait analysis was performed on 62 subjects with knee OA and 49 asymptomatic control subjects (normal subjects). The subjects with OA walked with a greater than normal peak adduction moment during early stance (p = 0.027). In the OA group, the mechanical axis was the best single predictor of the peak adduction moment during both early and late stance (R = 0.74, p < 0.001). The radiographic measures of OA severity in the medial compartment were also predictive of both peak adduction moments (R = 0.43 to 0.48, p < 0.001) along with the sum of the WOMAC subscales (R = -0.33 to -0.31, p < 0.017). The toe out angle was predictive of the peak adduction moment only during late stance (R = -0.45, p < 0.001). Once mechanical axis was accounted for, other factors only increased the ability to predict the peak knee adduction moments by 10 18%. While the mechanical axis was indicative of the peak adduction moments, it only accounted for about 50% of its variation, emphasizing the need for a dynamic evaluation of the knee joint loading environment. Understanding which clinical measures of OA are most closely associated with the dynamic knee joint loads may ultimately result in a better understanding of the disease process and the development of therapeutic interventions.     

Foot progression angle and the knee adduction moment: a cross-sectional investigation in knee osteoarthritis

OBJECTIVE: To test the hypothesis that an association exists between the characteristics of the knee adduction moment and foot progression angle (FPA) in asymptomatic individuals and those with mild to moderate and severe knee osteoarthritis (OA). DESIGN: Fifty asymptomatic individuals, 46 patients with mild to moderate and 44 patients with severe knee OA were recruited. Maximum knee adduction moment during late stance and principal component analysis (PCA) were used to describe the knee adduction moment captured during gait. Multiple regression models were used for each of the three group assignments to analyze the association between the independent variables and the knee adduction moment. RESULTS: FPA explained a significant amount of the variability associated with the shape of the knee adduction moment waveform for the asymptomatic and mild to moderate groups (P<0.05), but not for the severe group (P>0.05). Walking velocity alone explained significant variance associated with the shape of the knee adduction moment in the severe OA group (P<0.05). CONCLUSION: A toe out FPA was associated with altered knee adduction moment waveform characteristics, extracted using PCA, in asymptomatic individuals and those with mild to moderate knee OA only. These findings are directly implicated in medial knee compartment loading. This relationship was not evident in those with severe knee OA.     

The knee adduction moment during gait is associated with the adduction angle measured during computer-assisted total knee arthroplasty

Computer-assisted surgery can be used to measure 3-dimensional knee function during arthroplasty surgery; however, it is unknown if the movement of the knee measured during surgery is related to the in vitro, dynamic state of the knee joint, specifically the knee adduction moment during gait, which has been related to implant migration. The purpose of this study was to determine if the preoperative adduction moment is correlated with the knee abduction/adduction angle measured intraoperatively. A statistically significant correlation was found between the mean (r(2) = 0.59; P = .001) and peak (r(2) = 0.53; P = .003) preoperative knee adduction moment and the mean abduction/adduction angle measured intraoperatively. The association found in this study suggests the potential for incorporating functional information that relates to surgical outcome into surgical decision making using computer-assisted surgery.     

Control of frontal plane knee laxity during gait in patients with medial compartment knee osteoarthritis

OBJECTIVE: Patients with medial compartment knee osteoarthritis (OA) adopt an abnormal gait pattern, and often develop frontal plane laxity at the knee. The purpose of this study was to quantify the extent of frontal plane knee joint laxity in patients with medial knee OA and genu varum and to assess the effect of joint laxity on knee joint kinetics, kinematics and muscle activity during gait. DESIGN: Twelve subjects with genu varum and medial compartment knee osteoarthritis (OA group) and 12 age-matched uninjured subjects underwent stress radiography to determine the presence and magnitude of frontal plane laxity. All subjects also went through gait analysis with surface electromyography of the medial and lateral quadriceps, hamstrings, and gastrocnemius to calculate knee joint kinematics and kinetics and co-contraction levels during gait. RESULTS: The OA group showed significantly greater knee instability (P = 0.002), medial joint laxity (P = 0.001), greater medial quadriceps-medial gastrocnemius (VMMG) co-contraction (P = 0.043), and greater knee adduction moments (P = 0.019) than the control group. Medial joint laxity contributed significantly to the variance in both VMMG and the knee adduction moment during early stance. CONCLUSION: The presence of medial laxity in patients with knee OA is likely contributing to the altered gait patterns observed in those with medial knee OA. Greater medial co-contraction and knee adduction moments bodes poorly for the long-term integrity of the articular cartilage, suggesting that medial joint laxity should be a focus of interventions aimed at slowing the progression of disease in individuals with medial compartment knee OA.     

Proximal gait adaptations in medial knee OA

The purpose of this study was to examine interlimb differences in gait kinematics and kinetics in patients with symptomatic medial knee OA. The main objective was to identify hip joint movement strategies that might lower the knee adduction moment and also compensate for decreased knee flexion during weight acceptance. Gait analysis was performed on 32 patients with moderate medial compartment knee OA. Kinetic and kinematic data were calculated and side‐to‐side comparisons made. Radiographs were used to identify frontal plane alignment. No interlimb difference in the peak knee adduction moment was found (p = 0.512), whereas a greatly reduced hip adduction moment was seen on the involved side (p < 0.001) during the early part of stance. The involved limb flexed significantly less and hip and knee flexion moments were smaller compared to the uninvolved side. Gait adaptations involving a lateral sway of the trunk may successfully lead to relatively lower ipsilateral knee adduction moments, and would further be reflected by a lower adduction moment at the hip. Subjects did not compensate for less knee flexion by any dynamic means, and likely experience a resulting higher joint impact. These gait adaptations may have implications with respect to development of weakness of the ipsilateral hip musculature and progression of multiarticular OA. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:78–83, 2009     

Abnormal loading of the hip and knee joints in unilateral hip osteoarthritis persists two years after total hip replacement

A total hip replacement (THR) is a common and routine procedure to reduce pain and restore normal activity. Gait analysis can provide insights into functional characteristics and dynamic joint loading situation not identifiable by clinical examination or static radiographic measures. The present prospective longitudinal study tested whether 2 years after surgery a THR would restore dynamic loading of the knee and hip joints in the frontal plane to normal. Instrumented gait analysis was performed shortly before surgery and approximately 2 years after THR on 15 unilateral hip osteoarthritis (OA) patients. 15 asymptomatic matched individuals were recruited as healthy controls. Results showed that abnormal joint loading persisted 2 years after THR. The 2nd external knee adduction moment in terminal stance in the affected (?34%, p = 0.002, d = 1.22) and non‐affected limb (?25%, p = 0.035, d = 0.81) was lower compared to controls and thus indicated a shift in the knee joint load distribution from medial to lateral. A correlation analysis revealed that a smaller hip range of motion explained 46% of 2nd knee adduction moment alterations. In contrast, the 2nd external hip adduction moment in terminal stance was postoperatively higher in the affected (+22%, p = 0.007, d = 1.04) and non‐affected limb (+22%, p = 0.005, d = 1.05). Here, 51% of 2nd hip adduction moment alterations can be explained with a greater hip adduction angle. Patients with a THR may therefore be at higher risk for abnormal joint loading and thus for the development of OA in other joints of the lower extremities. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2167–2177, 2018.

     

An examination of the knee function during gait in children with myelomeningocele

In this retrospective study, 37 patients with myelomeningocele who had undergone gait analysis were examined. Patients were divided into groups based on the level of involvement (29 sides: L4; 26 sides: L5; 19 sides: S1-2). Results showed increased knee flexion and associated knee extensor moments with increasing level of neurologic involvement. The mean coronal plane knee position in stance was normal in all groups and not related to coronal plane knee moment. However, there was an increased incidence of a net knee adductor moment in stance with increasing involvement (mean, 0.02 +/-0.18 N.m/kg for the L4 group). The presence of a visual valgus thrust based on video records was not reliable in predicting an abnormal knee coronal plane moment. An abnormal knee adductor moment in stance was most highly related to coronal plane trunk motion (r = -0.62) and not tibial torsion (r = -0.340). Increased transverse plane range of motion of the knee was most highly related to transverse plane trunk motion (r = 0.67).     

Early tibial subchondral bone texture changes after arthroscopic partial meniscectomy in knees without radiographic OA: A prospective cohort study

Arthroscopic partial meniscectomy (APM) may lead to changes in underlying trabecular bone (TB) structure potentially promoting the development of knee joint osteoarthritis. Our aim was to investigate if there are early changes occurring in tibial subchondral TB texture in the leg undergoing medial APM compared with the unoperated non-injured contra-lateral leg. The bone texture was measured as the medial-to-lateral ratio of fractal dimensions (FD) calculated for regions selected on weight-bearing anteroposterior tibiofemoral x-rays. Twenty-one subjects before and 12 months after APM were included from 374 patients scheduled for unilateral medial APM. The medial-to-lateral ratio was calculated for horizontal, vertical, and roughest FDs respectively. Higher FD means higher bone roughness. Each FD was calculated over a range of scales using a variance orientation transform method. Mean values of medial-to-lateral horizontal FD calculated for APM knees at follow-up were higher than those at baseline. For unoperated knees the values were lower. The difference in the horizontal FD change from baseline to follow-up between APM and contra-lateral legs was 0.028 (95% CI, 0.004-0.052). The bone roughness changes may reflect the increase in peak knee adduction moment (KAM) and KAM impulse during walking reported for the same cohort in a previous study. They may also reflect early signs of osteoarthritis development and thus, we speculate that individuals with increased bone texture roughness ratio after APM might be at higher risk of knee osteoarthritis development.     

Lateral trunk lean explains variation in dynamic knee joint load in patients with medial compartment knee osteoarthritis

OBJECTIVE: To test the hypothesis that selected gait kinematics, particularly lateral trunk lean, observed in patients with medial compartment knee osteoarthritis explain variation in dynamic knee joint load. METHOD: In this cross-sectional observational study, 120 patients with radiographically confirmed varus gonarthrosis underwent three-dimensional gait analysis at their typical walking speed. We used sequential (hierarchical) linear regression to examine the amount of variance in dynamic knee joint load (external knee adduction moment) explained by static lower limb alignment (mechanical axis angle) and gait kinematics determined a priori based on their proposed effect on knee load (walking speed, toe-out angle, and lateral trunk lean angle). RESULTS: Approximately 50% of the variation in the first peak external knee adduction moment was explained by mechanical axis angle (25%), Western Ontario and McMaster Universities Osteoarthritis Index pain score (1%), gait speed (1%), toe-out angle (12%), and lateral trunk lean angle (13%). There was no confounding or interaction with Kellgren and Lawrence grade of severity. CONCLUSIONS: Gait kinematics, particularly lateral trunk lean, explain substantial variation in dynamic knee joint load in patients with medial compartment knee osteoarthritis. While largely ignored in previous gait studies, the effect of lateral trunk lean should be considered in future research evaluating risk factors and interventions for progression of knee osteoarthritis.     

Lower limb alignment and foot angle are related to stance phase knee adduction in normal subjects: A critical analysis of the reliability of gait analysis data

Anatomic and mechanical factors that affect loading in the knee joint can contribute to pathologic changes seen at the knee in degenerative joint disease and should be considered in treatment planning. The objectives of this study were to quantify the relationships between the alignment of the bones of the lower extremity, foot progression angle, and knee adduction moment, and to determine the reliability of our gait measurements. Gait analysis and complete radiographic evaluation of the lower extremity were performed on 11 healthy subjects. The gait measurements were recorded with an optoelectronic digitizer and a multicomponent force plate. The subjects who had radiographic measurements indicative of varus alignment of the lower extremity had statistically higher peaks in knee adduction moment in early stance. Conversely, those with valgus alignment of the lower extremity had statistically lower peaks in knee adduction moment in early stance. The subjects who had a large toe-out angle and low ankle inversion moment peaks in late stance had significantly lower peaks in knee adduction moment in late stance. These significant (low to moderate) correlations suggest that the limbs with more valgus alignment and those with a toe-out gait exhibited a reduced peak adduction moment at the knee. To verify the reproducibility of the data, gait analysis testing was performed on each lower limb on 2 separate days for each subject. Analysis of variance showed that there was no significant difference between test limbs or test days for each subject. Our results suggest that the alignment of the lower limb and the foot progression angle, which can be readily measured in a clinical setting, can serve as predictors of knee joint loading in healthy individuals. These findings may have important implications for both surgical and nonsurgical treatment of abnormalities of the knee joint.     

The effect of a subject-specific amount of lateral wedge on knee mechanics in patients with medial knee osteoarthritis.

We examined if a subject-specific amount of lateral wedge added to a foot orthosis could alter knee mechanics to potentially reduce the progression of knee osteoarthritis in patients with medial knee osteoarthritis. Twenty individuals with medial knee osteoarthritis (>/=2 Kellgren Lawrence grade) were prescribed a custom laterally wedged foot orthotic device. The prescribed wedge amount was the minimal wedge amount that provided the maximum amount of pain reduction during a lateral step-down test. Following an accommodation period, all subjects returned to the laboratory for a gait analysis. Knee mechanics were collected as the subjects walked at an intentional walking speed. Walking in the laterally wedged orthotic device significantly reduced the peak adduction moment during early stance (p < 0.01) compared to the nonwedged device. Similarly, the wedged orthotic device significantly reduced the knee adduction excursion from heel strike to peak adduction (p < 0.01) compared to the nonwedged device. No differences in the peak adduction moment during propulsion or peak adduction during stance were observed between the orthotic conditions. A subject-specific laterally wedged orthotic device was able to reduce the peak knee adduction moment during early stance, which is thought to be associated with the progression of knee osteoarthritis. Previous studies on this device have reported issues associated with foot discomfort when using wedge amounts >7 degrees; however, no such issues were reported in this study. Therefore, providing a custom laterally wedged orthotic device may potentially increase compliance while still potentially reducing disease progression.     

The effect of different types of insoles or shoe modifications on medial loading of the knee in persons with medial knee osteoarthritis: a randomised trial

Many conservative treatments exist for medial knee osteoarthritis (OA) which aims to reduce the external knee adduction moment (EKAM). The objective of this study was to determine the difference between different shoes and lateral wedge insoles on EKAM, knee adduction angular impulse (KAAI), external knee flexion moment, pain, and comfort when walking in individuals with medial knee OA. Seventy individuals with medial knee OA underwent three‐dimensional walking gait analysis in five conditions (barefoot, control shoe, typical wedge, supported wedge, and mobility shoe) with pain and comfort recorded concurrently. The change in EKAM, KAAI, external knee flexion moment, pain, and comfort were assessed using multiple linear regressions and pairwise comparisons. Compared with the control shoe, lateral wedge insoles and barefoot walking significantly reduced early stance EKAM and KAAI. The mobility shoe showed no effect. A significant reduction in latter stance EKAM was seen in the lateral wedge insoles compared to the other conditions, with only the barefoot condition reducing the external knee flexion moment. However, the mobility shoe showed significant immediate knee pain reduction and improved comfort scores. Different lateral wedge insoles show comparable reductions in medial knee loading and in our study, the mobility shoe did not affect medial loading. © 2015 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. J Orthop Res 33:1646–1654, 2015.     

Correlation between the knee adduction torque and medial contact force for a variety of gait patterns.

The external knee adduction torque has been proposed as a surrogate measure for medial compartment load during gait. However, a direct link between these two quantities has not been demonstrated using in vivo measurement of medial compartment load. This study uses in vivo data collected from a single subject with an instrumented knee implant to evaluate this link. The subject performed five different overground gait motions (normal, fast, slow, wide, and toe-out) with simultaneous collection of instrumented implant, video motion, and ground reaction data. For each trial, the knee adduction torque was measured externally while the total axial force applied to the tibial insert was measured internally. Based on data collected from the same subject performing treadmill gait under fluoroscopic motion analysis, a regression equation was developed to calculate medial contact force from the implant load cell measurements. Correlation analyses were performed for the stance phase and entire gait cycle to quantify the relationship between the knee adduction torque and both the medial contact force and the medial to total contact force ratio. When the entire gait cycle was analyzed, R(2) for medial contact force was 0.77 when all gait trials were analyzed together and between 0.69 and 0.93 when each gait trial was analyzed separately (p < 0.001 in all cases). For medial to total force ratio, R(2) was 0.69 for all trials together and between 0.54 and 0.90 for each trial separately (p < 0.001 in all cases). When only the stance phase was analyzed, R(2) values were slightly lower. These results support the hypothesis that the knee adduction torque is highly correlated with medial compartment contact force and medial to total force ratio during gait.     

Changes in gait velocity, mean knee flexion in stance, body mass index, and popliteal angle with age in ambulatory children with cerebral palsy

BACKGROUND: The purpose of this study was to explore changes in body mass index (BMI), gait velocity, mean knee flexion in stance, and popliteal angle with age in ambulatory children with cerebral palsy. METHODS: A cross-sectional sample of 188 ambulatory children with cerebral palsy Gross Motor Function Classification System II or III who had a motion analysis evaluation. Subjects had no previous surgical interventions and were between the ages of 4 and 21. Velocity was normalized to limb length, and BMI was converted to age-adjusted percentile scores (BMI-a). RESULTS: For GMFCS level II children, age and normalized velocity demonstrated a moderate and significant relationship (r = -0.4; P = 0.000). Age explained 20% of the variance in normalized velocity (P = 0.000). Weak but significant relationships were found between mean knee flexion in stance and normalized velocity (r = -0.3; P = 0.000) and popliteal angle and age (r = 0.3; P < 0.002). For GMFCS level III children, the following variables demonstrated a weak but significant association: normalized velocity and BMI-a (r = 0.3; P < 0.006), popliteal angle, and mean knee flexion in stance (r = 0.3; P < 0.022). Age was not associated with velocity, mean knee flexion in stance, BMI-a, or popliteal angle. CONCLUSIONS: For GMFCS level II children, as age increases, there is a slight decrease in normalized velocity, and with decreasing normalized velocity, there is slightly increased mean knee flexion in stance. For GMFCS level III children, age was not associated with slower velocities, increased mean knee flexion in stance, or increased popliteal angle. Increased BMI-a was not associated with slower gait velocities or increased mean knee flexion in stance. Increasing BMI-a was not associated with increasing age.     

Increased knee joint loads during walking are present in subjects with knee osteoarthritis

OBJECTIVE: This study tests the hypothesis that the peak external knee adduction moment during gait is increased in a group of ambulatory subjects with knee osteoarthritis (OA) of varying radiographic severity who are being managed with medical therapy. Tibiofemoral knee OA more commonly affects the medial compartment. The external knee adduction moment can be used to assess the load distribution between the medial and lateral compartments of the knee joint. Additionally, this study tests if changes in the knee angles, such as a reduced midstance knee flexion angle, or reduced sagittal plane moments previously identified by others as load reducing mechanisms are present in this OA group. DESIGN: Thirty-one subjects with radiographic evidence of knee OA and medial compartment cartilage damage were gait tested after a 2-week drug washout period. Thirty-one normal subjects (asymptomatic control subjects) with a comparable age, weight and height distribution were also tested. Significant differences in the sagittal plane knee motion and peak external moments between the normal and knee OA groups were identified using t tests. RESULTS: Subjects with knee OA walked with a greater than normal peak external knee adduction moment (P=0.003). The midstance knee flexion angle was not significantly different between the two groups (P=0.625) nor were the peak flexion and extension moments (P> 0.037). CONCLUSIONS: Load reducing mechanisms, such as a decreased midstance knee flexion angle, identified by others in subjects with endstage knee OA or reduced external flexion or extension moments were not present in this group of subjects with knee OA who were being managed by conservative treatment. The finding of a significantly greater than normal external knee adduction moment in the knee OA group lends support to the hypothesis that an increased knee adduction moment during gait is associated with knee OA.     

X-ray knee as a screening tool for osteoporosis

Cortical thickness (Cor-Th) of tibia varies considerably on X-ray knees. It was hypothesized that Cor-Th can be used for preliminary prediction of BMD. Ninety nine patients underwent a digital X-ray left knee fixed flexion PA view with an external calibration scale attached to X-ray plate and BMD by DXA using GE lunar machine (Madison, Wisconsin.). Cor-Th was measured at 5 selected levels (A,B,C,D, and E) ranging from 5-7 cm below the tibial plateau on its medial aspect. T-scores were recorded for BMD at AP spine, left forearm and left femur. Cor-Th of tibia at each level significantly correlated with each site of BMD measurement namely AP spine, left femur and left forearm. This correlation varied in the range from 0.241 to 0.426. For AP spine, it was maximum at level C (r=0.347, p<0.001) whereas for left femur and forearm sites, it was maximum at level B (r=0.426 &r=0.373 respectively, p<0.001). The correlation of Cor-Th with BMD varied with age. Above 56 years of age, Cor-Th at each level significantly correlated to BMD at each site. Medial tibial cortical thickness, 6 cm (level C) below tibial plateau can be used as preliminary predictor of patients who need a DXA scan.     

Kinematics of the ACL-deficient canine knee during gait: serial changes over two years.

The ACL-deficient dog is a model for investigating the development and progression of mechanically driven osteoarthrosis of the knee. ACL loss creates dynamic instability in the ACL-deficient knee which presumably leads to progressive joint degeneration, but the nature of this instability over the time course of disease development is not well understood. The goal of this study was to characterize three-dimensional motion of the canine knee during gait, before and serially for two years after ACL transection. Canine tibial-femoral kinematics were assessed during treadmill gait before and serially for two years after ACL transection (ACL-D group; 18 dogs) or sham transection (ACL-I group; five dogs). Kinematic data was collected at 250 frames/s using a biplane video-radiographic system. Six degree-of-freedom motions of the tibia relative to the femur were calculated, and values immediately prior to pawstrike as well as the maximum, minimum, midpoint and range of motion during early/mid stance were extracted. Between-group differences relative to baseline (pre-transection) values, as well as changes over time post-transection, were determined with a repeated-measures ANCOVA. In the ACL-D group, peak anterior tibial translation (ATT) increased by 10 mm (p < 0.001), and did not change over time (p=0.76). Pre-pawstrike ATT was similar to ACL-intact values early on (2-4 months) but then increased significantly over time, by 3.5 mm (p < 0.001). The range of ab/adduction motion nearly doubled after ACL loss (from 3.3 degrees to 6.1 degrees). The magnitude (midpoint) of knee adduction also increased significantly over time (mean increase 3.0 degrees; p = 0.036). All changes occurred primarily between 6 and 12 months. There were no significant differences between groups in the transverse plane, and no significant changes over time in the ACL-I group. In summary, peak anterior tibial translation and coronal-plane instability increased immediately after ACL loss, and did not improve with time. ATT just prior to pawstrike and mean knee adduction throughout stance became progressively more abnormal with time, with the greatest changes occurring between 6 and 12 months after ACL transection. This may be due to overload failure of secondary restraints such as the medial meniscus, which has been reported to fail in a similar timeframe in the ACL-deficient dog. The relationships between these complex mechanical alterations and the rate of OA development/progression are currently under investigation.     

Longitudinal changes in knee gait mechanics between 2 and 8 years after anterior cruciate ligament reconstruction

The purpose of this study was to longitudinally investigate changes in knee joint kinematics and kinetics from 2 to 8 years post‐ACLR. Seventeen subjects with primary unilateral transtibial ACLR performed bilateral gait analysis approximately 2 years and 8 years post‐ACLR. Seventeen matched healthy control subjects were also analyzed. Kinematic and kinetic comparisons between the ACLR and contralateral limbs over time were completed using a 2 × 2 (time, limb) repeated‐measures ANOVA. Unpaired Student's t‐tests were used to compare the ACLR and contralateral kinematics and kinetics to the control group. The ACLR and contralateral limbs had similar gait changes over time. Kinetic changes over time included a reduction in first (p = 0.048) and second (p < 0.001) peak extension moments, internal rotation moment (p < 0.001), adduction moment (first peak: p = 0.002, second peak: p = 0.009, impulse: p = 0.004) and an increase in peak knee flexion moment (p = 0.002). Kinematic changes over time included increases in peak knee flexion angle in the first half of stance (p = 0.026), minimum knee flexion angle in the second half of stance (p < 0.001), and average external rotation angle during stance (p = 0.007), and a reduction in average anterior femoral displacement during stance (p = 0.006). Comparison to healthy controls demonstrated improvement in some gait metrics over time. The results demonstrated longitudinal changes from 2 to 8 years after ACLR in knee joint kinetics and kinematics that have been related to clinical outcome after ACLR and the progression of knee OA, and support future larger and comprehensive investigations into long‐term changes in joint mechanics in the ACLR population. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1478–1486, 2018.

     

In healthy subjects without knee osteoarthritis, the peak knee adduction moment influences the acute effect of shoe interventions designed to reduce medial compartment knee load.

The purpose of this study was to evaluate shoe sole material stiffness changes and angle changes that are intended to reduce the peak knee adduction moment during walking. Fourteen physically active adults were tested wearing their personal shoes (control) and five intervention pairs, two with stiffness variations, two with angle variations, and a placebo shoe. The intervention shoes were evaluated based on how much they reduced the peak knee adduction moment compared to the control shoe. An ANOVA test was used to detect differences between interventions. Linear regression analysis was used to determine a relationship between the magnitude of the knee adduction moment prior to intervention and the effectiveness of the intervention in reducing the peak knee adduction moment. Peak knee adduction moments were reduced for the altered stiffness and altered angle shoes (p < 0.010), but not for the placebo shoe (p = 0.363). Additionally, linear regression analysis showed that subjects with higher knee adduction moments prior to intervention had larger reductions in the peak knee adduction moment (p < 0.010). These results demonstrate that shoe sole stiffness and angle interventions can be used to reduce the peak knee adduction moment and that subjects with initially higher peak knee adduction moments have higher reductions in their peak knee adduction moments.     

Verification of biomechanical factors of gait related to medial knee loading in patients 6 Months after total knee arthroplasty

BackgroundThe knee adduction moment (KAM) is considered an index for estimating the knee mechanical load, and increased KAM peak and KAM impulse are related to increased medial knee load and progression of knee joint degeneration. We aimed to verify the biomechanical factors of gait related to medial knee loading in patients 6 months after TKA.MethodsThirty-nine women who underwent TKA were enrolled. A three-dimensional gait analysis was performed 6 months postoperatively to generate data on the lower limb joint angle, moment, and power at the backward component (braking phase) and forward component (propulsion phase) peaks of the ground reaction force. Medial knee loading was evaluated using the time-integrated value of KAM during the stance period (KAM impulse). The higher the value of the KAM impulse, the higher the medial knee joint load. The relationships between the KAM impulse and the data for biomechanical factors were evaluated using partial correlation analysis with gait speed as a control factor.ResultsIn the braking phase, the KAM impulse positively correlated with the knee adduction angle (r = 0.377) and negatively correlated with the toe-out angle (r = −0.355). The KAM impulse positively correlated with the knee adduction angle (r = 0.402), the hip flexion moment (r = 0.335), and the hip adduction moment (r = 0.565) and negatively correlated with the toe-out angle (r = −0.357) in the propulsive phase.ConclusionThe KAM impulse 6 months after TKA was related to the knee adduction angle, hip flexion moment, hip adduction moment, and toe-out angle. These findings may provide fundamental data for controlling variable medial knee joint load after TKA and implementing patient management strategies to ensure implant durability.