Longitudinal Changes in the Total Knee Joint Moment After Anterior Cruciate Ligament Reconstruction Correlate With Cartilage Thickness Changes

This study investigated associations between changes in the total joint moment (TJM) at the knee and changes in cartilage thickness after anterior cruciate ligament reconstruction (ACLR). Seventeen subjects (five males; age: 29.6 ± 7.3 years) with unilateral ACLR underwent gait analysis and magnetic resonance imaging at baseline (2.2 ± 0.3 years post‐ACLR) and at long‐term follow‐up (7.7 ± 0.7 years post‐ACLR). Knee loading was assessed using the TJM, and differences in loading were analyzed using repeated measures analysis of variance. Pearson correlation coefficients assessed associations between changes in TJM and changes in (medial‐to‐lateral) M/L femoral cartilage thickness ratios in the ACLR limb. Bilaterally, there was no significant change in the magnitude of the TJM first peak (TJM1), however, there was a significant increase in the percent contribution of the knee flexion moment (KFM) (p < 0.001) and decrease in the percent contribution of the knee adduction moment (KAM) to TJM1 (p < 0.001). The change in the percent contributions of KFM and KAM to TJM1 were associated with changes in M/L femoral cartilage thickness in the ACLR limb. Specifically, subjects with smaller increases in KFM contribution (R = 0.521, p = 0.032) and smaller decreases in KAM contribution (R = ?0.521, p = 0.032) had a reduction in the M/L ratio in the central femoral subregion over the follow‐up period, with similar trends in the external femoral subregion. The study results provide new insight into changes in the loading environment at the knee joint prospectively following ACL reconstruction and give evidence that there are modifiable gait metrics that are associated with cartilage changes after ACLR. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1546–1554, 2019.     

Effect of center of pressure modulation on knee adduction moment in medial compartment knee osteoarthritis

The knee adduction moment (KAM) provides a major contribution to the elevated load in the medial compartment of the knee. An abnormally high KAM has been linked with the progression of knee osteoarthritis (OA). Footwear‐generated biomechanical manipulations reduce the magnitude of this moment by conveying a more laterally shifted trajectory of the foot's center of pressure (COP), reducing the distance between the ground reaction force and the center of the knee joint, thus lowering the magnitude of the torque. We sought to examine the outcome of a COP shift in a cohort of female patients suffering from medial knee OA. Twenty‐two female patients suffering from medial compartment knee OA underwent successive gait analysis testing and direct pedobarographic examination of the COP trajectory with a foot‐worn biomechanical device allowing controlled manipulation of the COP. Modulation of the COP coronal trajectory from medial to lateral offset resulted in a significant reduction of the KAM. This trend was demonstrated in subjects with mild‐to‐moderate OA and in patients suffering from severe stages of the disease. Our results indicate that controlled manipulation of knee coronal kinetics in individuals suffering from medial knee OA can be facilitated by customized COP modification. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1668–1674, 2011     

Decreased knee adduction moment does not guarantee decreased medial contact force during gait

Excessive contact force is believed to contribute to the development of medial compartment knee osteoarthritis. The external knee adduction moment (KAM) has been identified as a surrogate measure for medial contact force during gait, with an abnormally large peak value being linked to increased pain and rate of disease progression. This study used in vivo gait data collected from a subject with a force‐measuring knee implant to assess whether KAM decreases accurately predict corresponding decreases in medial contact force. Changes in both quantities generated via gait modification were analyzed statistically relative to the subject's normal gait. The two gait modifications were a “medial thrust” gait involving knee medialization during stance phase and a “walking pole” gait involving use of bilateral walking poles. Reductions in the first (largest) peak of the KAM (32–33%) did not correspond to reductions in the first peak of the medial contact force. In contrast, reductions in the second peak and angular impulse of the KAM (15–47%) corresponded to reductions in the second peak and impulse of the medial contact force (12–42%). Calculated reductions in both KAM peaks were highly sensitive to rotation of the shank reference frame about the superior–inferior axis of the shank. Both peaks of medial contact force were best predicted by a combination of peak values of the external KAM and peak absolute values of the external knee flexion moment (R² = 0.93). Future studies that evaluate the effectiveness of gait modifications for offloading the medial compartment of the knee should consider the combined effect of these two knee moments. Published by Wiley Periodicals, Inc. J Orthop Res 28:1348–1354, 2010     

Six‐week gait retraining program reduces knee adduction moment,reduces pain,and improves function for individuals with medial compartment knee osteoarthritis

This study examined the influence of a 6‐week gait retraining program on the knee adduction moment (KAM) and knee pain and function. Ten subjects with medial compartment knee osteoarthritis and self‐reported knee pain participated in weekly gait retraining sessions over 6 weeks. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and a 10‐point visual‐analog pain scale score were measured at baseline, post‐training (end of 6 weeks), and 1 month after training ended. Gait retraining reduced the first peak KAM by 20% (p < 0.01) post‐training as a result of a 7° decrease in foot progression angle (i.e., increased internal foot rotation), compared to baseline (p < 0.01). WOMAC pain and function scores were improved at post‐training by 29% and 32%, respectively (p < 0.05) and visual‐analog pain scale scores improved by two points (p < 0.05). Changes in WOMAC pain and function were approximately 75% larger than the expected placebo effect (p < 0.05). Changes in KAM, foot progression angle, WOMAC pain and function, and visual‐analog pain score were retained 1 month after the end of the 6‐week training period (p < 0.05). These results show that a 6‐week gait retraining program can reduce the KAM and improve symptoms for individuals with medial compartment knee osteoarthritis and knee pain. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1020–1025, 2013     

General scheme to reduce the knee adduction moment by modifying a combination of gait variables

Reducing the knee adduction moment (KAM) is a promising treatment for medial compartment knee osteoarthritis (OA). Although several gait modifications to lower the KAM have been identified, the potential to combine modifications and individual dose‐responses remain unknown. This study hypothesized that: (i) there is a general scheme consisting of modifications in trunk sway, step width, walking speed, and foot progression angle that reduces the KAM; (ii) gait modifications can be combined; and (iii) dose‐responses differ among individuals. Walking trials with simultaneous modifications in step width, walking speed, progression angle, and trunk sway were analyzed for 10 healthy subjects. Wider step width, slower speed, toeing‐in, and increased trunk sway resulted in reduced first KAM peak, whereas wider step width, faster speed, and increased trunk sway reduced the KAM angular impulse. Individual regressions accurately modeled the amplitude of the KAM variables relative to the amplitude of the gait modification variables, while the dose‐responses varied strongly among participants. In conclusion, increasing trunk sway, increasing step width, and toeing‐in are three gait modifications that could be combined to reduce KAM variables related to knee OA. Results also indicated that some gait modifications reducing the KAM induced changes in the knee flexion moment possibly indicative of an increase in knee loading. Taken together with the different dose‐responses among subjects, this study suggested that gait retraining programs should consider this general scheme of modifications with individualization of the modification amplitudes. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1547–1556, 2016.     

Muscles that do not cross the knee contribute to the knee adduction moment and tibiofemoral compartment loading during gait

The aims of this study were to evaluate and explain the individual muscle contributions to the medial and lateral knee compartment forces during gait, and to determine whether these quantities could be inferred from their contributions to the external knee adduction moment. Gait data from eight healthy male subjects were used to compute each individual muscle contribution to the external knee adduction moment, the net tibiofemoral joint reaction force, and reaction moment. The individual muscle contributions to the medial and lateral compartment forces were then found using a least‐squares approach. While knee‐spanning muscles were the primary contributors, non‐knee‐spanning muscles (e.g., the gluteus medius) also contributed substantially to the medial compartment compressive force. Furthermore, knee‐spanning muscles tended to compress both compartments, while most non‐knee‐spanning muscles tended to compress the medial compartment but unload the lateral compartment. Muscle contributions to the external knee adduction moment, particularly those from knee‐spanning muscles, did not accurately reflect their tendencies to compress or unload the medial compartment. This finding may further explain why gait modifications may reduce the knee adduction moment without necessarily decreasing the medial compartment force. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1586–1595, 2012     

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     

Baseline knee adduction moment interacts with body mass index to predict loss of medial tibial cartilage volume over 2.5 years in knee Osteoarthritis

This study aimed to determine the extent to which changes over 2.5 years in medial knee cartilage thickness and volume were predicted by: (1) Peak values of the knee adduction (KAM) and flexion moments; and (2) KAM impulse and loading frequency, representing cumulative load, after controlling for age, sex and body mass index (BMI). Adults with clinical knee osteoarthritis participated. At baseline and approximately 2.5 years follow‐up, cartilage thickness and volume of the medial tibia and femur were segmented from magnetic resonance imaging scans. Gait kinematics and kinetics, and daily knee loading frequency were also collected at baseline. Multiple linear regressions predicted changes in cartilage morphology from baseline gait mechanics. Data were collected from 52 participants (41 women) [age 61.0 (6.9) y; BMI 28.5 (5.7) kg/m²] over 2.56 (0.51) years. There were significant KAM peak‐by‐BMI (p = 0.023) and KAM impulse‐by‐BMI (p = 0.034) interactions, which revealed that larger joint loads in those with higher BMIs were associated with greater loss of medial tibial cartilage volume. In conclusion, with adjustments for age, sex, and cartilage measurement at baseline, large magnitude KAM peak and KAM impulse each interacted with BMI to predict loss of cartilage volume of the medial tibia over 2.5 years among individuals with knee osteoarthritis. These data suggest that, in clinical knee osteoarthritis, exposure to large KAMs may be detrimental to cartilage in those with larger BMIs. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2476–2483, 2017.

     

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.     

Cyclops lesions are associated with altered gait patterns and medial knee joint cartilage degeneration at 1 year after ACL‐reconstruction

In this exploratory study, gait analysis and quantitative MRI (QMRI) were used to assess biomechanical differences in patients that present with cyclops lesions at 12 months after ACL‐reconstruction (ACLR). Thirty ACLR patients without and 10 ACLR patients with cyclops lesions underwent 3T MR T _1ρ mapping of the reconstructed knee joint prior to ACLR and at 12 months after ACLR, as well as a gait assessment during a fixed walking speed at 12 months after ACLR. Both external sagittal and frontal plane knee joint moments and joint moment impulses were calculated and assessed throughout the stance phase of gait. ACLR patients with cyclops lesions demonstrated a significantly greater (34% larger, p = 0.03) first peak knee flexion moment (KFM) and KFM impulse (42% larger, p = 0.05), compared to those without cyclops lesions, which may suggest an increased load during the loading response phase of gait. There were no differences (p > 0.05) in knee extension or adduction joint moments or moment impulses. ACLR patients with cyclops lesions demonstrated a significantly increased change in T _1ρ (ΔT _1ρ = 4.7 ms, p = 0.03), over 12 months, within the central medial tibia. The results of the study suggest that ACLR patients with cyclops lesions demonstrate altered sagittal plane loading patterns which may be related to an increased rate of medial tibiofemoral cartilage degeneration at 12 months after ACLR. The first peak external KFM may be an important target for intervention programs in ACLR patients with cyclops lesions in order to possibly slow the onset or progression of medial tibiofemoral cartilage degeneration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2275–2281, 2017.

     

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.     

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.     

Knee joint unloading and daily physical activity associate with cartilage T2 relaxation times 1 month after ACL injury

Osteoarthritis (OA) is prevalent after anterior cruciate ligament (ACL) injury, but mechanismsunderlying its development are poorly understood. The purpose of this study was to determine if gait biomechanics and daily physical activity (PA) associate with cartilage T2 relaxation times, a marker of collagen organization and water content, 1 month after ACL injury. Twenty-seven participants (15–35 years old) without chondral lesions completed magnetic resonance imaging, three-dimensional gait analysis, and 1 week of PA accelerometry. Interlimb differences and ratios were calculated for gait biomechanics and T2 relaxation times, respectively. Multiple linear regression models adjusted for age, sex, and concomitant meniscus injury were used to determine the association between gait biomechanics and PA with T2 relaxation times, respectively. Altered knee adduction moment (KAM) impulse, less knee flexion excursion (kEXC) and higher daily step counts accounted for 35.8%–65.8% of T2 relaxation time variation in the weightbearing and posterior cartilage of the medial and lateral compartment (all p ≤ .011). KAM impulse was the strongest factor for T2 relaxation times in all models (all p ≤ .001). Lower KAM impulse associated with longer T2 relaxation times in the injured medial compartment (β = ?.720 to ?.901) and shorter T2 relaxation in the lateral compartment (β = .713 to .956). At 1 month after ACL injury, altered KAM impulse, less kEXC, and higher PA associated with longer T2 relaxation times, which may indicate poorer cartilage health. Statement of Clinical Significance: Gait biomechanics and daily PA are modifiable targets that may improve cartilage health acutely after ACL injury and slow progression to OA.     

Effective gait patterns for offloading the medial compartment of the knee

Gait modification offers a noninvasive option for offloading the medial compartment of the knee in patients with knee osteoarthritis. While gait modifications have been proposed based on their ability to reduce the external knee adduction moment, no gait pattern has been proven to reduce medial compartment contact force directly. This study used in vivo contact force data collected from a single subject with a force‐measuring knee replacement to evaluate the effectiveness of two gait patterns at achieving this goal. The first was a “medial thrust” gait pattern that involved medializing the knee during stance phase, while the second was a “walking pole” gait pattern that involved using bilateral walking poles commonly used for hiking. Compared to the subject's normal gait pattern, medial thrust gait produced a 16% reduction and walking pole gait a 27% reduction in medial contact force over stance phase, both of which were statistically significant based on a two‐tailed Mann–Whitney U‐test. While medial thrust gait produced little change in lateral and total contact force over the stance phase, walking pole gait produced significant 11% and 21% reductions, respectively. Medial thrust gait may allow patients with knee osteoarthritis to reduce medial contact force using a normal‐looking walking motion requiring no external equipment, while walking pole gait may allow patients with knee osteoarthritis or a knee replacement to reduce medial, lateral, and total contact force in situations where the use of walking poles is possible. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 1016–1021, 2009     

Contralateral cane use and knee joint load in people with medial knee osteoarthritis: the effect of varying body weight support

Objective

To evaluate the effect of varying body weight support (BWS) with contralateral cane use on medial knee load, measured by external knee adduction moment (KAM), in medial knee osteoarthritis (OA) participants. Influences of cane use technique, pain and malalignment on the cane’s load-reducing effects were investigated.

Method

Participants (n = 23) underwent three-dimensional gait analysis to measure KAM peaks (early and late stance) and impulse. Unaided walking was firstly analyzed. Following cane use training, participants placed pre-determined magnitudes of BWS through the cane (10%, 15% and 20% in random order), with visual feedback provided via a force-instrumented cane and projection screen. Contributions of cane use technique (peak BWS magnitude and timing, cane impulse (BWS∗time) anterior and lateral cane distance from limb) and Western Ontario McMaster Universities OA Index (WOMAC) pain and malalignment to KAM outcomes were evaluated using linear mixed models.

Results

Cane use reduced all KAM variables, with a dose–response effect apparent. Cane BWS impulse was important in reducing the early stance peak KAM (P < 0.001), peak BWS for late stance KAM (P < 0.001) and both BWS measures for KAM impulse reductions (P < 0.001). Variables contributing to efficacy of load-reduction differed across outcomes. Generally, greater reductions were achieved with longer lateral cane distances, peak BWS timing similar to KAM peaks, and shorter anterior cane distances. Greater pain and varus alignment improved load-reduction for some outcomes.

Conclusion

Contralateral cane use significantly reduced medial knee load, with a dose–response effect. Medial knee OA patients should be encouraged to maintain greater BWS across stance, with cane placement more lateral for optimum benefit.     

Immediate and short‐term effects of real‐time knee adduction moment feedback on the peak and cumulative knee load during walking

The peak external knee adduction moment (pKAM), KAM impulse, and peak knee flexion moment (pKFM) during gait are important loading variables in medial tibiofemoral osteoarthritis. We evaluated the effects of gait modification, using real‐time pKAM visual feedback, on pKAM, KAM impulse, and pKFM; and whether participants could maintain the KAM‐reducing gait after feedback removal. Eleven healthy individuals performed a series of walking trials on a split‐belt instrumented treadmill under four conditions of Baseline, Feedback, No Feedback Early, and No Feedback Late. Guided by real‐time feedback of pKAM, they modified their gait patterns to lower pKAM by 20%. Three‐dimensional joint kinematics/kinetics during each walking condition were recorded by a 12‐camera motion capture system and the instrumented treadmill. Change in each knee loading parameter from baseline across conditions was assessed using one‐way repeated‐measures analysis‐of‐variances. In the feedback limb, successful 20% reductions from baseline in pKAM and KAM impulse were achieved across all three conditions. There was a trend for concomitant pKFM increases, partially attenuating the beneficial effects of pKAM reduction. A carry‐over effect of KAM reduction in the non‐feedback limb was noted. The altered gait patterns were participant‐specific and multi‐modal; each participant reported a combination of two to three gait modification strategies used for pKAM reduction. Toe‐in and medial foot contact were the most reported strategies. The findings support the real‐time pKAM visual feedback as a tool for individualized gait modification to reduce knee load. Future studies to evaluate its effectiveness in persons with or at risk for medial knee osteoarthritis is warranted. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:397–404, 2018.     

Effects of lateral‐offset sole shoes on knee adduction moment in women with medial compartment knee osteoarthritis

This study aimed to determine the impact of wearing a lateral‐offset sole shoe (LOSS) on knee adduction moment (KAM) in patients with medial knee osteoarthritis (OA). From December 2012 to November 2016, patients with medial knee OA were recruited. Ninety‐three knees (50 left, 43 right) of 93 female patients were analyzed. The first peak KAMs were measured with patients (i) walking barefoot; (ii) walking in conventional shoes; and (iii) walking in LOSSs. The patients had grade 1 (n = 19), grade 2 (n = 49), grade 3 (n = 20), and grade 4 (n = 5) knee OA. First peak KAMs differed significantly in all three conditions (p = 0.031). In the post hoc analysis, first peak KAMs were significantly lower during LOSS walking than during conventional shoe walking (p = 0.001), but there were no differences in peak KAMs between barefoot and LOSS walking (p = 0.784). In the subgroup analysis, patients with grades 2 and 3 OA showed significantly lower first peak KAMs during LOSS walking than during conventional shoe walking (p = 0.029 and p = 0.011, respectively). Both the peak eversion ankle angle and moment of barefoot walking showed a significant increase compared with LOSS and conventional shoe walking, while there was no significant difference between LOSS and conventional shoe walking (p = 0.612 and p = 0.197, respectively). Our results suggest that LOSS wearing caused significant KAM reductions compared with conventional shoe wearing. Since LOSS wearing does not cause changes in the peak eversion ankle angle and moment during the load response, it may be an effective method to reduce the KAM in women with knee OA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1694–1700, 2018.

     

Adduction moment increases with age in healthy obese individuals

There is a need to understand how obesity and aging interact to cause an increased risk of medial knee osteoarthritis (OA). This study tested whether the knee adduction and flexion moments increase with age in healthy normal‐weight and obese adults, as well as the mechanism of this increase. We analyzed whether ground reaction force magnitude, knee alignment, step width, toe‐out angle, body volume distribution, and limb position (knee position relative to the pelvis center) are associated with the adduction moment and whether these variables also change with age. Ninety‐six healthy volunteers (60 normal‐weight and 36 obese) were tested using marker‐based gait analysis; knee alignment was based on marker positions during quiet standing. Adduction moment increased with age in obese (R² = 0.19), but not in normal‐weight individuals (R² = 0.01); knee flexion moment did not change with age in either group. In the obese, only knee alignment and limb position were related to the adduction moment (R² = 0.19 and 0.51), but only limb position changed with age (R² = 0.26). The resulting increase in adduction moment suggests greater medial compartment loads, which may combine with elevated levels of inflammation to contribute to the increased risk of medial OA in this population. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1414–1422, 2013     

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.     

Medial knee joint loading increases in those who respond to hyaluronan injection for medial knee osteoarthritis

Knee osteoarthritis (OA) is a cause of decline in function and the medial compartment is often affected. Intraarticular injection of hyaluronic acid (HA) is indicated as a symptom modifying treatment with at least 6 months passing between consecutive injection series. The effects of HA injection on gait variables have not been extensively examined. Therefore, our objective was to investigate the effects of HA injection on gait in people with medial knee OA. Twenty‐seven subjects were included; each was tested prior to treatment (baseline), no later than 3 weeks following the last injection (post‐HA), and again 5 months after treatment ended (follow‐up). Responder criteria were defined to identify responders and non‐responders. Subjects underwent 3D gait analysis, muscle activity was sampled, and co‐contraction indices were calculated. Responders experienced increased peak knee adduction moments post‐HA, whereas non‐responders did not. Improved self‐report scores were associated with increased knee adduction moments and increased medial co‐contraction. Pain relief may result in higher loading onto the already vulnerable medial compartment due to changes in lower limb mechanics and muscle activation patterns. Eventually this may result in a more rapid progression of joint deterioration. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1420–1425, 2009