Static and dynamic biomechanics of foot orthoses in people with medial compartment knee osteoarthritis

Are biomechanics during gait associated with the structural disease onset and progression of lower limb osteoarthritis? A systematic review and meta-analysis

OBJECTIVE

To evaluate if gait biomechanics are associated with increased risk of structurally diagnosed disease onset or progression of lower limb osteoarthritis (OA).

METHOD

A systematic review of Medline and Embase was conducted from inception to July 2021. Two reviewers independently screened records, extracted data and assessed risk of bias. Included studies reported gait biomechanics at baseline, and either structural imaging or joint replacement occurrence in the lower limb at follow-up. The primary outcome was the Odds Ratio (OR) (95% confidence interval (CI)) of the association between biomechanics and structural OA outcomes with data pooled for meta-analysis.

RESULTS

Twenty-three studies reporting 25 different biomechanical metrics and 11 OA imaging outcomes were included (quality scores ranged 12-20/21). Twenty studies investigated knee OA progression; three studies investigated knee OA onset. Two studies investigated hip OA progression. 91% of studies reported a significant association between at least one biomechanical variable and OA onset or progression. There was an association between frontal plane biomechanics with medial tibiofemoral and hip OA progression and sagittal plane biomechanics with patellofemoral OA progression. Meta-analyses demonstrated increased odds of medial tibiofemoral OA progression with greater baseline peak knee adduction moment (KAM) (OR: 1.88 [95%CI: 1.08, 3.29]) and varus thrust presence (OR: 1.97 [95%CI: 1.32, 2.96]).

CONCLUSION

Evidence suggests that certain gait biomechanics are associated with an increased odds of OA onset and progression in the knee, and progression in the hip.

REGISTRATION NUMBER

PROSPERO CRD42019133920.

The effect of a lateral wedge insole and a subtalar strap on gait parameters in knee osteoarthritis

Background: Lateral wedge insole (LWI) aims to reduce loading on medial compartment of tibiofemoral joint in mild knee osteoarthritis (KOA). This effect may be augmented by concomitant use of subtalar strap to fix the ankle joint. Moreover, longitudinal arch support embedded in insoles can cause foot comfort and may be beneficial for people with KOA. Therefore, this study aimed to assess the immediate effect of LWI with an arch support with and without a subtalar strap on the kinetics and kinematics of walking in mild KOA.

Methods: A convenient sample of 17 individuals with mild KOA (Kellgren and Lawrence grade II), aged ≥ 40 years were assessed in 3 conditions: without the insole; LWI; and LWI with a subtalar strap, where an arch support was embedded in all insoles. The primary outcomes were external knee adduction moment and angular impulse. The secondary outcomes were hip flexion and adduction moments, knee flexion angle, ankle eversion moment, and walking speed. The repeated measurements ANOVA was used to compare the primary and secondary outcomes between the conditions using SPSS. Significance level was set at 0.05.

Results: LWI and a subtalar strap can significantly increase the knee flexion angle at 0%-15% of the stance phase compared to no insole (p<0.001). No other changes were observed (p=0.142).

Conclusion: LWI with an arch, with or without a subtalar strap, cannot impose any immediate changes on the kinetics and kinematics of lower limb joints during walking in people with mild KOA.

The optimal degree of lateral wedge insoles for reducing knee joint load: a systematic review and meta-analysis

Background

Lateral wedge insoles are traditionally used to reduce the adduction moment that crosses the knee during walking in people with medial knee osteoarthritis. However, the best degree to reduce knee joint load is not yet well established.

Methods

Electronic databases were searched from their inception until May 2017. Included studies reported on the immediate biomechanical effects of different degrees of lateral wedge insoles during walking in people with knee osteoarthritis. The main measures of interest relating to the biomechanics were the first and second peak of external knee adduction moment and knee adduction angular impulse. For the comparison of the biomechanical effects of different degrees of insoles, the studies were divided in three subgroups: insoles with a degree higher than 0° and equal to or lower than 5°; insoles higher than 5° and equal to or lower than 9°; and insoles higher than 9°. Eligible studies were pooled using random-effects meta-analysis.

Results

Fifteen studies with a total of 415 participants met all eligibility criteria and were included in the final review and meta-analysis. The overall effect suggests that lateral wedge insoles resulted in a statistically significant reduction in the first peak (standardized mean difference [SMD] -0.25; 95% confidence interval [CI] -0.36, - 0.13; P < 0.001), second peak (SMD -0.26 [95% CI -0.48, - 0.04]; P = 0.02) and knee adduction angular impulse (SMD -0.17 [95% CI -0.31, - 0.03]; P = 0.02). The test of subgroups found no statistically significant differences.

Conclusion

Systematic review and meta-analysis suggests that lateral wedge insoles cause an overall slight reduction in the biomechanical parameters. Higher degrees do not show higher reductions than lower degrees. Prior analysis of biomechanical parameters may be a valid option for selecting the optimal angle of wedge that best fits in knee osteoarthritis patients with the lowest possible degree.

Combined effects of knee brace, laterally wedged insoles, and toe-out gait on knee adduction moment and fall risk in moderate medial knee osteoarthritis patients

BACKGROUND:

Knee osteoarthritis is a major contributor to the global burden of disease. There is a need of reducing knee joint load and to improve balance and physical function among knee osteoarthritis patients.

OBJECTIVES:

To test the hypothesis that toe-out gait will reduce second peak knee adduction moment further and increase fall risk when combined with knee brace and laterally wedged insole in knee osteoarthritis patients.

STUDY DESIGN:

Single visit study with repeated measures.

METHODS:

First and second peak knee adduction moments, fall risk and comfort level. First and second peak knee adduction moments were determined from three-dimensional gait analysis, completed under six randomized conditions: (1) natural, (2) knee brace, (3) knee brace + toe-out gait, (4) laterally wedged insole, (5) laterally wedged insole + toe-out gait, and (6) knee brace + laterally wedged insole + toe-out gait. Fall risk was assessed by Biodex Balance System using three randomized stability settings: (1) static, (2) moderate dynamic setting (FR12), and (3) high dynamic setting (FR8).

RESULTS:

The reduction in first peak knee adduction moment and second peak knee adduction moment was greatest (7.16% and 25.55%, respectively) when toe-out gait combine with knee brace and laterally wedged insole. Significant increase in fall risk was observed with knee brace + laterally wedged insole + toe-out gait (42.85%) at FR12. Similar significant balance reductions were found at FR8 condition for knee brace + toe-out gait (35.71%), laterally wedged insole + toe-out gait (28.57%), and knee brace + laterally wedged insole + toe-out gait (50%) as compared to natural. However, knee brace decreased fall risk at FR12 by 28.57%.

CONCLUSION:

There is a synergistic effect of toe-out when combined with knee brace and laterally wedged insole concurrently in second peak knee adduction moment reduction but with a greater degree of fall risk. Simultaneous use of conservative treatments also decreases comfort level.

CLINICAL RELEVANCE

Patients with mild and moderate knee osteoarthritis are usually prescribed conservative treatment techniques. This study will provide an insight whether or not a combination of these techniques have a synergistic effect in reducing knee joint load.

Finite element analysis of knee and ankle joint during gait based on motion analysis

Contact pressures in the articular cartilage during gait affect injuries and the degenerative arthritis of knee and ankle joints. However, only contact forces at the knee and ankle joints during gait can be estimated by using a rigid body dynamic model. The contact pressure distribution can be obtained quantitatively for a static posture by using finite element (FE) analysis in most cases. The purpose of this study is to develop a new method to obtain the contact pressure distribution at the knee and ankle joints during gait by integrating FE analysis with rigid body dynamic analysis. In this method, a reference FE model of the lower extremity is constructed first and is then transformed to each stance phase of the gait obtained from dynamic analysis by using homogeneous transformation. The muscle forces and ground reaction force (GRF) during gait obtained from the dynamic analysis were used as loading conditions for FE analysis. Finally, the contact pressure distribution at the tibia plateau cartilage and talus cartilage were estimated at the 1st peak, mid-stance, and the 2nd peak at the same time. The present method can provide the contact pressure distribution at the knee and ankle joints over the entire gait.

Effect of lateral wedge length on ambulatory knee kinetics

BACKGROUND

Lateral wedge insoles (LWI) were proposed to treat medial knee osteoarthritis through reductions of the ambulatory knee adduction moment (KAM). Limited attention was however paid to the LWI length, resulting in unclear understanding of its effect on KAM reductions. The knee flexion moment (KFM) was also shown to be important in knee osteoarthritis, but little is known about the effect of LWI length on it.

RESEARCH QUESTION

This study aimed to compare the KAM and KFM of healthy subjects walking with four different lengths of LWI, explicitly without LWI and with LWI below the hindfoot (HF), below the hindfoot and forefoot (HF + FF) and below the hindfoot, forefoot and hallux (HF + FF + HX) segments.

METHODS

Nineteen healthy participants (63% male; 24 ± 3 years old) walked in an instrumented gait lab with LWI of four different lengths. Repeated one-way ANOVAs and post-hoc t-tests were used to compare knee kinetics among LWI lengths.

RESULTS

The peak value of the KAM during the first half of stance and the KAM impulse differed with respect to the LWI length (p < 0.001). A length of at least HF + FF, but not necessarily longer, was needed to decrease both KAM parameters compared to walking without LWI. The LWI length had no effect on the peak value of the KFM during the first half of stance (p = 0.86).

SIGNIFICANCE

The results in this study could contribute to better selections of LWI for medial knee osteoarthritis and suggested that the length of the LWI could be a critical factor that should be considered in future research.

Prophylaxis of medial compartment gonarthrosis in varus knee - current state of knowledge

The progression of gonarthrosis results in reduction of physical activity. One of the factors that increase the risk of osteoarthrosis may be joint overload related to the malalignment of the mechanical axis of the lower extremity. The medial compartment (MC) of the knee is particularly susceptible to overload due to the external knee adduction moment (EKAM). Varus knee malalignment contributes to increased EKAM and thus results in increased MC loading. The purpose of this study is to present methods described in current literature aimed at reducing the disproportion in the distribution of loads on articular surfaces of medial and lateral knee compartments in people with varus knee malalignment. Methods have been divided into non-surgical (gait training, physiotherapy, and orthopedic supplies such as valgus braces, lateral wedge insoles, walking poles) and surgical ones (corrective osteotomy).

Combined effects of knee brace, laterally wedged insoles and toe-in gait on knee adduction moment and balance in moderate medial knee osteoarthritis patients

OBJECTIVE

To test the hypothesis that toe-in gait (TI) will further reduce first peak (Knee Adduction Moment) KAM and decrease balance when combined with a knee brace (KB) and laterally wedged insoles (LWI) in medial knee osteoarthritis (kOA) patients.

PARTICIPANTS

Twenty patients with bilateral symptomatic medial kOA.

INTERVENTIONS

4-point leverage-based KB, full-length LWI with 5° inclination and toe-in gait (TI).

MAIN OUTCOME MEASURES

First and second peak knee adduction moment (fKAM and sKAM respectively), balance and pain.

METHODS

The fKAM and sKAM were determined from 3-dimensional gait analysis with six randomized conditions: (1) N (without any intervention), (2) KB, (3) KB + TI, (4) LWI, (5) LWI + TI, (6) KB + LWI + TI. Balance was assessed by Biodex Balance System using three stability settings, (i) Static (ii) Moderate dynamic setting for fall risk (FR12) and (iii) High dynamic setting for fall risk (FR8).

RESULTS

The reduction in fKAM and sKAM was greatest (19.75% and 12%) when TI was combined with KB and LWI respectively. No change in balance was observed when TI combined with KB, and LWI and when used concurrently with both the orthosis at static and FR12 conditions. Significant balance reduction was found at FR8 for KB + TI (22.22%), and KB + LWI + TI (35.71%). Pain increased significantly for KB (258%), KB + TI (305%), LWI + TI (210%) and KB + LWI + TI (316%). LWI showed no effect on pain.

CONCLUSIONS

There is a synergistic effect of TI when combined with KB and LWI concurrently in sKAM reduction. However, the concurrent use of TI, KB and LWI decreases balance and pain as assessed on a highly dynamic platform.

Effects of an over-ground exoskeleton on external knee moments during stance phase of gait in healthy adults

BACKGROUND

Physical activity and exercise is central to conservative management of knee osteoarthritis (KOA), but is often difficult for patients with KOA to maintain over the decade or more prior to surgical management. Better approaches are needed for maintaining physical function and health in this population that can also address the patho-biomechanics of the osteoarthritic knee. The objective of the study is to quantify how a lower-extremity robotic exoskeleton (dermoskeleton) modifies the external knee moments during over-ground walking in a sample of healthy adults, and to evaluate these biomechanical modifications in the context of the osteoarthritic knee.

METHOD

Motion analysis data was acquired for 13 participants walking with and without the dermoskeleton. Force plate data, external knee moment arms, and knee moments in the laboratory and tibia frames of reference were computed, as well as time-distance parameters of walking, and compared between the two conditions.

RESULTS

Although gait speed was not different, users took shorter and wider steps when walking with the dermoskeleton. Ground reaction forces and early-stance knee moment increased due to the added mass of the dermoskeleton, but the knee adduction moment was significantly reduced in late stance phase of gait. There was no effect on the knee torsional moment when measured in the anatomical frame of reference, and the late-stance knee flexion moment was invariant.

CONCLUSIONS

The dermoskeleton demonstrated favorable biomechanical modifications at the knee in healthy adults while walking. Studies are warranted to explore this technology for enabling physical activity-based interventions in patients with KOA.

The effects of shoe-worn insoles on gait biomechanics in people with knee osteoarthritis: a systematic review and meta-analysis

OBJECTIVES

The effect of shoe-worn insoles on biomechanical variables in people with medial knee osteoarthritis has been studied extensively. The majority of research has focused specifically on the effect of lateral wedge insoles at the knee. The aim of this systematic review and meta-analysis was to summarise the known effects of different shoe-worn insoles on all biomechanical variables during level walking in this patient population to date.

METHODS

Four electronic databases were searched to identify studies containing biomechanical data using shoe-worn insole devices in the knee osteoarthritis population. Methodological quality was assessed and a random effects meta-analysis was performed on biomechanical variables reported in three or more studies for each insole.

RESULTS

Twenty-seven studies of moderate-to-high methodological quality were included in this review. The primary findings were consistent reductions in the knee adduction moment with lateral wedge insoles, although increases in ankle eversion with these insoles were also found.

CONCLUSION

Lateral wedge insoles produce small reductions in knee adduction angles and external moments, and moderate increases in ankle eversion. The addition of an arch support to a lateral wedge minimises ankle eversion change, and also minimises adduction moment reductions. The paucity of available data on other insole types and other biomechanical outcomes presents an opportunity for future research.

Effect of foot orthoses on the medial longitudinal arch in children with flexible flatfoot deformity: A three-dimensional moment analysis

Foot orthoses are often used to correct altered gait patterns. The purpose of this study was to investigate how foot orthoses can modify the magnitude of three dimensional moments of ankle, knee, and hip joints during a stride of gait in children with flexible flat feet. Bilateral gait data were collected from fourteen male children (age 10.2±1.4 years) suffering from flat feet syndrome. In order to obtain the kinematics data, a Vicon system with six cameras (100Hz) was used and two Kistler force plates (1000Hz) to record the kinetics data under each leg. Arc support foot orthoses were used as an intervention. Paired-sample T-test was used for within-group comparisons (α=0.05). The results of data analysis showed that foot orthoses can decrease the ankle evertor moment, knee and hip abductor moments and hip flexor moment in dominant lower limb. In non-dominant lower limb, using the orthoses can decrease evertor and internal rotator moments at the ankle, flexor and internal rotator moments at the knee and extensor moment at the hip, while it can increase dorsiflexor moment at the ankle. The findings imply that effects of orthoses on three dimensional moments differ in dominant and non-dominant lower limbs. Furthermore, results demonstrated that dominant and non-dominant lower limbs would also show different responses to the same intervention.

Speed dependent effects of laterally wedged insoles on gait biomechanics in healthy subjects

Laterally wedged insoles have been shown to be effective for the reduction of the knee adduction moment and other biomechanical variables that are associated with the pathogenesis of knee osteoarthritis. However, inconclusive results such as adverse effects in individual subjects or even no group-wise wedge effects have been presented in different studies and it has been suggested to identify variables that potentially confound the wedge effect. The main objective of this study was the investigation of interaction effects of lateral wedges with walking speed, as different self-selected speeds have mainly been used in previous studies. Twenty-two healthy subjects completed gait analysis trials on an instrumented treadmill. They walked in different speed conditions (0.9, 1.1, 1.3, 1.5m/s) with a neutral and a laterally wedged insole. Kinematics were acquired using infrared cinematography with reflective markers attached to the lower body. From the stance phase we extracted biomechanical parameters that are associated with knee joint loading and osteoarthritis severity. No interaction effect of lateral wedges and speed was observed for most biomechanical parameters except for the ankle eversion range of motion. The main effects of wedges were reductions of the external knee adduction moment and of the knee adduction angular impulse. All biomechanical variables changed with increasing speed. Only the lateral offset of the center of pressure did not respond to wedge or to speed changes. Our results suggest that different self-selected speeds do not confound the effect of laterally wedged insoles.

A systematic review and meta-analysis into the effect of lateral wedge arch support insoles for reducing knee joint load in patients with medial knee osteoarthritis

OBJECTIVE

The aim of this study was to evaluate the immediate effects of lateral wedge arch support insoles (LWAS) on reducing the knee joint load in patients with medial knee osteoarthritis (OA) compared with an appropriate control.

METHODS

Databases including Medline, EMBASE, Web of Science, Wiley Online Library, Cochrane library, and Google Scholar were searched with no limits on study date or language, from the earliest available date to October 31, 2016. The included studies had to have the aim of reducing knee load and have an appropriate control. The main measured values were the first and second peak external knee adduction moments (EKAM) and the knee adduction angular impulse (KAAI). The random-effects model was used for analyzing the eligible studies.

RESULTS

Nine studies met the inclusion criteria with a total of 356 participants of whom 337 received LWAS treatment. The risk of methodological bias scores (quality index) ranged from 21 to 27 of 32. Treatment with LWAS resulted in statistically significant reductions in the first peak EKAM (P = .005), the second peak EKAM (P = .01), and the KAAI (P = .03). However, among trials in which the control treatment was control shoes, the LWAS showed no associations on the first peak EKAM (P = .10) or the KAAI (P =  .06); among trials in which the control treatment was neutral insoles, the LWAS showed no associations on the second peak EKAM (P = .21) or the KAAI (P = .23). At the same time, the LWAS showed no statistically significant reduction on the first peak EKAM (P = .39) when compared with flat insoles.

CONCLUSION

Although meta-analysis outcomes of all studies indicated statistically significant associations between LWAS and reductions of the first peak EKAM, second peak EKAM and KAAI in people with medial knee OA while walking, different results existed in subgroups using various control conditions for comparison. These findings do not support the use of LWAS insoles for reducing knee load. An optimal LWAS treatment should provide the appropriate height of arch support and amount of lateral wedging. Further research should investigate the best combination of these 2 parameters to achieve efficacy without altered comfort.

Effect of unilateral and bilateral use of laterally wedged insoles with arch supports on impact loading in medial knee osteoarthritis

BACKGROUND

Increased impact loading is implicated in knee osteoarthritis development and progression.

OBJECTIVES

This study examined the impact ground reaction force (GRF) peak, its loading rate, its relative timing to stance phase timing, and walking speed during unilateral and bilateral use of laterally wedged insoles with arch supports.

STUDY DESIGN

Within-subject design.

METHODS

Thirty-three female patients with medial knee osteoarthritis were examined with (unilateral 6° and 11°, and bilateral 0°, 6°, and 11°) and without insole use.

RESULTS

Repeated measures MANOVA revealed that the impact force increased significantly in bilateral 11° versus unilateral 6° and without-insole conditions. The loading rate decreased significantly in unilateral 11° versus bilateral 6° insoles. The relative timing increased significantly in each of bilateral 6°, bilateral 11°, and unilateral 11° versus bilateral 0° insoles and in each of bilateral 11° and unilateral 11° versus without-insole condition. There were significant positive correlations between the walking speed and each of the force and loading rate. The Chi-square test revealed insignificant association between the insole condition and the presence of impact forces.

CONCLUSION

Unilateral 11° insoles are capable of reducing impact loading possibly through increasing foot pronation. Walking slowly is another possible strategy to reduce loading.

CLINICAL RELEVANCE

Unilaterally applied 11° laterally wedged insoles are capable of reducing and delaying the initial impact ground reaction forces and reducing their loading rates during walking in patients with medial knee osteoarthritis, thus reducing osteoarthritis progression. Walking slowly could also be used as a strategy to reduce impact loading.

Immediate and 1 week effects of laterally wedge insoles on gait biomechanics in healthy females

It is estimated that approximately 45% of the U.S. population will develop knee osteoarthritis, a disease that creates significant economic burdens in both direct and indirect costs. Laterally wedged insoles have been frequently recommended to reduce knee abduction moments and to manage knee osteoarthritis. However, it remains unknown whether the lateral wedge will reduce knee abduction moments over a prolonged period of time. Thus, the purposes of this study were to (1) examine the immediate effects of a laterally wedged insole in individuals normally aligned knees and (2) determine prolonged effects after the insole was worn for 1 week. Gait analysis was performed on ten women with and without a laterally wedged insole. After participants wore the wedges for a week, a second gait analysis was performed with and without the insole. The wedged insole did not affect peak knee abduction moment, although there was a significant increase in knee abduction angular impulse after wearing the insoles for 1 week. Furthermore, there was a significant increase in vertical ground reaction force at the instance of peak knee abduction moment with the wedges. While the laterally wedged insole used in the current study did not alter knee abduction moments as expected, other studies have shown alterations. Future studies should also examine a longer acclimation period, the influence of gait speed, and the effect of different shoe types with the insole.

A novel self-care biomechanical treatment for obese patients with knee osteoarthritis

AIM

To examine the effect of a novel biomechanical, home-based, gait training device on gait patterns of obese individuals with knee OA.

METHODS

This was a retrospective analysis of 105 (32 males, 73 females) obese (body mass index > 30 kg/m² ) subjects with knee OA who completed a 12-month program using a biomechanical gait training device and performing specified exercises. They underwent a computerized gait test to characterize spatiotemporal parameters, and completed the Western Ontario and McMaster Osteoarthritis Index (WOMAC) questionnaire and Short Form-36 (SF-36) Health Survey. They were then fitted with biomechanical gait training devices and began a home-based exercise program. Gait patterns and clinical symptoms were assessed after 3 and 12 months of therapy.

RESULTS

Each gait parameter improved significantly at 3 months and more so at 12 months (P = 0.03 overall). Gait velocity increased by 11.8% and by 16.1%, respectively. Single limb support of the more symptomatic knee increased by 2.5% and by 3.6%, respectively. There was a significant reduction in pain, stiffness and functional limitation at 3 months (P < 0.001 for each) that further improved at 12 months. Pain decreased by 34.7% and by 45.7%, respectively. Functional limitation decreased by 35.0% and by 44.7%, respectively. Both the Physical and Mental Scales of the SF-36 increased significantly (P < 0.001) at 3 months and more so following 12 months.

CONCLUSIONS

Obese subjects with knee OA who complied with a home-based exercise program using a biomechanical gait training device demonstrated a significant improvement in gait patterns and clinical symptoms after 3 months, followed by an additional improvement after 12 months.

Relationships among foot position, lower limb alignment, and knee adduction moment in patients with degenerative knee osteoarthritis

[Purpose] The aim of this study was to determine the relationships among the foot progression angle, foot rotation angle, lower limb alignment, and knee adduction moments in patients with degenerative knee osteoarthritis (OA). [Subjects] Forty-eight patients diagnosed with degenerative knee OA (Kellgren-Lawrence grades 2 and 3) were included. [Methods] To assess the lower extremity alignment and weight-bearing ratio, static radiographic measurement was used. Foot progression angle, foot rotation angle, and knee adduction moments were measured by using a three-dimensional motion analysis system. [Results] The results of this study were as follows: the foot progression angle in the early and late stance phase was significantly correlated with the first and second peak knee adduction moments; the weight-bearing ratio was significantly correlated with the first and second peak knee adduction moments; and the tibiofemoral angle was significantly correlated with the first and second peak knee adduction moments. [Conclusion] The results of the present study indicated that as the foot progression angle and the foot lateral rotation angle increased, the knee adduction moment decreased. The weight-bearing ratio and tibiofemoral angle assessment with mechanical axis alignment were correlated with the knee adduction moments. These parameters may be helpful for selecting therapeutic options for patients with degenerative knee OA.

Do laterally wedged insoles or valgus braces unload the medial compartment of the knee in patients with osteoarthritis?

BACKGROUND

The results of conservative treatment of knee osteoarthritis (OA) are generally evaluated in epidemiological studies with clinical outcome measures as primary outcomes. Biomechanical evaluation of orthoses shows that there are potentially beneficial biomechanical changes to joint loading; however, evaluation in relation to clinical outcome measures in longitudinal studies is needed.

QUESTIONS/PURPOSES

We asked (1) is there an immediate effect on gait in patients using a laterally wedged insole or valgus knee brace; (2) is there a late (6 weeks) effect; and (3) is there a difference between subgroups within each group with respect to patient compliance, body mass index, and OA status?

METHODS

This was a secondary analysis of data from a previous randomized controlled trial of patients with early medial knee OA. A total of 91 patients were enrolled in that trial, and 73 (80%) completed it after 6 months. Of the enrolled patients, 80 (88%) met prespecified inclusion criteria for analysis in the present study. The patients were randomized to an insole or brace. Gait was analyzed with and without wearing the orthosis (insole or brace) at baseline and after 6 weeks. Measurements were taken of the knee adduction moment, ground reaction force, moment arm, walking speed, and toe-out angle. Data were analyzed with regression analyses based on an intention-to-treat principle.

RESULTS

A mean reduction of 4% (±10) (95% confidence interval [CI], -0.147 to -0.03, p=0.003) of the peak knee adduction moment and 4% (±13) (95% CI, -0.009 to -0.001, p=0.01) of the moment arm at baseline was observed in the insole group when walking with an insole was compared with walking without an insole. A mean reduction of 1% (±10) (95% CI, -0.002 to -0.001, p=0.001) of the peak knee adduction moment and no reduction of the moment arm were measured after 6 weeks. No reduction of knee adduction moment, moment arm, or ground reaction force was seen in the brace group at baseline and after 6 weeks. Subgroup analysis showed no differences in biomechanical effect for obesity, stage of OA, and whether patients showed a clinical response to the treatment.

CONCLUSIONS

Laterally wedged insoles unload the medial compartment only at baseline in patients with varus alignment and by an amount that might not be clinically important. No biomechanical alteration was seen after 6 weeks of wearing the insole. Valgus brace therapy did not result in any biomechanical alteration. Taken together, this study does not show a clinically relevant biomechanical effect of insole and brace therapy in patients with varus medial knee OA.

LEVEL OF EVIDENCE

Level I, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Knee osteoarthritis: Clinical connections to articular cartilage structure and function

Articular cartilage is a unique biphasic material that supports a lifetime of compressive and shear forces across joints. When articular cartilage deteriorates, whether due to injury, wear and tear or normal aging, osteoarthritis and resultant pain can ensue. Understanding the basic science of the structure and biomechanics of articular cartilage can help clinicians guide their patients to appropriate activity and loading choices. The purpose of this article is to examine how articular cartilage structure and mechanics, may interact with risk factors to contribute to OA and how this interaction provides guidelines for intervention choices This paper will review the microstructure of articular cartilage, its mechanical properties and link this information to clinical decision making.

Effect of an ankle-foot orthosis on knee joint mechanics: a novel conservative treatment for knee osteoarthritis

BACKGROUND

Several conservative treatments for medial knee osteoarthritis such as knee orthosis and laterally wedged insoles have been shown to reduce the load in the medial knee compartment. However, those treatments also present limitations such as patient compliance and inconsistent results regarding the treatment success.

OBJECTIVE

To analyze the effect of an ankle-foot orthosis on the knee adduction moment and knee joint alignment in the frontal plane in subjects with knee varus alignment.

STUDY DESIGN

Controlled laboratory study, repeated measurements.

METHODS

In total, 14 healthy subjects with knee varus alignment were analyzed in five different conditions: without orthotic, with laterally wedged insoles, and with an ankle-foot orthosis in three different adjustments. Three-dimensional kinetic and kinematic data were collected during gait analysis.

RESULTS

Significant decreases in knee adduction moment, knee lever arm, and joint alignment in the frontal plane were observed with the ankle-foot orthosis in all three different adjustments. No significant differences could be found in any parameter while using the laterally wedged insoles.

CONCLUSION

The ankle-foot orthosis was effective in reducing the knee adduction moment. The decreases in this parameter seem to be achieved by changing the knee joint alignment and thereby reducing the knee lever arm in the frontal plane.

CLINICAL RELEVANCE

This study presents a novel approach for reducing the load in the medial knee compartment, which could be developed as a new treatment option for patients with medial knee osteoarthritis.

The dose-response relationship between lateral foot wedging and the reduction of knee adduction moment

BACKGROUND

Lateral foot wedges represent a biomechanical intervention aimed at reducing medial knee loads. However, the effects of varying wedge amounts on biomechanical variables and orthotic comfort have not been systematically studied. Further, arch height may influence the comfort of laterally wedged devices. Therefore, the primary purpose of this study was to examine the effect of incrementally increasing lateral wedge amounts on knee adduction moment parameters and subjective comfort. The secondary purpose was to relate arch height measures to the comfort of the devices.

METHODS

Twenty-five healthy subjects underwent three-dimensional instrumented gait analysis testing using seven inclinations of lateral wedging (0°, 2°, 4°, 6°, 8°, 10°, 12°). Subjects reported comfort level for each orthotic condition. Arch heights were measured in standing and sitting, and rigidity index and stiffness were calculated.

FINDINGS

The knee adduction moment decreased with wedge amounts up to 6°, but more aggressive amounts did not yield additional reductions. Comfort ratings did not change from baseline until wedge amounts exceeded 8°. In addition, arch height measures, arch rigidity index and stiffness did not relate to the comfort of the orthotic device regardless of the wedge amount.

INTERPRETATION

Knee adduction moment decreased with mild wedge amounts while maintaining comfort. Wedge amounts greater than 6° yielded little additional mechanical benefit and amounts greater than 8° compromised comfort. It appears that 4°-6° of lateral wedging are optimal in regard to desirable biomechanical change and comfort level in healthy individuals.

American Society of Biomechanics Clinical Biomechanics Award 2013: tibiofemoral contact location changes associated with lateral heel wedging--a weight bearing MRI study

BACKGROUND

Vertically open magnetic resonance imaging permits study of knee joint contact during weight bearing. Lateral wedging is a low cost intervention for knee osteoarthritis that may influence load distribution and contact. This study assessed the ability of feedback-assisted weight bearing magnetic resonance imaging to detect changes in tibiofemoral contact associated with lateral wedging.

METHODS

One knee in each of fourteen subjects with symptomatic knee osteoarthritis was studied, without specification of compartmental involvement. Knees were imaged during upright standing and at 20° knee flexion. Bilateral external heel wedges were used to provide non-wedged and 5° lateral wedging conditions. Computer modeling was used to measure the medial and lateral compartment contact patch center coordinates on the tibial plateau and the respective contact areas.

FINDINGS

Lateral heel wedging in flexion was associated with a significant anterior shift of the contact patch of the lateral femoral condyle. Changes with knee flexion were similar to previous reports: both medial and lateral contact centers moved posteriorly with flexion, and lateral condyle contact also moved laterally. Lateral condyle contact area significantly reduced with flexion, while lateral wedging did not significantly affect contact areas.

INTERPRETATION

In symptomatic knee osteoarthritis patients standing in knee flexion, weight bearing magnetic resonance imaging recorded an anterior shift of lateral condyle contact in response to lateral heel wedging. Future studies may investigate lateral wedging effects more specifically in candidates for this clinical intervention.

The use of a lateral wedge insole to reduce knee loading when ascending and descending stairs in medial knee osteoarthritis patients

BACKGROUND

Stair climbing is a challenging task to the elderly being the task with the first complaint in patients with mild to moderate knee osteoarthritis. Stair climbing results in around six times more compressive load transmitted through the knee joint than walking on level ground. The purpose of this study was to assess whether lateral wedge insoles would reduce medial compartment knee loading when ascending and descending stairs in patients with medial knee osteoarthritis.

METHODS

Eight patients with medial knee osteoarthritis were tested in random order with and without a pair of 5° off-the-shelf lateral wedge insoles for two separate activities (stair ascent and stair descent). Kinematic and kinetic data were collected for the lower extremity using a sixteen camera motion capture system and two force plates. Primary outcome measures were the external knee adduction moment and the knee adduction angular impulse.

FINDINGS

During stair ascent and descent, lateral wedge insoles significantly (P<0.05) reduced the 1st peak external knee adduction moment in early stance (ascent 6.8%, descent 8.4%), the trough in mid stance (ascent 13%, descent 10.7%), 2nd peak in the late stance (ascent 15%, descent 8.3%) and the knee adduction angular impulse compared to the control (standard shoe) with large effect sizes (0.75-0.95).

INTERPRETATION

In this first study on stairs, lateral wedge insoles consistently reduced the overall magnitude of medial compartment loading during stair ascent and descent. Further research is needed to determine the relationship of this with clinical results when ascending and descending stairs with lateral wedge insoles.

The immediate effect of lateral wedge insoles, with and without a subtalar strap, on the lateral trunk lean motion in patients with knee osteoarthritis

BACKGROUND

Orthotic interventions for knee osteoarthritis (OA) aim to reduce mechanical loading on the medial compartment of the knee and may lessen the lateral trunk lean as the most important compensatory gait strategy. The lateral wedge insole is a known orthotic intervention for knee OA. However, the question whether the addition of a subtalar strap to the wedge improves its effect has not been addressed in the literature.

OBJECTIVE

To compare the effects of lateral wedge insoles, with and without a subtalar strap, on the lateral trunk lean in patients with knee OA.

METHODS

Twenty-three patients aged over 40 years, with grade I or II OA of the medial compartment of one knee, based on the American College of Rheumatology criteria, were included in this study. The patients were diagnosed with OA based on a clinical examination, and the diagnosis was confirmed with radiographs. A 3-dimensional motion measurement system was used to collect the gait data for 3 different conditions: (1) with no insole, (2) with a lateral wedge insole, and (3) with a lateral wedge insole and a subtalar strap. The immediate effect of the 3 test conditions on the lateral trunk lean was compared during a gait cycle a stance phase and at the point of midstance.

RESULTS

Based on the laboratory coordinate system, the 3 conditions had no significant effect on the lateral trunk lean during a gait cycle and a stance phase and at the point of midstance in patients with knee OA.

CONCLUSION

The results of this study demonstrated that the lateral wedge insoles, with and without a subtalar strap, had no immediate effect on the lateral trunk lean in patients with knee OA. However, the long-term effect of lateral wedge insoles on the lateral trunk lean in these patients requires further investigation.

Customized foot insoles have a positive effect on pain, function, and quality of life in patients with medial knee osteoarthritis

BACKGROUND

Knee osteoarthritis (KOA) is a prevalent degenerative disease in older adults. Treatment strategies, including insoles, focus on reducing pain and physical disability. In medial KOA, insoles have been studied extensively with conflicting results, possibly due to heterogeneity in outcome measures and the intervention. We sought to investigate the effect of custom-made laterally wedged insoles on pain, function, and quality of life in patients with medial KOA.

METHODS

Fifty-one consecutive patients with medial KOA were prescribed custom-made insoles with arch support and a 5.0° to 8.7° lateral wedge. At follow-up, 42 of the 51 participants (22 men; mean age, 63 years; mean Kellgren-Lawrence, 3.4) participated. Retrospectively, participants were asked to rate the pain intensity in their affected knee before and after the intervention measured on a visual analog scale after 30 min of physical activity (primary outcome), at rest, at night, and after 50 m of walking. Additionally, they completed the Oxford Knee Score and the EQ-5D. The paired-samples t test was applied in the statistics.

RESULTS

The visual analog scale score after 30 min of physical activity was significantly reduced after the intervention (mean, 3.3 cm; 95% confidence interval, 2.1-4.5 cm; P < .001). The same significant changes were found in all of the secondary outcomes.

CONCLUSIONS

There was a significant reduction in pain and improvements in function and quality of life with custom-made laterally wedged insoles with arch support in older adults with mild-to-severe medial KOA. The customization of laterally wedged insoles may be essential for the effect in medial KOA.

A biomechanical perspective on physical therapy management of knee osteoarthritis

SYNOPSIS

Altered knee joint biomechanics and excessive joint loading have long been considered as important contributors to the development and progression of knee osteoarthritis. Therefore, a better understanding of how various treatment options influence the loading environment of the knee joint could have practical implications for devising more effective physical therapy management strategies. The aim of this clinical commentary was to review the pertinent biomechanical evidence supporting the use of treatment options intended to provide protection against excessive joint loading while offering symptomatic relief and functional improvements for better long-term management of patients with knee osteoarthritis. The biomechanical and clinical evidence regarding the effectiveness of knee joint offloading strategies, including contralateral cane use, laterally wedged shoe insoles, variable-stiffness shoes, valgus knee bracing, and gait-modification strategies, within the context of effective disease management is discussed. In addition, the potential role of therapeutic exercise and neuromuscular training to improve the mechanical environment of the knee joint is considered. Management strategies for treatment of joint instability and patellofemoral compartment disease are also mentioned. Based on the evidence presented as part of this clinical commentary, it is argued that special considerations for the role of knee joint biomechanics and excessive joint loading are necessary in designing effective short- and long-term management strategies for treatment of patients with knee osteoarthritis.

LEVEL OF EVIDENCE

Therapy, level 5.

Mechanical effectiveness of lateral foot wedging in medial knee osteoarthritis after 1 year of wear

The use of lateral foot wedging in the management of medial knee osteoarthritis is under scrutiny. Interestingly, there have been minimal efforts to evaluate biomechanical effectiveness with long-term use. Therefore, we aimed to evaluate dynamic knee loading (assessed using the knee adduction moment) and other secondary gait parameters in patients with medial knee osteoarthritis wearing lateral foot wedging at a baseline visit and after 1 year of wear. Three-dimensional gait data were captured in an intervention group of 19 patients with symptomatic medial knee osteoarthritis wearing their prescribed laterally wedged foot orthoses at 0 and 12 months. Wedge amounts were prescribed based on symptom response to a step-down test. A control group of 19 patients wearing prescribed neutral orthoses were also captured at 0 and 12 months. The gait of the intervention group wearing neutral orthoses was additionally captured. Walking speed and shoes were controlled. Analyses of variance were conducted to examine for group-by-time (between the groups in their prescribed orthoses) and condition-by-time (within the intervention group) interactions, main effects, and simple effects. We observed increased knee adduction moments and frontal plane motion over time in the control group but not the intervention group. Further, within the intervention group, the mechanical effectiveness of the lateral wedging did not decrease. In patients with medial knee osteoarthritis, the effects of lateral foot wedging on pathomechanics associated with medial knee osteoarthritis were favorable and sustained over time.

Foot center of pressure trajectory alteration by biomechanical manipulation of shoe design

BACKGROUND

Footwear-generated biomechanical manipulations have been shown to alter lower limb kinetics. It has been suggested that this is due to altered trajectory of the foot's center of pressure (COP), conveying a shift in location of the ground reaction force and modifying moments and forces acting on proximal body segments. However, past studies have focused on qualitative association between footwear design and the COP locus. Moreover, this association was calculated via indirect analysis. The purpose of the present study was to directly examine and quantify the correlation between measured footwear biomechanical manipulation and the location of the COP trajectory during gait.

METHODS

A novel biomechanical device allowing flexible positioning of 2 convex-shaped elements attached to its sole was utilized. A total of 20 healthy male adults underwent direct in-shoe pressure measurements while walking with the device set at 7 mediolateral configurations. COP data were collected during gait and analyzed with respect to different stance subphases.

RESULTS

COP location significantly correlated with a shift of the elements medially or laterally. The linear model describing this correlation was found to be statistically significant.

CONCLUSION

There was significant correlation between the plantar orientation of the shoe device configuration and the COP.

CLINICAL RELEVANCE

Changes in COP trajectory may be valuable in patients suffering from multiple foot disorders elevating pressure on the foot. Accurate COP control could aid in the manipulation of the forces acting on the proximal joints during gait. In addition, these findings may have implications in the field of biomechanical apparatus design and practice.

Long-Term Effects of AposTherapy in Patients with Osteoarthritis of the Knee: A Two-Year Followup

Several biomechanics treatments for knee osteoarthritis (OA) have emerged with the goal of reducing pain and improving function. Through this, researchers have hoped to achieve a transition from the pathological gait patterns to coordinated motor responses. The purpose of the study was to determine the long-term effects of a therapy using a biomechanical device in patients with knee OA. Patients with knee OA were enrolled to active and control groups. The biomechanical device used in therapy (AposTherapy) was individually calibrated to each patient in the active group. Patients in the control group received standard treatment. Outcomes were the Western Ontario and McMaster Osteoarthritis Index (WOMAC), Aggregated Locomotor Function (ALF), Short Form 36 (SF-36), and Knee Society Score assessments. The active and control groups were similar at the baseline (group difference in all scores P > 0.05). The active group showed a larger improvement over time between groups in all three WOMAC categories (F = 16.8, 21.7, and 18.1 for pain, stiffness, and function; all P < 0.001), SF-36 Physical Scale (F = 5.8; P = 0.02), Knee Society Knee Score (F = 4.3; P = 0.044 ), and Knee Society Function Score (F = 6.5; P = 0.014 ). At the two-year endpoint, the active group showed significantly better results (all P ≤ 0.001). The groups showed a difference of 4.9, 5.6, and 4.7 for the WOMAC pain, stiffness, and function scores, respectively, 10.8 s in ALF score, 30.5 in SF-36 Physical Scale, 16.9 in SF-36 Mental Scale, 17.8 in Knee Society Knee Score, and 25.2 in Knee Society Function Score. The biomechanical therapy examined was shown to significantly reduce pain and improve function and quality of life of patients with knee OA over the long term.

Comparison of the efficacy of laterally wedged insoles and bespoke unloader knee orthoses in treating medial compartment knee osteoarthritis

BACKGROUND

Patients suffering from medial compartment knee osteoarthritis (OA) may be treated with unloader knee orthoses or laterally wedged insoles.

OBJECTIVES

The aim of this study was to identify and compare the effects of them on the gait parameters and pain in these patients.

STUDY DESIGN

Quasi-experimental.

METHODS

Volunteer subjects with medial compartment knee OA (n = 24, mean age 59.29 ± 2.23 years) were randomly assigned to two separate groups and evaluated when wearing an unloader knee orthosis or insoles incorporating a 6° lateral wedge. Testing was performed at baseline and after six weeks of each orthosis use. A visual analog scale score was used to assess pain and gait analysis was utilized to determine gait parameters.

RESULTS

Both orthoses improved all parameters compared to the baseline condition (p = 0.000). However, no significant differences in pain (p = 0.649), adduction moment (p = 0.205), speed of walking (p = 0. 056) or step length (p = 0.687) were demonstrated between them. The knee range of motion (p = 0.000) were significantly different between the two interventions.

CONCLUSION

Both orthoses reduced knee pain. Maximum knee range of motion was increased by both interventions although it was 3 degrees less when wearing the knee orthosis. Clinical relevance Both orthoses reduce pain and improve gait anomalies in medial compartment knee OA. Our results suggest a laterally wedged insole can be an alternative conservative approach to unloader knee orthosis for treating symptoms of medial compartment knee OA.

Redistribution of knee stress using laterally wedged insole intervention: Finite element analysis of knee-ankle-foot complex

BACKGROUND

Laterally wedged insoles are widely applied in the conservative treatment for medial knee osteoarthritis. Experimental studies have been conducted to understand the effectiveness of such an orthotic intervention. However, the information was limited to the joint external loading such as knee adduction moment. The internal stress distribution is difficult to be obtained from in vivo experiment alone. Thus, a three-dimensional finite element model of the human knee-ankle-foot complex, together with orthosis, was developed in this study and used to investigate the redistribution of knee stress using laterally wedged insole intervention.

METHODS

Laterally wedged insoles with wedge angles of 0, 5, and 10° were fabricated for intervention. The subject-specific geometry of the lower extremity with details was characterized in the reconstruction of MR images. Motion analysis data and muscle forces were input to drive the model. The established finite element model was employed to investigate the loading responses of tibiofemoral articulation in three wedge angle conditions during simulated walking stance phase.

FINDINGS

With either of the 5° or 10° laterally wedged insole, significant decreases in von Mises stress and contact force at the medial femur cartilage region and the medial meniscus were predicted comparing with the 0° insole.

INTERPRETATION

The diminished stress and contact force at the medial compartment of the knee joint demonstrate the immediate effect of the laterally wedged insoles. The intervention may contribute to medial knee osteoarthritis rehabilitation.

Combined effects of a valgus knee brace and lateral wedge foot orthotic on the external knee adduction moment in patients with varus gonarthrosis

OBJECTIVE

To test the hypothesis that a custom-fit valgus knee brace and custom-made lateral wedge foot orthotic will have greatest effects on decreasing the external knee adduction moment during gait when used concurrently.

DESIGN

Proof-of-concept, single test session, crossover trial.

SETTING

Biomechanics laboratory within a tertiary care center.

PARTICIPANTS

Patients (n=16) with varus alignment and knee osteoarthritis (OA) primarily affecting the medial compartment of the tibiofemoral joint (varus gonarthrosis).

INTERVENTIONS

Custom-fit valgus knee brace and custom-made full-length lateral wedge foot orthotic. Amounts of valgus angulation and wedge height were tailored to each patient to ensure comfort.

MAIN OUTCOME MEASURES

The external knee adduction moment (% body weight [BW]*height [Ht]), frontal plane lever arm (cm), and ground reaction force (N/kg), determined from 3-dimensional gait analysis completed under 4 randomized conditions: (1) control (no knee brace, no foot orthotic), (2) knee brace, (3) foot orthotic, and (4) knee brace and foot orthotic.

RESULTS

The reduction in knee adduction moment was greatest when concurrently using the knee brace and foot orthotic (effect sizes ranged from 0.3 to 0.4). The mean decrease in first peak knee adduction moment compared with control was .36% BW*Ht (95% confidence interval [CI], -.66 to -.07). This was accompanied by a mean decrease in frontal plane lever arm of .59cm (95% CI, -.94 to -.25).

CONCLUSIONS

These findings suggest that using a custom-fit knee brace and custom-made foot orthotic concurrently can produce a greater overall reduction in the knee adduction moment, through combined effects in decreasing the frontal plane lever arm.

Kinetic and kinematic changes with the use of valgus knee brace and lateral wedge insoles in patients with medial knee osteoarthritis

The effect of a valgus knee brace and a lateral wedged insole on knee and ankle kinematics and kinetics was evaluated in ten patients with medial knee osteoarthritis (OA). The knee orthosis was tested in two valgus adjustments (4° and 8°), and the laterally wedged insole was fabricated with an inclination of 4°. A motion capture system and force platforms were used for data collection and joint moments were calculated using inverse dynamics. The valgus moment applied by the orthosis was also measured using a strain gauge implemented in the orthosis' rotational axis. For the second peak knee adduction moment, decreases of 18%, 21%, and 7% were observed between baseline and test conditions for the orthosis in 4° valgus, in 8° valgus, and insole, respectively. Similar decreases were observed for knee lever arm in the frontal plane. Knee adduction angular impulse decreased 14%, 18%, and 7% from baseline to conditions for the orthosis in 4° valgus, in 8° valgus, and insole, respectively. Knee angle in the frontal plane reached a more valgus position during gait using the valgus knee brace. The valgus moment applied by the orthosis with 8° valgus adjustment was 30% higher than with 4° valgus adjustment. The valgus knee orthosis was more effective than the laterally wedged insole in reducing knee adduction moment in patients with medial knee OA.

Effect of footwear on the external knee adduction moment - A systematic review

CONTEXT

Footwear modifications have been investigated as conservative interventions to decrease peak external knee adduction moment (EKAM) and pain associated with knee osteoarthritis (OA).

OBJECTIVE

To evaluate the literature on the effect of different footwear and orthotics on the peak EKAM during walking and/or running.

METHODS

A systematic search of databases resulted in 348 articles of which 33 studies were included.

RESULTS

Seventeen studies included healthy individuals and 19 studies included subjects with medial knee OA. Quality assessment (modified Downs and Black quality index) showed an (average±SD) of 73.1±10.1%. The most commonly used orthotic was the lateral wedge, with three studies on the medial wedge. Lateral wedging was associated with decreased peak EKAM in healthy participants and participants with medial knee OA while there is evidence for increased peak EKAM with the use of medial wedges. Modern footwear (subjects' own shoe, "stability" and "mobility" shoes, clogs) were likely to increase the EKAM compared to barefoot walking in individuals with medial knee OA. Walking in innovative shoes ("variable stiffness") decreased the EKAM compared to control shoes. Similarly, shoes with higher heels, sneakers and dress shoes increased EKAM in healthy individuals compared to barefoot walking.

CONCLUSIONS

Further development may be needed toward optimal footwear for patients with medial knee OA with the aim of obtaining similar knee moments to barefoot walking.

Foot center of pressure manipulation and gait therapy influence lower limb muscle activation in patients with osteoarthritis of the knee

BACKGROUND

Foot center of pressure (COP) manipulation has been associated with improved gait patterns. The purpose of this study was to determine lower limb muscle activation changes in knee osteoarthritis patients, both immediately after COP manipulation and when COP manipulation was combined with continuous gait therapy (AposTherapy).

METHODS

Fourteen females with medial compartment knee osteoarthritis underwent EMG analyzes of key muscles of the leg. In the initial stage, trials were carried out at four COP positions. Following this, gait therapy was initiated for 3 months. The barefoot EMG was compared before and after therapy.

RESULTS

The average EMG varied significantly with COP in at least one phase of stance in all examined muscles of the less symptomatic leg and in three muscles of the more symptomatic leg. After training, a significant increase in average EMG was observed in most muscles. Most muscles of the less symptomatic leg showed significantly increased peak EMG. Activity duration was shorter for all muscles of the less symptomatic leg (significant in the lateral gastrocnemius) and three muscles of the more symptomatic leg (significant in the biceps femoris). These results were associated with reduced pain, increased function and improved spatiotemporal parameters.

CONCLUSIONS

COP manipulation influences the muscle activation patterns of the leg in patients with knee osteoarthritis. When combined with a therapy program, muscle activity increases and activity duration decreases.

Lateral wedge insoles for medial knee osteoarthritis: effects on lower limb frontal plane biomechanics

BACKGROUND

Lateral wedges reduce the peak knee adduction moment and are advocated for knee osteoarthritis. However some patients demonstrate adverse biomechanical effects with treatment. Clinical management is hampered by lack of knowledge about their mechanism of effect. We evaluated effects of lateral wedges on frontal plane biomechanics, in order to elucidate mechanisms of effect.

METHODS

Seventy three participants with knee osteoarthritis underwent gait analysis with and without 5° lateral wedges. Frontal plane parameters at the foot, knee and hip were evaluated, including peak knee adduction moment, knee adduction angular impulse, center of pressure displacement, ground reaction force, and knee-ground reaction force lever arm.

FINDINGS

Lateral wedges reduced peak knee adduction moment and knee adduction angular impulse (-5.8% and -6.3% respectively, both P<0.001). Although reductions in peak moment were correlated with more lateral center of pressure (r=0.25, P<0.05), less varus malalignment (r values 0.25-0.38, P<0.05), reduced knee-ground reaction force lever arm (r=0.69, P<0.01), less hip adduction (r=0.24, P<0.05) and a more vertical frontal plane ground reaction force vector (r=0.67, P<0.001), only reduction in knee-ground reaction force lever arm was significantly predictive in regression analyses (B=0.056, adjusted R(2)=0.461, P<0.001).

INTERPRETATION

Lateral wedges significantly reduce peak knee adduction moment and knee adduction angular impulse. It seems a reduced knee-ground reaction force lever arm with lateral wedges is the central mechanism explaining their load-reducing effects. In order to understand why some patients do not respond to treatment, future evaluation of patient characteristics that mediate wedge effects on this lever arm is required.

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.

Biomechanical changes accompanying unilateral and bilateral use of laterally wedged insoles with medial arch supports in patients with medial knee osteoarthritis

BACKGROUND

Laterally wedged insoles have controversial effect in treating medial compartment knee osteoarthritis. This study examined the effects of unilateral and bilateral use of insoles having medial arch supports and of different inclinations on the frontal plane external hip, knee, subtalar moments and pelvic alignment.

METHODS

Kinetic and kinematic gait parameters were collected from 21 patients with primary medial knee osteoarthritis. The insoles' inclinations were 0, 6 and 11°, where each of the 6° and 11° was used once unilaterally and another bilaterally while the 0° was used bilaterally as a control.

FINDINGS

The Multivariate Analysis of Variance revealed significant increase in the external subtalar eversion moment using either of the 6° or 11° laterally wedged vs the 0° non-wedged insole conditions (P=0.003). Moreover, there were significant increases in the external eversion moment using the 11° vs the 6° insole conditions (P<0.05). However, there were no significant differences for the remaining tested variables (P>0.05). The bivariate correlations revealed significant negative correlations between the subtalar eversion and knee adduction moments (r=-0.409, P=0.000) and the subtalar eversion and hip adduction moments (r=-0.226, P=0.049), and positive correlation between the hip and knee adduction moments (r=0.268, P=0.019).

INTERPRETATION

The non-significant reduction in the external knee adduction moment may question the efficacy of using wedged insoles having medial arch supports in treating patients with medial knee osteoarthritis. Additionally, using such insoles did not produce appreciable mechanical effects on remote articulations as the hip and pelvis.

In-shoe plantar pressure measurements for patients with knee osteoarthritis: Reliability and effects of lateral heel wedges

Although plantar pressure measurement systems are being used increasingly during gait analyses to investigate foot orthotics, there is limited information describing test-retest reliability of such measurements. Objectives of this study were to (1) examine the test-retest reliability of lateral heel pressure (LHP) and centre of pressure (COP) during walking with and without lateral heel wedges, and (2) evaluate the effects of 4° and 8° lateral heel wedges on the magnitude of LHP, the pathway of the COP and the peak external knee adduction moment (KAM) in subjects with and without knee osteoarthritis (OA). Twenty-six subjects, 12 patients with knee OA and 14 healthy subjects, were evaluated during three lateral heel wedge conditions (control, 4° and 8°) with standardized footwear. Three-dimensional analyses of gait with optical motion capture, floor-mounted force plate and in-shoe plantar pressure were completed on two occasions. Intraclass correlation coefficients (ICC(2, 1)) for LHP were excellent (0.79-0.83) while ICCs for COP in the medial-lateral and anterior-posterior directions were more variable (0.66-0.86). Reliability was slightly diminished when using heel wedges. Standard errors of measurement suggested considerable day-to-day variability in an individual's measures. Lateral heel wedges significantly (p<0.001) increased LHP, shifted COP anteriorly and laterally, and decreased the KAM. No significant differences were observed between subjects with and without OA. Although the day-to-day variability appears too large to confidently evaluate changes in individual patients, and decreases in reliability with increases in wedge size indicate caution, these results suggest in-shoe measurement of LHP and COP are appropriate for use in studies evaluating biomechanical effects of foot orthoses for knee OA.

Conservative biomechanical strategies for knee osteoarthritis

Knee osteoarthritis (OA) is one of the most prevalent forms of this disease, with the medial compartment most commonly affected. The direction of external forces and limb orientation during walking results in an adduction moment that acts around the knee, and this parameter is regarded as a surrogate measure of medial knee compression. The knee adduction moment is intimately linked with the development and progression of knee OA and is, therefore, a target for conservative biomechanical intervention strategies, which are the focus of this Review. We examine the evidence for walking barefoot and the use of lateral wedge insoles and thin-soled, flexible shoes to reduce the knee adduction moment in patients with OA. We review strategies that directly affect the gait, such as walking with the foot externally rotated ('toe-out gait'), using a cane, lateral trunk sway and gait retraining. Valgus knee braces and muscle strengthening are also discussed for their effect upon reducing the knee adduction moment.