Gait retraining using real-time feedback in patients with medial knee osteoarthritis: Feasibility and effects of a six-week gait training program

Knee loading and joint pain during daily activities in people with knee osteoarthritis: A systematic review and meta-analysis

BACKGROUND

Knee loading is associated with the severity and progression of knee osteoarthritis, while knee pain contributes to reduced functional ability and quality of life. In this systematic review, we quantified knee loading and knee pain during different daily activities in people with knee osteoarthritis and explored methodological reasons for differences between studies.

METHODS

PubMed, Web of Science, Scopus, and manual searches were performed up to July 2024, to retrieve studies measuring knee loading and knee pain in walking, sit-to-stand and stair climbing of people with knee osteoarthritis. Descriptive data synthesis and meta-analysis were performed using a mixed-effect model.

FINDINGS

183 studies were included. Walking led to the greatest knee loading, followed by stair climbing and finally sit-to-stand, although only sit-to-stand was significantly lower than the others (p < 0.001). Stair ascent had the greatest knee pain, followed by walking, stair descent and then sit-to-stand. In addition, our results show a strong negative correlation between knee loading and pain during walking (r = -0.507).

INTERPRETATION

The trend of knee loading across activities, while non-significant, is consistent with our previous experimental study. The differences compared to other studies are likely be due to the high heterogeneity in the tested population and differences in methodology. Additionally, there were a substantial number of studies only examining a single activity (primarily walking), which could bias the results. Therefore, future studies should detail participant characteristic and experiment design. In addition, inclusion of a control group is recommended to account for knee loading offsets when comparing results across studies.

Toe-in and toe-out gait retraining interventions for individuals with knee osteoarthritis trial: A pilot randomised clinical trial

BACKGROUND

Gait retraining, through altering foot progression angle, has the potential to reduce pain and offload the medial tibiofemoral compartment in people with knee osteoarthritis. This pilot study aimed to evaluate the feasibility of toe-in and toe-out gait retraining on self-reported pain and physical function, and proxy measures of medial knee load, in individuals with medial knee osteoarthritis.

METHODS

Twenty participants with symptomatic medial knee osteoarthritis were randomly allocated to receive either toe-in or toe-out gait retraining for six-weeks, consisting of weekly clinician-supervised sessions and ≥ 30 min of daily self-practice. Feedback was guided by wearable sensors and a pressure-sensitive mat. Primary outcomes included recruitment rate, data completeness, adverse events, adherence, achievability, and intervention acceptability. Secondary outcomes were proxy measures of medial knee load, and self-reported pain and physical function. Differences in feasibility and self-reported outcomes were interpreted via sample t-test using intention-to-treat analysis. The effect of the intervention group on knee biomechanics was evaluated using linear mixed modelling.

FINDINGS

Recruitment was acceptable (n = 4/month) with excellent data completeness (93 %) and attendance (82 %). Acceptability was moderate and similar between groups. There were no differences in average knee pain and physical function between groups over time, and both groups reduced maximum knee pain following the intervention (35 % improvement, p = 0.012). There were no differences in biomechanical outcomes between groups over time.

INTERPRETATION

Toe-in and toe-out gait retraining is feasible and improves pain in people with knee osteoarthritis. A full-scale randomised clinical trial is warranted and should consider individualising the intervention.

Intra- and interlimb effects of gait retraining in individuals with knee hyperextension

BACKGROUND

Gait retraining, which typically focuses on the most severely affected limb or joint, has shown promising results in treating faulty running and walking patterns. The closed-chain nature of gait during the stance phase may influence kinematic changes in the adjacent joints of the trained leg. In addition, the coupled nature of the lower extremity motion of gait suggests that changes in one leg may transfer to the other. This study aimed to assess the intra- and inter-limb transfer of kinematic changes following gait retraining to reduce knee extension in individuals with hyperextension walking patterns.

METHODS

Seventeen women with knee hyperextension gait patterns participated in six treadmill retraining sessions. All participants received verbal and real-time visual kinematic feedback in the form of knowledge of results. This intervention study took place at the Gait Analysis Laboratory at the University of Iowa. Mean peak sagittal-plane lower extremity joint kinematics during overground walking at pretraining, post-training, and 1- and 8-month follow-ups were calculated for analysis and comparisons.

FINDINGS

The post-training changes in ankle range of motion returned to baseline values by the 8-month follow-up. There was a significant transfer effect of kinematic changes to the untrained knee following gait retraining.

INTERPRETATION

Training one knee did not result in long-term compensatory kinematic changes in the other joints. In addition, the improvements in knee extension range of motion were transferred to the untrained knee and retained at the 8-month follow-up. This study supports the use of gait retraining as an effective clinical intervention.

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

BACKGROUND

Impairments in unilateral ankle propulsion may result from restriction by an external device or pathology such as lower limb amputation. Models of gait suggest this reduction may lead to increased collisional force on the contralateral side, potentially increasing force through the knee and increasing the risk of knee pain or osteoarthritis.

RESEARCH QUESTION

How do restrictions in unilateral ankle propulsive force affect contralateral knee joint loading in otherwise healthy individuals?

METHODS

18 individuals without impairment walked on a treadmill at 1.5 m/s for two conditions: one free of restrictions, and one where a randomized limb's ankle propulsive force was restricted using an off-the-shelf ankle-foot orthosis (AFO). Ankle propulsive power, lower extremity joint work, and ground reaction force variables were calculated for the final 3 gait cycles of each condition. Tibiofemoral joint contact force (TJCF) for the limb contralateral to the AFO was calculated through a standard OpenSim workflow utilizing the gait2392 model. Intra-limb pair-wise comparisons were made between conditions.

RESULTS

Compared to walking unrestricted, the limb wearing the AFO demonstrated a significant reduction in peak ankle propulsive power and positive ankle work by approximately 50 % each (p<0.01). With ankle restriction, the ipsilateral knee significantly increased positive work (p<0.01). The overall propulsion produced by that limb did not change between conditions, demonstrated by a lack of change in anterior ground reaction force impulse (p=0.11). The knee of the limb contralateral to the AFO did not display differences in any TJCF variable between conditions (all p>0.07).

SIGNIFICANCE

These results suggest a unilateral deficit in ankle propulsion will not increase contralateral knee joint forces in individuals who are able to use other joints of the limb to compensate for the loss of ankle function. However, further research should investigate this relationship in those who display pathologies that may prevent more proximal compensations.

The effect of foot orientation modifications on knee joint biomechanics during daily activities in people with and without knee osteoarthritis

BACKGROUND

Altered gait could influence knee joint moment magnitudes and cumulative damage over time. Gait modifications have been shown to reduce knee loading in people with knee osteoarthritis during walking, although this has not been explored in multiple daily activities. Therefore, this study investigated the effect of different foot orientations on knee loading during multiple daily activities in people with and without knee osteoarthritis.

METHODS

Thirty people with knee osteoarthritis and twenty-nine without (control) performed walking, stair ambulation and sit-to-stand across a range of foot progression angles (neutral, toe-in, toe-out and preferred). Peak knee adduction moment, knee adduction moment impulse and knee pain were compared across a continuous range of foot orientations, between activities, and groups.

FINDINGS

Increased foot progression angle (more toe-in) reduced 1st peak knee adduction moment across all activities in both knee osteoarthritis and control (P < 0.001). There was a greater reduction in knee adduction moment in the control group during walking and stair ambulation (P ≤ 0.006), where the knee osteoarthritis group already walked preferably less toe-out than the control group. Under preferred condition, stair descent had the greatest knee loading and knee pain compared to other activities.

INTERPRETATION

Although increased foot progression angle (toward toe-in) appeared to be more effective in reducing knee loading for all activities, toe-in modification might not benefit stair ambulation. Future gait modification should likely be personalised to each patient considering the individual difference in preferred gait and knee alignment required to shift the loading medially or laterally.

Effects of gait intervention using the draw-in maneuver on knee joint function and the thoracic kyphosis angle in knee osteoarthritis

BACKGROUND

To evaluate whether the knee adduction moment (KAM) could be reduced by a short instruction in the Draw-in (DI) maneuver in healthy adults, and whether knee joint function would improve with a longer DI gait intervention in patients with knee osteoarthritis (OA).

METHOD

In Study 1, healthy adults received 10 minutes supervised instruction in DI gait in and then practiced the gait independently for 10 minutes. Three-dimensional motion analysis measurement was performed in each phase. In Study 2, patients with OA performed a 20-minute DI gait intervention daily for 6 weeks. At baseline and after 6 weeks, knee pain, the Knee injury and Osteoarthritis Outcome Score, the MOS 8 item Short-Form Health Survey, thoracic kyphosis angle, knee joint range of motion, knee extension muscle strength, hip abduction muscle strength, and activity level were evaluated.

RESULTS

In Study 1, the DI gait to decrease KAM could be learning following only 10 minutes of instruction and 10 minutes of self-practice in healthy adults. In Study 2, knee pain was reduced by 19 % and the thoracic kyphosis angle was reduced by 2.6° after 6 weeks. No significant changes in other parameters were detected, and the implementation rate was 86 ± 14 %.

SIGNIFICANCE

In healthy adults, DI gait instruction for 10 minutes of instruction and 10 minutes of self-practice reduced the KAM. In patients with knee OA, 20 minutes of DI gait per day for 6 weeks may reduce knee pain and thoracic kyphosis.

Biomechanical Effects of Manipulating Preferred Cadence During Treadmill Walking in Patients With ACL Reconstruction

BACKGROUND

Abnormal gait is common after anterior cruciate ligament reconstruction (ACLR) which may influence osteoarthritis risk in this population. Yet few gait retraining options currently exist in ACLR rehabilitation. Cueing cadence changes is a simple, low-cost method that can alter walking mechanics in healthy adults, but few studies have tested its effectiveness in an ACLR population. Here, we evaluated the acute effects of altering cadence on knee mechanics in patients 9 to 12 months post ACLR.

HYPOTHESIS

Cueing larger steps will facilitate larger knee angles and moments, while cueing smaller steps would induce smaller knee angles and moments.

STUDY DESIGN

Randomized cross-sectional design.

LEVEL OF EVIDENCE

Level 3.

METHODS

Twenty-eight patients with unilateral ACLR underwent gait assessments on a treadmill at preferred pace. Preferred walking gait was assessed first to obtain preferred cadence. Participants then completed trials while matching an audible beat set to 90% and 110% of preferred cadence in a randomized order. Three-dimensional sagittal and frontal plane biomechanics were evaluated bilaterally.

RESULTS

Compared with preferred cadence, cueing larger steps induced larger peak knee flexion moments (KFMs) and knee extension excursions bilaterally (P < 0.01), whereas cueing smaller steps only reduced knee flexion excursions (P < 0.01). Knee adduction moments remain unchanged across conditions and were similar between limbs (P > 0.05). Peak KFMs and excursions were smaller in the injured compared with uninjured limb (P < 0.01).

CONCLUSION

Frontal plane gait outcomes were unchanged across conditions suggesting acute cadence manipulations result in mainly sagittal plane adaptations. Follow-up studies using a longitudinal cadence biofeedback paradigm may be warranted to elucidate the utility of this gait retraining strategy after ACLR.

CLINICAL RELEVANCE

Cueing changes in walking cadence can target sagittal plane knee loading and joint range of motion in ACLR participants. This strategy may offer high clinical translatability given it requires relatively minimal equipment (ie, free metronome app) outside of a treadmill.

IMU-Based Kinematics Estimation Accuracy Affects Gait Retraining Using Vibrotactile Cues

Wearable sensing using inertial measurement units (IMUs) is enabling portable and customized gait retraining for knee osteoarthritis. However, the vibrotactile feedback that users receive directly depends on the accuracy of IMU-based kinematics. This study investigated how kinematic errors impact an individual's ability to learn a therapeutic gait using vibrotactile cues. Sensor accuracy was computed by comparing the IMU-based foot progression angle to marker-based motion capture, which was used as ground truth. Thirty subjects were randomized into three groups to learn a toe-in gait: one group received vibrotactile feedback during gait retraining in the laboratory, another received feedback outdoors, and the control group received only verbal instruction and proceeded directly to the evaluation condition. All subjects were evaluated on their ability to maintain the learned gait in a new outdoor environment. We found that subjects with high tracking errors exhibited more incorrect responses to vibrotactile cues and slower learning rates than subjects with low tracking errors. Subjects with low tracking errors outperformed the control group in the evaluation condition, whereas those with higher error did not. Errors were correlated with foot size and angle magnitude, which may indicate a non-random bias. The accuracy of IMU-based kinematics has a cascading effect on feedback; ignoring this effect could lead researchers or clinicians to erroneously classify a patient as a non-responder if they did not improve after retraining. To use patient and clinician time effectively, future implementation of portable gait retraining will require assessment across a diverse range of patients.

Clinically significant effects of gait modification on knee pain: A systematic review and meta-analysis

BACKGROUND

Knee pain is the main symptom of knee osteoarthritis. Walking is effective against knee pain, and some studies have shown that gait modification can also relieve this condition. However, the quality of evidence for the clinically significant effects of gait modification on knee pain has not been examined.

OBJECTIVE

This systematic review and meta-analysis aimed to evaluate the level of evidence for the clinically significant effects of gait modification on knee pain and determine if the effects are greater than the minimal clinically important difference (MCID).

METHODS

We comprehensively searched electronic databases such as MEDLINE, Cochrane Central Register of Controlled Trials, Physiotherapy Evidence Database, and Cumulative Index to Nursing and Allied Health Literature. Intervention studies with experimental groups who received gait modification and control groups who did not were evaluated. The Grading of Recommendations Assessment, Development and Evaluation system was used to assess the level of evidence.

RESULTS

Nine studies met the inclusion criteria. All were included in the systematic review and two in the meta-analysis. Results showed that gait modification have significant effects (p= 0.02), and the quality of evidence was very low. However, several studies have revealed that the effects of gait modification, when used as a foot-focused intervention, were greater than the MCID.

CONCLUSIONS

We concluded that there is a lack of high-quality evidence that supports the general efficacy of gait modification. Although based on low-quality evidence, when applied to the foot, it may have clinically significant effects.

The effectiveness of a 6-week biofeedback gait retraining programme in people with knee osteoarthritis: protocol for a randomised controlled trial

BACKGROUND

Gait retraining is a common therapeutic intervention that can alter gait characteristics to reduce knee loading in knee osteoarthritis populations. It can be enhanced when combined with biofeedback that provides real-time information about the users' gait, either directly (i.e. knee moment feedback) or indirectly (i.e. gait pattern feedback). However, it is unknown which types of biofeedback are more effective at reducing knee loading, and also how the changes in gait affect pain during different activities of daily living. Therefore, this study aims to evaluate the acute (6 weeks of training) and chronic (1 month post training) effects of biofeedback based on personalised gait patterns to reduce knee loading and pain in people with knee osteoarthritis, as well as examine if more than one session of knee moment feedback is needed to optimise the gait patterns.

METHODS

This is a parallel group, randomised controlled trial in a symptomatic knee osteoarthritis population in which participants will be randomised into either a knee moment biofeedback group (n = 20), a gait pattern biofeedback group (n = 20) or a control group (n = 10). Supervised training sessions will be carried out weekly for six continuous weeks, with real-time biofeedback provided using marker-based motion capture and an instrumented treadmill. Baseline, post-intervention and 1-month follow-up assessments will be performed to measure knee loading parameters, gait pattern parameters, muscle activation, knee pain and functional ability.

DISCUSSION

This study will identify the optimal gait patterns for participants' gait retraining and compare the effectiveness of gait pattern biofeedback to a control group in reducing knee loading and index knee pain. Additionally, this study will explore how many sessions are needed to identify the optimal gait pattern with knee moment feedback. Results will be disseminated in future peer-reviewed journal articles, conference presentations and internet media to a wide audience of clinicians, physiotherapists, researchers and individuals with knee osteoarthritis.

TRIAL REGISTRATION

This study was retrospectively registered under the International Standard Randomised Controlled Trial Number registry on 7th March 2023 (ISRCTN28045513).

Toe-in and toe-out gait retraining interventions to reduce proxy measures of medial knee joint load in people with medial knee osteoarthritis: Protocol for a randomised placebo-controlled trial

OBJECTIVE

Our primary aim is to determine the effect of a six-week toe-in, toe-out and active placebo gait retraining program on proxy measures of medial knee joint load and varus thrust in people with medial knee osteoarthritis. Our secondary aim is to determine the intervention effects on patient reported outcomes and physical function and determine if changes are maintained at three-months follow-up.

METHODS

We will conduct a three-arm randomised placebo-controlled trial. Ninety participants with medial knee osteoarthritis will be randomised and stratified via varus thrust status (presence/absence) to: toe-in, toe-out or placebo gait retraining (an intervention that does not change proxy measures of medial knee joint load). The intervention involves weekly clinician-supervised sessions with biofeedback, knee osteoarthritis education, motor learning and behaviour change principles, and daily gait retraining practice. Primary outcomes are proxy measures of medial knee joint load: knee adduction moment (early- and late-stance peaks and impulse), and varus thrust (presence/absence). Secondary outcomes include pain, physical function, medication and health care utilisation, quality of life, work ability, treatment blinding, intervention credibility and other biomechanical outcomes. Assessment timepoints are at baseline, six weeks (post intensive training), and three-months following the six-week intervention.

CONCLUSION

Our trial will determine whether toe-in or toe-out gait retraining is most effective at reducing proxy measures of medial knee joint load and varus thrust in people with medial knee osteoarthritis. This study will also evaluate if toe-in or toe-out gait retraining interventions are superior at improving pain, physical function and quality of life compared to placebo.

CLINICAL TRIAL REGISTRATION

This clinical trial protocol is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12621000414819).

Association of tibial acceleration during walking to pain and impact loading in adults with knee osteoarthritis

BACKGROUND

Higher impact loading during walking is implicated in the pathogenesis of knee osteoarthritis. Accelerometry enables the measurement of peak tibial acceleration outside the laboratory. We characterized the relations of peak tibial acceleration to knee pain and impact loading during walking in adults with knee osteoarthritis.

METHODS

Adults with knee osteoarthritis reported knee pain then walked at a self-selected speed on an instrumented treadmill for 3 min with an ankle-worn inertial measurement unit. Ground reaction forces and tibial acceleration data were sampled for 1 min. Vertical impact peaks, and average and peak instantaneous load rates were determined and averaged across 10 steps. Peak tibial acceleration was extracted for all steps and averaged. Pearson's correlations and multiple linear regression analyses assessed the relation of peak tibial acceleration to pain and impact loading metrics, independently and after controlling for gait speed and pain.

FINDINGS

Higher peak tibial acceleration was associated with worse knee pain (r = 0.39; p = 0.01), and higher vertical average (r = 0.40; p = 0.01) and instantaneous (r = 0.46; p = 0.004) load rates. After adjusting for gait speed and pain, peak tibial acceleration was a significant predictor of vertical average (R2 = 0.33; p = 0.003) and instantaneous (R2 = 0.28; p = 0.02) load rates, but not strongly associated with vertical impact peak.

INTERPRETATIONS

Peak tibial acceleration during walking is associated with knee pain and vertical load rates in those with knee osteoarthritis. Clinicians can easily access measures of peak tibial acceleration with wearable sensors equipped with accelerometers. Future work should determine the feasibility of improving patient outcomes by using peak tibial acceleration to inform clinical management.

Feasibility of mitigating out-toeing gait using compression tights with inward-directing taping lines

Out-toeing gait may cause alterations in lower limb biomechanics that could lead to an increased risk of overuse injuries. Surgery and physical therapy are conventional methods for mitigating such gait, but they are costly and time-consuming. Wearable devices like braces and orthoses are used as affordable alternatives, but they apply non-negligible stress on the skin. Haptic feedback-delivering shoes were also recently developed, but they require actuators and power sources. The purpose of our study is to develop compression tights with inward directing taping lines that apply compression to lower limb muscles and segments to facilitate inward rotation of the foot, overcoming the drawbacks of previous methods. These compression tights were manufactured to fit the average height, leg length, hip girth, and waist girth of South Korean females in their twenties. The efficacy of these compression tights was evaluated by comparing walking kinematics and user satisfaction of 12 female dancers with an out-toeing gait under three conditions: wearing tights with taping lines, tights without taping lines, and basic bicycle shorts. The foot rotation angles and joint kinematics were recorded using a pressure-pad treadmill and motion capture system, respectively. Multiple pairwise comparisons revealed that the compression tights with inward-directing lines significantly reduced foot rotation angles (up to an average of 20.1%) compared with the bicycle shorts (p = 0.002 and 0.001 for dominant and non-dominant foot, respectively) or the compression tights without taping lines (p = 0.005 and p = 0.001 for dominant and non-dominant foot, respectively). Statistical parametric mapping revealed significant main effects of the tight type on joint kinematics. Also, t-tests revealed that the participants reported significantly higher ratings of perceived functionality and usability on the compression tights with inward-directing taping lines. In conclusion, we developed a comfortable and practical apparel-type wearable and demonstrated its short-term efficacy in mitigating out-toeing gait.

Real-Time Ground Reaction Force and Knee Extension Moment Estimation During Drop Landings Via Modular LSTM Modeling and Wearable IMUs

This work investigates real-time estimation of vertical ground reaction force (vGRF) and external knee extension moment (KEM) during single- and double-leg drop landings via wearable inertial measurement units (IMUs) and machine learning. A real-time, modular LSTM model with four sub-deep neural networks was developed to estimate vGRF and KEM. Sixteen subjects wore eight IMUs on the chest, waist, right and left thighs, shanks, and feet and performed drop landing trials. Ground embedded force plates and an optical motion capture system were used for model training and evaluation. During single-leg drop landings, accuracy for the vGRF and KEM estimation was R2 = 0.88 ± 0.12 and R2 = 0.84 ± 0.14, respectively, and during double-leg drop landings, accuracy for the vGRF and KEM estimation was R2 = 0.85 ± 0.11 and R2 = 0.84 ± 0.12, respectively. The best vGRF and KEM estimations of the model with the optimal LSTM unit number (130) require eight IMUs placed on the eight selected locations during single-leg drop landings. During double-leg drop landings, the best estimation on a leg only needs five IMUs placed on the chest, waist, and the leg's shank, thigh, and foot. The proposed modular LSTM-based model with optimally-configurable wearable IMUs can accurately estimate vGRF and KEM in real-time with relatively low computational cost during single- and double-leg drop landing tasks. This investigation could potentially enable in-field, non-contact anterior cruciate ligament injury risk screening and intervention training programs.

Diverse parameters of ambulatory knee moments differ with medial knee osteoarthritis severity and are combinable into a severity index

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

Remotely delivered, individualized, and self-directed gait modification for knee osteoarthritis: A pilot trial

BACKGROUND

Gait modification interventions have reported variable results and relied on in-person biofeedback limiting clinical accessibility. Our objective was to assess a remotely delivered and self-directed gait modification for knee osteoarthritis.

METHODS

This was an unblinded, 2-arm, delayed control, randomized pilot trial (NCT04683913). Adults aged ≥50 years with symptomatic medial knee osteoarthritis were randomized to an immediate group (Week 0: Baseline, Intervention; Week 6: Follow-up, Week 10: Retention) or delayed group (Week 0: Baseline, Wait Period, Week 6: Secondary Baseline, Intervention, Week 12: Follow-up, Week 16: Retention). Participants practiced modifying their foot progression angle "as much as was comfortable" while receiving support via weekly telerehabilitation appointments and remote monitoring with an instrumented shoe. Primary outcomes included participation, foot progression angle modification magnitude, confidence, difficulty, and satisfaction while secondary outcomes included symptoms and knee biomechanics during gait.

RESULTS

We screened 134 people and randomized 20. There was no loss to follow up and 100% attendance at the telerehabilitation appointments. By follow up, participants reported high confidence (8.6/10), low difficulty (2.0/10), and satisfaction (75%) with the intervention and no significant adverse events. Foot progression angle was modified by 11.4° ± 5.6, which was significantly different (p < 0.001, η²_g = 0.8) when compared between groups. No other between-group differences were significant, while several significant pre-post improvements in pain (d = 0.6, p = 0.006) and knee moments (d = 0.6, p = 0.01) were observed.

INTERPRETATION

A personalized, self-directed gait modification supported with telerehabilitation is feasible, and the preliminary effects on symptoms and biomechanics align with past trials. A larger trial is warranted to evaluate efficacy.

Multi-day monitoring of foot progression angles during unsupervised, real-world walking in people with and without knee osteoarthritis

BACKGROUND

Foot progression angle is a biomechanical target in gait modification interventions for knee osteoarthritis. To date, it has only been evaluated within laboratory settings.

METHODS

Adults with symptomatic knee osteoarthritis (n = 30) and healthy adults (n = 15) completed two conditions: 1) treadmill walking in the laboratory (5-min), and 2) real-world walking outside of the laboratory (1-week). Foot progression angle was estimated via shoe-embedded inertial sensing. We calculated the foot progression angle magnitude (median) and variability (interquartile range, coefficient of variation), and used mixed models to compare outcomes between the conditions, participant groups, and disease severities. Reliability was quantified by the intraclass correlation coefficient, standardized error of the measurement, and the minimum detectable change.

FINDINGS

Foot progression angle magnitude did not differ between groups or conditions but variability significantly higher in real-world walking (P < 0.001). Structural and symptomatic severity were unrelated to FPA in either walking condition, except for real-world coefficient of variation which was higher for moderate-severe structural osteoarthritis compared to the treadmill for those with mild structural severity (P < 0.034). All real-world outcomes showed excellent reliability including intraclass correlation coefficients above 0.95. The participants recorded a mean (standard deviation) of 298 (33) and 10,447 (5232) steps in the laboratory and real-world walking conditions, respectively.

INTERPRETATION

This study provides the first characterization of foot progression angles during real-world walking in people with and without symptomatic knee osteoarthritis. These results indicate that foot progression angles can be feasibly and reliably measured in unsupervised real-world walking conditions.

Simulated Tibiofemoral Joint Reaction Forces for Three Previously Studied Gait Modifications in Healthy Controls

Gait modifications, such as lateral trunk lean (LTL), medial knee thrust (MKT), and toe-in gait (TIG), are frequently investigated interventions used to slow the progression of knee osteoarthritis. The Lerner knee model was developed to estimate the tibiofemoral joint reaction forces (JRF) in the medial and lateral compartments during gait. These models may be useful for estimating the effects on the JRF in the knee as a result of gait modifications. We hypothesized that all gait modifications would decrease the JRF compared to normal gait. Twenty healthy individuals volunteered for this study (26.7 ± 4.7 years, 1.75 ± 0.1 m, 73.4 ± 12.4 kg). Ten trials were collected for normal gait as well as for the three gait modifications: LTL, MKT, and TIG. The data were used to estimate the JRF in the first and second peaks for the medial and lateral compartments of the knee via opensim using the Lerner knee model. No significant difference from baseline was found for the first peak in the medial compartment. There was a decrease in JRF in the medial compartment during the loading phase of gait for TIG (6.6%) and LTL (4.9%) and an increasing JRF for MKT (2.6%). but none was statistically significant. A significant increase from baseline was found for TIG (5.8%) in the medial second peak. We found a large variation in individual responses to gait interventions, which may help explain the lack of statistically significant results. Possible factors influencing these wide ranges of responses to gait modifications include static alignment and the impacts of variation in muscle coordination strategies used, by participants, to implement gait modifications.

Determining the optimal gait modification strategy for patients with knee osteoarthritis: Trunk lean or medial thrust?

BACKGROUND

The gait modification strategies Trunk Lean and Medial Thrust have been shown to reduce the external knee adduction moment (EKAM) in patients with knee osteoarthritis which could contribute to reduced progression of the disease. Which strategy is most optimal differs between individuals, but the underlying mechanism that causes this remains unknown.

RESEARCH QUESTION

Which gait parameters determine the optimal gait modification strategy for individual patients with knee osteoarthritis?

METHODS

Forty-seven participants with symptomatic medial knee osteoarthritis underwent 3-dimensional motion analysis during comfortable gait and with two gait modification strategies: Medial Thrust and Trunk Lean. Kinematic and kinetic variables were calculated. Participants were then categorized into one of the two subgroups, based on the modification strategy that reduced the EKAM the most for them. Multiple logistic regression analysis with backward elimination was used to investigate the predictive nature of dynamic parameters obtained during comfortable walking on the optimal modification gait strategy.

RESULTS

For 68.1 % of the participants, Trunk Lean was the optimal strategy in reducing the EKAM. Baseline characteristics, kinematics and kinetics did not differ significantly between subgroups during comfortable walking. Changes to frontal trunk and tibia angles correlated significantly with EKAM reduction during the Trunk Lean and Medial Thrust strategies, respectively. Regression analysis showed that MT is likely optimal when the frontal tibia angle range of motion and peak knee flexion angle in early stance during comfortable walking are high (R²_Nagelkerke = 0.12).

SIGNIFICANCE

Our regression model based solely on kinematic parameters from comfortable walking contained characteristics of the frontal tibia angle and knee flexion angle. As the model explains only 12.3 % of variance, clinical application does not seem feasible. Direct assessment of kinetics seems to be the most optimal strategy for selecting the most optimal gait modification strategy for individual patients with knee osteoarthritis.

Walking with shorter stride length could improve knee kinetics of patients with medial knee osteoarthritis

Walking with a shorter stride length (SL) was recently proposed for gait retraining in medial knee osteoarthritis; however it was never assessed in this patient population. This study tested the hypothesis that shortening SL while maintaining walking speed reduces knee adduction (KAM) and flexion (KFM) moments in patients with medial knee osteoarthritis. Walking trials with normal SL and SL reduced by 0.10 m and 0.15 m were recorded for 15 patients (10 men, 55.5 ± 8.7 years old, 24.6 ± 3.0 kg/m²). SL was modified using an augmented reality system displaying target footprints on the floor. Repeated one-way ANOVAs and post-hoc paired t-tests were performed to compare gait measures between normal and reduced SL. The individual effects of SL reduction were analyzed using descriptive statistics. Group analysis indicated significant decreases in KAM impulse with both SL reductions (p < 0.05). No systematic change was observed in the first peaks KAM and KFM when walking with reduced SL (p > 0.05). Individually, 33 % of the patients decreased the peak KAM, whereas 20 % decreased the KAM impulse. Among these patients with a decrease in peak KAM or in KAM impulse, 0 % and 33 % had a simultaneous increase in peak KFM, respectively. In conclusion, this study showed that SL shortening can decrease kinetic measures associated with the progression of medial knee osteoarthritis in some patients, demonstrating the importance of considering SL modifications on an individual basis. While further research is necessary, notably regarding dose-response relationships and long-term effects, these findings are particularly encouraging because SL reductions could be easily integrated into rehabilitation protocols.

The Immediate Effect of Backward Walking on External Knee Adduction Moment in Healthy Individuals

Backward walking (BW) has been recommended as a rehabilitation intervention to prevent, manage, or improve diseases. However, previous studies showed that BW significantly increased the first vertical ground reaction force (GRF) during gait, which might lead to higher loading at the knee. Published reports have not examined the effects of BW on medial compartment knee loading. The objective of this study was to investigate the effects of BW on external knee adduction moment (EKAM). Twenty-seven healthy adults participated in the present study. A sixteen-camera three-dimensional VICON gait analysis system, with two force platforms, was used to collect the EKAM, KAAI, and other biomechanical data during BW and forward walking (FW). The first (P < 0.001) and second (P < 0.001) EKAM peaks and KAAI (P =0.02) were significantly decreased during BW when compared with FW. The BW significantly decreased the lever arm length at the first EKAM peak (P =0.02) when compared with FW. In conclusion, BW was found to be a useful strategy for reducing the medial compartment knee loading even though the first peak ground reaction force was significantly increased.

Effects of computer-aided rowing exercise systems on improving muscle strength and function in older adults with mild knee osteoarthritis: a randomized controlled clinical trial

Background

Osteoarthritis (OA) is common in aged adults and can result in muscle weakness and function limitations in lower limbs. Knee OA affects the quality of life in the elderly. Technology-supported feedback to achieve lower impact on knee joints and individualized exercise could benefit elderly patients with knee OA. Herein, a computer-aided feedback rowing exercise system is proposed, and its effects on improving muscle strength, health conditions, and knee functions of older adults with mild knee OA were investigated.

Methods

Thirty-eight older adults with mild knee OA and satisfying the American College of Rheumatology (ACR) clinical criteria participated in this randomized controlled clinical trial. Each subject was randomly assigned to a computer-aided rowing exercise (CRE) group (n = 20) or a control group (CON) (n = 18) that received regular resistance exercise programs two times per week for 12 weeks. Outcome measurements, including the Western Ontario and MacMaster Universities (WOMAC), muscle strength and functional fitness of the lower limbs, were evaluated before and after the intervention.

Results

Participants’ functional fitness in the CRE group exhibited significantly higher adjusted mean post-tests scores, including the WOMAC (p = 0.006), hip abductors strength (kg) (MD = 2.36 [1.28, 3.44], p = 5.67 × 10^–5), hip adductors strength (MD = 3.04 [1.38, 4.69], p = 0.001), hip flexors strength (MD = 4.01 [2.24, 5.78], p = 6.46 × 10⁻⁵), hip extensors strength (MD = 2.88 [1.64, 4.12], p = 4.43 × 10⁻⁵), knee flexors strength (MD = 2.03 [0.66, 3.41], p = 0.005), knee extensors strength (MD = 1.80 [0.65, 2.94], p = 0.003), and functional-reach (cm) (MD = 3.74 [0.68, 6.80], p = 0.018), with large effect sizes (η² = 0.17–0.42), than those in the CON group after the intervention.

Conclusions

Older adults with knee OA in the CRE group exhibited superior muscle strength, health conditions, and functional fitness improvements after the 12-week computer-aided rowing exercise program than those receiving the conventional exercise approach.

Trial registration

The Institutional Review Board of the Taipei Medical University approved the study protocol (no. N201908020, 27/05/2020) and retrospectively registered at ClinicalTrials.gov (trial registry no. NCT04919486, 09/06/2021).

Effects of neuromuscular gait modification strategies on indicators of knee joint load in people with medial knee osteoarthritis: A systematic review and meta-analysis

OBJECTIVES

This systematic review aimed to determine the effects of neuromuscular gait modification strategies on indicators of medial knee joint load in people with medial knee osteoarthritis.

METHODS

Databases (Embase, MEDLINE, Cochrane Central, CINAHL and PubMed) were searched for studies of gait interventions aimed at reducing medial knee joint load indicators for adults with medial knee osteoarthritis. Studies evaluating gait aids or orthoses were excluded. Hedges' g effect sizes (ES) before and after gait retraining were estimated for inclusion in quality-adjusted meta-analysis models. Certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Seventeen studies (k = 17; n = 362) included two randomised placebo-controlled trials (RCT), four randomised cross-over trials, two case studies and nine cohort studies. The studies consisted of gait strategies of ipsilateral trunk lean (k = 4, n = 73), toe-out (k = 6, n = 104), toe-in (k = 5, n = 89), medial knee thrust (k = 3, n = 61), medial weight transfer at the foot (k = 1, n = 10), wider steps (k = 1, n = 15) and external knee adduction moment (KAM) biofeedback (k = 3, n = 84). Meta-analyses found that ipsilateral trunk lean reduced early stance peak KAM (KAM1, ES and 95%CI: -0.67, -1.01 to -0.33) with a dose-response effect and reduced KAM impulse (-0.37, -0.70 to -0.04) immediately after single-session training. Toe-out had no effect on KAM1 but reduced late stance peak KAM (KAM2; -0.42, -0.73 to -0.11) immediately post-training for single-session, 10 or 16-week interventions. Toe-in reduced KAM1 (-0.51, -0.81 to -0.20) and increased KAM2 (0.44, 0.04 to 0.85) immediately post-training for single-session to 6-week interventions. Visual, verbal and haptic feedback was used to train gait strategies. Certainty of evidence was very-low to low according to the GRADE approach.

CONCLUSION

Very-low to low certainty of evidence suggests that there is a potential that ipsilateral trunk lean, toe-out, and toe-in to be clinically helpful to reduce indicators of medial knee joint load. There is yet little evidence for interventions over several weeks.

Predicting knee adduction moment response to gait retraining with minimal clinical data

Knee osteoarthritis is a progressive disease mediated by high joint loads. Foot progression angle modifications that reduce the knee adduction moment (KAM), a surrogate of knee loading, have demonstrated efficacy in alleviating pain and improving function. Although changes to the foot progression angle are overall beneficial, KAM reductions are not consistent across patients. Moreover, customized interventions are time-consuming and require instrumentation not commonly available in the clinic. We present a regression model that uses minimal clinical data—a set of six features easily obtained in the clinic—to predict the extent of first peak KAM reduction after toe-in gait retraining. For such a model to generalize, the training data must be large and variable. Given the lack of large public datasets that contain different gaits for the same patient, we generated this dataset synthetically. Insights learned from a ground-truth dataset with both baseline and toe-in gait trials (N = 12) enabled the creation of a large (N = 138) synthetic dataset for training the predictive model. On a test set of data collected by a separate research group (N = 15), the first peak KAM reduction was predicted with a mean absolute error of 0.134% body weight * height (%BW*HT). This error is smaller than the standard deviation of the first peak KAM during baseline walking averaged across test subjects (0.306%BW*HT). This work demonstrates the feasibility of training predictive models with synthetic data and provides clinicians with a new tool to predict the outcome of patient-specific gait retraining without requiring gait lab instrumentation.

Gait retraining is a conservative intervention for knee osteoarthritis shown to reduce pain and improve function. Although customizing a treatment plan for each patient results in a better therapeutic response, customization cannot yet be performed outside of the gait laboratory, preventing research advances from becoming part of clinical practice. Our work aimed to build a model that accurately predicts whether a patient with knee osteoarthritis will benefit from non-invasive gait retraining using measures that can be easily collected in the clinic. To overcome the lack of large datasets required to train predictive models, we generated data synthetically (N = 138) based on limited ground-truth examples, and we provide experimental evidence for the model’s ability to generalize to real data (N = 15). Our results contribute toward a future in which clinicians can use data collected in the clinic to easily identify patients who would respond to therapeutic gait retraining.

Inertial Sensor-to-Segment Calibration for Accurate 3D Joint Angle Calculation for Use in OpenSim

Inertial capture (InCap) systems combined with musculoskeletal (MSK) models are an attractive option for monitoring 3D joint kinematics in an ecological context. However, the primary limiting factor is the sensor-to-segment calibration, which is crucial to estimate the body segment orientations. Walking, running, and stair ascent and descent trials were measured in eleven healthy subjects with the Xsens InCap system and the Vicon 3D motion capture (MoCap) system at a self-selected speed. A novel integrated method that combines previous sensor-to-segment calibration approaches was developed for use in a MSK model with three degree of freedom (DOF) hip and knee joints. The following were compared: RMSE, range of motion (ROM), peaks, and R² between InCap kinematics estimated with different calibration methods and gold standard MoCap kinematics. The integrated method reduced the RSME for both the hip and the knee joints below 5°, and no statistically significant differences were found between MoCap and InCap kinematics. This was consistent across all the different analyzed movements. The developed method was integrated on an MSK model workflow, and it increased the sensor-to-segment calibration accuracy for an accurate estimate of 3D joint kinematics compared to MoCap, guaranteeing a clinical easy-to-use approach.

Quantifying Region-Specific Elastic Properties of Distal Femoral Articular Cartilage: A Shear-Wave Elastography Study

Knee osteoarthritis is a disease with the degeneration of articular cartilage as its main feature. Cartilage thickness cannot become a single index to evaluate cartilage degeneration, so it is essential to also evaluate the stiffness. The purposes were as follows: (1) to examine test-retest reliabilities of the elastic modulus measurement in distal femoral articular cartilage (FAC) and compare the changes in specific-regional of distal FAC, (2) to explore the difference in distal FAC stiffness and thickness between the dominant and nondominant sides, and (3) to examine the correlation between the elastic properties of cartilage and the thickness of cartilage. Twenty healthy participants were recruited. The stiffness of distal FAC at the lateral femoral condyle (LFC), medial femoral condyle (MFC), and intercondylar notch (IN) was quantified using shear-wave elastography (SWE). Intra- and interrater reliabilities were excellent for measuring the stiffness of distal FAC (ICC: 0.83-0.98). About a 50% increase in the stiffness of LFC (40.78 kPa) was found when compared with IN (21.82 kPa) and MFC (18.34 kPa). No significant difference was found between the dominant and nondominant sides in distal FAC stiffness and thickness. There was no correlation between the stiffness and thickness of the distal FAC. In conclusion, SWE can quantify the stiffness of the distal FAC.

Differences between adults and adolescents in responding to hip and knee pattern feedback during gait

Visual feedback techniques have shown potential in interventions aiming to retrain deviated gait patterns. Understanding the abilities of different age groups to modify their gait is needed to optimize interventions. Twelve adults (6F, 6 M; 26.3 ± 5.9 yrs.) and twelve adolescents (4F, 8 M; 13.6 ± 2.3 yrs) without disabilities participated in one training session. During the session, the responses to a visual kinematic feedback task in which one hip or knee target pattern was modified while unmodified target patterns were maintained in the other hip and knee joints were investigated. Limb orientation and acceleration data were collected using Inertial Measurement Units (IMU) (Xsens Awinda, Enschede, The Netherlands) with a sampling frequency of 60 Hz. Adults tended to outperform adolescents in tracking modified target patterns and showed smaller errors in unmodified regions of modified patterns (p = 0.045); they also outperformed adolescents in unmodified joints (Contralateral Hip: p = 0.003; Contralateral Knee: p = 0.002; Ipsilateral Joint: p = 0.048). These findings suggest different levels of awareness of the need and/or ability to minimize errors across joints, in turn suggesting the need for specialization of training for these age groups.

Conservative interventions to improve foot progression angle and clinical measures in orthopedic and neurological patients - A systematic review and meta-analysis

To establish the comparative effects of conservative interventions on modifying foot progression angle (FPA) in children and adults with orthopaedic and neurological disease was the main aim of the literature review. Pubmed, Embase, Cinahl, and Web of Science were systematically searched for studies evaluating the effects of conservative interventions on correcting the FPA. The study protocol was registered with PROSPERO (CRD42020143512). Two reviewers independently assessed studies for inclusion and quality. Studies that assessed conservative interventions that could have affected the FPA and objectively measured the FPA were included. Within group Mean Differences (MD) and Standardized Mean Differences (SMDs) of the interventions were calculated for the change in FPA and gait performance (walking speed, stride/step length) and clinical condition (pain). Intervention effects on FPA were synthesized via meta-analysis or qualitatively. 41 studies were identified. For patients with knee osteoarthritis gait training interventions (MD = 6.69° and MD = 16.06°) were significantly more effective than mechanical interventions (MD = 0.44°) in modifying the FPA towards in-toeing (p < 0.00001). Increasing or decreasing the FPA significantly improved pain in patients with medial knee OA. Results were inconclusive for the effectiveness of gait training and mechanical devices in patients with neurological diseases. Gait feedback training is more effective than external devices to produce lasting improvements in FPA, reduce pain, and maintain gait performance in patients with medial knee OA. However, in neurological patients, the effects of external devices on improvements in FPA depends on the interaction between patient-specific impairments and the technical properties of the external device.

Wearable Real-Time Haptic Biofeedback Foot Progression Angle Gait Modification to Assess Short-Term Retention and Cognitive Demand

Foot progression angle gait (FPA) modification is an important part of rehabilitation for a variety of neuromuscular and musculoskeletal diseases. While wearable haptic biofeedback could enable FPA gait modification for more widespread use than traditional tethered, laboratory-based approaches, retention, and cognitive demand in FPA gait modification via wearable haptic biofeedback are currently unknown and may be important to real-life implementation. Thus, the purpose of this study was to assess the feasibility of wearable haptic biofeedback to assess short-term retention and cognitive demand during FPA gait modification. Ten healthy participants performed toe-in (target 10 degrees change in internal rotation) and toe-out (target 10 degrees change in external rotation) haptic gait training trials followed by short-term retention trials, and cognitive multitasking trials. Results showed that participants were able to initially respond to the wearable haptic feedback to modify their FPA to adopt the new toe-in (9.7 ± 0.8 degree change in internal rotation) and toe-out (8.9 ± 1.0 degree change in external rotation) gait patterns. Participants retained the modified gait pattern on average within 3.9 ± 3.6 deg of the final haptic gait training FPA values. Furthermore, cognitive multitasking did not influence short-term retention in that there were no differences in gait performance during retention trials with or without cognitive multitasking. These results demonstrate that wearable haptic biofeedback can be used to assess short-term retention and cognitive demand during FPA gait modification without the need for traditional, tethered systems.

Effects of an Exercise Therapy Targeting Knee Kinetics on Pain, Function, and Gait Kinetics in Patients With Knee Osteoarthritis: A Randomized Clinical Trial

In this study, the effects of an exercise therapy comprising yoga exercises and medial-thrust gait (YogaMT) on lower-extremity kinetics, pain, and function in patients with medial knee osteoarthritis were investigated. Fifty-nine patients were randomly allocated to three treatment groups: (a) the YogaMT group practiced yoga exercises and medial thrust gait, (b) the knee-strengthening group performed quadriceps- and hamstring-strengthening exercises, and (c) the treadmill walking group practiced normal treadmill walking in 12 supervised sessions. The adduction and flexion moments of the hip, knee, and ankle; pain intensity; and 2-min walking test were assessed before and after treatment and at 1-month follow-up. The YogaMT group experienced a significant reduction in knee adduction moment. All groups showed significant improvement in pain and function. The YogaMT may reduce medial knee load in patients with knee osteoarthritis in the short term. A larger clinical trial is required to investigate the long-term outcomes of this intervention.

Real-Time Musculoskeletal Kinematics and Dynamics Analysis Using Marker- and IMU-Based Solutions in Rehabilitation

This study aims to explore the possibility of estimating a multitude of kinematic and dynamic quantities using subject-specific musculoskeletal models in real-time. The framework was designed to operate with marker-based and inertial measurement units enabling extensions far beyond dedicated motion capture laboratories. We present the technical details for calculating the kinematics, generalized forces, muscle forces, joint reaction loads, and predicting ground reaction wrenches during walking. Emphasis was given to reduce computational latency while maintaining accuracy as compared to the offline counterpart. Notably, we highlight the influence of adequate filtering and differentiation under noisy conditions and its importance for consequent dynamic calculations. Real-time estimates of the joint moments, muscle forces, and reaction loads closely resemble OpenSim's offline analyses. Model-based estimation of ground reaction wrenches demonstrates that even a small error can negatively affect other estimated quantities. An application of the developed system is demonstrated in the context of rehabilitation and gait retraining. We expect that such a system will find numerous applications in laboratory settings and outdoor conditions with the advent of predicting or sensing environment interactions. Therefore, we hope that this open-source framework will be a significant milestone for solving this grand challenge.

Learning Gait Modifications for Musculoskeletal Rehabilitation: Applying Motor Learning Principles to Improve Research and Clinical Implementation

Gait modifications are used in the rehabilitation of musculoskeletal conditions like osteoarthritis and patellofemoral pain syndrome. While most of the research has focused on the biomechanical and clinical outcomes affected by gait modification, the process of learning these new gait patterns has received little attention. Without adequate learning, it is unlikely that the modification will be performed in daily life, limiting the likelihood of long-term benefit. There is a vast body of literature examining motor learning, though little has involved gait modifications, especially in populations with musculoskeletal conditions. The studies that have examined gait modifications in these populations are often limited due to incomplete reporting and study design decisions that prohibit strong conclusions about motor learning. This perspective draws on evidence from the broader motor learning literature for application in the context of modifying gait. Where possible, specific gait modification examples are included to highlight the current literature and what can be improved on going forward. A brief theoretical overview of motor learning is outlined, followed by strategies that are known to improve motor learning, and finally, how assessments of learning need to be conducted to make meaningful conclusions.

Comparing walking biomechanics of older females in maximal, minimal, and traditional shoes

BACKGROUND

Knee osteoarthritis (OA) is a degenerative joint disease that affects millions of individuals each year. Several biomechanical variables during walking have been identified as risk factors for developing knee OA, including the peak external knee adduction moment (KAM) and the knee flexion angle at initial contact. Many interventions have been studied to help mitigate these risk factors, including footwear. However, it is largely unknown how varying shoe cushioning may affect walking biomechanics related to knee OA risk.

RESEARCH QUESTION

What is the effect of maximally and minimally cushioned shoes on walking biomechanics compared to a traditionally cushioned shoe in older females?

METHODS

Walking biomechanics in three shoes (maximal, traditional, minimal) were collected on 16 healthy females ages 50-70 using an 8-camera 3D motion capture system and two embedded force plates. Key biomechanical variables related to knee OA disease risk were compared between shoes using repeated measures ANOVAs.

RESULTS

The KAM was significantly larger in the maximal shoe (p = 0.005), while the knee flexion angle at initial contact was significantly larger in both the maximal and minimal shoe compared to the traditional shoe (p = .000). Additionally, the peak knee flexion angle (p = .000) and the loading rates of the vertical ground reaction force were (instantaneous: p = 0.001; average: p = .010) were significantly higher in the minimal shoe.

SIGNIFICANCE

While these results are specific to the shoes used in this study, clinicians should exercise caution in prescribing maximal or minimal shoes to females in this age group who may be at risk of knee OA given these results. Research is needed on the effect of these shoes in patients with knee OA.

Decreasing the ambulatory knee adduction moment without increasing the knee flexion moment individually through modifications in footprint parameters: A feasibility study for a dual kinetic change in healthy subjects

Gait retraining is gaining in interest to reduce loading associated to knee osteoarthritis (OA) progression. So far, interventions focused on reducing the peak knee adduction moment (pKAM) and it remains unclear if this can be done individually without increasing the peak knee flexion moment (pKFM). Additionally, while modifying foot progression angle (FPA) and step width (SW) is common, little is known about modifications in stride length (SL). This study aimed at characterizing the feasibility of a dual kinetic change, consisting in reducing the pKAM by at least 10% without increasing the pKFM. It also aimed to evaluate the added value of SL modifications in achieving the dual kinetic change. Gait trials with modifications in FPA, SW and SL were recorded for 11 young healthy subjects in a laboratory equipped with an augmented-reality system displaying instruction footprints on the floor. All participants achieved the dual kinetic change with at least one of the modifications. Seven participants achieved it with FPA modification, three with SW modification, and seven with SL modification. In conclusion, this study showed that it is feasible to achieve the dual kinetic change individually through subject-specific modifications in footprint parameters, suggesting that, in the future, gait retraining could aim for more specific kinetic changes than simply pKAM reductions. Modifying SL allowed achieving the dual kinetic change, stressing out the value of this parameter for gait retraining, in addition to FPA and SW. Finally, an augmented-reality approach was introduced to help footprint parameter modifications in the framework of knee OA.

The effect of modifying foot progression angle on the knee loading parameters in healthy participants with different static foot postures

BACKGROUND

Studies have found that toe-in gait reduced the peak knee adduction moment (KAM) during early stance, while toe-out gait reduced the peak KAM during late stance. However, some other studies found that toe-in or toe-out gait could reduce the KAM throughout stance phase. There is still a divergence of opinion on the use of toe-in or toe-out gait for reducing the KAM.

RESEARCH QUESTION

This study aimed to investigate whether static foot posture affected participants' biomechanical responses to three self-selected foot progression angles (FPA): neutral, toe-out and toe-in.

METHODS

Twenty-seven healthy participants were recruited for this FPA gait modification experiment and classified into three groups: neutral (n = 8), supination (n = 9) and pronation (n = 10), based on the Foot Posture Index (FPI). The kinematic and kinetic data were recorded with Vicon motion capture system and three force plates. The knee adduction moment and ankle eversion moment were calculated using an inverse dynamics model. The effect of the FPA modification on the knee loading parameters was analysed by the Friedman non-parametric test.

RESULTS

The KAM results in the neutral group showed that the toe-in gait modification reduced the first peak of the KAM (KAM1), while the KAM1 was increased in the supination group. The effect of the FPA modification on the KAM1 did not reach significance in the pronation group. The toe-out gait modification reduced the second peak (KAM2) regardless of the static posture.

SIGNIFICANCE

Different static foot postures were correlated with different peak KAM during the early stance phase due to FPA modification. These data suggest that the assessment of static foot posture provides a reference on how to offer adequate FPA modification for knee OA patients with different foot postures.

Biomechanical effects of manipulating peak vertical ground reaction force throughout gait in individuals 6-12 months after anterior cruciate ligament reconstruction

BACKGROUND

We aimed to determine the effect of cueing an increase or decrease in the vertical ground reaction force impact peak (peak in the first 50% of stance) on vertical ground reaction force, knee flexion angle, internal knee extension moment, and internal knee abduction moment waveforms throughout stance in individuals 6-12 months after an anterior cruciate ligament reconstruction.

METHODS

Twelve individuals completed 3 conditions (High, Low, and Control) where High and Low Conditions cue a 5% body weight increase or decrease, respectively, in the vertical ground reaction force impact peak compared to usual walking. Biomechanics during High and Low Conditions were compared to the Control Condition throughout stance.

FINDINGS

The High Condition resulted in: (a) increased vertical ground reaction forces at each peak and decreased during mid-stance, (b) greater knee excursion (i.e., greater knee flexion angle in early stance and a more extended knee in late stance), (c) greater internal extension moment for the majority of stance, and (d) lesser second internal knee abduction moment peak. The Low Condition resulted in: (a) vertical ground reaction forces decreased during early stance and increased during mid-stance, (b) decreased knee excursion, (c) increased internal extension moment throughout stance, and (d) decreased internal knee abduction moment peaks.

INTERPRETATION

Cueing a 5% body weight increase in vertical ground reaction force impact peak resulted in a more dynamic vertical ground reaction force loading pattern, increased knee excursion, and a greater internal extension moment during stance which may be useful in restoring gait patterns following anterior cruciate ligament reconstruction.

Proprioceptive neuromuscular facilitation improves pain and descending mechanics among elderly with knee osteoarthritis

PURPOSE

Knee osteoarthritis (KOA) is a common disease that causes pain and limits functionality in the elderly during daily activities, especially during stair descent. Proprioceptive neuromuscular facilitation (PNF) practices promote multiple-plane joint movements, which relieve pain and increase joint range of motion (ROM). This study aims to examine the effects of a 12-week PNF intervention on pain relief, passive and active joint ROM, external knee adduction moment (KAM), and hip adduction moment (HAM) in the elderly with KOA during stair descent.

MATERIALS AND METHODS

Seventy-six elderly who were diagnosed with KOA were assessed for eligibility and, 36 of them met the inclusive criteria, were randomly divided into two groups: the twelve-week PNF intervention group and the control group. Pain score was measured by the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Passive joint ROM was measured using a goniometer. Active joint ROM, KAM, and HAM during stair descent were measured using a motion analysis system with a force platform. All the data were recorded at weeks 0, 6, and 12.

RESULTS

Compared to the control group, the PNF group showed a decreased pain score; increased passive hip, knee, and ankle ROM; a decreased minimum knee flexion angle, and increased HAM during stair descent.

PERSPECTIVE

Proprioceptive neuromuscular facilitation intervention is a successful method to relieve symptoms of KOA. It relieves pain without increasing KAM, enhances passive ROM, increases active knee flexion ROM, and increases HAM during stair descent in the elderly with KOA.

Changes in ambulatory knee adduction moment with lateral wedge insoles differ with respect to the natural foot progression angle

Lateral wedge insoles (LWI) have been proposed to reduce the knee adduction moment (KAM) during walking; a biomechanical modification notably sought in case of medial knee osteoarthritis. However, the inter-individual inconsistency in KAM changes with LWI limits their therapeutic use. Although the foot progression angle (FPA) has been frequently discussed in KAM modifications literature, there is a lack of data regarding a possible relationship between this gait measure and changes in KAM with LWI. This study aimed to test if KAM changes with LWI differ with respect to the natural FPA and to compare KAM-related variables between individuals walking with smaller and larger natural FPA. Twenty-two healthy participants (14 males, 24 ± 3 years, 22.7 ± 2.7 kg/m²) underwent gait analysis with and without LWI. They were divided into two groups based on their natural FPA, and changes in KAM 1st peak, KAM impulse, and KAM-related variables were compared between groups. KAM 1st peak and impulse decreased with LWI in the smaller natural FPA group (p ≤ 0.006), while only KAM impulse decreased in the larger natural FPA group (p < 0.001). The difference in KAM 1st peak changes was explained by a less reduced lever arm in participants walking with larger natural FPA. In conclusion, this study brought new insight into the variability in KAM response to LWI. If the findings are confirmed in patients with medial knee osteoarthritis, the FPA could become a simple measure to help identify the patients more likely to reduce their KAM with LWI.

Real-Time Three-Dimensional Knee Moment Estimation in Knee Osteoarthritis: Toward Biodynamic Knee Osteoarthritis Evaluation and Training

We investigated differences in knee kinetic variables (external knee adduction, flexion, internal rotation moments, and impulses) between patients with knee osteoarthritis (KOA) and healthy controls during stepping on a custom elliptical trainer; and searched knee kinetic variable candidates for real-time biofeedback and for complementing diagnosis/evaluation on the elliptical trainer based on the knee kinetic variables' associations with the knee injury and osteoarthritis outcome score (KOOS). Furthermore, we explored potential gait re-training strategies on the elliptical trainer by investigating the knee kinetic variables' associations with 3-D ankle angles. The knee kinetic variables and ankle angles were determined in real-time in a patient group of 10 patients with KOA and an age-and sex-matched control group of 10 healthy subjects. The mean peak external knee adduction moment of the patient group was 47% higher than that of the control group. The KOOS-Sports and Recreational Activities and KOOS-Pain scores were found to be significantly associated with the knee kinetic variables. All the ankle angles were associated with the knee kinetic variables. The findings support the use of the knee kinetic variables on the elliptical trainer to complement KOA diagnosis quantitatively and provide potential real-time KOA gait re-training strategies/guides.