Effects of footwear on the knee adduction moment in medial knee osteoarthritis: classification criteria for flat flexible vs stable supportive shoes

Measurement and reporting of footwear characteristics in running biomechanics: A systematic search and narrative synthesis of contemporary research methods

This review aimed to synthesise the methods for assessing and reporting footwear characteristics among studies evaluating the effect of footwear on running biomechanics. Electronic searches of Scopus®, EBSCO, PubMed®, ScienceDirect®, and Web of Science® were performed to identify original research articles of the effect of running footwear on running biomechanics published from 1^st January 2015 to 7^th October 2020. Risk of bias among included studies was not assessed. Results were presented via narrative synthesis. Eligible studies compared the effect of two or more footwear conditions in adult runners on a biomechanical parameter. Eighty-seven articles were included and data from 242 individual footwear were extracted. Predominantly, studies reported footwear taxonomy (i.e., classification) and manufacturer information, however omitted detail regarding the technical specifications of running footwear and did not use validated footwear reporting tools. There is inconsistency among contemporary studies in the methods by which footwear characteristics are assessed and reported. These findings point towards a need for consensus regarding the reporting of these characteristics within biomechanical studies to facilitate the conduct of systematic reviews and meta-analyses pertaining to the effect of running footwear on running biomechanics.

Shoes for self-managing chronic hip Pain: the SCHIPP randomized clinical trial protocol

BACKGROUND

Chronic hip pain is common and disabling and is largely due to osteoarthritis (OA). Self-management is recommended by international OA clinical guidelines yet there are few effective treatment options. Footwear has been suggested as a self-management approach, given that foot motion influences hip forces. Currently, guidelines advocate 'stable supportive' shoes for people with OA, however this is based solely on expert opinion given no research has investigated whether these shoes are effective at reducing symptoms in people with OA-related chronic hip pain. Therefore, this randomized controlled trial (RCT) aims to determine if stable supportive footwear reduces hip pain during walking compared to flat flexible footwear in people with chronic hip pain consistent with OA.

METHODS

This trial is a 6-month, participant- and assessor-blinded, pragmatic, comparative effectiveness, superiority RCT conducted in Melbourne, Australia. We are recruiting 120 participants aged over 45 years with chronic hip pain consistent with OA from the community. Following baseline assessment, participants are randomized to receive either i) stable supportive shoes or ii) flat flexible shoes. Participants are permitted to choose two different pairs of shoes in their allocated group from a range of options that match prespecified shoe classification criteria. They are advised to wear either pair of study shoes daily for a minimum of 6 hours each day for 6 months. The primary outcome is the 6-month change in average hip pain on walking in the last week. Secondary outcomes include changes in other measures of hip pain, symptoms, function in daily living and sports and recreation, hip-related quality of life, pain at other sites, adverse events, and physical activity. Other measures include co-intervention use, adherence, shoe comfort, descriptive characteristics, footwear characteristics, and objective foot measures.

DISCUSSION

This RCT will determine whether stable supportive shoes reduce hip pain during walking more than flat flexible shoes in people with chronic hip pain. Outcomes will help to inform footwear recommendations in international clinical guidelines for OA-related chronic hip pain, which to date have been based solely on expert opinion because of an absence of RCTs.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry reference: ACTRN12621001532897.

Effect of motion control versus neutral walking footwear on pain associated with lateral tibiofemoral joint osteoarthritis: a comparative effectiveness randomised clinical trial

OBJECTIVES

To determine if motion control walking shoes are superior to neutral walking shoes in reducing knee pain on walking in people with lateral knee osteoarthritis (OA).

DESIGN

Participant-blinded and assessor-blinded, comparative effectiveness, superiority randomised controlled trial.

SETTING

Melbourne, Australia.

PARTICIPANTS

People with symptomatic radiographic lateral tibiofemoral OA from the community and our volunteer database.

INTERVENTION

Participants were randomised to receive either motion control or neutral shoes and advised to wear them >6 hours/day over 6 months.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was change in average knee pain on walking over the previous week (11-point Numeric Rating Scale (NRS), 0-10) at 6 months. The secondary outcomes included other measures of knee pain, physical function, quality of life, participant-perceived change in pain and function, and physical activity.

RESULTS

We planned to recruit 110 participants (55 per arm) but ceased recruitment at 40 (n=18 motion control shoes, n=22 neutral shoes) due to COVID-19-related impacts. All 40 participants completed 6-month outcomes. There was no evidence that motion control shoes were superior to neutral shoes for the primary outcome of pain (mean between-group difference 0.4 NRS units, 95% CI -1.0 to 1.7) nor for any secondary outcome. The number of participants experiencing any adverse events was similar between groups (motion control shoes: n=5, 28%; neutral shoes: n=4, 18.2%) and were minor.

CONCLUSIONS

Motion control shoes were not superior to neutral shoes in improving knee pain on walking in symptomatic radiographic lateral tibiofemoral joint OA. Further research is needed to identify effective treatments in this important but under-researched knee OA subgroup.

TRIAL REGISTRATION NUMBER

ACTRN12618001864213.

Tibiofemoral contact force differences between flat flexible and stable supportive walking shoes in people with varus-malaligned medial knee osteoarthritis: A randomized cross-over study

Objective

To compare the effect of stable supportive to flat flexible walking shoes on medial tibiofemoral contact force (MTCF) in people with medial knee osteoarthritis and varus malalignment.

Design

This was a randomized cross-over study. Twenty-eight participants aged ≥50 years with medial knee osteoarthritis and varus malalignment were recruited from the community. Three-dimensional full-body motion, ground reaction forces and surface electromyograms from twelve lower-limb muscles were acquired during six speed-matched walking trials for flat flexible and stable supportive shoes, tested in random order. An electromyogram-informed neuromusculoskeletal model with subject-specific geometry estimated bodyweight (BW) normalized MTCF. Waveforms were analyzed using statistical parametric mapping with a repeated measures analysis of variance model. Peak MTCF, MTCF impulse and MTCF loading rates (discrete outcomes) were evaluated using a repeated measures multivariate analysis of variance model.

Results

Statistical parametric mapping showed lower MTCF in stable supportive compared to flat flexible shoes during 5–18% of stance phase (p = 0.001). For the discrete outcomes, peak MTCF and MTCF impulse were not different between the shoe styles. However, mean differences [95%CI] in loading impulse (-0.02 BW·s [-0.02, 0.01], p<0.001), mean loading rate (-1.42 BW·s^-1 [-2.39, -0.45], p = 0.01) and max loading rate (-3.26 BW·s^-1 [-5.94, -0.59], p = 0.02) indicated lower measure of loading in stable supportive shoes compared to flexible shoes.

Conclusions

Stable supportive shoes reduced MTCF during loading stance and reduced loading impulse/rates compared to flat flexible shoes and therefore may be more suitable in people with medial knee osteoarthritis and varus malalignment.

Trial registration

Australian and New Zealand Clinical Trials Registry (12619000622101).

Walking-related knee contact forces and associations with knee pain across people with mild, moderate and severe radiographic knee osteoarthritis: a cross-sectional study

OBJECTIVE

To investigate knee contact forces (KCFs), and their relationships with knee pain, across grades of radiographic knee osteoarthritis (OA) severity.

DESIGN

Cross-sectional exploratory analysis of 164 participants with medial knee OA. Radiographic severity was classified as mild (grade 2), moderate (grade 3) or severe (grade 4) using the Kellgren & Lawrence (KL) scale. Walking knee pain was assessed using an 11-point numerical rating scale. External knee adduction moment (external KAM) and internal muscle forces were used to calculate medial, lateral and total KCFs using a musculoskeletal computational model. Force-time series across stance phase of gait were compared across KL grades using Statistical Parametric Mapping. Associations between KCFs and pain across KL grades were assessed using linear models.

RESULTS

Medial KCFs during early and middle stance were higher in participants with KL3 and KL4 compared to those with KL2. In contrast, lateral KCFs were higher in those with KL2 compared to KL3 and KL4 in middle to late stance. The external loading component (i.e., KAM) of the medial KCF during middle to late stance was also greater in participants with KL3 and KL4 compared to those with KL2, whereas the internal (i.e., muscle) component was greater in those with KL3 and KL4 compared to KL3 during early stance. There were no associations between medial KCF and knee pain in any KL grade.

CONCLUSIONS

Medial and lateral KCFs differ between mild, moderate and severe radiographic knee OA but are not associated with knee pain severity for any radiographic OA grade.

Knee Pain Reduction Using a Shock-Absorbing Sole

BACKGROUND

The biomechanics of the foot and leg are responsible for shock absorption during human gait. Lack of shock absorption is known to be a key component of knee pain. This study compares a new model of shoe sole with a built-in modification intended to absorb shock with a traditional sole shoe to examine whether shoe design modifications can help alleviate knee pain.

METHODS

A double-blind randomized controlled study was performed. Fifty-two adults with overuse symptoms of knee pain, either unilateral or bilateral, were enrolled and randomly assigned to use the intervention sole or the traditional sole shoes. For 5 weeks, participants wore either the shoe with the intervention sole or the shoe with the traditional sole, rating their knee pain on a 10-point visual analog scale at study onset, midway, and study completion.

RESULTS

After 5 weeks, participants using the intervention sole shoe reported an average reduction in knee pain of 85%, significantly better than participants using the traditional sole shoe (P < .001), whose average pain scores increased. Positive effects on back and foot pain were also observed in those with the intervention sole shoe compared with the traditional sole shoe.

CONCLUSIONS

The intervention shock-absorbing sole represents an approach to midsole and outsole construction that can potentially increase shock absorption and decrease knee pain during prolonged standing and walking.

Analysis of invoked slips while wearing flip-flops in wet and dry conditions: Does alternative footwear alter slip kinematics?

Minimal footwear has become more ubiquitous; however, it may increase slip severity. This study specifically examined the slipping kinematics of flip-flop sandals. Invoked slips from standing were evaluated in dry and wet tile, and a unique wet footbed + wet tile condition, with 40, 50, and 60% bodyweight (BW) committed to the slipping foot. Water did not alter peak slip velocity (PV) at 40% BW, but PV increased with greater slip-foot force on wet tile by ~1 m/s. Interestingly, when floor-contact was lost during the slip, the flip-flops could come off the heel. This decoupling occurred most often when both the tile and footbed were either dry or wet. Given that both decoupling and greater PV were observed on wet tile, slipping in flip-flops under wet conditions may have more serious consequences. The results highlight that slips may occur at both the foot-flip-flop, and flip-flop-tile interfaces.

The Effect of Flat Flexible Versus Stable Supportive Shoes on Knee Osteoarthritis Symptoms : A Randomized Trial

BACKGROUND

Experts recommend that persons with knee osteoarthritis wear stable supportive shoes; however, evidence suggests that flat flexible shoes may be more beneficial.

OBJECTIVE

To compare flat flexible with stable supportive shoes for knee osteoarthritis symptoms.

DESIGN

Participant- and assessor-blinded randomized trial. (Prospectively registered with the Australian New Zealand Clinical Trials Registry [ACTRN12617001098325]).

SETTING

Community.

PARTICIPANTS

164 patients with moderate to severe symptomatic radiographic medial knee osteoarthritis.

INTERVENTION

Flat flexible (n = 82) or stable supportive shoes (n = 82), worn for at least 6 hours a day for 6 months.

MEASUREMENTS

Primary outcomes were changes in walking pain (measured by an 11-point numerical rating scale) and physical function (as assessed by the Western Ontario and McMaster Universities Osteoarthritis Index subscale of 0 to 68 points) at 6 months. Secondary outcomes included additional pain and function measures, physical activity, and quality of life. Other measures included adverse events.

RESULTS

Of 164 participants recruited, 161 (98%) completed 6-month primary outcomes. No evidence was found that flat flexible shoes were superior to stable supportive shoes in primary outcomes. Evidence did show a between-group difference in change in pain favoring stable supportive shoes (mean difference, 1.1 units [95% CI, 0.5 to 1.8 units]; P = 0.001) but not function (mean difference, 2.3 units [CI, -0.9 to 5.5 units]; P = 0.167). Improvements in knee-related quality of life and ipsilateral hip pain favored stable supportive shoes (mean difference, -5.3 units [CI, -10.0 to -0.5 units] and 0.7 units [CI, 0.0 to 1.4 units], respectively). Flat flexible shoes were not superior to stable supportive shoes for any secondary outcome. Fewer participants reported adverse events with stable supportive shoes (n = 12 [15%]) compared with flat flexible shoes (n = 26 [32%]) (risk difference, -0.17 [CI, -0.30 to -0.05]).

LIMITATION

No "usual shoes" control group and a select patient subgroup, which may limit generalizability.

CONCLUSION

Flat flexible shoes were not superior to stable supportive shoes. Contrary to our hypothesis, stable supportive shoes improved knee pain on walking more than flat flexible shoes.

PRIMARY FUNDING SOURCE

National Health and Medical Research Council.

Footwear for osteoarthritis of the lateral knee: protocol for the FOLK randomised controlled trial

BACKGROUND

Structural features of lateral tibiofemoral (TF) joint osteoarthritis (OA) occur in up to half of all people with knee OA, and co-existing lateral TF OA is associated with worse knee pain in people with mixed compartmental knee OA. Clinical guidelines for management of knee OA advocate advice about appropriate footwear, yet there is no research evaluating which types of footwear are best for managing pain associated with lateral TF OA. Biomechanical evidence suggests that "motion-control" footwear, which possess midsoles that are stiffer medially compared to laterally, may shift load away from the lateral compartment of the knee and thus may reduce knee pain associated with lateral TF OA. The primary aim of this study is to compare the effects of motion-control shoes to neutral shoes on knee pain in people with predominantly lateral TF OA.

METHODS

This will be an assessor- and participant-blinded, two-arm, comparative effectiveness randomized controlled trial (RCT) conducted in Melbourne, Australia. We will recruit a minimum of 92 people with painful lateral TF OA from the community. Participants will be randomly allocated to receive either motion-control shoes or neutral shoes and will be instructed to wear their allocated shoes for a minimum of 6 h per day for 6 months. The primary outcome is change in self-reported knee pain on walking, measured using a numerical rating scale, assessed at baseline and 6 months. Secondary outcomes include other measures of knee pain, physical function, quality of life, participant-perceived change in pain and function, and physical activity levels.

DISCUSSION

This study will compare the efficacy of motion-control shoes to neutral shoes for people with painful lateral TF OA. Findings will be the first to provide evidence of the effects of footwear on knee pain in this important subgroup of people with knee OA and allow clinicians to provide accurate advice about the most appropriate footwear for managing pain associated with lateral TF OA.

TRIAL REGISTRATION

This trial has been prospectively registered by the Australian New Zealand Clinical Trials Registry on 15/11/2018 (reference: ACTRN12618001864213).

Medial Unloader Braces and Lateral Heel Wedges Do not Alter Gait Biomechanics in Healthy Young Adults

Context: Orthotic devices such as medial unloader knee braces and lateral heel wedges may limit cartilage loading following trauma or surgical repair. However, little is known regarding their effects on gait biomechanics in young, healthy individuals who are at risk of cartilage injury during physical activity due to greater athletic exposure compared with older adults. Objective: Determine the effect of medial unloader braces and lateral heel wedges on lower-extremity kinematics and kinetics in healthy, young adults. Design: Cross-sectional crossover design. Setting: Laboratory setting. Patients: Healthy, young adults who were recreationally active (30 min/d for 3 d/wk) between 18 and 35 years of age, who were free from orthopedic injury for at least 6 months, and with no history of lower-extremity orthopedic surgery. Interventions: All subjects completed normal over ground walking with a medial unloader brace at 2 different tension settings and a lateral heel wedge for a total of 4 separate walking conditions. Main Outcome Measures: Frontal plane knee angle at heel strike, peak varus angle, peak internal knee valgus moment, and frontal plane angular impulse were compared across conditions. Results: The medial unloader brace at 50% (-2.04° [3.53°]) and 100% (-1.80° [3.63°]) maximum load placed the knee in a significantly more valgus orientation at heel strike compared with the lateral heel wedge condition (-0.05° [2.85°]). However, this difference has minimal clinical relevance. Neither of the orthotic devices altered knee kinematics or kinetics relative to the control condition. Conclusions: Although effective in older adults and individuals with varus knee alignment, medial unloader braces and lateral heel wedges do not influence gait biomechanics in young, healthy individuals.

Relationship between knee abduction moment with patellofemoral joint reaction force, stress and self-reported pain during stair descent in women with patellofemoral pain

BACKGROUND

Increased external knee abduction moment has been proposed as a risk factor for patellofemoral pain. This alteration is thought to be associated with elevated patellofemoral joint reaction force and stress, however these relationships remain poorly explored. Therefore, this study aimed at comparing knee abduction moment parameters (peak, rate of moment development and impulse), patellofemoral joint reaction force and stress of women with patellofemoral pain and pain-free controls during stair descent; and investigating the relationship among these variables with self-reported pain.

METHODS

Kinetic data was obtained by inverse-dynamics equations and a previously reported algorithmic model was used to determine patellofemoral joint reaction force and stress. Participants' worst pain in the last month and pain level during stair descent were evaluated using a visual analogue scale.

FINDINGS

Women with patellofemoral pain presented higher peak, rate of moment development and impulse of the external knee abduction moment, patellofemoral joint reaction force and stress (p = 0.005 to 0.04, effect size = 0.52 to 0.96) during stair descent than pain-free controls. Only knee abduction moment impulse presented positive moderate correlations with worst pain level in the last month (r = 0.53, p < 000.1), pain level during stair descent (r = 0.33, p = 0.042), patellofemoral joint reaction force (r = 0.65, p < 000.1) and stress (r = 0.58, p < 000.1).

INTERPRETATION

These findings indicate that strategies aimed at decreasing external knee abduction moment impulse could reduce the load over the patellofemoral joint and improve pain of women with patellofemoral pain.

Towards secondary prevention of early knee osteoarthritis

Osteoarthritis (OA) of the knee is the most common arthritic disease, yet a convincing drug treatment is not available. The current narrative review focuses on integration of scientific evidence and professional experience to illustrate which management approaches can be taken for prototypical individual patient profiles with early knee OA. Animal models suggest that: (1) OA can progress even in the presence of fully recovered movement kinetics, kinematics and muscle activation patterns; (2) muscle weakness is an independent risk factor for the onset and possibly the rate of progression of knee OA; (3) onset and progression of OA are not related to body weight but appear to depend on the percentage of body fat. From studies in the human model, one could postulate that risk factors associated with progression of knee OA include genetic traits, preceding traumatic events, obesity, intensity of pain at baseline, static and dynamic joint malalignment and reduced muscle strength. Taken this into account, an individual can be identified as early knee OA at high risk for disease progression. A holistic patient-tailored management including education, supportive medication, weight loss, exercise therapy (aerobic, strengthening and neuromuscular) and behavioural approaches to improve self-management of early knee OA is discussed in individual prototypic patients. Secondary prevention of early knee OA provides a window of opportunity to slow down or even reverse the disease process. Yet, as the sheer number of patients early in the OA disease process is probably large, a more structured approach is needed to provide appropriate care depending on the patient's individual risk profile.

Footwear for self-managing knee osteoarthritis symptoms: protocol for the Footstep randomised controlled trial

BACKGROUND

Knee osteoarthritis (OA) is a leading cause of musculoskeletal pain and disability globally, and abnormal knee loading is central to disease pathogenesis. Clinical guidelines recommend clinicians provide advice regarding appropriate footwear for people with knee OA, yet there is little research comparing the effects of different footwear on knee OA symptoms. Research suggests that wearing flat flexible shoes is associated with lower knee joint loads compared to stable supportive shoe styles. This two-arm pragmatic, comparative effectiveness randomised controlled trial will compare the effects of daily use of flat flexible shoes and stable supportive shoes on knee OA clinical outcomes, over 6 months.

METHODS

164 people with symptomatic medial tibiofemoral OA of moderate to severe radiographic severity (Kellgren and Lawrence Grade 3 & 4) will be recruited from the community. Following baseline assessment, participants will be randomly allocated to receive either i) flat flexible shoes or; ii) stable supportive shoes. Participants will choose two different pairs of shoes from a selection that fulfil the criteria in their allocated shoe class. Limited disclosure will blind participants to group allocation. Participants will be instructed to wear their allocated shoes daily for 6 months (minimum of 6 h/day), after which participants will be reassessed. The primary outcomes are knee pain severity on walking (measured by numerical rating scale) and self-reported physical function (measured by the Western Ontario and McMaster Universities Osteoarthritis Index), assessed at baseline and 6 months. Secondary outcomes include additional measures of knee pain, function, sport and recreation participation and quality-of-life (measured using subscales of the Knee Osteoarthritis Outcome Score), as well as pain at other sites (measured by numerical rating scale), self-reported global ratings of change in pain and physical function (measured by 7-point rating scale), and physical activity levels (measured by Physical Activity Scale for the Elderly).

DISCUSSION

This study will determine whether daily wear of flat flexible shoes improves clinical outcomes in the management of knee OA, compared to stable supportive shoes. Findings will assist clinicians in providing evidence-based advice regarding appropriate footwear for people with knee OA to self-manage symptoms.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry reference: ACTRN12617001098325 . Registered 28/07/2017.

Current status and future prospects for disease modification in osteoarthritis

OA is a chronic, progressive and disabling joint disease, leading to a poor quality of life and an enormous social and economic burden. Current therapies for OA patients remain limited, which creates an area of huge unmet medical need. For some time, researchers have been looking for approaches that can inhibit the structural progression of OA. A variety of potential disease-modifying OA drugs have been developed, targeting cartilage, inflammatory pathways or subchondral bone. In addition, non-pharmacological therapies, including joint distraction and weight loss, draw increasing attention, with some showing disease-modifying potential. Thus we performed a comprehensive review to discuss the current status of disease-modifying therapies in OA and appraise the potentials of emerging novel agents.

Moderators and mediators of effects of unloading shoes on knee pain in people with knee osteoarthritis: an exploratory analysis of the SHARK randomised controlled trial

OBJECTIVE

To investigate moderators and biomechanical mediators of effects of unloading shoes on knee pain in people with knee osteoarthritis (OA).

METHODS

Exploratory analysis from 164 participants in a clinical trial comparing unloading (ASICS GEL-Melbourne OA) to conventional walking shoes. The primary outcome was 6-month change in knee pain (11-point numerical rating scale (NRS)). Moderators included baseline peak knee adduction moment (KAM), radiographic severity (Kellgren & Lawrence (KL) scale), body mass, foot posture, neuropathic pain and diffuse knee pain. Mediators included change in peak KAM and KAM impulse.

RESULTS

Radiographic severity was the only moderator to interact with footwear group (P = 0.02). Participants with KL = 2 experienced greater pain reductions with conventional compared to unloading shoes (mean difference in change in pain -1.64 units, 95% CI -3.07, -0.21), while unloading shoes tended to result in greater pain reductions than conventional shoes in KL = 3 (0.98, 95% CI -0.44, 2.39) and KL = 4 (0.64, 95% CI -0.64, 1.93). No variable showed any significant mediating effect in the entire cohort. However, there was some evidence that unloading shoes may reduce pain through reductions in peak KAM (indirect effect -0.31, 95% CIs -0.65, 0.03; P = 0.07) in people with KL ≥ 3, compared to conventional shoes.

CONCLUSION

Unloading shoes conferred additional symptomatic benefits over conventional shoes in people with moderate to severe knee OA. There was some evidence effects may be mediated by a reduction in peak KAM. However, we were underpowered for subgroup analyses. These patients may represent a subgroup to which biomechanical interventions designed to reduce the KAM may be more effectively targeted.