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

Associations between static foot posture, dynamic in-shoe plantar foot forces and knee pain in people with medial knee osteoarthritis: A cross-sectional exploratory study

OBJECTIVE

To investigate relationships between static foot posture, dynamic plantar foot forces and knee pain in people with medial knee osteoarthritis (OA).

DESIGN

Data from 164 participants with symptomatic, moderate to severe radiographic medial knee OA were analysed. Knee pain was self-reported using a numerical rating scale (NRS; scores 0-10; higher scores worse) and the Knee Injury and Osteoarthritis Outcome Score pain subscale (KOOS; scores 0-100; lower scores worse). Static foot posture was assessed using clinical tests (foot posture index, foot mobility magnitude, navicular drop). Dynamic plantar foot forces (lateral, medial, whole foot, medial-lateral ratio, arch index) were measured using an in-shoe plantar pressure system while walking. Relationships between foot posture and plantar forces (independent variables) and pain (dependent variables) were evaluated using linear regression models, unadjusted and adjusted for sex, walking speed, Kellgren & Lawrence grade, shoe category, and body mass (for dynamic plantar foot forces).

RESULTS

No measure of static foot posture was associated with any knee pain measure. Higher medial-lateral foot force ratio at midstance, and a higher arch index during overall stance, were weakly associated with higher knee pain on the NRS (regression coefficient = 0.69, 95% confidence interval (CI) 0.09 to 1.28) and KOOS (coefficient=3.03, 95% CI 0.71 to 5.35) pain scales, respectively.

CONCLUSION

Dynamic plantar foot forces, but not static foot posture, were associated with knee pain in people with medial knee OA. However, the amount of pain explained by increases in plantar foot force was small; thus, these associations are unlikely to be clinically meaningful.

Associations amongst dynamic knee stiffness during gait, quadriceps stiffness, and the incidence of knee osteoarthritis over 24 months: a cohort study with a mediation analysis

BACKGROUND

Decreased strength and increased stiffness of the quadriceps have been associated with a higher risk of developing knee osteoarthritis (OA) in elders. Dynamic joint stiffness (DJS) represents collective resistance from active and passive knee structures for dynamic knee motions. Elevated sagittal knee DJS has been associated with worsening of cartilage loss in knee OA patients. Altered quadriceps properties may affect DJS, which could be a mediator for associations between quadriceps properties and knee OA. Hence, this study aimed to examine whether DJS and quadriceps properties would be associated with the development of clinical knee OA over 24 months, and to explore the mediation role of DJS in associations between quadriceps properties and knee OA.

METHODS

This was a prospective cohort study with 162 healthy community-dwelling elders. Gait analysis was conducted to compute DJS during the loading response phase. Quadriceps strength and stiffness were evaluated using a Cybex dynamometer and shear-wave ultrasound elastography, respectively. Knee OA was defined based on clinical criteria 24 months later. Logistic regression with generalized estimating equations was used to examine the association between quadriceps properties and DJS and incident knee OA. Mediation analysis was performed to explore the mediation role of DJS in associations between quadriceps properties and the incidence of knee OA.

RESULTS

A total of 125 participants (65.6 ± 4.0 years, 58.4% females) completed the 24-month follow-up, with 36 out of 250 knees identified as clinical knee OA. Higher DJS (OR = 1.86, 95%CI: 1.33-2.62), lower quadriceps strength (1.85, 1.05-3.23), and greater quadriceps stiffness (1.56, 1.10-2.21) were significantly associated with a higher risk of clinical knee OA. Mediation analysis showed that the DJS was not a significant mediator for the associations between quadriceps properties and knee OA.

CONCLUSIONS

Higher sagittal knee dynamic joint stiffness, lower quadriceps strength, and greater quadriceps stiffness are potential risk factors for developing clinical knee OA in asymptomatic elders. Associations between quadriceps properties and knee OA may not be mediated by dynamic joint stiffness. Interventions for reducing increased passive properties of the quadriceps and knee joint stiffness may be beneficial for maintaining healthy knees in the aging population.

Osteoarthritis year in review 2023: Biomechanics

Biomechanics plays a significant yet complex role in osteoarthritis (OA) onset and progression. Identifying alterations in biomechanical factors and their complex interactions is critical for gaining new insights into OA pathophysiology and identification of clearly defined and modifiable mechanical treatment targets. This review synthesized biomechanics studies from March 2022 to April 2023, from which three themes relating to human gait emerged: (1) new insights into the pathogenesis of OA using computational modeling and machine learning, (2) technology-enhanced biomechanical interventions for OA, and (3) out-of-lab biomechanical assessments of OA. We further highlighted future-focused areas which may continue to advance the field of biomechanics in OA, with a particular emphasis on exploiting technology to understand and treat biomechanical mechanisms of OA outside the laboratory. The breadth of studies included in this review highlights the complex role of biomechanics in OA and showcase numerous innovative and outstanding contributions to the field. Exciting cross-disciplinary efforts integrating computational modeling, mobile sensors, and machine learning methods show great promise for streamlining in vivo multi-scale biomechanics workflows and are expected to underpin future breakthroughs in the understanding and treatment of biomechanics in OA.

Do imaging findings modify the effect of non-surgical treatment in patients with knee and hip osteoarthritis? A systematic literature review

OBJECTIVES

To review the available evidence on diagnostic imaging findings in knee and hip osteoarthritis (OA) as treatment effect modifiers in non-surgical OA interventions.

METHODS

MEDLINE, Embase and The Cochrane Central Register of Controlled Trials were searched from the earliest records published to 22 March 2022. Studies in knee and hip OA reporting subgroup analyses in randomised controlled trials with imaging findings as potential treatment effect modifiers were included. Studies were critically appraised using the Cochrane risk of bias tool and a subgroup analysis quality assessment.

RESULTS

Of 10 014 titles and abstracts screened, eight studies met the inclusion criteria, six on knee OA and two on hip OA. The studies investigated effect modifiers in exercise therapy, intra-articular injections and unloading shoes. Imaging findings assessed as potential treatment effect modifiers were radiographic OA severity, hip effusion (ultrasound), bone marrow lesions and meniscal pathology (MRI). Two studies fulfilled the methodological quality criteria for assessing effect modification. One reported that radiographic knee OA severity modified the effect of unloading shoes on walking pain. Those with more severe radiographic knee OA had a greater response to shoe inserts. One reported no interaction between radiographic OA severity or joint effusion and the effect of intraarticular injections of corticosteroid or hyaluronic acid in hip OA, indicating no difference in response in people with greater hip joint effusion or radiographic OA severity compared with those with less severe joint disease.

CONCLUSION

Overall, methodological limitations and very few studies do not permit conclusions on diagnostic imaging findings as effect modifiers in non-surgical interventions in knee and hip OA.Radiographic severity of knee OA potentially modifies the effect of unloading shoes.

PROSPERO REGISTRATION NUMBER

CRD42020181934.

How Do Nonsurgical Interventions Improve Pain and Physical Function in People With Osteoarthritis? A Scoping Review of Mediation Analysis Studies

OBJECTIVE

Nonsurgical interventions are recommended for osteoarthritis (OA). However, how interventions change pain and physical function is unclear. Therefore, the objectives of this scoping review were to 1) identify what potential mediators of nonsurgical interventions on pain and physical function have been evaluated and 2) summarize the findings according to intervention, joint, and outcome.

METHODS

We searched Medline, Embase, CINAHL, Cochrane Central Register of Controlled Trials, and Scopus databases. Studies were included if they conducted a mediation analysis on a randomized controlled trial evaluating a nonsurgical intervention on OA of any joint. Outcomes were pain and physical function.

RESULTS

Nine knee OA studies, evaluating diet plus exercise, exercise, unloading shoes, high-expectation communication during acupuncture, and telephone-based weight loss plus exercise were identified. Except for weight loss and self-efficacy, putative mediators (knee muscle perfusion/extensor strength/adduction moment, systemic inflammatory biomarkers, physical activity, dietary intake, and pain beliefs) were evaluated by single studies. Ten mediators partially mediated intervention (diet plus exercise, exercise, high-expectation communication) effects on pain and physical function. Eight mediators were common to pain and function (reduced weight, increased knee extensor strength, and increased self-efficacy). Constant knee flexor muscle perfusion partially mediated exercise effects on pain, and knee pain relief partially mediated exercise effects on function.

CONCLUSION

In knee OA, some evidence suggests that the benefits of 1) diet and exercise are mediated through changes in body weight, systemic inflammation, and self-efficacy; 2) exercise is mediated through changes in knee muscle strength and self-efficacy; and 3) high-expectation communication style is mediated through changes in self-efficacy.

Association between changes in the knee adduction moment and changes in knee pain and function in response to non-surgical biomechanical interventions for medial knee osteoarthritis: a systematic review

There is lack of understanding of the relationship between knee adduction moment (KAM) reductions and improvements in pain or function in patients with knee osteoarthritis (KOA). Moreover, there is no systematic review describing the longitudinal relationship between KAM changes and subsequent changes in pain and/or physical function. We aimed (1) to investigate the relationship between changes in KAM induced by non-surgical biomechanical interventions and consecutive changes in pain and/or physical function in patients with medial KOA and (2) to compare this relationship for different interventions. We considered eligible all RCTs using biomechanical interventions aimed to reduce KAM in KOA patients, that measured pain/function. We used Cohen's d effect size to quantify outcome measurements. 14 papers reporting 11 studies were identified. Braces were tested in 6 studies, insoles in 5 studies, shoes in 3 studies and gait retraining in 2 studies. Methodological differences were large among studies. Large effect sizes (≥0.8) changes in pain/function were observed with interventions having at least a small KAM effect size (≥0.2), suggesting an association between KAM and pain/function changes. A linear trend was observed between inter-intervention KAM and VAS pain effect sizes, based on 4 studies. No firm conclusions could be drawn for the different intervention types. There was a trend toward larger KAM reductions leading to larger improvements in pain/function in non-surgical biomechanical interventions. Additional high-quality RCT with consistent methodology are needed to fully characterize the association between KAM and pain/function changes.

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).

The effectiveness of foot orthoses in the treatment of medial knee osteoarthritis: A systematic review

BACKGROUND

Knee osteoarthritis is a disease of the joint causing decreased function and pain. Currently, treatments range from medication to surgery, with the use of different insoles and footwear recommended. These methods are effective by either correcting the position of the knee or providing shock absorption. However, there is little understanding of the effective characteristics of these devices.

RESEARCH QUESTION

This paper aims to investigate this question and provide future areas of research to help better define treatment guidelines. Foot orthoses are an example of non-pharmacological conservative treatments mentioned in National Institute for Health and Care Excellence (NICE) guidelines to treat knee osteoarthritis (OA). These include lateral wedge insoles (LWI), developed with the intention of load reduction of the knee. Different footwear has also been shown to affect pain, biomechanical and functional outcomes in knee OA patients.

METHODS

To address what features of LWIs and footwear make them effective in the treatment of knee OA, scientific databases were used to search for papers on this topic and then selected to be included based on pre-defined criteria. Data were extracted and analysed from these studies to provide a basis for possible areas for future development of these foot orthoses, and research required to improve clinical treatment guidelines. Databases used were PubMed, Scopus and Web of Science.

RESULTS AND SIGNIFICANCE

Thirty-four out of 226 papers were included after application of inclusion and exclusion criteria. Regarding LWIs, the characteristics showing the most beneficial effect on either biomechanical, functional or pain outcomes were customisation, full-length, 5° elevation, shock absorption and arch support. For footwear, barefoot mimicking soles produced the most favourable biomechanics. Results also showed that insoles work in correcting the position of the knee, but it may or may not affect patients' pain and function.

Effect of lateral wedged insoles on the knee internal contact forces in medial knee osteoarthritis

BACKGROUND

Lateral wedge insoles (LWIs) are non-surgical interventions used in medial knee osteoarthritis (KOA) aiming at restoring correct joint biomechanics. However, the mechanical efficacy of LWIs, based on modulation of the external knee adduction moment, is partially proved and high variability in response to these devices was observed.

RESEARCH QUESTION

The principal aim of the study was to employ subject-specific musculoskeletal models to investigate the immediate effect of LWIs on the medial compressive force (MCF) in a population with medial KOA and varus alignment.

METHODS

Fifteen adults (8 healthy controls age 56±3.4, BMI 25.2±2.2, hip-knee-ankle angle -1.3±2.3; and 7 KOA participants age 62±6.6, BMI 31.7±3.9, hip-knee-ankle angle 6.3±2) were recruited. Subject-specific LWIs were designed in CAD based on shape capture of the foot and manufactured via 3D printing. The required degree of heel post was added to the orthotic shell to create insoles with 0°, 5° and 10° of lateral wedge. Gait data were collected for each condition and a musculoskeletal model implemented in the Anybody Modeling System estimated the CFs normalised per bodyweight. The effect of the LWIs with respect to the baseline on the peak and the impulse of the MCF were tested with a Wilcoxon non-parametric test for paired samples.

RESULTS

For the KOA group, LWIs did not reduce significantly the impulse and the peak of the MCF. No dose-response trend according to the degree of wedging was observed. A high inter-subject variability was found: the impulse of the MCF varied between -12%, +10%, the peak between -5%, +7%. Moreover, LWIs had no consistent effect on shifting the load from the medial to the lateral compartment.

SIGNIFICANCE

Subject-specific response to LWIs in a cohort of medial KOA patients was observed. Further studies are necessary to maximise the mechanical effect of LWIs on restoring normal knee joint mechanics.