Altering Knee Abduction Angular Impulse Using Wedged Insoles for Treatment of Patellofemoral Pain in Runners: A Six-Week Randomized Controlled Trial

<div><p>Objective</p><p>Determine if a change in internal knee abduction angular impulse (KAAI) is related to pain reduction for runners with patellofemoral pain (PFP) by comparing lateral and medial wedge insole interventions, and increased KAAI and decreased KAAI groups.</p><p>Design</p><p>Randomized controlled clinical trial (<a href="http://ClinicalTrials.gov" target="_blank">ClinicalTrials.gov</a> ID# NCT01332110).</p><p>Setting</p><p>Biomechanics laboratory and community.</p><p>Patients</p><p>Thirty-six runners with physician-diagnosed PFP enrolled in the trial, and 27 were analyzed.</p><p>Interventions</p><p>Runners with PFP were randomly assigned to either an experimental 3 mm lateral wedge or control 6 mm medial wedge group. Participants completed a biomechanical gait analysis to quantify KAAIs with their assigned insole, and then used their assigned insole for six-weeks during their regular runs. Usual pain during running was measured at baseline and at six-week follow-up using a visual analog scale. Statistical tests were performed to identify differences between wedge types, differences between biomechanical response types (i.e. increase or decrease KAAI), as well as predictors of pain reduction.</p><p>Main Outcome Measures</p><p>Percent change in KAAI relative to neutral, and % change in pain over six weeks.</p><p>Results</p><p>Clinically meaningful reductions in pain (>33%) were measured for both footwear groups; however, no significant differences between footwear groups were found (<i>p</i> = 0.697). When participants were regrouped based on KAAI change (i.e., increase or decrease), again, no significant differences in pain reduction were noted (<i>p</i> = 0.146). Interestingly, when evaluating absolute change in KAAI, a significant relationship between absolute % change in KAAI and % pain reduction was observed (<i>R</i>² = 0.21; <i>p</i> = 0.030), after adjusting for baseline pain levels.</p><p>Conclusion</p><p>The greater the absolute % change in KAAI during running, the greater the % reduction in pain over six weeks, regardless of wedge type, and whether KAAIs increased or decreased. Lateral and medial wedge insoles were similar in effectiveness for treatment of PFP.</p><p>Clinical Relevance</p><p>Altering KAAI should be a focus of future PFP research. Lateral wedges should be studied further as an alternative therapy to medial wedges for management of PFP.</p><p>Trial Registration</p><p>ClinicalTrials.gov <a href="https://clinicaltrials.gov/ct2/show/NCT01332110?term=NCT01332110" target="_blank">NCT01332110</a></p></div

Scatter plot showing relationship between absolute change in knee abduction angular impulse (KAAI) with wedged intervention and pain reduction over 6 weeks.

<p>The regression analysis in this article also adjusted for baseline pain; however a 2-dimensional graph is shown here for clarity.</p

The wedged insole conditions tested in this study.

<p>On right, the 6mm medial wedge is shown. On left, the 3mm lateral wedge is shown.</p

Main results of this study are displayed for each footwear group, and the regroupings^* after the six-week intervention.

<p>* subjects were regrouped based on whether they experienced increased or decreased KAAIs with their assigned footwear, regardless of wedge type</p><p>† significant at α = 0.05</p><p>Mean differences between groups are shown with 95% confidence intervals. Negative % change values indicate that there was a decrease from baseline.</p

CONSORT diagram showing subject flow through trial.

<p>CONSORT diagram showing subject flow through trial.</p

History and Physical Inclusion/Exclusion Criteria.

<p>The criteria used to diagnose patellofemoral pain syndrome and participant eligibility in this study are shown.</p

Participant-reported use of co-interventions for patellofemoral pain during the six-week trial.

<p>*subjects were regrouped based on whether they experienced increased or decreased KAAIs with their assigned footwear, regardless of wedge type</p><p>†some participants used more than one</p><p>Participant-reported use of co-interventions for patellofemoral pain during the six-week trial.</p

Photograph of an experimental trial occurring.

<p>The motion capture cameras, force platform, timing system, and retroreflective markers can be seen.</p