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Objective: To explore the relationship between knee crepitus, quadriceps muscle thickness and isometric strength in individuals with patellofemoral pain (PFP)., Design: Cross-sectional., Participants: Individuals with PFP., Main Outcome Measures: Participants with PFP underwent assessments for presence, frequency and severity of knee crepitus. Real-time ultrasound images of the quadriceps muscles (rectus femoris, vastus medialis and lateralis) at rest and during contraction were obtained, muscle thickness was measured in both conditions. Maximal voluntary isometric contraction tests were performed to measure knee extensor strength. The relationship between knee crepitus and quadriceps muscle thickness and knee extensor strength was explored using logistic and linear regressions., Results: Sixty individuals with PFP were included (age: 24; 60% women; 38% with crepitus). Knee crepitus severity was related to rectus femoris and vastus medialis thickness during rest (R 2  = 0.19 and 0.09, respectively) and contraction (R 2  = 0.16 and 0.07, respectively) and with vastus lateralis during contraction (R2 = 0.08). Isometric knee extensor strength was not related to knee crepitus presence, frequency, or severity., Conclusion: Higher severity of knee crepitus is related to lower quadriceps muscle thickness in individuals with PFP. There is no relationship between the presence and frequency of knee crepitus with quadriceps muscle thickness or knee extensor strength., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objective: To compare the effectiveness of adjunct treatments combined with exercise to exercise alone in people with patellofemoral pain (PFP) and explore the quality of intervention descriptions in randomised controlled trials (RCTs)., Design: Systematic review., Data Sources: Seven databases were searched in November 2023., Eligibility: RCTs that evaluated the effectiveness of any adjunct treatment combined with exercise to exercise alone on self-reported pain and function in people with PFP., Results: We included 45 RCTs (2023 participants), with 25 RCTs (1050 participants) contributing to meta-analyses. Pooled analysis indicated very low-certainty evidence that neuromuscular electrical stimulation or monopolar dielectric diathermy combined with exercise leads to small and large improvements in self-reported pain when compared with exercise alone (standardised mean difference (95% CI)=-0.27 (-0.53 to -0.02) and -2.58 (-4.59 to -0.57), respectively) in the short-term. For self-reported pain and function, very low-certainty evidence indicates that knee taping, whole-body vibration, electromyographic biofeedback and knee brace combined with exercise do not differ from exercise alone. Interventions are poorly described in most RCTs, adjunct treatments scored on average 14/24 and exercise therapy 12/24 in the Template for Intervention Description and Replication checklist., Conclusion: Neuromuscular electrical stimulation and monopolar dielectric diathermy combined with exercise seem to improve self-reported pain in people with PFP compared with exercise alone. Knee taping, whole-body vibration, electromyographic biofeedback and knee brace do not offer additional benefits to exercise alone. Most interventions are poorly described, which is detrimental to translating research knowledge into clinical practice., Prospero Registration Number: CRD42020197081., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Patellofemoral pain (PFP) is a prevalent musculoskeletal disorder associated with functional impairments. Although postural control is commonly assessed in people with PFP, there are inconsistent results regarding potential postural control deficits in this population., Research Question: This review aims to evaluate whether postural control is impaired in people with patellofemoral pain (PFP) and the effectiveness of interventions on postural control measures., Methods: We searched six databases from their inception to May 5, 2023. We included studies assessing clinic- or laboratory-based postural control measures in people with PFP compared to pain-free controls, and intervention studies with PFP populations. We assessed risk of bias using the Joanna Briggs Institute critical appraisal checklists and the Cochrane Risk of Bias 2 tool. We assessed the certainty of evidence using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. We used random-effects meta-analyses considering subgroups based on type of task, measure, and intervention., Results: Fifty-three studies were included. Very low certainty evidence indicated that people with PFP have shorter anterior (SMD = 0.53, 95 %CI:0.16,0.90), posteromedial (SMD = 0.54, 95 %CI:0.04,1.03) and posterolateral (SMD = 0.59, 95 %CI:0.11,1.07) reach distance, and worse composite score (SMD = 0.46, 95 %CI:0.22,0.70). Very low to moderate certainty evidence indicated that people with PFP have worse anterior-posterior and overall stability indexes during single-leg stance (SMD = -0.71, 95 %CI:-1.29,-0.14; SMD = -0.63, 95 %CI:-0.94,-0.32) and overall stability index during double-leg stance (SMD = -0.39, 95 %CI:-0.78,-0.00), but no differences in center of pressure area during stair ascent (SMD = 0.32, 95 %CI:-2.72, 3.36). Low certainty evidence indicated that kinesio taping improved anterior reach distance (SMD = -0.49, 95 %CI:-0.89,-0.09), while no significant differences were observed between pre- and post-intervention outcomes for conventional rehabilitation and rigid taping., Significance: Clinicians should use clinic- (star excursion or Y-balance tests) and laboratory-based (stability indexes) measures to identify impairments of postural control in people with PFP. Low certainty of evidence suggests short-term improvement in postural control with kinesio taping., Competing Interests: Declaration of Competing Interest We affirm that we have no financial affiliation or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript. We also affirm that we have no other conflict of interest (e.g., personal associations or involvement) that has played a role in the design, execution, analysis and interpretation of data or writing of this manuscript. Each of the authors has read and concurs with the content in the final manuscript. The material within has not been and will not be submitted for publication elsewhere except as an abstract., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: We compared body mass index (BMI), body fat, and skeletal muscle mass between (1) a mixed-sex nonathletic cohort of people with patellofemoral pain (PFP) and pain-free people, and (2) a nonathletic cohort of people with PFP and pain-free people subgrouped by sex (i.e., men and women with PFP vs. pain-free men and women)., Methods: This cross-sectional study included 114 people with PFP (71 women, 43 men) and 54 pain-free controls (32 women, 22 men). All participants attended a single testing session to assess body composition measures, which included BMI, percentage of body fat (%BF Bioimpedance ), and skeletal muscle mass (both assessed by bioelectrical impedance analysis), and percentage of body fat (%BF Skinfold ) (assessed by skinfold caliper analysis). A one-way univariate analysis of covariance (age and physical activity levels as covariates) was used to compare body composition measures between groups (i.e., PFP vs. pain-free group; women with PFP vs. pain-free women; men with PFP vs. pain-free men)., Results: Women with PFP presented significantly higher BMI, %BF Bioimpedance , and %BF Skinfold , and lower skeletal muscle mass compared to pain-free women (p ≤ 0.04; effect size : ‒0.47 to 0.85). Men with PFP and men and women combined had no differences in BMI, %BF Bioimpedance , %BF Skinfold , and skeletal muscle mass compared to their respective pain-free groups (p > 0.05)., Conclusion: Our findings indicate that BMI and body composition measures should be considered as part of the evaluation and management of people with PFP, especially in women, who have demonstrated higher BMI and body fat and lower skeletal muscle mass compared to pain-free controls. Future studies should not assess body composition measures in a mixed-sex population without distinguishing men participants from women participants., (Copyright © 2021. Production and hosting by Elsevier B.V.)

Objective: The aim of this systematic review and correlation meta-analysis was to identify factors associated with kinesiophobia in individuals with patellofemoral pain (PFP) and to identify interventions that may reduce kinesiophobia in individuals with PFP., Methods: Seven databases were searched for articles including clinical factors associated with kinesiophobia or interventions that may reduce kinesiophobia in individuals with PFP. Two reviewers screened articles for inclusion, assessed risk of bias and quality, and extracted data from each study. A mixed-effects model was used to calculate correlations of function and pain with kinesiophobia using individual participant data. Meta-analyses were performed on interventional articles; Grading of Recommendations, Assessment, Development, and Evaluation was used to evaluate certainty of evidence. Results were reported narratively when pooling was not possible., Results: Forty-one articles involving 2712 individuals were included. Correlation meta-analyses using individual participant data indicated a moderate association between self-reported function and kinesiophobia (n = 499; r = -0.440) and a weak association between pain and kinesiophobia (n = 644; r = 0.162). Low-certainty evidence from 2 articles indicated that passive treatment techniques were more effective than minimal intervention in reducing kinesiophobia (standardized mean difference = 1.11; 95% CI = 0.72 to 1.49). Very low-certainty evidence from 5 articles indicated that interventions to target kinesiophobia (psychobehavioral interventions, education, and self-managed exercise) were better in reducing kinesiophobia than physical therapist treatment approaches not specifically targeting kinesiophobia (standardized mean difference = 1.64; 95% CI = 0.14 to 3.15)., Conclusion: Higher levels of kinesiophobia were moderately associated with poorer function and weakly associated with higher pain in individuals with PFP. Taping and bracing may reduce kinesiophobia immediately after use, and specific kinesiophobia-targeted interventions may reduce kinesiophobia following the full intervention; however, the certainty of evidence is very low., Impact: Assessment of kinesiophobia in clinical practice is recommended, on the basis of the relationships identified between kinesiophobia and other important factors that predict outcomes in individuals with PFP., (© The Author(s) 2023. Published by Oxford University Press on behalf of the American Physical Therapy Association. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Purpose: This study aimed to (a) investigate the proportion of overweight/obesity in a cohort of young adults with patellofemoral pain (PFP) and (b) explore the association of body mass index (BMI), body fat, and lean mass with functional capacity and hip and knee strength in people with PFP., Methods: We included a mixed-sex sample of young adults (18-35 years old) with PFP (n = 100). Measurements for BMI, percentage of body fat, and lean mass (assessed by bioelectrical impedance) were obtained. Functional capacity was assessed by the Anterior Knee Pain Scale, plank test, and single-leg hop test. Strength of the knee extensors, knee flexors, and hip abductors was evaluated isometrically using an isokinetic dynamometer. The proportion of overweight/obesity was calculated based on BMI. The association between BMI, body fat, and lean mass and functional capacity and strength was investigated using partial correlations, followed by hierarchical regression analysis, adjusted for covariates (sex, bilateral pain, and current pain level)., Results: A total of 38% of our cohort had their BMI categorized as overweight/obese. Higher BMI was associated with poor functional capacity (ΔR 2  = 0.06-0.12, p ≤ 0.001) and with knee flexion strength only (ΔR 2  = 0.04, p = 0.030). Higher body fat was associated with poor functional capacity (ΔR 2  = 0.05-0.15, p ≤ 0.015) and reduced strength (ΔR 2  = 0.15-0.23, p < 0.001). Lower lean mass was associated with poor functional capacity (ΔR 2  = 0.04-0.13, p ≤ 0.032) and reduced strength (ΔR 2  = 0.29- 0.31, p < 0.001)., Conclusion: BMI, body fat, and lean mass should be considered in the assessment and management of young people with PFP because it may be detrimental to function and strength., (Copyright © 2021. Production and hosting by Elsevier B.V.)

Objectives: To systematically evaluate the literature and estimate the prevalence, incidence, and burden of gradual-onset knee injuries in team ball-sports., Design: Systematic review with meta-analysis., Methods: Six databases (MEDLINE, EMBASE, Web of Science, CINAHL, SPORTDiscus, SCOPUS) were searched from inception to June 2021. Cohort studies of team ball-sports reporting the number of gradual-onset knee injuries were included. Study quality was assessed using a modified Newcastle-Ottawa scale. Studies were pooled using a Freeman-Tukey Double arcsine transformation (prevalence) and a Poisson random effects regression model (incidence, burden)., Results: Forty-nine studies that captured gradual-onset knee injuries (unclassified, patellofemoral pain, tendinopathies, and iliotibial band friction syndrome) across 15 team ball-sports were included. For unclassified gradual-onset knee injuries, prevalence was 4 % (95 % Confidence Interval (CI) 2 % to 7 %, I 2  = 96 %), incidence was 0.32 per 1000 player-hours (95 % CI 0.25 to 0.43, I 2  = 88 %), and burden was 3.24 days lost per 1000 player-hours (95 % CI 1.95 to 5.37, I 2  = 99 %). For patellofemoral pain, prevalence was 6 % (95 % CI 1 % to 13 %, I 2  = 93 %), and incidence was 0.07 per 1000 player-hours (95 % CI 0.04 to 0.12, I 2  = 67 %). For tendinopathies, prevalence was 1 % (95 % CI 0 % to 2 %, I 2  = 68 %), incidence was 0.07 per 1000 player-hours (95 % CI 0.04 to 0.11, I 2  = 76 %), and burden was 2.14 days lost per 1000 player-hours (95 % CI 1.23 to 3.71, I 2  = 92 %)., Conclusions: Estimates of prevalence, incidence and burden generated from this systematic review quantify the extent of gradual-onset knee injuries in team ball-sports. Further research is required to assess whether age, sport, and participation level are predictors of gradual-onset knee injuries., (Copyright © 2022 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Objectives: Investigate the association of fear of movement and (re)injury with clinical outcomes in women with patellofemoral pain (PFP)., Methods: This cross-sectional study included 92 women with PFP who completed the TAMPA scale for kinesiophobia. The TAMPA score and its two subscales - activity avoidance and somatic focus were correlated with BMI, physical activity level, pain catastrophizing scale, health-related quality of life, pain sensitivity via pressure pain threshold, self-reported disability, and worst knee pain in last month., Results: Greater fear of movement and (re)injury, activity avoidance, and somatic focus were correlated with lower local pain sensitivity (rho = -0.29 to -0.55), lower health-related quality of life (rho = -0.38 to -0.42), greater pain catastrophizing (rho = 0.41 to 0.47), and greater self-reported disability (rho = -0.31 to -0.52). Greater fear of movement and (re)injury and activity avoidance were correlated with adjacent and remote pain sensitivity (rho = -0.24 to -0.39). Greater fear of movement and (re)injury and somatic focus were correlated with greater worst knee pain in last month (rho = 0.21 to 0.32). Fear of movement and (re)injury predicted pain measures, disability, and health-related quality of life (p ≤ 0.010)., Conclusion: The relationship of greater fear of movement and (re)injury with greater disability, pain catastrophizing, pain sensitization, and poorer health-related quality of life highlights the potential importance of considering this psychological feature of PFP during assessment and management.

Context: To determine (1) whether physical function and fear of movement are prospectively associated with the risk of females developing patellofemoral pain (PFP) and (2) whether they change following development of PFP., Design: Prospective observational study., Methods: A total of 114 asymptomatic females (18-22 y old) completed assessment of physical function (forward step-down test and single-leg hop for distance) and fear of movement using the Tampa Scale for Kinesiophobia at baseline and 2-year follow-up. Presence of symptoms of PFP was monitored bimonthly., Results: Ninety participants (retention rate = 79%) completed the 2-year follow-up assessment, with 27 (24% of the cohort) developing PFP. Physical function, including forward step-down test (P = .659) and single-leg hop for distance (P = .825), and fear of movement (P = .479) were not associated with the risk of developing PFP. Females who developed PFP presented with reduced forward step-down repetitions (mean difference = 2.8; 95% confidence interval, 0.2 to 5.3) and single-leg hop for distance (10.2; 95% confidence interval, 2.7 to 17.7 cm) at 2-year follow-up. There was no statistically significant difference between those who did and did not develop PFP for fear of movement (-3.4; 95% confidence interval, -7.0 to 0.2)., Conclusions: Physical function and fear of movement were not associated with the risk of developing PFP in young females. However, the change over time in the step-down and single-leg hop for distance tests may suggest that, even in the early stages of PFP, young females present impaired physical function compared with females who did not develop symptoms. Fear of movement may develop due to persistent PFP, and does not appear to be a risk factor or key feature in females with PFP of short symptoms duration.

Background: Young adults with patellofemoral pain (PFP) have a high prevalence of being overweight or obese, which is associated with impaired lower limb function and muscle weakness. However, the impact of being overweight or obese on pain sensitivity has not been explored., Objectives: We investigated the association between body fat, skeletal muscle mass, and body mass index (BMI) with pressure hyperalgesia and self-reported pain in young adults with PFP., Methods: 114 adults with PFP (24 ± 5 years old, 62% women) were recruited. Demographics and self-reported pain (current and worst knee pain intensity in the previous month - 0-100 mm visual analog scale) were recorded. Body fat and skeletal muscle mass were measured using bioelectrical impedance. Pressure hyperalgesia was measured using a handheld algometer (pressure pain threshold) at three sites: center of patella of the painful knee, ipsilateral tibialis anterior, and contralateral upper limb. The association between body fat, skeletal muscle mass, and BMI with pressure hyperalgesia and self-reported pain were investigated using partial correlations and hierarchical regression models (adjusted for sex, bilateral pain, and symptoms duration)., Results: Higher body fat and lower skeletal muscle mass were associated with local, spread, and widespread pressure hyperalgesia (ΔR 2 =0.09 to 0.17, p ≤ 0.001; ΔR 2 =0.14 to 0.26, p<0.001, respectively), and higher current self-reported pain (ΔR 2 =0.10, p<0.001; ΔR 2 =0.06, p = 0.007, respectively). Higher BMI was associated with higher current self-reported pain (ΔR 2 =0.10, p = 0.001), but not with any measures of pressure hyperalgesia (p>0.05)., Conclusion: Higher body fat and lower skeletal muscle mass help to explain local, spread, and widespread pressure hyperalgesia, and self-reported pain in people with PFP. BMI only helps to explain self-reported pain. These factors should be considered when assessing people with PFP and developing their management plan, but caution should be taken as the strength of association was generally low., Competing Interests: Conflicts of interest The authors declare no conflicts of interest., (Copyright © 2022 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: Impaired knee extension biomechanics and spinal excitability have been reported in women with patellofemoral pain, but their relationship has not been explored. A significant relationship between them could indicate the need for investigating the potential benefits of disinhibitory interventions for women with patellofemoral pain. Thus, this study aimed to investigate the relationship between vastus medialis Hoffmann reflex and (1) maximal isometric, concentric and eccentric knee extensor strength and rate of torque development; (2) knee extensor torque steadiness; and (3) knee extensor moment during functional tasks; in women with patellofemoral pain., Methods: Spinal excitability of twenty-four participants was assessed by the amplitude of maximal vastus medialis Hoffmann reflex. Knee extensor strength, rate of torque development and torque steadiness were assessed using an isokinetic dynamometer. Knee extensor moment during step-down and stair descent tasks were obtained using a three-dimensional motion analysis system., Findings: A moderate negative relationship was found between vastus medialis Hoffmann reflex and knee extensor torque steadiness (r = -0.35; p = 0.05); whereas a moderate positive relationship was found with maximal isometric knee extensor strength (r = 0.37; p = 0.044). No significant relationships were found between vastus medialis Hoffmann reflex and the other variables., Interpretation: Our findings provide insight on the relationship between spinal excitability and neuromuscular control of maximal and submaximal isometric torque production in women with patellofemoral pain. Conversely, spinal excitability does not seem to be related with dynamic torques and moments of the knee extensors in women with patellofemoral pain., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Context: Patellofemoral pain (PFP) is prevalent and challenging to manage. Most patients with PFP are unsatisfied with their knee function at 6 months after treatment and report ongoing pain up to 16 years after diagnosis. The confidence and knowledge of athletic trainers (ATs) in providing evidence-based care to people with PFP is unknown., Objective: To investigate the confidence and knowledge of ATs in the diagnosis, risk factors, prognosis, and treatment with current evidence for PFP., Design: Cross-sectional study., Setting: Online survey., Patient or Other Participants: A random sample of 3000 ATs were invited to participate; 261 completed the survey (10% participation rate, 88% completion rate)., Main Outcome Measures(s): We surveyed AT demographics, confidence in PFP management, and knowledge related to diagnosis, risk factors, prognosis, and treatment. The confidence and knowledge of ATs in managing PFP was assessed. Their beliefs about evidence were compared with the available evidence (ie, consensus statements, position statements, systematic reviews)., Results: Of the ATs surveyed, 91% were confident that their management of PFP aligned with the current evidence, but only 59% were confident in identifying risk factors for PFP development. In addition, 91% to 92% of ATs agreed that quadriceps and hip muscle weakness were risk factors for PFP, which aligns with the current evidence for the former but not the latter. Moreover, 93% to 97% of ATs' responses related to therapeutic exercise aligned with current evidence. However, 35% to 48% supported the use of passive treatments, such as electrophysical agents and ultrasound, which did not align with the current evidence., Conclusions: Most ATs were aware of supporting evidence for therapeutic exercise in PFP management and were confident providing it, creating a strong foundation for evidence-based care. However, varying levels of awareness of the evidence related to risk factors and passive treatments for PFP highlight the need for professional development initiatives to better align ATs' knowledge with the current evidence., (© by the National Athletic Trainers' Association, Inc.)

Objective: To decide clinical and research priorities on pain features and psychological factors in persons with patellofemoral pain., Design: Consensus development process., Methods: We undertook a 3-stage process consisting of (1) updating 2 systematic reviews on quantitative sensory testing of pain features and psychological factors in patellofemoral pain, (2) an online survey of health care professionals and persons with patellofemoral pain, and (3) a consensus meeting with expert health care professionals. Participants responded that they agreed, disagreed, or were unsure that a pain feature or psychological factor was important in clinical practice or as a research priority. Greater than 70% participant agreement was required for an item to be considered important in clinical practice or a research priority., Results: Thirty-five health care professionals completed the survey, 20 of whom attended the consensus meeting. Thirty persons with patellofemoral pain also completed the survey. The review identified 5 pain features and 9 psychological factors-none reached 70% agreement in the patient survey, so all were considered at the meeting. After the meeting, pain catastrophizing, fear-avoidance beliefs, and pain self-efficacy were the only factors considered clinically important. All but the thermal pain tests and 3 psychological factors were considered research priorities., Conclusion: Pain catastrophizing, pain self-efficacy, and fear-avoidance beliefs were factors considered important in treatment planning, clinical examination, and prognostication. Quantitative sensory tests for pain were not regarded as clinically important but were deemed to be research priorities, as were most psychological factors. J Orthop Sports Phys Ther 2022;52(1):29-39. doi:10.2519/jospt.2022.10647 .

Patellofemoral pain is a common and often debilitating musculoskeletal condition. Clinical translation and evidence synthesis of patellofemoral pain research are compromised by heterogenous and often inadequately reported study details. This consensus statement and associated checklist provides standards for REPORTing of quantitative PatelloFemoral Pain (REPORT-PFP) research to enhance clinical translation and evidence synthesis, and support clinician engagement with research and data collection. A three-stage Delphi process was initiated at the 2015 International Patellofemoral Research Network (iPFRN) retreat. An initial e-Delphi activity (n=24) generated topics and items, which were refined at the 2017 iPFRN retreat, and voted on prior to and following the 2019 iPFRN retreat (n=51 current and past retreat participants). Voting criteria included 'strongly recommended' (essential), 'recommended' (encouraged) and uncertain/unsure. An item was included in the checklist if ≥70% respondents voted 'recommended'. Items receiving ≥70% votes for 'strongly recommended' were labelled as such. The final REPORT-PFP checklist includes 31 items (11 strongly recommended, 20 recommended), covering (i) demographics (n=2,4); (ii) baseline symptoms and previous treatments (n=3,7); (iii) outcome measures (2,4); (iv) outcomes measure description (n=1,2); (v) clinical trial methodology (0,3) and (vi) reporting study results (n=3,0). The REPORT-PFP checklist is ready to be used by researchers and clinicians. Strong stakeholder engagement from clinical academics during development means consistent application by the international patellofemoral pain research community is likely. Checklist adherence will improve research accessibility for clinicians and enhance future evidence synthesis., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Abstract: Ferreira, AS, de Oliveira Silva, D, Ferrari, D, Magalhães, FH, Pappas, E, Briani, RV, Pazzinatto, MF, and de Azevedo, FM. Knee and hip isometric force steadiness are impaired in women with patellofemoral pain. J Strength Cond Res 35(10): 2878-2885, 2021-The purposes were as follows: to compare knee extension and hip abduction force steadiness and maximal strength between women with patellofemoral pain (PFP) and pain-free women; and to investigate whether maximal strength, self-reported pain during force-matching tasks, self-reported knee function, symptoms duration, and physical activity level are associated with knee extension and hip abduction force steadiness. Thirty women with PFP and 30 pain-free women were recruited. Knee extension and hip abduction maximal voluntary isometric contractions and submaximal isometric force-matching tasks were evaluated using an isokinetic dynamometer. Subjects were asked to match a target force corresponding to 10% of their maximal isometric voluntary contraction while force steadiness was computed as the coefficient of variation (CV) of the exerted force. Women with PFP had significant 36% lower knee extension and 33% lower hip abduction peak strength. They also had significant 70% lower knee extension force steadiness and 60% lower hip abduction force steadiness (i.e., higher CV) than pain-free women. Self-reported pain and self-reported knee function were significantly associated (r = 0.61, p < 0.001; r = -0.35, p = 0.05) and able to predict 41% of the variance of knee extensor force steadiness. Hip abductor maximum strength was significantly associated (r = -0.57; p = 0.001) and able to predict 32% of the variance of hip abductor force steadiness. These findings indicate that muscle impairments in PFP go beyond only low knee and hip muscle strength because women with PFP also present deficits in knee extension and hip abduction force steadiness. Evidence-based treatments aiming at improving force steadiness may be a promising addition to PFP rehabilitation programs., (Copyright © 2019 National Strength and Conditioning Association.)

Abstract: Ferreira, AS, de Oliveira Silva, D, Barton, CJ, Briani, RV, Taborda, B, Pazzinatto, MF, and de Azevedo, FM. Impaired isometric, concentric, and eccentric rate of torque development at the hip and knee in patellofemoral pain. J Strength Cond Res 35(9): 2492-2497, 2021-The aims of this study were to compare maximal muscle strength and rate of torque development (RTD) of knee extensor and hip abductor during isometric, concentric, and eccentric contractions between women with and without patellofemoral pain (PFP). Thirty-eight women with PFP (PFPG) and 38 pain-free women (CG) participated in this study. Isometric, concentric, and eccentric maximal torque and RTD of knee extensor and hip abductor were assessed using an isokinetic dynamometer. Rate of torque development was calculated as the change in torque over the change in time from torque onset to 30, 60, and 90% of the maximal torque (RTD30%, RTD60%, and RTD90%) during isometric, concentric, and eccentric contractions. PFPG had lower isometric, concentric, and eccentric knee extensor maximal torque (29.9, 28.3, and 26.7%) compared with the CG. For knee extensor RTD, PFPG had slower isometric RTD30% (17.8%), RTD60% (21.5%), and RTD90% (23.4%); slower concentric RTD30% (35.7%), RTD60% (29.3%), and RTD90% (28.2%); and slower eccentric RTD30% (20.5%), RTD60% (25.2%), and RTD90% (22.5%) compared with the CG. PFPG had lower isometric, concentric, and eccentric hip abductor maximal torque (28.3, 21.8, and 17%) compared with the CG. For hip abductor RTD, PFPG had slower isometric RTD30% (32.6%), RTD60% (31.1%), and RTD90% (25.4%); slower concentric RTD90% (11.5%); and slower eccentric RTD30% (19.8%), RTD60% (26.4%), and RTD90% (24%) compared with the CG. In conclusion, women with PFP presented deficits in both maximal strength and RTD of knee extensor and hip abductor during isometric, concentric, and eccentric contractions, which highlight the potential importance of addressing different aspects of muscle function through exercise therapy., (Copyright © 2019 National Strength and Conditioning Association.)

Objectives: To compare trunk and knee biomechanics of women with and without patellofemoral pain (PFP) and knee crepitus during stair ascent., Design: Cross-sectional., Setting: Laboratory-based study., Participants: 29 women with PFP and knee crepitus (PFP Crepitus ); 28 women with PFP and no knee crepitus (PFP NOCrepitus ); 17 pain-free women with knee crepitus (Pain-free Crepitus ); and 29 pain-free women without knee crepitus (Pain-free NOCrepitus )., Main Outcome Measures: Peak trunk flexion, peak knee flexion, mean knee angular velocity, knee extensor moment at peak knee flexion, peak and impulse of the knee extensor moment., Results: PFP Crepitus group performed the stair ascent task with reduced peak knee flexion compared to Pain-free Crepitus (p = 0.04; Effect size = -0.85) and Pain-free NOCrepitus (p = 0.03; Effect size = -0.75). No significant differences among groups were found for peak trunk flexion (p = 0.979), knee angular velocity (p = 0.420), knee extensor moment at peak knee flexion (p = 0.933), peak (p = 0.290) and impulse (p = 0.122) of the knee extensor moment., Conclusion: Women with concomitant PFP and knee crepitus demonstrated reduced knee flexion during stair ascent, but no significant differences for trunk flexion and knee extensor moment variables were found., Competing Interests: Declaration of competing interest None declared., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Deficits in knee flexor strength and rate of torque development (RTD) might be present in women with patellofemoral pain (PFP). In addition, maximal strength and RTD of the knee flexors and extensors might be related with subjective and objective function in women with PFP. However, both conjectures are still poorly understood., Research Question: Do women with PFP have deficits in the maximal strength and RTD of the knee flexors and extensors during isometric, concentric, and eccentric contractions? Is there a relationship between maximal strength and RTD of the knee flexors and extensors with subjective and objective function in women with PFP?, Methods: Fifty-six women with, and 46 women without, PFP participated. Maximal strength and RTD (to 30% and 60% maximal torque) during isometric, concentric, and eccentric contractions of the knee flexors and extensors were assessed using an isokinetic dynamometer. Objective assessment included single leg hop test (SLHT) and forward step-down test (FSDT). Subjective assessment involved the anterior knee pain scale., Results: Women with PFP had small to large deficits in maximal strength and RTD of the knee flexors and extensors during isometric, concentric and eccentric contractions (Effect sizes: -0.43 to -1.10; p ≤ 0.016). Small to moderate correlations of maximal concentric and eccentric knee flexor strength and RTD with SLHT and FSDT (r = 0.28 to 0.41; p ≤ 0.037) were identified. Subjective or objective function were not correlated with maximal isometric knee flexor strength and RTD, or any knee extensor measures (p > 0.05)., Significance: Maximal strength and RTD deficits of the knee flexors and extensors were identified in this female PFP cohort, but they were unrelated to subjective function. The relationship of concentric and eccentric knee flexor strength and RTD deficits with poor objective function should be considered in future exercise trials for women with PFP., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Altered patellofemoral joint (PFJ) loading and elevated kinesiophobia are commonly reported in people with patellofemoral pain (PFP). However, the relative relationship of these physical-psychological variables with pain and disability in people with PFP is unknown., Aim: To explore the relationship of PFJ loading during stair ascent and kinesiophobia, with self-reported pain and disability in women with PFP., Methods: Fifty-seven women with PFP completed the Tampa Scale for Kinesiophobia, a Visual Analog Scale (0-100 mm) for pain during stair ascent, and the Anterior Knee Pain Scale (disability). Stair ascent mechanics were assessed via three-dimensional motion analysis while participants ascended an instrumented seven-step staircase. Peak PFJ contact force and stress, and PFJ contact force and stress loading rates were estimated using a musculoskeletal model. The relationships of PFJ kinetics during stair ascent and kinesiophobia, with the Anterior Knee Pain Scale (disability) and pain during stair ascent, were evaluated with Spearman rank correlation. Variables (kinetics and kinesiophobia) significantly correlating with the dependent variables (pain and disability) were inserted in linear regression models., Results: Kinesiophobia was moderately associated with self-reported pain (rho = 0.37) and disability (rho = -0.58) in women with PFP. No PFJ loading variables were found to be associated with self-reported pain or disability (P > .05). Kinesiophobia explained 14% of the variance of participants' pain while ascending stairs and 33% of the variance of participant's self-reported disability., Conclusion: Addressing kinesiophobia during treatment of women with PFP may be important to reduce self-reported pain and disability., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: To evaluate the credibility and accuracy of PFP-specific web-based content., Design: Cross-sectional evaluation of web-based information., Methods: The study protocol was registered with PROSPERO (CRD42018088671). Two search engines (Google and Bing) were used to search for websites offering information about PFP. Two reviewers assessed the websites for credibility-related and PFP-specific content. PFP-specific content was evaluated according to agreement with current international PFP consensus statements. Based on this, content was rated as (i) Accurate/Clearly described; (ii) Partially accurate/Description lacks clarity; (iii) Inaccurate/Misleading description; or (iv) Not mentioned., Results: After exclusion of duplicates, forty online websites were included in our analyses. 43% of websites did not mention their source of information, and 48% did not mention if the source material was peer-reviewed. Misleading/inaccurate information was most commonly found in the definition of PFP (20% websites) and clinical examination (15%). Twenty-two percent of websites recommended surgery as treatment. The item most frequently rated as accurate/clearly described was PFP terminology (87.5%)., Conclusion: This study highlights missing, inaccurate or poorly described web-based PFP information. Due to the commonality of PFP and potential for improving self-management, there is an urgent need to develop more accurate and comprehensive web-based patient education resources for PFP., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Patellofemoral pain (PFP) impairs joint- and health-related quality of life and may be associated with knee osteoarthritis. We developed a novel, 2-phase, stepped-care approach for PFP, combining (1) self-directed web-based education and exercise therapy with (2) physiotherapist-supported education and exercise therapy. Physiotherapy sessions can be provided using 2 different modalities: face-to-face and telerehabilitation., Objective: This study aims to (1) determine the feasibility of our stepped-care approach, (2) explore patient-reported outcomes following self-directed web-based education and exercise therapy in people with PFP (phase 1), and (3) estimate the differences in treatment effects between face-to-face and telerehabilitation to support further education and exercise therapy (phase 2) in those who had not completely recovered following self-directed care., Methods: Phase 1 involved 6 weeks of self-directed web-based education and exercise therapy. Phase 2 involved random allocation to a further 12 weeks of physiotherapist-led (up to 8 sessions) education and exercise therapy delivered face-to-face or via telerehabilitation to participants who did not rate themselves as completely recovered following phase 1. Feasibility indicators of process, adherence, and participant retention were collected as primary outcomes alongside patient-reported outcomes on Global Rating of Change and knee pain, disability, knee-related quality of life, pain catastrophism, kinesiophobia, and knee self-efficacy. All participants were assessed at baseline, 6 weeks, and 18 weeks., Results: A total of 71 participants were screened to identify 35 participants with PFP to enter the study. Overall, 100% (35/35) and 88% (31/35) of the participants were followed up with at 6 and 18 weeks, respectively. In phase 1 of the study, participants accessed the My Knee Cap website for an average of 6 (7.5) days and performed the exercises for an average of 2.5 (3.6) times per week. A total of 20% (7/35) of the participants reported that they had completely recovered at 6 weeks. Furthermore, 93% (26/28) of the participants who were followed up and had not completely recovered at 6 weeks agreed to be enrolled in phase 2. No statistically significant differences were found between the face-to-face and telerehabilitation groups for any outcome. The novel stepped-care approach was associated with marked improvement or complete recovery in 40% (14/35) of the participants following phase 1 and 71% (25/35) of the participants following phase 2., Conclusions: Self-directed web-based education and exercise therapy for people with PFP is feasible, as noted by the high rate of participant retention and home exercise adherence achieved in this study. Furthermore, 20% (7/35) of people reported complete recovery at 6 weeks. Both face-to-face and telerehabilitation physiotherapy should be considered for those continuing to seek care, as there is no difference in outcomes between these delivery modes. Determining the efficacy of the stepped-care model may help guide more efficient health care for PFP., (©Danilo De Oliveira Silva, Marcella F Pazzinatto, Kay M Crossley, Fabio M Azevedo, Christian J Barton. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 22.07.2020.)

Objective: To evaluate the effect of education interventions compared with any type of comparator on managing patellofemoral pain (PFP)., Design: Intervention systematic review. PROSPERO identifier: CRD42018088671., Literature Search: MEDLINE, Embase, CINAHL, and Web of Science were searched for studies evaluating the effect of education on clinical and functional outcomes in people with PFP., Study Selection Criteria: Two reviewers independently assessed studies for inclusion and quality. We included randomized controlled trials on PFP where at least 1 group received an education intervention (in isolation or in combination with other interventions)., Data Synthesis: Available data were synthesized via meta-analysis where possible; data that were not appropriate for pooling were synthesized qualitatively. Interpretation was guided by the Grading of Recommendations Assessment, Development and Evaluation approach., Results: Nine trials were identified. Low-credibility evidence indicated that health education material alone was inferior to exercise therapy for pain and function outcomes. Low- and very low-credibility evidence indicated that health professional-delivered education alone produced outcomes similar to those of exercise therapy combined with health professional-delivered education for pain and function, respectively., Conclusion: Health professional-delivered education may produce similar outcomes in pain and function compared to exercise therapy plus health professional-delivered education in people with PFP. J Orthop Sports Phys Ther 2020;50(7):388-396. Epub 29 Apr 2020. doi:10.2519/jospt.2020.9400 .

Objective: To investigate the effect of a knee brace compared with minimal intervention on self-reported kinesiophobia and function, objective function, and physical activity level in people with patellofemoral pain (PFP)., Design: Single-blind randomized controlled trial (1:1), parallel., Participants: Individuals with PFP (N=50)., Main Outcome Measures: Primary: kinesiophobia (Tampa Scale for Kinesiophobia). Secondary: self-reported function (Anterior Knee Pain Scale), physical activity level (International Physical Activity Questionnaire), and objective function (forward step-down test). Outcomes were assessed at baseline (T 0 ), at the end of the intervention (2wk) (T 1 ), and at 6 weeks after baseline (T 2 )., Intervention: Participants were randomly assigned to 1 of 2 interventions groups: (1) use of knee brace for 2 weeks during daily living, sports, or painful tasks (brace group) and (2) educational leaflet with information about PFP (leaflet group)., Results: The knee brace reduced kinesiophobia in people with PFP compared with minimal intervention with moderate effect size at T 1 =mean difference (95% CI) -5.56 (-9.18 to -1.93) and T 2 =-5.24 (-8.58 to -1.89). There was no significant difference in self-reported and objective function and physical activity level., Conclusions: The knee brace improved kinesiophobia immediately after intervention (at 2wk) and at 6-week follow-up in people with PFP compared with minimal intervention. A knee brace may be considered within clinically reasoned paradigms to facilitate exercise therapy interventions for people with PFP., (Copyright © 2019 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Objective: To (i) compare objective function in a range of tasks between people with and without patellofemoral pain (PFP); and (ii) evaluate the relationship of objective function with hip muscle capacity and self-reported function in people with PFP., Design: Cross-sectional., Settings: Laboratory., Participants: Thirty-two physically active people (16 with PFP and 16 controls)., Main Outcome Measures: Functional assessments included stair climbing (time), single-legged chair stand (repetitions), step down (repetitions), forward hop for distance and side hop (repetitions). Hip abductor and extensor capacity assessments included power, endurance, isometric and dynamic strength. Self-reported function included the Kujala scale and Patellofemoral sub-scale of the Knee injury and Osteoarthritis Outcome Score (KOOS-PF)., Results: The PFP group was 15% slower climbing stairs (effect size [ES] = 0.90), performed 12% fewer chair stands (ES = 0.62) and forward hopped 20% shorter (ES = 0.79) compared to controls. Lower hip muscle strength and power correlated with lower objective function (r = 0.52-0.78). Lower Kujala scores correlated with longer stair climbing time (r = -0.53)., Conclusion: People with PFP have objective functional impairments, that are associated with reduced hip muscle capacity, indicating progressive resistance training may be beneficial. Absence of a strong correlation between self-reported, and objective, function indicates assessment of both when treating people with PFP is warranted., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objectives: To compare trunk muscle thickness of women with and without patellofemoral pain (PFP) and to assess the association of trunk muscle thickness with self-reported pain of women with PFP., Methods: Forty-four women were recruited and divided into 2 groups: a PFP group (n = 22) and a pain-free group (n = 22). The thickness of the following trunk muscles was obtained by B-mode ultrasound imaging: transversus abdominis, obliquus internus (OI), obliquus externus (OE), rectus abdominis, and multifidus. Self-reported pain was measured on a visual analog scale., Results: The 44 participants were 18 to 35 years old. Women with PFP had lower thickness of the OI and OE than pain-free women, with moderate or large effect sizes ranging from -0.78 to -0.98, which was negatively related to self-reported pain correlations (r = -0.53 to -0.40). The contraction ratios of the OI and OE were also lower in women with PFP than in pain-free women (P < .05). No differences between groups were found for the transversus abdominis, multifidus, and rectus abdominis, with also no correlation with self-reported pain., Conclusions: Lower thickness of the OI and OE is present in women with PFP, which is related to self-reported pain. These findings might help in understanding the alterations in trunk biomechanics of individuals with PFP and the mechanisms by which interventions targeting trunk muscle strength are beneficial to individuals with PFP., (© 2019 by the American Institute of Ultrasound in Medicine.)

Objectives: To evaluate the feasibility of a 12-week progressive resistance training program for people with patellofemoral pain (PFP) targeting proximal muscle strength and power; and resulting clinical and muscle capacity outcomes., Design: Feasibility study., Setting: Clinical environment., Participants: Mixed-sex sample of people with PFP., Main Outcome Measures: Feasibility outcomes included eligibility, recruitment rate, intervention adherence, and drop-outs. Secondary outcomes included perceived recovery, physical function (AKPS and KOOS-PF), worst pain (VAS-cm), kinesiophobia (Tampa), physical activity (IPAQ), and hip strength (isometric and 10 repetition maximum) and power., Results: Eleven people, from 36 who responded to advertisements, commenced the program. One participant withdrew. Ten participants who completed the program reported improvement (3 completely recovered; 6 marked; and 1 moderate). Higher AKPS (effect size [ES] = 1.81), improved KOOS-PF (ES = 1.37), and reduced pain (ES = 3.36) occurred alongside increased hip abduction and extension dynamic strength (ES = 2.22 and 1.92, respectively) and power (ES = 0.78 and 0.77, respectively). Isometric strength improved for hip abduction (ES = 0.99), but not hip extension., Conclusion: A 12-week progressive resistance training program targeting proximal muscle strength and power is feasible and associated with moderate-large improvements in pain, function, and hip muscle capacity in people with PFP. Further research evaluating the efficacy of progressive resistance training is warranted., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objectives: The aims of this study were threefold: (1) to compare the amplitude of patellar tendon reflex (T-reflex) between women with patellofemoral pain (PFP) and pain-free controls; (2) to compare the amplitude of vastus medialis Hoffmann reflex (VM H-reflex) between women with PFP and pain-free controls; (3) to investigate the association between the amplitude of patellar T-reflex and VM H-reflex in women with PFP and pain-free controls., Design: Cross-sectional observational study., Setting: Laboratory of biomechanics and motor control., Participants: Thirty women with PFP and 30 pain-free women aged 18 to 35 years (N=60)., Main Outcome Measures: Peak-to-peak amplitudes of maximal VM H-reflex (elicited via electrical stimulation on the femoral nerve) and patellar T-reflex (elicited via mechanical percussion on the patellar tendon) were estimated., Results: Women with PFP had significant lower amplitude of patellar T-reflex (mean difference=0.086; 95% confidence interval=0.020 to 0.151; P=.010; moderate effect) and VM H-reflex (mean difference=0.150; 95% confidence interval =0.073 to 0.227; P<.001; large effect) compared to pain-free controls. The VM H-reflex was strongly correlated with patellar T-reflex in both PFP group (r=0.66; P<.001) and control group (r=0.72; P<.001)., Conclusions: As the T-reflex is easier to perform than H-reflex assessments in a clinical setting, it represents a feasible option to assess the impaired excitability of the stretch reflex pathway associated with PFP., (Copyright © 2018 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Background: Evidence indicates the presence of both kinesiophobia and knee extension strength deficits in women with patellofemoral pain (PFP). Both impairments may contribute to apparent compensatory gait patterns including reduced cadence and peak knee flexion during stair negotiation., Research Question: Is kinesiophobia or knee extension strength associated with movement pattern in women with patellofemoral pain?, Methods: Forty women with PFP were assessed with three-dimensional kinematic analyses during stair descent; isokinetic dynamometry of the knee extensors (isometric, concentric and eccentric); and the Tampa scale for kinesiophobia. Pearson coefficients were calculated to determine relationship among variables., Results: Kinesiophobia correlated significantly with cadence (r = -0.62, p < 0.001), and peak knee flexion (r = -0.76, p < 0.001). No significant correlations were found between any knee extensor strength variables and kinematics (cadence or peak knee flexion); or kinesiophobia (p > 0.05)., Significance: Findings of this study could suggest addressing strength impairments alone may not adequately address kinesiophobia and movement pattern impairments in women with PFP. However, high-quality randomised controlled trials are needed to test this assumption. Further value may be added if currently evidence-based knee strengthening exercise is combined with education and/or graded exposure to address kinesiophobia, and consideration to gait retraining to address altered movement patterns at the knee., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objectives: (i) To compare kinesiophobia, pain catastrophism and objective function between women with patellofemoral pain (PFP) and pain-free; (ii) to investigate the association of kinesiophobia and pain catastrophism with objetive function in women with PFP., Design: Case-control., Setting: Laboratory-based., Participants: Fifty-five women with PFP and forty pain-free women., Main Outcome Measures: Kinesiophobia and pain catastrophism were assessed using the Tampa Scale of Kinesiophobia and Pain Catastrophizing Scale, respectively. Forward step-down, single leg hop, and modified star balance tests were used to assess objective function. Independent t-tests were used for between-groups comparisons and Pearson correlation coefficients were used to investigate the association between the outcomes., Results: Women with PFP had significantly worse kinesiophobia (p < 0.001; Effect size (ES) = 1.16), pain catastrophism (p < 0.001; ES = 1.57), and poorer objective function (step-down, (p < 0.001; ES = 0.99); single-leg hop (p = 0.002; ES = 0.74); modified star balance (p < 0.001; ES = 0.66) than pain-free controls. Kinesiophobia and pain catastrophism were not correlated with objective function., Conclusion: Greater kinesiophobia, pain catastrophism and poorer objective function is evident in women with PFP, compared to pain-free controls. Kinesiophobia and pain catastrophism were not associated with objective function in women with PFP. Future research is necessary to understand how other physical and psychological factors might affect objective function., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Objective: To evaluate differences in clinical measures of hip abductor and extensor capacity (strength, endurance and power) in people with patellofemoral pain (PFP) compared to asymptomatic controls., Design: Cross-sectional., Settings: Laboratory., Participants: Thirty-two physically active people (16 with PFP and 16 controls)., Main Outcome Measures: Strength was evaluated isometrically using a hand-held dynamometer and dynamically using 10 repetitions maximum (10RM) tests. Power was assessed using a linear position transducer. Endurance was assessed using maximum number of repetitions., Results: The PFP group had significant deficits compared to the control group in isometric strength (21-25%) for hip abduction (ES = 0.98) and extension (ES = 0.85); in 10RM (15-18%) for hip abduction (ES = 0.72) and extension (ES = 0.85); and in power (24-31%) for hip abduction (ES = 0.80), and extension (ES = 0.94). No difference was identified for hip abduction and extension in endurance tests., Conclusion: Clinical assessments can identify deficits in isometric and dynamic hip strength, as well as power in people with PFP. Hip muscle capacity deficits in people with PFP including strength and power highlight a potential need for more progressive resistance training in this population., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

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.

The present study aimed at investigating whether the neuromuscular system behaves differently (in terms of force and muscle activity generation) as a function of the task being performed (i.e. maximal voluntary efforts vs stair negotiation) and the presence of patellofemoral pain (PFP) and possible influences of pain intensity. Thirty-eight women with (n = 19) and without PFP (n = 19) had their knee strength (extension joint torque) measured during maximal voluntary isometric contractions (MVIC) and electromyography (EMG) data recorded during both MVIC and stair ascent tasks, which were performed before and after a loading protocol designed to exacerbate pain symptoms. Women with PFP displayed lower levels of vastus medialis (p = 0.002) and vastus lateralis (p = 0.032) EMG activation during MVIC assessments. Conversely, the PFP group showed higher levels of vastus medialis muscle activity during stair climbing (p = 0.007), which happened exclusively after the loading protocol. Similarly, women with PFP displayed lower knee extensor torque only during the MVIC tests performed after the loading protocol, which was moderately correlated with the increase in self-reported pain (p = 0.041, r = 0.37), whereas the changes in EMG activity during stair ascent were not correlated with changes in pain intensity (p = 0.215, r = 0.12). These results suggest that, in comparison to pain-free controls, women with PFP display lower levels of quadriceps EMG activation during maximal contractions, but higher activation during dynamic tasks (stair ascent). In addition, the moderate association between the decrease in knee extensor torque and increase in self-reported pain indicates that care should be taken by clinicians during quadriceps strength evaluation in women with PFP, as misleading outcomes may emerge if the intensity of knee pain is not considered during screening. Additionally, rehabilitation strategies should focus on both restoring neuromuscular control and increasing muscle strength., Competing Interests: The authors have declared that no competing interests exist.

Objectives: To investigate pain level and function limitation in adolescent athletes and physically active non-athletes with PFP., Design: Cross-sectional study., Setting: Adolescent athletes were recruited at a sport center complex. Adolescent non-athletes were recruited from upper secondary schools., Participants: 108 adolescents diagnosed with PFP: 42 adolescent athletes and 66 adolescent non-athletes., Main Outcome Measures: To evaluate the level of pain, a visual analog scale (VAS) was used and to evaluate the overall function, the Knee Outcome in Osteoarthritis Survey (KOOS) was used., Results: The adolescent athletes scored significantly higher in the VAS (Mean difference = 0.97 (95% CI = 0.35; 1.60) p = 0.003) compared to adolescent non-athletes. Adolescent athletes scored lower in the KOOS - Symptoms, Pain, Knee-related quality of life and Sport and recreation dimensions - than the non-athletes, however, the minimally clinically important difference was not achieved in Pain dimension. There was no significant difference in the Activities of daily living dimension of the KOOS., Conclusions: Adolescent athletes presented higher levels of pain and lower physical function status compared with physically active non-athletes. This provides an important insight to the management of PFP in adolescent athletes as worst functional status is linked with poor prognosis in patients with PFP., (Copyright © 2018. Published by Elsevier Ltd.)

Patellofemoral pain affects a large proportion of the population, from adolescents to older adults, and carries a substantial personal and societal burden. An international group of scientists and clinicians meets biennially at the International Patellofemoral Research Retreat to share research findings related to patellofemoral pain conditions and develop consensus statements using best practice methods. This consensus statement, from the 5th International Patellofemoral Research Retreat held in Australia in July 2017, focuses on exercise therapy and physical interventions (eg, orthoses, taping and manual therapy) for patellofemoral pain. Literature searches were conducted to identify new systematic reviews and randomised controlled trials (RCTs) published since the 2016 Consensus Statement. The methodological quality of included systematic reviews and RCTs was graded using AMSTAR and PEDro, respectively. Evidence-based statements were developed from included papers and presented to a panel of 41 patellofemoral pain experts for consensus discussion and voting. Recommendations from the expert panel support the use of exercise therapy (especially the combination of hip-focused and knee-focused exercises), combined interventions and foot orthoses to improve pain and/or function in people with patellofemoral pain. The use of patellofemoral, knee or lumbar mobilisations in isolation, or electrophysical agents, is not recommended. There is uncertainty regarding the use of patellar taping/bracing, acupuncture/dry needling, manual soft tissue techniques, blood flow restriction training and gait retraining in patients with patellofemoral pain. In 2017, we launched the International Patellofemoral Research Network (www.ipfrn.org) to consolidate and grow our patellofemoral research community, facilitate collaboration and disseminate patellofemoral pain knowledge to clinicians and the general public. The 6th International Patellofemoral Research Retreat will be held in Milwaukee, Wisconsin, USA, in October 2019., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Objectives: (i) To assess the reliability of knee crepitus measures, (ii) to investigate the association between knee crepitus and PFP; (iii) to investigate the relationship between knee crepitus with self-reported function, physical activity and pain., Design: Cross-sectional., Setting: Laboratory-based study., Participants: 165 women with PFP and 158 pain-free women., Main Outcome Measures: Knee crepitus test, anterior knee pain scale (AKPS) and self-reported worst knee pain in the last month, knee pain after 10 squats and knee pain after 10 stairs climbing., Results: Knee crepitus clinical test presented high reliability Kappa value for PFP group was 0.860 and for pain-free group was 0.906. There is a significantly greater proportion of those with crepitus in the PFP group than in the pain-free group (OR = 4.19). Knee crepitus had no relationship with function (rpb = 0.03; p = 0.727), physical activity level (rpb = 0.010; p = 0.193), worst pain (rpb = 0.11; p = 0.141), pain climbing stairs (rpb = 0.10; p = 0.194) and pain squatting (rpb = 0.02; p = 0.802)., Conclusion: Women who presents knee crepitus have 4 times greater odds to be in a group with PFP compared to those who do not. However, knee crepitus has no relationship with self-reported clinical outcomes of women with PFP., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Objectives: Compare anthropometric characteristics, function, kinesiophobia, catastrophism and knee extensor strength between women (i) with PFP and crepitus (PFP crepitus ); (ii) with PFP and no crepitus (PFP NOcrepitus ); (iii) without PFP and crepitus (Pain-free crepitus ); and (iv) without PFP and no crepitus (Pain-free NOcrepitus )., Design: Cross-sectional., Setting: Laboratory study., Participants: 65 women with PFP and 51 pain-free women., Main Outcome Measures: Objective assessment of knee crepitus, forward step-down and single leg hop tests; knee extensor strength tests; and subjective ratings of function, kinesiophobia, pain catastrophising and knee stiffness., Results: Crepitus was more common in women with PFP (50.7%) compared to those without (33.3%) (χ (1) 2 =4.17;p=0.031). PFP crepitus and PFP NOcrepitus groups had lower self-reported function; and higher kinesiophobia, catastrophism and knee stiffness compared to Pain-free crepitus and Pain-free NOcrepitus groups (p < 0.001). PFP crepitus , PFP NOcrepitus and Pain-free crepitus groups had lower functional performance compared to the Pain-free NOcrepitus group (p < 0.040). PFP crepitus and PFP NOcrepitus groups had lower isometric, concentric and eccentric knee extensor strength compared to the Pain-free NOcrepitus group (p < 0.041), but not the pain-free crepitus group. PFP crepitus presented higher BMI than other groups (p = 0.001)., Conclusion: Kinesiophobia, catastrophism, knee stiffness, strength and physical function are all impaired in women with PFP, regardless of crepitus. In pain-free women, crepitus was associated with poorer objective function., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Patellofemoral pain (PFP) is one of the most prevalent conditions within sports medicine, orthopaedic and general practice settings. Long-term treatment outcomes are poor, with estimates that more than 50% of people with the condition will report symptoms beyond 5 years following diagnosis. Additionally, emerging evidence indicates that PFP may be on a continuum with patellofemoral osteoarthritis. Consensus of world leading clinicians and academics highlights the potential benefit of delivering tailored interventions, specific to an individual's needs, to improve patient outcome. This clinical masterclass aims to develop the reader's understanding of PFP aetiology, inform clinical assessment and increase knowledge regarding individually tailored treatment approaches. It offers practical application guidance, and additional resources, that can positively impact clinical practice., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: The etiology of patellofemoral pain (PFP) is thought to be the result of increased patellofemoral joint (PFJ) load and aberrant lower extremity mechanics, including altered vertical ground reaction forces (VGRF). However, few studies have investigated the association between an increase in pain and VGRF loading rates in the context of PFP. Thus, this study aimed to investigate the immediate effects of PFJ loading on pain and VGRF loading rate, and to see if there is a link between modification of both pain and VGRF loading rate during stair negotiation., Methods: Thirty-four women with PFP underwent VGRF analysis during stair negotiation under two conditions: with (condition 2) and without (condition 1) being previously submitted to a PFJ loading protocol in order to or not to exacerbate their knee pain, respectively., Results: The VGRF loading rates were significantly higher in condition 2 (Mean ± standard deviation (SD)=4.0±0.6N/s) compared to condition 1 (Mean±SD=3.6±0.5N/s) during stair ascent and during stair descent (Mean±SD: condition 1=6.3±1.1N/s; condition 2=7.0±1.4N/s). In addition, VGRF loading rates were higher during stair descent compared to stair ascent in both conditions. There were significant correlations between the increase in pain and VGRF loading rate during both tasks., Conclusion: There seemed to be an important relation between the increase in pain and VGRF loading rates in women with PFP. Based on these findings, interventions aimed at reducing VGRF loading rates are important in the context of PFP., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Patellofemoral pain (PFP) has been linked to increased patellofemoral joint stress as a result of excessive hip internal rotation. Lower hip strength and/or excessive rearfoot eversion have been used to explain such altered movement pattern; however, it is unknown which one is the best predictor of excessive hip internal rotation., Research Question: To investigate if peak rearfoot eversion and/or peak concentric hip abductor strength can predict peak hip internal rotation during stair ascent in women with PFP., Methods: This cross-sectional study included thirty-seven women with PFP which underwent three-dimensional kinematic analysis during stair ascent and hip abductor strength analysis in an isokinetic dynamometer. A forced entry linear regression model analysis was carried out to determine which independent variables present the best capability to predict the hip internal rotation., Results: Peak concentric hip abductor strength significantly predicted peak hip internal rotation during stair ascent (R 2  = 0.27, p = 0.001). Peak rearfoot eversion did not predict peak hip internal rotation during stair ascent (R 2  < 0.01, p = 0.62). A Post-hoc analysis was conducted to explore if a subgroup with excessive rearfoot eversion would predict hip internal rotation. Based on a previous reported cut-off point, 48.6% of the participants were classified as excessive rearfoot eversion. For the subgroup with excessive rearfoot eversion, peak concentric hip abductor strength and peak rearfoot eversion significantly predicted peak hip internal rotation during stair ascent (R 2  = 0.26, p = 0.02; R 2  = 0.42, p = 0.003, respectively). For non-excessive rearfoot eversion subgroup, peak concentric hip abductor strength significantly predicted peak hip internal rotation during stair ascent (R 2  = 0.53; p < 0.001); and peak rearfoot eversion did not (R 2  = 0.01; p = 0.65)., Significance: Findings indicate that hip muscle strength seems to be related with hip internal rotation in all women with PFP. Rearfoot eversion seems to be related with hip internal rotation only in a subgroup with excessive rearfoot eversion., (Copyright © 2018. Published by Elsevier B.V.)

This study investigated whether women with patellofemoral pain (PFP) present kinematic alterations in proximal, local, and distal factors simultaneously, and determined the association between the number of kinematic alterations, pain level, and functional status. A three-dimensional motion analysis system was used to analyze the peak hip adduction, peak knee flexion, and peak rearfoot eversion, addressing the proximal, local, and distal factors, respectively, in fifty women. Functional status and pain level were assessed using the anterior knee pain scale (AKPS) and a visual analogic scale. Receiver operating characteristic curves were calculated to identify participants with and without kinematic alterations and the number of them was obtained for each participant. Associations between the number of kinematic alterations, pain level, and AKPS score were determined by the Pearson correlation. Results showed that 52% of women with PFP presented at least two kinematic alterations of which 24% were local/proximal, 16% local/distal, and 12% proximal/distal. Three kinematic alterations were found in 48% of the women with PFP. A strong positive correlation was found between the number of kinematic alterations and pain (r=0.78; p<0.001). A strong negative correlation was found between the number of altered kinematics and functional status (r=-0.79; p<0.001). Findings revealed that women with PFP presented at least two kinematic alterations and a higher number of kinematic alterations was associated with higher pain levels and lower functional status. Clinicians should carefully assess movement pattern of women with PFP as it could indicate a more severe condition, which is associated with a poor prognosis., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Patellofemoral pain (PFP) is one of the most common conditions in orthopedic practice while recent evidence has suggested that it may be a predisposing factor to patellofemoral osteoarthritis. In addition to biomechanical alterations associated with the pathomechanisms underlying PFP, the investigation of neurophysiological alterations has provided novel information in the understanding of the pathophysiology of PFP. For instance, women with PFP present lower amplitude of the vastus medialis (VM) H-reflexes compared to pain-free controls, which suggests that the excitability of spinal reflexes might be a promising tool for discriminating woman with PFP in clinical practice. However, the cross-sectional design of the current research does not inform whether the reduced excitability predisposes to or is the consequence of PFP. Therefore, two hypotheses can be raised: (1) the reduction in excitability of the α-motoneurons is a risk factor for PFP; Or, (2) the reduction in H-reflex excitability is a consequence of PFP due to pain. If the former hypothesis is proven correct, it may help in the early identification of individuals with PFP. If the latter, it may help understand the reduced excitability as a consequence of the long-term pain, which may be interfering in the recovery of individuals with PFP in a long-term basis. In addition, exploring such hypotheses may have direct rehabilitative and prevention implications for PFP and its putative progression to knee osteoarthritis., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objectives: To compare pressure pain threshold (PPT) around the knee (local hyperalgesia) and at a site remote to the knee (widespread hyperalgesia) between female runners with and without patellofemoral pain (PFP); and to evaluate the relationship between running volume, self-reported knee function and PPT measures., Design: Cross-sectional study., Methods: Twenty female runners with PFP and twenty pain-free female runners participated in the study. PPTs were measured using a handheld pressure algometer at four sites in the patellar region: quadriceps tendon, medial patella, lateral patella and patellar tendon; and on the contralateral upper limb. Additionally, all participants were asked to report their average weekly running volume in a typical month and answer the anterior knee pain scale (AKPS) questionnaire., Results: For all sites, female runners with PFP presented lower PPT measures in comparison with control group (P<0.017). There were negative correlations between AKPS and running volume (ρ=-0.88; P<0.001) and between all PPTs and the running volume in the PFP group with correlation (ρ) values ranging between -0.46 and -0.70 (P<0.022). There were positive correlations between all PPTs and AKPS with correlation (ρ) value from 0.50 to 0.69 (P<0.030)., Conclusion: Lower PPTs locally and remote to the knee in female runners with PFP indicate the presence of local and widespread hyperalgesia. Additionally, this hyperalgesia, which is related to self-reported knee function, appears to be increased by greater running volumes. Development and evaluation of non-mechanical interventions for the management of running-related PFP in females may be needed to address this apparent hyperalgesia., (Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Objective: To determine the association between the amplitude of vastus medialis (VM) Hoffmann reflex (H-reflex) and pain level, self-reported physical function, and chronicity of pain in women with patellofemoral pain (PFP)., Design: Cross-sectional study., Setting: Laboratory of biomechanics and motor control., Participants: Women diagnosed with PFP (N=15) aged 18 to 35 years., Interventions: Not applicable., Main Outcome Measures: Data on worst pain level during the previous month, self-reported physical function, and symptom duration (chronicity) were collected from the participants. Maximum evoked responses were obtained by electrical stimulation applied to the femoral nerve and peak-to-peak amplitudes of normalized maximal H-reflexes (maximal Hoffmann reflex/maximal motor wave ratios) of the VM were calculated. A Pearson product-moment correlation matrix (r) was used to explore the relations between the amplitude of VM H-reflex and worst pain during the previous month, self-reported function, and chronicity of pain., Results: Strong negative correlations were found between the amplitude of VM H-reflex and worst pain in the previous month (r=-.71; P=.003) and chronicity (r=-.74; P=.001). A strong positive correlation was found between the amplitude of VM H-reflex and self-reported physical function (r=.62; P=.012)., Conclusions: The strong and significant relations reported in this study suggest that women with PFP showing greater VM H-reflex excitability tend to have lower pain, better physical function, and more recent symptoms. Therefore, rehabilitation strategies designed to increase the excitability of the monosynaptic stretch reflex should be considered in the treatment of women with PFP if their effectiveness is demonstrated in future studies., (Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Background: Several hypotheses have been proposed to explain the pathomechanisms underlying patellofemoral pain (PFP). Concurrent evaluation of lower limb mechanics in the same PFP population is needed to determine which may be more important to target during rehabilitation. This study aimed to investigate possible differences in rearfoot eversion, hip adduction, and knee flexion during stair ascent; the relationship between these variables; and the discriminatory capability of each in identifying females with PFP., Method: Thirty-six females with PFP and 31 asymptomatic controls underwent three-dimensional kinematic analyses during stair ascent. Between-group comparisons were made for peak rearfoot eversion, hip adduction, and knee flexion. Pearson's correlation coefficients were calculated to evaluate relationships among these parameters. Receiver operating characteristic curves were applied to identify the discriminatory capability of each., Findings: Females with PFP ascended stairs with reduced peak knee flexion, greater peak hip adduction and peak rearfoot eversion. Peak hip adduction (>10.6°; sensitivity=67%, specificity=77%) discriminated females with PFP more effectively than rearfoot eversion (>5.0°; sensitivity=58%, specificity=67%). Reduced peak hip adduction was found to be associated with reduced peak knee flexion (r=0.54, p=0.002) in females with PFP., Interpretation: These findings indicate that proximal, local, and distal kinematics should be considered in PFP management, but proximally targeted interventions may be most important. The relationship of reduced knee flexion with reduced hip adduction also indicates a possible compensatory strategy to reduce patellofemoral joint stress, and this may need to be addressed during rehabilitation., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Altered hip, knee and foot kinematics have been systematically observed in individuals with patellofemoral pain (PFP). However, less attention has been given to the altered dynamic postural control associated with PFP. Additionally, the relative contribution of kinematic impairments to the postural behavior of subjects with PFP remains an open question that warrants investigation. The aims of this study were: i) to investigate possible differences in hip adduction, rearfoot eversion, knee flexion and displacement area of the center of pressure (COP) in individuals with PFP in comparison to controls during stair ascent; and (ii) to determine which kinematic parameter is the best predictor of the displacement area of the COP measured during the stance phase of the stair ascent., Methods: Twenty-nine females with PFP and 25 asymptomatic pain-free females underwent three-dimensional kinematic and COP analyses during stair ascent. Between-group comparisons were made using independent t-tests. Regression models were performed to identify the capability of each kinematic factor in predicting the displacement area of the COP., Results: Reduced knee flexion and displacement area of the COP as well as increased peak hip adduction and peak rearfoot eversion were observed in individuals with PFP as compared to controls. Peak hip adduction was the best predictor of the displacement area of the COP (r(2)=23.4%)., Conclusions: The excessive hip adduction was the biggest predictor of the displacement area of the COP., Clinical Relevance: Based on our findings, proximally targeted interventions may be of major importance for the functional reestablishment of females with PFP., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The aims of this study were to examine group differences in muscle activation onset of the vastus medialis (VM) in relation to the vastus lateralis (VL) and pain level during stair ascent in females with patellofemoral pain (PFP) who maintain high and moderate levels of physical activity; to determine the association between physical activity level and muscle activation onset. Forty-three females with PFP and thirty-eight pain-free females were recruited and divided into four groups based on their level of physical activity: females with PFP (n=26) and pain-free females (n=26) who practiced a moderate level of physical activity and females with PFP (n=17) and pain-free females (n=12) who practiced an intense amount of physical activity. Participants were asked to ascend a seven-step staircase and the VM and VL activation onset was determined. Females with PFP who practiced high level of physical activity demonstrated delayed onset of VM (4.06ms) compared to healthy females (-14.4ms). Conversely, females with PFP who practiced moderate level of physical activity did not present VM delay (-2.48ms) in comparison to healthy females (-9.89ms). Furthermore, physical activity significantly correlated to the muscle activation onset difference (p=0.005; R=0.60). These findings may explain why controversial results regarding VM and VL muscle activation onset have been found., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Individuals with patellofemoral pain (PFP) use different motor strategies during unipodal support in stair climbing activities, which may be assessed by vertical ground reaction force parameters. Thus, the aims of this study were to investigate possible differences in first peak, valley, second peak, and loading rate between recreational female athletes with PFP and pain-free athletes during stair climbing in order to determine the association and prediction capability between these parameters, pain level, and functional status in females with PFP. Thirty-one recreational female athletes with PFP and 31 pain-free recreational female athletes were evaluated with three-dimensional kinetics while performing stair climbing to obtain vertical ground reaction force parameters. A visual analog scale was used to evaluate the usual knee pain. The anterior knee pain scale was used to evaluate knee functional score. First peak and loading rate were associated with pain (r = .46, P = .008; r = .56, P = .001, respectively) and functional limitation (r = .31, P = .049; r = -.36, P = .032, respectively). Forced entry regression revealed the first peak was a significant predictor of pain (36.5%) and functional limitation (28.7%). Our findings suggest that rehabilitation strategies aimed at correcting altered vertical ground reaction force may improve usual knee pain level and self-reported knee function in females with PFP.

Background: The elevated Q-angle seems to be one of the most suggested factors contributing to patellofemoral pain. Females with patellofemoral pain are often evaluated through static clinical tests in clinical practice. However, the adaptations seem to appear more frequently in dynamic conditions. Performing static vs. dynamic evaluations of widely used measures would add to the knowledge in this area. Therefore, the aim of this study was to determine the reliability and discriminatory capability of three Q-angle measurements: a static clinical test, peak dynamic knee valgus during stair ascent and a static measurement using a three-dimensional system., Method: Twenty-nine females with patellofemoral pain and twenty-five pain-free females underwent clinical Q-angle measurement and static and dynamic knee valgus measurements during stair ascent, using a three-dimensional system. All measurements were obtained and comparisons between groups, reliability and discriminatory capability were calculated., Findings: Peak dynamic knee valgus was found to be greater in the patellofemoral pain group. On the other hand, no significant effects were found for static knee valgus or clinical Q-angle measurements between groups. The dynamic variable demonstrated the best discriminatory capability. Low values of reliability were found for clinical Q-angle, in contrast to the high values found for the three-dimensional system measurements., Interpretation: Based on our findings, avoiding or correcting dynamic knee valgus during stair ascent may be an important component of rehabilitation programs in females with patellofemoral pain who demonstrate excessive dynamic knee valgus. Q-angle static measurements were not different between groups and presented poor values of discriminatory capability., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Despite its high incidence, patellofemoral pain etiology remains unclear. No prior study has compared surface electromyography frequency domain parameters and surface electromyography time domain variables, which have been used as a classic analysis of patellofemoral pain., Methods: Thirty one women with patellofemoral pain and twenty eight pain-free women were recruited. Each participant was asked to descend a seven step staircase and data from five successful trials were collected. During the task, the vastus medialis and vastus lateralis muscle activities were monitored by surface electromyography. The data were processed and analyzed in four variables of the frequency domain (median frequency, low, medium and high frequency bands) and three time domain variables (Automatic, Cross-correlation and Visual Onset between the vastus medialis and vastus lateralis muscles). Reliability, Receiver Operating Characteristic curves and regression models were performed., Findings: The medium frequency band was the most reliable variable and different between the groups for both muscles, also demonstrated the best values of sensitivity and sensibility, 72% and 69% for the vastus medialis and 68% and 62% for the vastus lateralis, respectively. The frequency variables predicted the pain of individuals with patellofemoral pain, 26% for the vastus medialis and 20% for the vastus lateralis, being better than the time variables, which achieved only 7%., Interpretation: The frequency domain parameters presented greater reliability, diagnostic accuracy and capacity to predict pain than the time domain variables during stair descent and might be a useful tool to diagnose individuals with patellofemoral pain., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Excessive rearfoot eversion is thought to be a risk factor for patellofemoral pain development, due to the kinesiological relationship with ascendant adaptations. Individuals with patellofemoral pain are often diagnosed through static clinical tests, in scientific studies and clinical practice. However, the adaptations seem to appear in dynamic conditions. Performing static vs. dynamic evaluations of widely used measures would add to the knowledge in this area. Thus, the aim of this study was to determine the reliability and differentiation capability of three rearfoot eversion measures: rearfoot range of motion, static clinical test and static measurement using a three-dimensional system., Method: A total of 29 individuals with patellofemoral pain and 25 control individuals (18-30 years) participated in this study. Each subject underwent three-dimensional motion analysis during stair climbing and static clinical tests. Intraclass correlation coefficient and standard error measurements were performed to verify the reliability of the variables and receiver operating characteristic curves to show the diagnostic accuracy of each variable. In addition, analyses of variance were performed to identify differences between groups., Findings: Rearfoot range of motion demonstrated higher diagnostic accuracy (an area under the curve score of 0.72) than static measures and was able to differentiate the groups. Only the static clinical test presented poor and moderate reliability. Other variables presented high to very high values., Interpretation: Rearfoot range of motion was the variable that presented the best results in terms of reliability and differentiation capability. Static variables do not seem to be related to patellofemoral pain and have low accuracy values., (Copyright © 2014 Elsevier Ltd. All rights reserved.)