Knee and Hip Isometric Force Steadiness Are Impaired in Women With Patellofemoral Pain.

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.

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

BACKGROUND: Increased external knee abduction moment has been proposed as a risk factor for patellofemoral pain. This alteration is thought to be associated with elevated patellofemoral joint reaction force and stress, however these relationships remain poorly explored. Therefore, this study aimed at comparing knee abduction moment parameters (peak, rate of moment development and impulse), patellofemoral joint reaction force and stress of women with patellofemoral pain and pain-free controls during stair descent; and investigating the relationship among these variables with self-reported pain. METHODS: Kinetic data was obtained by inverse-dynamics equations and a previously reported algorithmic model was used to determine patellofemoral joint reaction force and stress. Participants' worst pain in the last month and pain level during stair descent were evaluated using a visual analogue scale. FINDINGS: Women with patellofemoral pain presented higher peak, rate of moment development and impulse of the external knee abduction moment, patellofemoral joint reaction force and stress (p = 0.005 to 0.04, effect size = 0.52 to 0.96) during stair descent than pain-free controls. Only knee abduction moment impulse presented positive moderate correlations with worst pain level in the last month (r = 0.53, p < 000.1), pain level during stair descent (r = 0.33, p = 0.042), patellofemoral joint reaction force (r = 0.65, p < 000.1) and stress (r = 0.58, p < 000.1). INTERPRETATION: These findings indicate that strategies aimed at decreasing external knee abduction moment impulse could reduce the load over the patellofemoral joint and improve pain of women with patellofemoral pain.

Knee crepitus is prevalent in women with patellofemoral pain, but is not related with function, physical activity and pain.

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.

Reliability and Validity of Frontal Plane Kinematics of the Trunk and Lower Extremity Measured With 2-Dimensional Cameras During Athletic Tasks: A Systematic Review With Meta-analysis.

BACKGROUND: Two-dimensional (2-D) analysis is commonly used to quantify frontal plane kinematics of the trunk and lower extremity. However, there are conflicting results regarding the reliability and validity of these measurements. OBJECTIVE: To synthesize the current literature to determine whether 2-D analysis is a reliable and valid method of measuring frontal plane kinematics of the trunk and lower extremity during squatting, landing, and cutting tasks. METHODS: For this systematic review with meta-analysis, MEDLINE, CINAHL, Embase, Scopus, and SPORTDiscus databases were searched from inception until March 2017. The authors included 16 studies that evaluated the reliability and/or validity of 2-D measurements of frontal plane trunk and/or lower extremity kinematics when compared to 3-D measurements during any of the following tasks: squatting, landing, or cutting. RESULTS: Intrarater reliability (intraday and interday) and interrater reliability of the 2-D video measurements varied from moderate to excellent. In terms of validity, there was poor agreement between the 2-D and 3-D methods, with no correlation between 2-D knee frontal plane projection angle and 3-D knee frontal plane angles (r = 0.127, P = .094) for the single-leg squat, but a moderate to good relationship (r = 0.619, P<.001) for the landing task. CONCLUSION: Two-dimensional video analysis of frontal plane trunk and lower extremity kinematics is reliable, but this appears to be dependent on the task and the type of reliability evaluated. The current evidence does not support the use of 2-D video analysis for measuring trunk and lower extremity frontal plane kinematics when accurate measures are required. LEVEL OF EVIDENCE: Diagnosis, level 3. J Orthop Sports Phys Ther 2018;48(10):812-822. Epub 12 Jun 2018. doi:10.2519/jospt.2018.8006.

Which is the best predictor of excessive hip internal rotation in women with patellofemoral pain: Rearfoot eversion or hip muscle strength? Exploring subgroups.

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 (R2 = 0.27, p = 0.001). Peak rearfoot eversion did not predict peak hip internal rotation during stair ascent (R2 < 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 (R2 = 0.26, p = 0.02; R2 = 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 (R2 = 0.53; p < 0.001); and peak rearfoot eversion did not (R2 = 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.

Higher pain level and lower functional capacity are associated with the number of altered kinematics in women with patellofemoral pain.

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.

Outpatient versus inpatient anterior cruciate ligament reconstruction: A systematic review with meta-analysis.

BACKGROUND: Efforts to reduce the financial costs related to anterior cruciate ligament reconstruction (ACLR) include reducing the length of hospitalization of the patient undergoing ACLR. However, it is unclear if inpatient and outpatient ACLR differ in terms of safety, satisfaction, costs and clinical outcomes. AIM: To systematically review and synthesize the literature that directly compared costs and outcomes after outpatient and inpatient ACLR. METHODS: Studies that directly compared outcomes of inpatient and outpatient ACLR were retrieved via searches in MEDLINE, EMBASE, CINAHL, AMED, Cochrane, SPORTDiscus, Web of Science and SCOPUS databases. Random effects meta-analysis and descriptive analysis were performed for relevant outcomes. RESULTS: Costs analysis suggests that outpatient ACLR may be a cost effective procedure with savings ranging from $1371 to $7390. There were no differences for systemic and local complications p=0.64 (odds ratio 1.65, 95% confidence interval 0.20 to 13.49) and p=0.72 (0.81, 0.26 to 2.56) respectively, or pain in the second and seventh days after surgery, p=0.78 (mean difference -0.16; 95% confidence interval -1.28 to 0.96) and p=0.44 (0.48, -0.75 to 1.71), respectively. However, the outpatient group had less pain than the inpatient group in the first and third days after surgery, p=0.0001 (-0.39, -0.57 to -0.21) and p=0.0001(-0.39, -0.39 to -0.20), respectively. Descriptive analysis revealed that the outpatient group experienced similar or better satisfaction, strength and knee function compared to the inpatient group. CONCLUSION AND KEY FINDINGS: Complications, pain, satisfaction, knee function and strength are similar or better after outpatient compared to inpatient ACLR. Furthermore, cost savings may be achieved with outpatient ACLR. However, included studies presented low methodological quality and the quality of evidence was very low, so these results need to be confirmed by future studies. REGISTRATION NUMBER: PROSPERO (CRD42015024990).

Vastus Medialis Hoffmann Reflex Excitability Is Associated With Pain Level, Self-Reported Function, and Chronicity in Women With Patellofemoral Pain.

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.

Lower Amplitude of the Hoffmann Reflex in Women With Patellofemoral Pain: Thinking Beyond Proximal, Local, and Distal Factors.

OBJECTIVES: To investigate whether vastus medialis (VM) Hoffmann reflexes (H-reflexes) differ on the basis of the presence or absence of patellofemoral pain (PFP) and to assess the capability of VM H-reflex measurements in accurately discriminating between women with and without PFP. DESIGN: Cross-sectional study. SETTING: Laboratory of biomechanics and motor control. PARTICIPANTS: Women (N=30) aged 18 to 35 years were recruited, consisting of 2 groups: women with PFP (n=15) and asymptomatic controls (n=15). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Maximum evoked responses were obtained by electrical stimulation applied to the femoral nerve, and peak-to-peak amplitudes of maximal Hoffmann reflex (Hmax) and maximal motor wave (Mmax) ratios were calculated. Independent samples t tests were performed to identify differences between groups, and a receiver operating characteristic curve was constructed to assess the discriminatory capability of VM H-reflex measurements. RESULTS: VM Hmax/Mmax ratios were significantly lower in participants with PFP than in pain-free participants (P=.007). In addition, the VM Hmax/Mmax ratios presented large and balanced discriminatory capability values (sensitivity, 73%; specificity, 67%). CONCLUSIONS: This study is the first to show that VM H-reflexes are lower in women with PFP than in asymptomatic controls. Therefore, increasing the excitation of the spinal cord in PFP participants may be essential to maintaining the gains acquired during the rehabilitation programs.

Delayed onset of electromyographic activity of the vastus medialis relative to the vastus lateralis may be related to physical activity levels in females with patellofemoral pain.

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.

Q-angle static or dynamic measurements, which is the best choice for patellofemoral pain?

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.

Ângulo Q e pronação subtalar não são bons preditores de dor e função em indivíduos com síndrome da dor femoropatelar / Ángulo Q y pronación subtalar no son buenos predictores del dolor y función en individuos con síndrome de dolor femoropatelar / Q angle and subtalar pronation are not good predictors of pain and function in individuals with patellofemoral pain syndrome

RESUMO Este estudo teve como objetivo avaliar a capacidade dos testes clínicos de mensuração do ângulo Q e pronação subtalar em predizer a dor e as limitações funcionais referidas por indivíduos com Síndrome da Dor Femoropatelar (SDFP). Trinta e um indivíduos com SDFP foram recrutados para este estudo. O questionário Anterior Knee Pain Scale foi utilizado para identificar as limitações funcionais, e a Escala Visual Analógica de dor para a dor vivenciada por esses indivíduos referente ao último mês. Foram realizados dois testes clínicos estáticos, mensuração do ângulo Q e mensuração da postura da pronação subtalar. Os valores dos testes foram inseridos em modelos de regressão linear e múltipla para a obtenção do R2 e dos coeficientes de regressão para medidas não contínuas padronizadas com o nível de significância estabelecido em α=0,05. Ambos os testes, quando inseridos isoladamente em modelos de regressão lineares, obtiveram resultados baixos de predição de dor e função. Por outro lado, quando inseridos conjuntamente em modelos de regressão múltipla, os testes explicaram 9% e 4% da dor e das limitações funcionais de indivíduos com SDFP, respectivamente. Embora tenha sido observada melhora da predição da dor e limitação funcional quando os testes foram avaliados em conjunto, os achados deste estudo mostram que ambas as medidas - ângulo Q e pronação subtalar - não são bons preditores de dor e limitações funcionais de indivíduos com SDFP.a prática do método Pilates, houve melhora na atividade física de lazer, mobilidade toracoabdominal, força muscular respiratória e redução da circunferência da cintura. No entanto, em comparação com o Grupo Controle, o método Pilates não promoveu alterações relevantes na função pulmonar, mobilidade toracoabdominal, força muscular respiratória e características antropométricas de mulheres saudáveis que não realizaram programa de exercício físico.

RESUMEN El objetivo de este estudio fue evaluar la capacidad de de las pruebas clínicas de medición del ángulo Q y pronación subtalar en predecir el dolor y las limitaciones funcionales mencionados por individuos con Síndrome de Dolor Femoropatelar (SDFP). Treinta y un individuos con SDFP fueron reclutados para este estudio. El cuestionario Anterior Knee Pain Scale fue utilizado para identificar las limitaciones funcionales; mientras la Escala Visual Analógica del dolor para identificar el dolor experimentado por los individuos en el último mes. Se realizaron dos ensayos clínicos estadísticos, medición del ángulo Q y medición de la postura de la pronación subtalar. Los valores de las pruebas fueron insertados en modelos de regresión linear y múltiple para obtener el R2 y los coeficientes de regresión para medidas no continuas estandarizadas con el nivel de significancia establecido en α=0,05. Ambas pruebas cuando insertadas aisladamente en modelos de regresión lineares obtuvieron resultados bajos de predicción de dolor y función. Por otro lado, cuando insertados en modelos de regresión múltiple, los ensayos explicaron el 9% y 4% del dolor y de las limitaciones funcionales de individuos con SDFP, respectivamente. Aunque hubo mejora de la predicción del dolor y de la limitación funcional cuando las pruebas se evaluaron juntas, los resultados de este estudio muestran que ambas las medidas, el ángulo Q y la pronación subtalar, no son buenos predictores del dolor y de las limitaciones funcionales de individuos con SDFP.

ABSTRACT This study aimed to evaluate the clinical trials' ability in Q angle measurement and subtalar pronation to predict the pain and functional limitations alluded by individuals with Patellofemoral Pain Syndrome (PFPS). Thirty-one individuals with PFPS were recruited for this study. The Anterior Knee Pain Scale questionnaire was used to identify the functional limitations and the Visual Analogue Scale of pain was used to identify the pain experienced by these individuals in the last month. Two clinical trials were performed, measurement of Q angle and posture measurement of the subtalar pronation. The values of the tests were inserted into linear and multiple regression models to obtain the R2and the coefficients of regression for non-continuous measures standardized with the significance level established at α = 0.05. Both tests when placed separately in linear regression models obtained low results for predicting pain and function. On the other hand, when inserted together in multiple regression models the tests explained 9% and 4% of the pain and of the functional limitations of individuals with PFPS, respectively. Although the prediction of pain and functional limitations has improved when the tests were evaluated together, our findings show that both measures, Q angle and subtalar pronation, are not good predictors of pain and functional limitations of individuals with PFPS.

Vertical Ground Reaction Forces are Associated with Pain and Self-Reported Functional Status in Recreational Athletes with Patellofemoral Pain.

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.

Reduced knee flexion is a possible cause of increased loading rates in individuals with patellofemoral pain.

BACKGROUND: Stair ascent is an activity that exacerbates symptoms of individuals with patellofemoral pain. The discomfort associated with this activity usually results in gait modification such as reduced knee flexion in an attempt to reduce pain. Although such compensatory strategy is a logical approach to decrease pain, it also reduces the normal active shock absorption increasing loading rates and may lead to deleterious and degenerative changes of the knee joint. Thus, the aims of this study were (i) to investigate whether there is reduced knee flexion in adults with PFP compared to healthy controls; and (ii) to analyze loading rates in these subjects, during stair climbing. METHOD: Twenty-nine individuals with patellofemoral pain and twenty-five control individuals (18-30 years) participated in this study. Each subject underwent three-dimensional kinematic and kinetic analyses during stair climbing on two separate days. Between-groups analyses of variance were performed to identify differences in peak knee flexion and loading rates. Intraclass correlation coefficient was performed to verify the reliability of the variables. FINDINGS: On both days, the patellofemoral pain group demonstrated significantly reduced peak knee flexion and increased loading rates. In addition, the two variables obtained high to very high reliability. INTERPRETATION: Reduced knee flexion during stair climbing as a strategy to avoid anterior knee pain does not seem to be healthy for lower limb mechanical distributions. Repeated loading at higher loading rates may be damaging to lower limb joints.

Ângulo Q e pronação subtalar não são bons preditores de dor e função em indivíduos com síndrome da dor femoropatelar / No son buenos indicadores de dolor y de limitaciones funcionales el ángulo Q y la pronación subastragalina en los sujetos con síndrome de dolor patelofemoral / Q angle and subtalar pronation are not good predictors for pain and function in subjects with patellofemoral pain syndrome

Este estudo teve como objetivo avaliar a capacidade dos testes clínicos de mensuração do ângulo Q e pronação subtalar em predizer a dor e as limitações funcionais referidas por indivíduos com Síndrome da Dor Femoropatelar (SDFP). 31 indivíduos com SDFP foram recrutados para este estudo. O questionário Anterior Knee Pain Scale foi utilizado para identificar as limitações funcionais, e a Escala Visual Analógica de dor foi utilizada para identificar a dor vivenciada por esses indivíduos referente ao último mês. Foram realizados dois testes clínicos estáticos, mensuração do ângulo Q e mensuração da postura da pronação subtalar. Os valores dos testes foram inseridos em modelos de regressão linear e múltipla para a obtenção do R2 e dos coeficientes de regressão para medidas não contínuas padronizadas com o nível de significância estabelecido em α=0,05. Ambos os testes quando inseridos isoladamente em modelos de regressão lineares obtiveram resultados baixos de predição de dor e função. Por outro lado, quando inseridos conjuntamente em modelos de regressão múltipla, os testes explicaram 9% e 4% da dor e das limitações funcionais de indivíduos com SDFP, respectivamente. Embora houve melhora da predição da dor e limitação funcional quando os testes foram avaliados em conjunto, as descobertas deste estudo mostram que ambas as medidas, ângulo Q e pronação subtalar, não são bons preditores de dor e limitações funcionais de indivíduos com SDFP.

En este estudio se buscó evaluar la capacidad de las pruebas clínicas de mediciones del ángulo Q y de la pronación subastragalina como indicadores del dolor y de las limitaciones funcionales en los sujetos con Síndrome de Dolor Patelofemoral (SDFP). A los 31 participantes con SDFP del estudio se les aplicaron el cuestionario Anterior Knee Pain Scale para identificar las limitaciones funcionales y la Escala Visual Analógica para medir el dolor sentido por ellos en el último mes. Se realizó dos pruebas clínicas estáticas, la medición del ángulo Q y la de postura de pronación subastragalina. Los valores de las pruebas se insertaron en los modelos de regresión lineal y múltiple para la obtención del R2 y de los coeficientes de regresión de las medidas no constantes con el nivel estándar de significancia de un α=0,05. Ambas pruebas fueron insertadas separadamente en los modelos de regresión lineales y resultaron en índices bajos de dolor y función. En cambio, cuando insertadas juntas a los modelos de regresión múltiple, mostraron un 9% y un 4% de los dolores y de las limitaciones de los sujetos con SDFP, respectivamente. Aunque haya demostrado esta mejora, los resultados de este estudio llaman la atención para las dos medidas, la del ángulo Q y la de la pronación subastragalina, que no son buenos indicadores del dolor y de las limitaciones funcionales en los sujetos con SDFP.

The aim of this study was to evaluate the capability of Q angle and subtalar pronation clinical tests in predict pain and functional limitations reported by individuals with patellofemoral pain syndrome (PFPS). 31 individuals with PFPS were recruited for this study. The Anterior Knee Pain Scale questionnaire was applied to identify the functional limitations and the Visual Analogue Scale was used to identify the pain referred during the last month. Two clinical tests were performed in order to obtain the Q angle and subtalar pronation measurements. The values ​​of the tests were entered in a multiple and linear regression models to obtain the R2 and the regression coefficients for non-continuous standardized measures, with a statistical significance set at α=0.05. Both tests, when entered separately into the linear regression models achieved low values of pain and function prediction. On the other hand, when placed together in a multiple regression model, the tests explained 9% and 4% of the pain and functional limitations of the individuals with PFPS, respectively. Although there was an improvement in the pain and function limitation prediction when the tests were analyzed together, our findings showed that both measurement, Q angle and subtalar pronation, are not good predictors of pain and functional limitations of individuals with PFPS.

Reliability of electromyography parameters during stair deambulation in patellofemoral pain syndrome / Reprodutibilidade de parâmetros eletromiográficos durante a subida e descida de escada na síndrome da dor femoropatelar / Reproducibilidad de los parámetros electromiográficos durante ascenso y descenso de escaleras en la síndrome de dolor patelofemoral

Reliability is essential to all aspects of the measure, as it shows the quality of the information and allows rational conclusions with regard to the data. There has been controversial results regarding the reliability of electromyographic parameters assessed during stair ascent and descent in individuals with patellofemoral pain syndrome (PFPS). Therefore, this study aims to determine the reliability of time and frequency domain electromyographic parameters on both gestures in women with PFPS. Thirty-one women with PFPS were selected to participate in this study. Data from vastus lateralis and medialis were collected during stair deambulation. The selected parameters were: automatic onset, median frequency bands of low, medium and high frequency. Reliability was determined by intraclass correlation coefficient and the standard error of measurement. The frequency domain variables have shown good reliability, with the stair ascent presenting the best rates. On the other hand, onset has proved to be inconsistent in all measures. Our findings suggest that stair ascent is more reliable than stair descent to evaluate subjects with PFPS in the most cases.

A reprodutibilidade é essencial para todos os aspectos da medida, uma vez que mostra a qualidade da informação e permite conclusões racionais no que diz respeito aos dados. Além disso, os resultados são controversos sobre parâmetros eletromiográficos avaliados durante a subida e descida de escada em indivíduos com síndrome da dor femoropatelar (SDFP). Portanto pretende-se determinar a reprodutibilidade de parâmetros eletromiográficos nos domínios do tempo e da frequência em ambos os gestos em mulheres com SDFP. Foram selecionadas 31 mulheres com SDFP. Os dados dos músculos vasto lateral e vasto medial foram coletados durante a subida e a descida de escada. Os parâmetros selecionados foram: o onset automático, frequência mediana, bandas de baixa, média e alta frequência. Determinou-se a reprodutibilidade através do coeficiente de correlação intraclasse e do erro padrão da medida. As variáveis no domínio da frequência apresentaram boa reprodutibilidade, com a subida apresentando os melhores índices, e o onset mostrou-se inconsistente. Os resultados sugerem que a subida de escada é mais confiável do que a descida da escada para avaliar indivíduos com SDPF na maioria dos casos.

La reproducibilidad es esencial para todos los aspectos de la medida, ya que muestra la calidad de la información y permite conclusiones racionales con respecto a los datos. Además, los resultados son controvertidos en parámetros electromiográficos evaluados durante el ascenso y descenso escaleras en las personas con síndrome de dolor patelofemoral (SDPF). Por eso tenemos la intención de determinar la reproducibilidad de los parámetros electromiográficos en el tiempo y la frecuencia en ambos gestos en mujeres con SDPF. 31 mujeres com SDPF fueron seleccionadas. Se recogieron datos del vasto lateral y medial durante ascenso y descenso de escaleras. Los parámetros seleccionados fueron: inicio automático, frecuencia mediana, bandas de baja, media y alta frecuencia. La reproducibilidad se determinó mediante el coeficiente de correlación intraclase y el error estándar de medición. Las variables en el dominio de la frecuencia mostraron buena reproducibilidad, el ascenso presentó lós mejores índices, y el inicio demostró ser inconsistente. Estos resultados sugieren que el ascenso de la escalera es más confiable que el descenso para evaluar individuos con SDPF en la mayoría de los casos.

Reliability and differentiation capability of dynamic and static kinematic measurements of rearfoot eversion in patellofemoral pain.

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.

Comparison of frequency and time domain electromyography parameters in women with patellofemoral pain.

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.

Diagnostic accuracy of the electromyography parameters associated with anterior knee pain in the diagnosis of patellofemoral pain syndrome.

OBJECTIVE: To assess the diagnostic accuracy of the surface electromyography (sEMG) parameters associated with referred anterior knee pain in diagnosing patellofemoral pain syndrome (PFPS). DESIGN: Sensitivity and specificity analysis. SETTING: Physical rehabilitation center and laboratory of biomechanics and motor control. PARTICIPANTS: Pain-free subjects (n=29) and participants with PFPS (n=22) selected by convenience. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: The diagnostic accuracy was calculated for sEMG parameters' reliability, precision, and ability to differentiate participants with and without PFPS. The selected sEMG parameter associated with anterior knee pain was considered as an index test and was compared with the reference standard for the diagnosis of PFPS. Intraclass correlation coefficient, SEM, independent t tests, sensitivity, specificity, negative and positive likelihood ratios, and negative and positive predictive values were used for the statistical analysis. RESULTS: The medium-frequency band (B2) parameter was reliable (intraclass correlation coefficient=.80-.90), precise (SEM=2.71-3.87 normalized unit), and able to differentiate participants with and without PFPS (P<.05). The association of B2 with anterior knee pain showed positive diagnostic accuracy values (specificity, .87; sensitivity, .70; negative likelihood ratio, .33; positive likelihood ratio, 5.63; negative predictive value, .72; and positive predictive value, .86). CONCLUSIONS: The results provide evidence to support the use of EMG signals (B2-frequency band of 45-96 Hz) of the vastus lateralis and vastus medialis muscles with referred anterior knee pain in the diagnosis of PFPS.

Exploratory study of electromyographic behavior of the vastus medialis and vastus lateralis at neuromuscular fatigue onset / Estudo exploratório do comportamento eletromiográfico do músculo vasto medial e vasto lateral no início da fadiga neuromuscular / Estudio exploratorio de la conducta electromiográfica del vasto medial y vasto lateral en la aparición de fatiga neuromuscular

This study aimed to determine and analyze the neuromuscular fatigue onset by median frequency (MDF) and the root mean square (RMS) behavior of an electromyographic signal (EMG). Eighteen healthy men with no prior knee problems initially performed three maximum voluntary isometric contractions (MVIC). After two days of MVIC test, participants performed a fatiguing protocol in which they performed submaximal knee-extension contractions at 20% and 70% MVIC held to exhaustion. The MDF and RMS values from the EMG signals were recorded from the vastus medialis (VM) and the vastus lateralis (VL). Analysis of the MDF and RMS behavior enabled identification of neuromuscular fatigue onset for VM and VL muscles in 20% and 70% loads. Alterations between the VM and VL in the neuromuscular fatigue onset, at 20% and 70% MVIC, were not significant. These findings suggest that the methodology proposal was capable of indicating minute differences sensible to alterations in the EMG signals, allowing identification of the moment when the MDF and the RMS showed significant changes in behavior. The methodology used was also a viable one for describing and identifying the neuromuscular fatigue onset by means of the analysis of EMG signals...

Este estudo teve como objetivo determinar e analisar o início da fadiga neuromuscular pelo comportamento do sinal de eletromiográfico (EMG) da frequência mediana (FM) e do root mean square (RMS). Dezoito homens saudáveis, sem problemas no joelho, realizaram inicialmente três contrações isométricas voluntárias máximas (CVMs). Após dois dias de CVM os sujeitos realizaram um protocolo de fadiga em que realizaram contrações submáximas de extensão do joelho em 20% e 70% da CVM até a exaustão. Os valores dos sinais de FM e RMS foram registrados a partir do vasto medial (VM) e vasto lateral (VL). A análise do comportamento da FM e RMS permitiu a identificação do início da fadiga neuromuscular para os músculos VM e VL em 20% e 70% da carga máxima. Alterações entre o VM e VL no início da fadiga neuromuscular, com 20% e 70% do MVIC, não foram significativas. Estes resultados sugerem que a metodologia proposta foi capaz de indicar diferenças mínimas sensíveis a alterações nos sinais EMG, permitindo a identificação do momento em que a FM e o RMS apresentaram mudanças significativas no seu comportamento. A metodologia utilizada também foi viável para descrever e identificar o aparecimento da fadiga neuromuscular por meio de análise de sinais de EMG...

Este estudio tieve como objetivo determinar y analizar la aparición de fatiga neuromuscular por la frecuencia media (FM) y la media de la raíz cuadrada (RMS) de lo señal electromiográfico (EMG). Dieciocho hombres saludables que no tienen problemas de rodilla previas inicialmente realizaron tres contracciones máximas voluntarias (CVM). Después de dos días de CVM los sujetos realizaron un protocolo de fatiga en la que se presentaron submáximas de extensión de rodilla en 20% y el 70% CVM hasta el agotamiento. Los valores de FM y RMS de las señales EMG se registraron desde el vasto medial (VM) y el vasto lateral (VL). Análisis del comportamiento de FM y RMS activado identificación de inicio fatiga neuromuscular para VM y músculos VL y 20% y el 70 % de la carga maxima. Las alteraciones entre el VM y VL en el inicio de la fatiga neuromuscular, en el 20% y el 70% de la CVM, no fueron significativas. Estos hallazgos sugieren que la propuesta de metodología fue capaz de indicar las diferencias minutos sensibles a las alteraciones en las señales de EMG, que permitan identificar el momento en que el FM y el RMS mostraron cambios significativos en el comportamiento. La metodología utilizada fue también una opción viable para la descripción y la identificación de la aparición de fatiga neuromuscular por medio del análisis de las señales de EMG...