Functional tests and isokinetic knee assessment in street runner athletes correlation / Correlación entre pruebas funcionales y evaluación isokinética de rodilla en practicantes de carrera de calle / Correlação entre testes funcionais e avaliação isocinética do joelho em atletas corredores de rua

ABSTRACT Introduction: The assessment of biomechanical changes related to the lower limbs is necessary in clinical practice to measure the potential risks of injury and the influences on existing dysfunction. Biomechanical changes related to previous ankle injuries are known to influence the performance of the entire lower limb. Objective: The aim of this study was to correlate muscle strength tests, performance tests and ankle stability with the Single Hop Test (SHT). Methods: 82 amateur runners were evaluated with isokinetic tests of quadriceps and hamstring muscle strength, as well as Y Balance Test (YBT), Weight-bearing Lung Test (WBLT), and the SHT. Results: The results showed there was a significant correlation between the SHT and the YBT in subjects with hamstring/quadriceps ratio (I/Q ratio) <0.55, and the length of the unilateral SHT with the peak torque of ipsilateral knee extensors. Conclusion: The study was successful in correlating the functional tests in question with the results obtained in isokinetic dynamometry. Level of Evidence V; Cross-Sectional Study.

RESUMEN Introducción: La evaluación de los cambios biomecánicos relacionados con las extremidades inferiores es necesaria en la práctica clínica para medir los riesgos potenciales de lesión y las influencias sobre la disfunción existente. Se sabe que los cambios biomecánicos relacionados con lesiones previas de tobillo influyen en el rendimiento de toda la extremidad inferior. Objetivo: Correlacionar las pruebas de fuerza muscular, las pruebas de rendimiento y la estabilidad del tobillo con la prueba de salto simple (Single Hop Test, SHT). Métodos: Se evaluó a 82 corredores aficionados con pruebas isocinéticas de fuerza muscular de cuádriceps e isquiotibiales, además de pruebas como Y Balance Test (YBT), Weight-bearing Lung Test (WBLT) y la prueba SHT. Resultados: Los resultados mostraron que existía una correlación significativa entre el SHT y el YBT en sujetos con ratio isquiotibiales/cuádriceps (ratio I/Q) <0,55, y la longitud del SHT unilateral con el par máximo de los extensores de la rodilla ipsilateral. Conclusión: El estudio logró correlacionar las pruebas funcionales en cuestión con los resultados obtenidos en la dinamometría isocinética. Nivel de Evidencia V; Estudio Transversal.

RESUMO Introdução: A avaliação de alterações biomecânicas relacionadas aos membros inferiores é necessária na prática clínica para mensurar os riscos potenciais de alguma lesão e as influencias sobre uma disfunção existente. As alterações biomecânicas relacionadas a lesões prévias de tornozelo são conhecidas pela influência na performance de todo o membro inferior. Objetivo: Correlacionar testes de força muscular, testes de performance e estabilidade do tornozelo com o teste de salto simples (Single Hop Test - SHT). Métodos: Foram avaliados 82 corredores amadores com testes isocinéticos de força muscular de quadríceps e isquiotibiais, além de testes Y Balance Test (YBT), Weight-bearing Lung Test (WBLT), e o SHT. Resultados: Os resultados demonstraram haver correlação significativa entre o SHT e o YBT nos indivíduos com relação Isquiotibiais/Quadríceps (relação I/Q) <0,55, e o comprimento do SHT unilateral com o pico de torque de extensores de joelho ipsilateral. Conclusão: O estudo foi bem sucedido em correlacionar os testes funcionais em questão com os resultados obtidos na dinamometria isocinética. Nível de Evidência V; Estudo Transversal.

Identification of Ankle Injury Risk Factors in Professional Soccer Players Through a Preseason Functional Assessment.

BACKGROUND: Etiologically, the risk of an ankle injury depends on extrinsic and intrinsic factors, such as muscle strength asymmetry, decreased flexibility, and decreased proprioception, as well as patient age and history of injuries. PURPOSE/HYPOTHESIS: The purpose of this study was to identify risk factors present in the preseason assessment that may predispose professional soccer players to ankle injuries. We hypothesized that analysis of these parameters could relate the incidence of injuries to the deficits found during the preseason period, enabling the identification of risk factors to predict the occurrence of injuries. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 89 professional soccer athletes were evaluated in the preseason period; the evaluation included athlete history and anthropometric data collection, an isokinetic ankle evaluation, and functional tests: the Dorsiflexion Lunge Test and Y-Balance Test (YBT). The athletes were monitored during the competitive period, and the incidence of injuries was surveyed. The association of quantitative variables and injury outcomes was analyzed using the Student t test for independent samples, with P < .05. For the association of categorical variables and injury outcomes, the chi-square test was performed, with P < .05. RESULTS: A higher incidence of ankle injuries was associated with lower YBT scores in the dominant (P = .04) and nondominant (P = .01) limbs. A higher body mass index was also associated with a higher injury occurrence (P = .01). CONCLUSION: Functional tests, such as the YBT, are indicated tools for assessing the physical capacities and possible risks of ankle sprains, as they can evaluate the ankle functional capacity in a complex way, identifying athletes more prone to ankle injuries. Athletes' body mass index should also be taken into account to prevent such injuries.

Preseason intrinsic risk factors-associated odds estimate the exposure to proximal lower limb injury throughout the season among professional football players.

BACKGROUND/AIM: Football players frequently face the occurrence of non-contact musculoskeletal injuries. The purpose of the study was to verify whether the evaluation of combined risk factors could produce a score system to determine the probability of injury in football players during the Brazilian football season. METHODS: Sixty-two male professional soccer players recruited from the first and second division soccer teams, with ages between 18 and 36 years. Functional performance evaluations were carried out at the beginning of the preseason which included strength and jumping tests, history of injuries and characteristics of athletes. RESULTS AND CONCLUSIONS: The results were grouped and a score/monogram was constructed.

Is hip strengthening the best treatment option for females with patellofemoral pain? A randomized controlled trial of three different types of exercises.

OBJECTIVE: To evaluate the effect of three types of exercise intervention in patients with patellofemoral pain and to verify the contributions of each intervention to pain control, function, and lower extremity kinematics. METHODS: A randomized controlled, single-blinded trial was conducted. Forty women with patellofemoral pain were randomly allocated into four groups: hip exercises, quadriceps exercises, stretching exercises and a control group (no intervention). Pain (using a visual analog scale), function (using the Anterior Knee Pain Scale), hip and quadriceps strength (using a handheld isometric dynamometer) and measuring lower limb kinematics during step up and down activities were evaluated at baseline and 8 weeks post intervention. RESULTS: All treatment groups showed significant improvements on pain and Anterior Knee Pain Scale after intervention with no statistically significant differences between groups except when compared to the control group. Only hip and quadriceps groups demonstrated improvements in muscle strength and knee valgus angle during the step activities. CONCLUSION: Hip strengthening exercises were not more effective for pain relief and function compared to quadriceps or stretching exercises in females with patellofemoral pain. Only hip and quadriceps groups were able to decrease the incidence of dynamic valgus during step-down activity. This study was approved by Brazilian Clinical Trials Registry registration number: RBR-6tc7mj (http://www.ensaiosclinicos.gov.br/rg/RBR-6tc7mj/).

Cardiac and Musculoskeletal Responses to the Effects of Passive and Active Tilt Test in Healthy Subjects.

BACKGROUND: Maintenance of orthostatism requires the interaction of autonomic and muscle responses for an efficient postural control, to minimize body motion and facilitate venous return in a common type of syncope called neurocardiogenic syncope (NCS). Muscle activity in standing position may be registered by surface electromyography, and body sway confirmed by displacement of the center of pressure (COP) on a force platform. These peripheral variables reflect the role of muscles in the maintenance of orthostatism during the active tilt test, which, compared with muscle activity during the passive test (head-up tilt test), enables the analyses of electromyographic activity of these muscles that may anticipate the clinical effects of CNS during these tests. OBJECTIVE: to evaluate and compare the effects of a standardized protocol of active and passive tests for CNS diagnosis associated with the effects of Valsalva maneuver (VM). METHODS: twenty-thee clinically stable female volunteers were recruited to undergo both tests. EMG electrodes were placed on muscles involved in postural maintenance. During the active test, subjects stood on a force platform. In addition to electromyography and the platform, heart rate was recorded during all tests. Three VMs were performed during the tests. RESULTS: progressive peripheral changes were observed along both tests, more evidently during the active test. CONCLUSION: the active test detected changes in muscle and cardiovascular responses, which were exacerbated by the VM.

Cardiac and Musculoskeletal Responses to the Effects of Passive and Active Tilt Test in Healthy Subjects / Respostas Cardíacas e Musculoesqueléticas aos Efeitos do Tilt Test Passivo e Ativo em Indivíduos Saudáveis

Abstract Background: Maintenance of orthostatism requires the interaction of autonomic and muscle responses for an efficient postural control, to minimize body motion and facilitate venous return in a common type of syncope called neurocardiogenic syncope (NCS). Muscle activity in standing position may be registered by surface electromyography, and body sway confirmed by displacement of the center of pressure (COP) on a force platform. These peripheral variables reflect the role of muscles in the maintenance of orthostatism during the active tilt test, which, compared with muscle activity during the passive test (head-up tilt test), enables the analyses of electromyographic activity of these muscles that may anticipate the clinical effects of CNS during these tests. Objective: to evaluate and compare the effects of a standardized protocol of active and passive tests for CNS diagnosis associated with the effects of Valsalva maneuver (VM). Methods: twenty-thee clinically stable female volunteers were recruited to undergo both tests. EMG electrodes were placed on muscles involved in postural maintenance. During the active test, subjects stood on a force platform. In addition to electromyography and the platform, heart rate was recorded during all tests. Three VMs were performed during the tests. Results: progressive peripheral changes were observed along both tests, more evidently during the active test. Conclusion: the active test detected changes in muscle and cardiovascular responses, which were exacerbated by the VM.

Resumo Fundamento: A manutenção do ortostatismo requer interação das respostas autonômicas e musculares para um controle postural eficiente e minimizar oscilações do corpo e facilitar o retorno venoso frente a um tipo comum de síncope chamada neurocardiogênica (SNC). A atividade da musculatura na posição de pé pode ser documentada por meio da eletromiografia de superfície (EMG) e as oscilações do corpo confirmadas pelo deslocamento do centro de pressão (CP) sobre uma plataforma de força. Estas variáveis periféricas mostram o papel muscular na manutenção do ortostatismo durante o tilt test ativo bem como esta atividade muscular ser comparada durante o teste passivo, Head-Up Tilt test, na tentativa de verificar alterações na atividade eletromiográfica destes músculos que podem antecipar os efeitos clínicos da SNC durante estes testes. Objetivo: Avaliar e comparar os efeitos de um protocolo padronizado para testes ativo e passivo de detecção da SNC associado ao efeito da manobra de valsalva (MV). Métodos: 23 voluntárias mulheres clinicamente saudáveis foram recrutadas para realizar ambos os testes. Os eletrodos da EMG foram posicionados em músculos associados com a manutenção postural, além de durante o teste ativo os sujeitos realizarem a postura ortostática sobre uma plataforma de força. Foi registrado além da EMG e da plataforma, a frequência cardíaca durante todo o teste. Três MV foram realizadas durante os testes. Resultados: Alterações periféricas foram verificadas de maneira progressiva ao longo dos testes, sendo mais evidente durante o teste ativo. Conclusão: o teste ativo verificou mudanças mais evidentes nas respostas musculares e cardiovasculares, amplificadas pela MV.

Muscle strength analysis of hip and knee stabilizers in individuals with Patellofemoral Pain Syndrome / Análisis de la fuerza muscular de los estabilizadores del cuadril y de la rodilla en sujetos con Síndrome de Dolor Patelofemoral / Análise da força muscular dos estabilizadores do quadril e joelho em indivíduos com Síndrome da Dor Femoropatelar

The Patellofemoral Pain Syndrome is one of the most common disorders of the knee, characterized by pain in the frontal part of the knee, which is worsened by activities that increase compressive forces on the joint. Alterations in the muscle strength of the quadriceps and hip stabilizer muscles can change patellar biomechanics, increasing joint stress and exacerbating pain symptoms. The aim of the study was to compare the strength of the hip and knee stabilizing muscles of women without and with Patellofemoral Pain Syndrome. The study included 45 women, 20 volunteers without the syndrome and 25 with Patellofemoral Pain Syndrome. Using an isometric dynamometer, the strength of the knee flexors and extensors, hip abductors and adductors, hip external rotators, medial rotators, hip flexors and hip extensors was evaluated. Women with Patellofemoral Pain Syndrome had 22% less strength of the internal rotators and 23% less strength of the knee extensors compared to healthy ones. As for the other muscle groups assessed, no differences were found. Therefore, the present study emphasizes that the quadriceps muscles are still the most affected muscle in individuals with the Patellofemoral Pain Syndrome.

El Síndrome de Dolor Patelofemoral es uno de los trastornos más frecuentes de la rodilla, caracterizado por dolor anterior en la rodilla, que se agrava con actividades que aumentan las fuerzas compresivas en la articulación. Alteraciones en el estándar de fuerza muscular del cuádriceps o de la musculatura estabilizadora del cuadril podrían cambiar la biomecánica de la articulación patelofemoral y así aumentar el estrés articular y exacerbar los síntomas de dolor. El objetivo de eso estudio fue relacionar la fuerza de la musculatura del cuadril y de la rodilla en mujeres con y sin el síndrome. Eso estudio incluyó 45 voluntarias, 20 sin y 25 con el Síndrome de Dolor Patelofemoral. La fuerza isométrica de los músculos flexores y extensores de la rodilla, abductores, aductores, flexores, extensores, rotadores laterales y mediales del cuadril fue evaluada por una célula de carga ajustada. Mujeres con el Síndrome de Dolor Patelofemoral presentaron reducción del 22% de la fuerza de los rotadores mediales de cuadril y un 23% de los extensores de la rodilla, cuando comparadas con las sin el Síndrome de Dolor Patelofemoral. No fueron observadas diferencias en la fuerza isométrica entre los otros grupos musculares. Por lo tanto, los datos de eso trabajo resaltan que la musculatura quadricipital y los rotadores mediales del cuadril son los más comprometidos en sujetos con el Síndrome de Dolor Patelofemoral.

A Síndrome da Dor Femoropatelar é uma das desordens mais frequentes do joelho, caracterizada por dor anterior no joelho, que se agrava com atividades que aumentam as forças compressivas na articulação. Alterações no padrão de força muscular do quadríceps ou da musculatura estabilizadora do quadril poderiam alterar a biomecânica da articulação femoropatelar e, assim, aumentar o estresse articular e exacerbar sintomas de dor. O objetivo deste estudo foi comparar a força da musculatura de quadril e joelho em mulheres com e sem tal síndrome. Participaram deste estudo 45 voluntárias, sendo 20 sem e 25 com a Síndrome da Dor Femoropatelar. A força isométrica dos músculos flexores e extensores de joelho, abdutores, adutores, flexores, extensores, rotadores laterais e mediais do quadril foi avaliada por uma célula de carga adaptada. Mulheres com Síndrome da Dor Femoropatelar apresentaram redução de 22% da força dos rotadores mediais de quadril e 23% dos extensores de joelho, em comparação àquelas sem a Síndrome da Dor Femoropatelar. Não foram observadas diferenças na força isométrica entre os outros grupos musculares. Portanto, os dados deste trabalho reforçam que a musculatura quadricipital e os rotadores mediais do quadril são os mais comprometidos em indivíduos com Síndrome da Dor Femoropatelar.

Braking and propulsive impulses in individuals with patellofemoral pain syndrome when walking up and down stairs / Análise dos impulsos de frenagem e de propulsão em indivíduos com síndrome da dor femoropatelar durante subida e descida de degraus / Análisis de los impulsos de frenado y propulsión en la personas con síndrome de dolor patelofemoral durante la actividad de subir y bajar un escalón

Patellofemoral pain syndrome (PFPS) is a prevalent clinical condition and it affects gait behavior. Braking and propulsive impulses are important biomechanical parameters obtained from ground reaction forces (GRF), which combine the amount of force applied over a period of time. The aim of this study was to evaluate these impulses while walking up and down stairs in healthy controls and PFPS individuals. The results did not reveal significant differences in braking and propulsive impulses between groups during these activities. Thus, the painful condition on a simple functional activity was insufficient to change the motor strategy to walking up or down the stairs...

"Análise dos impulsos de frenagem e de propulsão em indivíduos com síndrome da dor femoropatelar durante subida e descida de degraus." A síndrome da dor femoropatelar (SDFP) é uma condição clínica prevalente e que afeta o comportamento da marcha. Impulsos de frenagem e propulsão são importantes parâmetros biomecânicos obtidos a partir da força de reação do solo que combinam a quantidade de força aplicada sobre um período de tempo. O objetivo deste estudo foi avaliar esses impulsos durante a subida e descida de degraus em indivíduos controle saudáveis e com SDFP. Os resultados não revelaram diferenças significativas nos impulsos de frenagem e propulsão entre os grupos durante essas atividades. Assim, a condição dolorosa em uma atividade funcional simples foi insuficiente para modificar a estratégia motora de descer ou subir degraus...

"Análisis de los impulsos de frenado y propulsión en la personas con síndrome de dolor patelofemoral durante la actividad de subir y bajar un escalón." El Síndrome de dolor patelofemoral (SDPF) es una condición médica prevalente que afecta al comportamiento de la marcha. Impulso de propulsión y de frenado son parámetros biomecánicos importantes obtenidos a partir de la fuerza de reacción del suelo que combinan la cantidad de fuerza aplicada durante un período de tiempo. El objetivo del estudio fue evaluar estos impulsos durante las actividades de subir y bajar un escalón en sujetos sanos y con SDP. Los resultados no mostraron diferencias significativas en los impulsos de frenado y propulsion entre los grupos durante las actividades. Por lo tanto, Por lo tanto, la condición dolorosa en una actividad funcional simple, no fue suficiente para cambiar la estratégia de subir y bajar un escalón...

The effect of a patellar bandage on the postural control of individuals with patellofemoral pain syndrome.

A patellar bandage is often used by individuals with patellofemoral pain syndrome (PPS) to reduce pain and the additional sensorial input improves proprioception of the knee joint. The aim of this work was to assess the effect of a patellar bandage on the postural control of individuals with and without PPS. [Subjects and Methods] An analysis was performed of variables of center of pressure (CoP) as recorded by a force plate. Information about the forces and moments in three directions was used to obtain the CoP. Thirty women participated in this study: 15 with PPS and 15 without PPS. All subjects performed 3 trials in a unipodal stance with and without a patellar bandage. The force plate data were used to calculate the following variables: CoP sway area, CoP displacement frequency, and CoP mean velocity for the anteroposterior (AP) and mediolateral (ML) directions. A the linear mixed effects model was used for statistical analysis. [Results] Postural sway was significantly reduced in individuals with PPS when a patellar bandage was applied. [Conclusion] Additional sensory input from a patellar bandage increase proprioceptive feedback and this could be related to the improvement in postural control of PPS subjects.

Contribuição da avaliação dos sinais clínicos em pacientes com síndrome da dor patelofemural / Contribution of the evaluation of the clinical signals in patients with patellofemoral pain syndrome

Objetivo: Como a síndrome da dor patelofemoral (SDPF) é uma desordem comum, caracterizada por etiologia multifatorial e o mais prevalente sintoma na SDPF é uma dor difusa e usualmente localizada na região retropatelar, entretanto, com sinais e sintomas que podem estar relacionados como pronação subtalar excessiva, torsão tibial externa, alterações no deslocamento patelar, amplitude de movimento do joelho dolorosa, dor nas bordas patelares, tensão muscular e alterações no ângulo quadricipital (ângulo Q). O objetivo deste trabalho foi verificar a frequência destes sinais e sintomas associados a um questionário de dor anterior no joelho. Métodos: Trinta e nove voluntárias sedentárias foram avaliadas, divididas em dois grupos, SDPF (19) e controle (20). Estas voluntárias foram avaliadas quanto aos sinais e sintomas supracitados além da avaliação da dor por meio de questionário. Resultados: os resultados demonstraram uma frequência elevada de relatos dolorosos em seis de treze questões, em relação ao grupo controle. Conclusão: De acordo com estes achados, concluímos que a avaliação funcional de indivíduos com SDFP deve ser constituída de um questionário de dor anterior no joelho e uma avaliação das características de sinais e sintomas para exame de todo o membro inferior estático e durante situações funcionais. Nível de Evidência II, Estudos Diagnósticos.

Objective: As patellofemoral pain syndrome (PFPS) is a common disorder characterized by multifactorial etiology and whose the most prevalent symptom is a diffuse pain, usually located on the retropatellar region, however, it also shows signs and symptoms that can be related as excessive subtalar pronation, external tibial torsion, patellar displacement alterations, painful range of motion of the knee, pain in the patellar borders, muscular tightness and changes in quadriceps angle (Q Angle), the objective of this work was to determine the frequency of these signs and symptoms associated to a previous knee pain questionnaire. Methods: thirty-nine sedentary female volunteers had been evaluated, divided in two groups, PFPS (19) and Control (20). These subjects were evaluated for signs and symptoms described above, in addition to pain assessment by questionnaire. Results: the results demonstrated a high frequency of pain in six of the thirteen questions in relation to the control group. Conclusion: according to these findings, we conclude that the functional evaluation of individuals with PFPS should consist of a previous knee pain questionnaire and an evaluation of the characteristic signs and symptoms for examination of the entire lower limb during static and functional situations. Level of Evidence II, Diagnostic Studies.

Contribution of the evaluation of the clinical signals in patients with patellofemoral pain syndrome.

OBJECTIVE: As patellofemoral pain syndrome (PFPS) is a common disorder characterized by multifactorial etiology and whose the most prevalent symptom is a diffuse pain, usually located on the retropatellar region, however, it also shows signs and symptoms that can be related as excessive subtalar pronation, external tibial torsion, patellar displacement alterations, painful range of motion of the knee, pain in the patellar borders, muscular tightness and changes in quadriceps angle (Q Angle), the objective of this work was to determine the frequency of these signs and symptoms associated to a previous knee pain questionnaire. METHODS: Thirty-nine sedentary female volunteers had been evaluated, divided in two groups, PFPS (19) and Control (20). These subjects were evaluated for signs and symptoms described above, in addition to pain assessment by questionnaire. RESULTS: The results demonstrated a high frequency of pain in six of the thirteen questions in relation to the control group. CONCLUSION: According to these findings, we conclude that the functional evaluation of individuals with PFPS should consist of a previous knee pain questionnaire and an evaluation of the characteristic signs and symptoms for examination of the entire lower limb during static and functional situations. Level of Evidence II, Diagnostic Studies.

Correlation between trochlear groove depth and patellar position during open and closed kinetic chain exercises in subjects with anterior knee pain.

The purpose of this study was to correlate the trochlear shape and patellar tilt angle and lateral patellar displacement at rest and maximal voluntary isometric contraction (MVIC) exercises during open (OKC) and closed kinetic chain (CKC) in subjects with and without anterior knee pain. Subjects were all women, 20 who were clinically healthy and 19 diagnosed with anterior knee pain. All subjects were evaluated and subjected to magnetic resonance exams during OKC and CKC exercise with the knee placed at 15, 30, and 45 degrees of flexion. The parameters evaluated were sulcus angle, patellar tilt angle and patellar displacement using bisect offset. Pearson's r coefficient was used, with p < .05. Our results revealed in knee pain group during CKC and OKC at 15 degrees that the increase in the sulcus angle is associated with a tilt increase and patellar lateral displacement. Comparing sulcus angle, patellar tilt angle and bisect offset values between MVIC in OKC and CKC in the knee pain group, it was observed that patellar tilt angle increased in OKC only with the knee flexed at 30 degrees. Based on our results, we conclude that reduced trochlear depth is correlated with increased lateral patellar tilt and displacement during OKC and CKC at 15 degrees of flexion in people with anterior knee pain. By contrast, 30 degrees of knee flexion in CKC is more recommended in rehabilitation protocols because the patella was more stable than in other positions.

Analysis of the center of pressure displacement, ground reaction force and muscular activity during step exercises.

Anterior Knee Pain (AKP) is considered as one of the most common, yet misunderstood, knee pathologies. The aim of this study was to evaluate the displacement area of the center of pressure, Ground Reaction Force (GRF), and the electromyography activity of the hip and the quadriceps muscles in healthy and AKP individuals during the step-up and step-down exercises. Both groups (Control group and AKP group) were composed of 15 volunteers submitted to the exercises on a force plate. The AKP group presented greater displacement area of the center of pressure for all the situations evaluated than the Control group (p<0.05), as well as a lesser magnitude of the GRF during the step-down exercise. The AKP group presented lower electromyography activity than the Control group in all situations evaluated. AKP individuals do not have muscle imbalances; they present a lower electromyography activity of the stabilizing muscles of the patella and hip and show greater instability in activities such as step up and down compared to normal subjects.

Analysis of patellar stabilizers muscles and patellar kinematics in anterior knee pain subjects.

Patella stabilizer muscle response and patellar kinematics were evaluated in 19 women with anterior knee pain (AKP) and 20 healthy women during maximum voluntary isometric contraction (MVIC) with the knee positioned at 15°, 30° and 45° flexion during open (OKC) and closed (CKC) kinetic chain exercises. Patellar kinematics was evaluated through patellar tilt and displacement, and the electrical activity of patellar stabilizers through the root mean square normalized during MVIC and OKC with the knee at 90° flexion. Data revealed that the vastus medialis oblique muscle (VMO) was more active in the control group compared to the AKP group during OKC exercises with the knee at 45° flexion. However, no difference in the patellar kinematics was observed between these groups; nevertheless, the correlation between these parameters also showed, with the knee at 45° flexion, that lateral patellar tilt increase was associated with a reduction in the activity of lateral patellar stabilizers in the control group and with an increase in the VMO activity in the AKP group. In conclusion, electrical activity is an important factor in evaluating AKP and in AKP treatment evolution.

Evaluating patellar kinematics through magnetic resonance imaging during open- and closed-kinetic-chain exercises.

PURPOSE: To evaluate patellar kinematics of volunteers without knee pain at rest and during isometric contraction in open-and closed-kinetic-chain exercises. METHODS: Twenty individuals took part in this study. All were submitted to magnetic resonance imaging (MRI) during rest and voluntary isometric contraction (VIC) in the open and closed kinetic chain at 15 degrees, 30 degrees, and 45 degrees of knee flexion. Through MRI and using medical e-film software, the following measurements were evaluated: sulcus angle, patellar-tilt angle, and bisect offset. The mixed-effects linear model was used for comparison between knee positions, between rest and isometric contractions, and between the exercises. RESULTS: Data analysis revealed that the sulcus angle decreased as knee flexion increased and revealed increases with isometric contractions in both the open and closed kinetic chain for all knee-flexion angles. The patellar-tilt angle decreased with isometric contractions in both the open and closed kinetic chain for every knee position. However, in the closed kinetic chain, patellar tilt increased significantly with the knee flexed at 15 degrees. The bisect offset increased with the knee flexed at 15 degrees during isometric contractions and decreased as knee flexion increased during both exercises. CONCLUSION: VIC in the last degrees of knee extension may compromise patellar dynamics. On the other hand, it is possible to favor patellar stability by performing muscle contractions with the knee flexed at 30 degrees and 45 degrees in either the open or closed kinetic chain.