The purpose of this study was to examine the independent effects of anterior knee pain (AKP) on bilateral ground reaction force (GRF) during running, with a focus on GRF applied to the uninvolved leg, which, prior to this study, had never been evaluated. Twelve volunteers completed three data collection sessions, that corresponded to one of three conditions (control, sham, and pain), in a counterbalanced order. For each session, subjects ran for five minutes. For the pain and sham sessions, respectively, hypertonic and isotonic saline were infused into the infrapatellar fat pad of the right leg during the running, while no infusion was involved in the control session. GRF data were collected during the final 30 seconds of running. Functional statistics were used to determine the effects of session and leg (right and left) on vertical and anterior-posterior GRF throughout the stance phase of running. A mixed model ANOVA was used to determine the effect of session and leg on vertical GRF load rate, impulse due to vertical, propulsive, and braking GRFs. A repeated measures ANOVA was used to determine the effect of session and time on subject-perceived pain. Alpha was set to 0.05 for all statistical comparisons. Unexpectedly, no significant session × leg interaction existed for vertical GRF at any time point during stance phase of running. Similarly, the experimental AKP did not affect impulse due to vertical GRF or load rate for the vertical GRF. There was, however, a significant session × leg interaction for anterior-posterior GRF. For the pain session, involved-leg braking GRF was 11% greater than uninvolved-leg braking GRF, during the first 9% of stance phase. There was also a significant between-session difference for involved-leg braking impulse (p = 0.023) and uninvolved-leg propulsive impulse (p = 0.027). The mean involved-leg braking impulses were 11.3 Ns (± 0.6), 13.2 Ns (± 0.6) and 13.2 Ns (± 0.6) for the pain, control, and sham sessions, respectively. Mean uninvolved-leg propulsive impulses were 14.8 Ns (± 1.3), 13.6 Ns (± 1.3), and 13.5 Ns (± 1.3) for the pain, control, and sham sessions, respectively. These differences in anterior-posterior GRF might reflect a compensatory unloading of the involved leg due to AKP.

Submitted by MARCELLA FERRAZ PAZZINATTO null (ferraz_mar@hotmail.com) on 2016-05-13T17:13:57Z No. of bitstreams: 1 Dissertacao_final.pdf: 1372783 bytes, checksum: 82c520a2d6f64d7158d4001c043c712b (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-05-16T16:48:45Z (GMT) No. of bitstreams: 1 pazzinatto_mf_me_prud.pdf: 1372783 bytes, checksum: 82c520a2d6f64d7158d4001c043c712b (MD5) / Made available in DSpace on 2016-05-16T16:48:45Z (GMT). No. of bitstreams: 1 pazzinatto_mf_me_prud.pdf: 1372783 bytes, checksum: 82c520a2d6f64d7158d4001c043c712b (MD5) Previous issue date: 2016-04-29 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A dor femoropatelar (DFP) é considerada um “enigma ortopédico”, e uma das desordens musculoesqueléticas mais desafiadoras para se gerenciar. Isso porque até o presente momento não se tem definição acerca da(s) causa(s) que podem levar a esta desordem. Há mais de duas décadas têm-se investigado a presença de alterações biomecânicas em indivíduos com DFP durante as mais diversas atividades, como corrida, subida e descida de escada, agachamento e salto. Os parâmetros eletromiográficos (EMG) relacionados ao tempo e amplitude de ativação dos músculos vasto lateral (VL) e vasto medial (VM) são frequentemente abordados em estudos com essa população, no entanto, os resultados são controversos e acredita-se que uma das possíveis causas para essa inconsistência seja a característica intermitente dos sintomas. Ou seja, em determinados momentos a dor está presente e em outros não, independente da atividade que esteja sendo desenvolvida. Sabe-se que a dor recorrente pode levar a alterações no mecanismo central de controle da dor gerando respostas exageradas frente a estímulos dolorosos (hiperalgesia). Acredita-se que mulheres com DFP apresentam hiperalgesia tanto local quanto generalizada, no entanto, não se sabe o quanto a presença da dor no momento da avaliação pode alterar esses mecanismos de hiperalgesia. Diante disso, os objetivos gerais desta dissertação foram analisar o quanto a presença da dor afeta a hiperalgesia e os parâmetros EMG em mulheres com DFP, além de determinar pontos de corte para identificar a presença de hiperalgesia em mulheres com DFP. Os parâmetros EMG foram avaliados durante o gesto de subida de escada, e assim como os limiares pressóricos de dor (LPD) e a escala visual analógica (EVA) de dor, foram coletados em dois momentos antes e após um protocolo de esforço da articulação femoropatelar. Este protocolo foi realizado com o intuito de exacerbar os sintomas específicos da DFP e consistiu em 15 subidas de escada com 35% do peso corporal alocado em uma mochila e com ritmo demarcado por um metrônomo (96 degraus/min). Observou-se que mulheres com DFP apresentam LPDs reduzidos em comparação com mulheres assintomáticas e após o protocolo de esforço os LPDs avaliados ao redor do joelho, no grupo com DFP, reduziram significativamente comparado a avaliação prévia, no entanto, não houve diferença no LPD do ponto distante. Os pontos de corte encontrados apresentaram bons valores de acurácia diagnóstica, podendo ser úteis para a prática clínica na discriminação de indivíduos com e sem hiperalgesia. Já quanto aos parâmetros EMG avaliados em mulheres com DFP antes e após o protocolo de esforço, não houve diferença entre o início da ativação dos músculos VM e VL na presença da dor, mas houve aumento na amplitude do sinal EMG do VL e, consequentemente, redução na razão de ativação VM/VL após o protocolo de esforço. De acordo com estes resultados observa-se que a presença da dor é capaz de alterar os mecanismos centrais de modulação da dor, aumentando a hiperalgesia no local da desordem. A confirmação da presença de hiperalgesia local e generalizada em mulheres com DFP é de fundamental importância para traçar estratégias de tratamento, e a definição de pontos de corte capazes de discriminar os indivíduos quanto a presença de hiperalgesia facilita o gerenciamento desta desordem. E curiosamente os tratamentos visando o equilíbrio na ativação dos músculos VM e VL parecem não ser a melhor opção já que esse quesito não sofreu alteração diante do principal sintoma da DFP. / As there is no definition about etiological factors of patellofemoral pain (PFP), it is considered an “orthopaedic enigma” and one of musculoskeletal disorders most challenging to manage. More than two decades, researchers have investigated the presence of biomechanics alteration in individuals with PFP during different activities as run, stair deambulation, squatting and jump. The electromyographic (EMG) parameters related to timing and amplitude of activation of vastus lateralis (VL) and vastus medialis (VM) muscles are often addressed in studies with PFP. However, the results are controversial and a plausible explanation may be the intermitent characteristic of the symptoms. In other words, at certain times the pain is present and not in others, regardless of the activity that is being developed. It is knowing that recurrent pain may result in dysfunctional analgesic control generating exaggerated responses to painful stimuli (hyperalgesia). Women with FPF present local and widespread hyperalgesia, however, it is unknown how the presence of pain at the moment of evaluation may alter the hyperalgesia. Thus, the overall aims were to analyze how the presence of pain affects hyperalgesia and EMG parameters in women with PFP, moreover, to determine cutoff points to identify the presence of hyperalgesia in women with PFP. EMG parameters were evaluated during stair climbing. EMG parameters, pressure pain thresholds (PPTs) and visual analogue scale of pain (VAS) were collected in two conditions: before and after a patellofemoral joint loading protocol. This protocol aimed to arouse the specific symptoms of PFP and it was composed to 15 stair deambulation with 35% of body mass allocated in a backpack and the rhythm was demarcated by a metronome (96 steps/min). The women presented lower PPTs compared to pain free group. After the protocol, the PPTs around the knee decreased, whereas the PPT at a remote site to the knee not changed in women with PFP. The PPT cutoff points presented good capability to discriminate women with and without PFP. There was no difference in VL and VM onset of activation in presence of pain, however, the VL amplitude increased and VM/VL activation ratio decreased after the patellofemoral joint loading protocol. According to these results, the presence of pain changed the central mechanisms of pain modulation, increasing hyperalgesia at the site of the disorder. The cutoff points can guide clinicians towards identifying the presence of local and widespread hyperalgesia in women with PFP. Thus, clinicians may be able to identify which patients would benefit from non-mechanical interventions focusing on components aimed at pain neuroscience education. Interestingly, the treatments aiming to reduce the imbalance between VM and VL muscles do not seem to be the best option insofar as this parameter did not change in the presence of the main symptom of PFP. / FAPESP: 2014/10839-0

“Excessive” and/or “delayed” subtalar joint (STJ) pronation has been linked to overuse injuries because of its influence on tibial internal rotation (TIR). The transfer of STJ pronation to TIR occurs via the talocrual joint, believed to have limited transverse plane motion. However, studies have shown the talocrural joint to have more transverse plane motion than once believed, therefore it is feasible that the STJ will only influence the motion of the tibia once this motion has been exhausted. Currently, studies evaluating this relationship have focused on peak joint angles and excursion without reference to the amount of motion available at the ankle joint complex (AJC). Therefore the purpose of these studies were to evaluate whether runners with anterior knee pain (AKP) utilize a greater percentage of their available eversion motion (eversion buffer), evaluate the effects of small eversion buffers on coordination, and evaluate the influence of orthotics on those with AKP and with the smallest eversion buffers. This study found healthy and injured runners, for the most part, presented with no significant differences in traditional pronation related variables. The one exception was peak pronation velocity, where injured runners demonstrated faster velocities. On the other hand injured runners had significantly smaller eversion buffers which lead them to change their coordinative pattern earlier during stance. This difference in pattern also caused the intra-individual coupling variability to peak earlier during stance. Orthotics successfully controlled the kinematics of the AJC and increased the eversion buffer of injured runners and in those displaying the smallest buffers. While orthotics successfully influenced the kinematics of the AJC, they did not influence those of the tibia and knee. These changes at the AJC did not have a strong impact on the coordinative patterns of the lower extremity, however demonstrated a trend toward being able to influence the intra-individual coupling variability. In summary, injured runners demonstrated smaller eversion buffers and changed their coordinative pattern earlier during stance. While orthotics successfully increased the eversion buffer, they did not strongly influence coordination variables. Future studies analyzing pronation related variables in injured populations should evaluate them relative to the available motion at the AJC.

Study Design: Cross-sectional. Background: Although decreased hip abduction and lateral rotation strength has been found in females with patellofemoral pain syndrome (PFPS), few studies have included males. Aim: To determine if hip abduction and lateral rotation strength is decreased in males with PFPS. Methods: Eight males participated. Isometric hip abduction and external rotation strength was measured with a hand-held dynamometer. Four subjects had unilateral patellofemoral pain (mean age = 26.5 ± 7.5 years) and 4 asymptomatic subjects were controls (mean age = 23 ± 6.4 years). The recorded measurements from the symptomatic legs were compared with the asymptomatic legs, and also with the controls. Results: No significant differences in hip abduction or lateral rotation strength were found between the symptomatic and asymptomatic legs of male subjects with PFPS. The PFPS subjects did not have generally weaker hip strength compared with the asymptomatic controls. Conclusion: Males with PFPS do not appear to have decreased hip abduction and lateral rotation strength. However, the sample size was too small for conclusions to be drawn. This study can be used as a preliminary step in gathering evidence about factors affecting PFPS in males, which may in turn shed light on appropriate clinical treatments.

No description available.

Context: Knee pain is experienced by many people. Because of this, authors have started researching the effects of pain on lower extremity mechanics and also on static and dynamic postural control. However, the effects of pain are difficult to study due to associated confounding variables. Objective: We asked: (1) Will experimentally-induced anterior knee pain alter perceived pain using the visual analogue scale? ; (2) will perceived pain affect postural control as measured by center-of-pressure during static and dynamic movement? Design: Crossover. Setting: Biomechanics laboratory. Participants: Fifteen healthy subjects. Intervention: Each subject participated in single leg quiet stance, landing, and walking trials under three conditions (pain, sham, control), at three different times for each condition (pre-injection, injection, and post-injection). Main Outcome Measures: The dependent variables were measured at pre-injection, injection, and post-injection. Pain was measured using the visual analogue scale across all three times during each condition. Center-of-pressure sway was measured during single leg quiet stance to calculate the average center-of-pressure velocity in the anterior-posterior and medial-lateral directions. The center-of-pressure time to stabilization was measured in anterior-posterior, medial-lateral, and vertical directions, and center-of-pressure trajectory excursion was measured in the medial-lateral direction during walking. Results: Perceived pain was significant (P < 0.05) but did not affect postural control as measured by center-of-pressure medial-lateral and anterior-posterior sway during single leg quiet stance, in time to stabilization during landing, and in medial-lateral excursion during walking. Conclusions: Injection of hypertonic saline resulted in statistically significant perceived pain but did not affect postural control as measured by center-of-pressure medial-lateral and anterior-posterior sway during single leg quiet stance, in time to stabilization during landing, and medial-lateral excursion during walking.

Background Patients with patellofemoral pain (PFS) are common in primary health care. Young women are most affected, limiting them in everyday life and in sports. There is an increased risk of PFS in case of impaired strength and motor control in proximal musculature. Consensus prevails that therapeutic physical training should be included as part of rehabilitation, where the multimodal method is the golden standard. Purpose The aim is to evaluate the efficacy of tailored physiotherapy intervention involving motor control and strength training of proximal musculature combined with education with respect to pain, strength and function in patients with patellofemoral pain. Method A single subject experimental design study (SSED) consisting of three young women with PFS was conducted. The design is an A-B design, which includes a baseline phase with repeated measurements (A) and an intervention phase with tailored physiotherapy (B). The primary outcome measures were estimated with a visual analog scale (VAS) as well as strength measurement of proximal musculature with a handheld dynamometer (HHD). The secondary outcome measure was self-perceived function, estimated with Patient Specific Functional Scale (PSFS). Results The results of this SSED show that tailored physiotherapy intervention involving motor control and strength training of proximal musculature combined with education can be effective for young women with PFS. The results are not entirely consistent in terms of pain, strenght and self-perceived function where one in three participants showed significant (alpha 0.05) reduced pain and two out of three participants showed significant (alpha 0.05) improvement of self-perceived function. Regarding strength, there was no significant (alpha 0.05) effect on the affected side of any of the participants:  Conclusion Motor control and strength training of proximal musculature combined with education may be effective for young women with PFS with respect to pain and self-perceived function.

A Síndrome da Dor Anterior no Joelho (SDAJ) caracteriza-se por uma dor difusa retropatelar e peripatelar na articulação do joelho, exacerbada por atividades de sobrecarga sobre a articulação femoropatelar. Muitos estudos têm sido realizados no sentido de compreender os mecanismos causadores da SDAJ e suas consequências. Entre os aspectos pesquisados encontram-se a ativação muscular, relação de ativação e de capacidade de geração de força entre os músculos vasto medial e vasto lateral, a força quadriciptal e dos músculos do quadril, e as alterações mecânicas do membro inferior. Segundo a literatura, um dos principais fatores de risco para o desenvolvimento dessa patologia é a fraqueza dos extensores do joelho. A fraqueza dos extensores do joelho pode estar associada à inibição muscular (IM) que o músculo quadríceps femoral sofre em função dos estímulos dolorosos. Esta alteração na geração de força e na capacidade de ativação muscular parecem alterar a morfologia do quadríceps e influenciar as alterações mecânicas ao nível da articulação femoropatelar. Para o melhor do nosso conhecimento, não foi encontrado na literatura nenhum estudo sistemático que investigasse simultaneamente os diversos aspectos da SDAJ, tentando assim estabelecer uma relação entre os aspectos morfológicos, mecânicos e elétricos dos extensores do joelho com a SDAJ. O presente estudo tem por objetivo comparar as propriedades mecânicas, morfológicas e mioelétricas dos extensores do joelho entre sujeitos acometidos pela SDAJ e um grupo controle saudável (GC). Nossa hipótese era de que os pacientes com SDAJ apresentarão uma redução nas propriedades mecânicas, morfológicas e mioelétricas dos extensores do joelho em decorrência da inibição muscular (IM) crônica produzida pela síndrome. Além disso, o estudo também tem por objetivo avaliar se existe diferença na metodologia de aplicação da técnica de interpolação de abalo para avaliação da IM do quadríceps a partir da comparação do uso de estímulos elétricos supramáximos sobre o nervo femoral (padrão ouro) com a estimulação sobre o ponto motor (nova metodologia) em sujeitos saudáveis e indivíduos com SDAJ. Nossa hipótese era de que a estimulação sobre o ponto motor será menos desconfortável que sobre o nervo femoral e os resultados de IM serão menos variáveis (com uma menor dispersão) em função desse menor desconforto. No Capítulo I, foi realizado um levantamento da literatura sobre as variáveis que foram avaliadas no decorrer do estudo, buscando informar ao leitor o que já foi feito na área, as lacunas e contradições acerca da SDAJ. No Capítulo II, foi realizado um estudo transversal sobre a avaliação da IM do quadríceps femoral, a partir da Técnica de Interpolação de Abalo (ITT), com a aplicação do abalo sobre o nervo femoral (NF) e sobre o ponto motor (PM). Vinte e nove sujeitos do sexo feminino, com idade entre 20 e 40 anos, sintomáticas (SDAJ, n=16) e assintomáticas (GC, n=13) para SDAJ, foram submetidas a avaliação da IM sobre o PM e NF no ângulo de 60° de flexão do joelho (0°=extensão máxima). Os resultados demonstraram que, para o grupo SDAJ, o PM apresenta resultados inferiores de IM comparado ao NF; já para o GC, os resultados foram semelhantes entre os dois pontos de estimulação. No Capítulo III foram realizadas avaliações da capacidade funcional, da IM e das propriedades mecânicas, morfológicas e mioelétricas dos extensores do joelho. Trinta e duas mulheres, com idade entre 20 e 40 anos, sintomáticas (SDAJ, n=16) e assintomáticas (GC, n=16) para SDAJ, foram avaliadas. Os resultados apontam para uma maior IM e reduções na capacidade funcional, no torque isométrico, na espessura da cartilagem femoropatelar e na arquitetura muscular do grupo SDAJ em relação ao GC. A revisão de literatura realizada no Capítulo I demonstrou que a literatura apresenta divergências sobre as alterações neuromecânicas decorrentes da SDAJ em mulheres. Os resultados do Capítulo II indicam que a avaliação da IM por meio da ITT é melhor tolerada por mulheres jovens sintomáticas para SDAJ quando avaliada no NF em comparação ao PM. Já no Capítulo III foram observados maiores valores de IM e reduções na capacidade funcional, torque isométrico, espessura da cartilagem femoropatelar e arquitetura muscular nos sujeitos com SDAJ em comparação ao GC saudável. / The Anterior Knee Pain (AKP) syndrome is characterized by retropatellar and peripatellar diffuse pain in the knee joint, exacerbated by overloading activities on the patellofemoral joint. Many studies have been carried out to understand the causal mechanisms of AKP and its consequences. Among the researched aspects are muscle activation, relationship of activation and capacity of strength generation between the vastus medialis and the vastus lateralis muscles, the strength of quadriceps and hip muscles, and mechanical changes of the lower limb. According to the literature, one of the main risk factors for the development of this pathology is the knee extensors weakness. This knee extensors weakness might be associated with the muscle inhibition (MI) that the femoral quadriceps muscle suffers as a result of painful stimuli. These changes in strength generation and muscle activation capacity appear to change the quadriceps morphology and influence mechanical changes at the patellofemoral joint level. To the best of our knowledge, there is no systematic study in the literature that simultaneously investigated the various aspects of AKP, trying to establish a relationship between the morphological, mechanical and electrical aspects of the knee extensors in subjects with AKP. This study aimed to compare the knee extensors mechanical, morphological and myoelectric properties between subjects affected by AKP and a control group (CG). Our hypothesis was that patients with AKP should present a reduction in the knee extensors mechanical, morphological and myoelectric properties due to chronic muscle inhibition (MI) produced by the syndrome. In addition, the study also aimed to evaluate whether there are differences in methodology for application of the interpolated twitch technique for evaluation of the quadriceps MI by comparing the use of supramaximal electrical stimulation on the femoral nerve (gold standard) with stimulation on the motor point (new methodology) in healthy subjects and subjects affected by AKP. Our hypothesis was that the stimulation on the motor point should be less uncomfortable than on the femoral nerve and MI results should be less variable (with lower dispersion) due to such lower discomfort. In Chapter I, a literature review on the variables that were evaluated throughout the study was carried out, seeking to inform the reader on what has already been done in the area, on gaps and contradictions regarding AKP. Chapter II presents a transversal study on the assessment of the quadriceps MI with the use of the Interpolated Twitch Technique (ITT), with application of twitch on the femoral nerve (FN) and on the motor point (MP). Twenty-nine women, aged between 20 and 40 years, symptomatic (AKP, n=16) and asymptomatic (CG, n=13) for AKP, were subjected to evaluation of MI on the MP and FN at an angle of 60° of knee flexion (0°=fully extended). Results showed that, for the AKP group, MP has inferior results of MI when compared to FN; results are similar between the two stimulation points for the CG. In Chapter III, evaluations of functional capacity, MI and knee extensors mechanical, morphological and myoelectric properties were carried out. Thirty-two women, aged between 20 and 40 years, symptomatic (AKP, n =16) and asymptomatic (CG, n =16) for AKP were evaluated. Results indicated greater MI and reductions in functional capacity, in isometric torque, in patellofemoral cartilage thickness and in muscle architecture in the AKP group compared to CG. Results from literature review conducted in Chapter I showed disagreement about neuromechanics changes resulting from SDAJ in women. Chapter II results indicated that the evaluation of IM through ITT is better tolerated by young women symptomatic for SDAJ when evaluated in the NF compared to the PM. Chapter III showed higher MI values and reductions in functional capacity, isometric torque, patellofemoral cartilage thickness and muscle architecture in subjects with SDAJ compared to a healthy GC.

Anterior knee pain (AKP) is a common, chronic lower limb musculoskeletal overuse condition that represents substantial morbidity to those affected, and has a significant impact on the health care industry. Health practitioners frequently prescribe foot orthoses in the management of AKP as an alternative or adjunct to multimodal physiotherapy. The primary aim of this thesis was to investigate the clinical efficacy of foot orthoses in AKP, utilising high-quality research methodologies. The two systematic reviews conducted have identified a significant gap in the literature regarding evidence from randomised clinical trials (RCTs) for foot orthoses in AKP and other lower limb overuse conditions. While the best evidence for AKP management was for multimodal physiotherapy, there was insufficient evidence to support or refute the use of foot orthoses in the treatment of lower limb overuse conditions, including AKP. Meta-analysis provided evidence to support the use of foot orthoses in the prevention of the first incidence of lower limb overuse conditions. An interesting finding was evidence from pooled and individual study data of no difference between custom and prefabricated foot orthoses in both treatment and prevention of lower limb overuse conditions, inferring that either type of orthosis may be utilised. Both systematic reviews highlighted substantial methodological flaws of the included studies, and recommended that future studies include larger participant numbers, longer participant follow-up, more consistent use of reliable and valid outcome measures and reporting of outcome data, and utilisation of the CONSORT guidelines in the design and reporting of RCTs. A 12-month prospective RCT investigated the short- and long-term clinical efficacy of prefabricated foot orthoses in the treatment of 179 participants with AKP. Foot orthoses were more effective than flat shoe inserts in the short term, implying that their contoured form has some therapeutic effect. Foot orthoses were not significantly different to multimodal physiotherapy over 12 months, nor was there any benefit in adding foot orthoses to physiotherapy. Considering that all groups experienced clinically meaningful long-term improvements in pain and function, clinicians may prescribe foot orthoses for AKP to hasten recovery. Findings of post-hoc analyses to develop a clinical prediction rule indicate that those of older age and shorter height, who have a lower severity of AKP and a more mobile midfoot, are more than twice as likely to experience a successful outcome with foot orthoses. As a secondary aim, this thesis has provided a more comprehensive profile of AKP as a condition. Baseline data from the RCT participants confirms previous reports of higher rates of AKP in females, and a tendency towards bilaterality and chronicity. This AKP sample did not differ from asymptomatic individuals in terms of body mass index, physical activity level, general and mental health, and foot posture, although they tended to have a more mobile foot under load. These characteristics tend to be homogenous across a number of published RCTs, indicating that the findings of the RCT described above are likely to be generalisable to the broader population with AKP. An additional finding in this group was that those with AKP of long duration, higher pain levels, lower functional levels, and an overall lower score on a specific measure of AKP have a poorer prognosis over 12 months, irrespective of their age, gender or morphometry. These findings suggest that, in order to improve prognosis and the chance of a successful outcome, the primary goals of intervention should be to reduce the severity and duration of AKP, through the use of early intervention with foot orthoses, multimodal physiotherapy, or a combination of the two.

A Síndrome da Dor Anterior no Joelho (SDAJ) caracteriza-se por uma dor difusa retropatelar e peripatelar na articulação do joelho, exacerbada por atividades de sobrecarga sobre a articulação femoropatelar. Muitos estudos têm sido realizados no sentido de compreender os mecanismos causadores da SDAJ e suas consequências. Entre os aspectos pesquisados encontram-se a ativação muscular, relação de ativação e de capacidade de geração de força entre os músculos vasto medial e vasto lateral, a força quadriciptal e dos músculos do quadril, e as alterações mecânicas do membro inferior. Segundo a literatura, um dos principais fatores de risco para o desenvolvimento dessa patologia é a fraqueza dos extensores do joelho. A fraqueza dos extensores do joelho pode estar associada à inibição muscular (IM) que o músculo quadríceps femoral sofre em função dos estímulos dolorosos. Esta alteração na geração de força e na capacidade de ativação muscular parecem alterar a morfologia do quadríceps e influenciar as alterações mecânicas ao nível da articulação femoropatelar. Para o melhor do nosso conhecimento, não foi encontrado na literatura nenhum estudo sistemático que investigasse simultaneamente os diversos aspectos da SDAJ, tentando assim estabelecer uma relação entre os aspectos morfológicos, mecânicos e elétricos dos extensores do joelho com a SDAJ. O presente estudo tem por objetivo comparar as propriedades mecânicas, morfológicas e mioelétricas dos extensores do joelho entre sujeitos acometidos pela SDAJ e um grupo controle saudável (GC). Nossa hipótese era de que os pacientes com SDAJ apresentarão uma redução nas propriedades mecânicas, morfológicas e mioelétricas dos extensores do joelho em decorrência da inibição muscular (IM) crônica produzida pela síndrome. Além disso, o estudo também tem por objetivo avaliar se existe diferença na metodologia de aplicação da técnica de interpolação de abalo para avaliação da IM do quadríceps a partir da comparação do uso de estímulos elétricos supramáximos sobre o nervo femoral (padrão ouro) com a estimulação sobre o ponto motor (nova metodologia) em sujeitos saudáveis e indivíduos com SDAJ. Nossa hipótese era de que a estimulação sobre o ponto motor será menos desconfortável que sobre o nervo femoral e os resultados de IM serão menos variáveis (com uma menor dispersão) em função desse menor desconforto. No Capítulo I, foi realizado um levantamento da literatura sobre as variáveis que foram avaliadas no decorrer do estudo, buscando informar ao leitor o que já foi feito na área, as lacunas e contradições acerca da SDAJ. No Capítulo II, foi realizado um estudo transversal sobre a avaliação da IM do quadríceps femoral, a partir da Técnica de Interpolação de Abalo (ITT), com a aplicação do abalo sobre o nervo femoral (NF) e sobre o ponto motor (PM). Vinte e nove sujeitos do sexo feminino, com idade entre 20 e 40 anos, sintomáticas (SDAJ, n=16) e assintomáticas (GC, n=13) para SDAJ, foram submetidas a avaliação da IM sobre o PM e NF no ângulo de 60° de flexão do joelho (0°=extensão máxima). Os resultados demonstraram que, para o grupo SDAJ, o PM apresenta resultados inferiores de IM comparado ao NF; já para o GC, os resultados foram semelhantes entre os dois pontos de estimulação. No Capítulo III foram realizadas avaliações da capacidade funcional, da IM e das propriedades mecânicas, morfológicas e mioelétricas dos extensores do joelho. Trinta e duas mulheres, com idade entre 20 e 40 anos, sintomáticas (SDAJ, n=16) e assintomáticas (GC, n=16) para SDAJ, foram avaliadas. Os resultados apontam para uma maior IM e reduções na capacidade funcional, no torque isométrico, na espessura da cartilagem femoropatelar e na arquitetura muscular do grupo SDAJ em relação ao GC. A revisão de literatura realizada no Capítulo I demonstrou que a literatura apresenta divergências sobre as alterações neuromecânicas decorrentes da SDAJ em mulheres. Os resultados do Capítulo II indicam que a avaliação da IM por meio da ITT é melhor tolerada por mulheres jovens sintomáticas para SDAJ quando avaliada no NF em comparação ao PM. Já no Capítulo III foram observados maiores valores de IM e reduções na capacidade funcional, torque isométrico, espessura da cartilagem femoropatelar e arquitetura muscular nos sujeitos com SDAJ em comparação ao GC saudável. / The Anterior Knee Pain (AKP) syndrome is characterized by retropatellar and peripatellar diffuse pain in the knee joint, exacerbated by overloading activities on the patellofemoral joint. Many studies have been carried out to understand the causal mechanisms of AKP and its consequences. Among the researched aspects are muscle activation, relationship of activation and capacity of strength generation between the vastus medialis and the vastus lateralis muscles, the strength of quadriceps and hip muscles, and mechanical changes of the lower limb. According to the literature, one of the main risk factors for the development of this pathology is the knee extensors weakness. This knee extensors weakness might be associated with the muscle inhibition (MI) that the femoral quadriceps muscle suffers as a result of painful stimuli. These changes in strength generation and muscle activation capacity appear to change the quadriceps morphology and influence mechanical changes at the patellofemoral joint level. To the best of our knowledge, there is no systematic study in the literature that simultaneously investigated the various aspects of AKP, trying to establish a relationship between the morphological, mechanical and electrical aspects of the knee extensors in subjects with AKP. This study aimed to compare the knee extensors mechanical, morphological and myoelectric properties between subjects affected by AKP and a control group (CG). Our hypothesis was that patients with AKP should present a reduction in the knee extensors mechanical, morphological and myoelectric properties due to chronic muscle inhibition (MI) produced by the syndrome. In addition, the study also aimed to evaluate whether there are differences in methodology for application of the interpolated twitch technique for evaluation of the quadriceps MI by comparing the use of supramaximal electrical stimulation on the femoral nerve (gold standard) with stimulation on the motor point (new methodology) in healthy subjects and subjects affected by AKP. Our hypothesis was that the stimulation on the motor point should be less uncomfortable than on the femoral nerve and MI results should be less variable (with lower dispersion) due to such lower discomfort. In Chapter I, a literature review on the variables that were evaluated throughout the study was carried out, seeking to inform the reader on what has already been done in the area, on gaps and contradictions regarding AKP. Chapter II presents a transversal study on the assessment of the quadriceps MI with the use of the Interpolated Twitch Technique (ITT), with application of twitch on the femoral nerve (FN) and on the motor point (MP). Twenty-nine women, aged between 20 and 40 years, symptomatic (AKP, n=16) and asymptomatic (CG, n=13) for AKP, were subjected to evaluation of MI on the MP and FN at an angle of 60° of knee flexion (0°=fully extended). Results showed that, for the AKP group, MP has inferior results of MI when compared to FN; results are similar between the two stimulation points for the CG. In Chapter III, evaluations of functional capacity, MI and knee extensors mechanical, morphological and myoelectric properties were carried out. Thirty-two women, aged between 20 and 40 years, symptomatic (AKP, n =16) and asymptomatic (CG, n =16) for AKP were evaluated. Results indicated greater MI and reductions in functional capacity, in isometric torque, in patellofemoral cartilage thickness and in muscle architecture in the AKP group compared to CG. Results from literature review conducted in Chapter I showed disagreement about neuromechanics changes resulting from SDAJ in women. Chapter II results indicated that the evaluation of IM through ITT is better tolerated by young women symptomatic for SDAJ when evaluated in the NF compared to the PM. Chapter III showed higher MI values and reductions in functional capacity, isometric torque, patellofemoral cartilage thickness and muscle architecture in subjects with SDAJ compared to a healthy GC.