Quadriceps femoris muscle activity in patellofemoral pain syndrome

Abstract

To elucidate and attempt to dissociate the two mechanisms, neuromuscular and mechanical, underlying patellofemoral pain syndrome, 18 subjects, divided into two groups based on a diagnosis of patellofemoral pain syndrome and the knee Q angle, were studied. The control group was asymptomatic and exhibited a normal Q angle (mean, 8.25 degrees), whereas the other group, diagnosed as patellofemoral pain syndrome patients, reported knee pain and had an above-normal Q angle (mean, 21.05 degrees). All subjects were tested for isometric maximum knee extension at 90 degrees, 30 degrees, and 15 degrees of knee flexion while they were seated in a special restraining chair. During testing, surface electromyography at the oblique and long fibers of the vastus medialis, and at the vastus lateralis were recorded along with the knee moment of force. The integrated electromyographic signals associated with the peak torque for all of the vastus muscles, along with the vastus medialis obliquus:vastus lateralis and vastus medialis longus:vastus lateralis activity ratios showed no significant differences between groups nor between the three angles, suggesting that all vasti measured were consistently active throughout the studied range of motion. This suggests that the neural drive was not affected in the patellofemoral pain syndrome patients. However, when the five patients showing the largest Q angles were isolated, they revealed a significantly smaller vastus medialis obliquus:vastus lateralis ratio when compared to the other group. The same ratio was also significantly smaller at 15 degrees compared to 90 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Avaliação eletromiográfica e ressonância magnética do joelho de indivíduos com síndrome da dor femoropatelar

“…These results corroborate those of Mariani and Caruso 22 and Boucher et al 23 who investigated the VMO and VLL in the last 30° of knee extension. Both found a decrease in the VMO activity of the PFPS group in relation to the VLL, noting imbalance between the medial and lateral components.…”

Análise funcional dos estabilizadores patelares

“…Embora a diferença não tenha sido significante, Boucher et al (3) , também encontraram maior atividade do VLL a 15º do que a 90º. Da mesma forma, Escamilla et al (6) também relataram maior atividade do múscu-lo VLL nos últimos graus de extensão.…”

“…The muscles VMO and VLL electromyographic activity have been studied in each opening kinetic chain and in different angles of knee flexion (3,4,6,15) . However, despite Weinstabl et al (23) suggest functional differences between the VLL and VLO muscles, the electrical pattern activity has not been studied yet.…”

“…A atividade eletromiográfica dos músculos VMO e VLL tem sido bastante estudada em cadeia cinética aberta e em diferentes ângulos de flexão do joelho (3,4,6,15) . No entanto, apesar de Weinstabl et al (23) sugerirem diferenças funcionais entre os músculos VLL e VLO, o padrão de atividade elétrica destes músculos ainda não foi estudado.…”

Ultrasonographic evaluation and comparison of articular cartilage of the femur condyles between the limbs in patients with an elevated Q angle

“…The authors of other studies concerning the value of the Q angle in the knee joint most often delineate data for a single person [31,32] or a group of people [33][34][35][36]. Measurement is sometimes limited only to the right limb [37,38] or the limb affected by symptoms [39].…”