Contribuição dos segmentos proximais e distais da cadeia cinética para a rotação da patela no plano frontal

Abstract

Altered positioning of the patella in the frontal plane (patellar rotation) may influence negatively the manner how the tensile forces generated by the quadriceps are transmitted to the patellar tendon. Individuals with thismisalignment may have both the medial and the lateral tendon portions of the patellar tendon lengthened unevenly. This mechanism may overload certain areas of the tendon and lead to the development of pathological processes. Imposition of altered forces on the patellas soft tissues, generated from a muscular imbalance and / or a change in the stiffness of passive structures of the musculoskeletal system, may result in patellar rotation due to uneven tensions offered by the patellar retinaculum. Interactions between active and passive components of proximal and distal segments of patellofemoral joint define the behavior of the retinaculum. The identification of the factors involved in the production of patellar rotation may help us to design strategies forprevention and rehabilitation procedures to minimize the changes in patellar alignment and its repercussions. Patellar rotations in the frontal plane, which can be determined through measurements of McConnell and Arnos angles, are usually neglected in the evaluation of athletes and have been poorly investigated in the literature. Therefore, the aim of this study was to analyze the predictive factors of patellar rotation in the frontal plane. A total of 168 individuals were evaluated at Laboratório de Prevenção e Reabilitação de Lesões Esportivas and Minas Tenis Clube. The evaluation consisted of the following tests organized in stations: isometric hip abductor torque, passive range of motion (ROM) of hip internal rotation (IR), shank-forefoot alignment (SFA) and patellar alignment in the frontal plane (McConnells and Arnos angles). In order to capture the interactions between selected predictors, CART(Classification and Regression Tree) was used, since it is a robust method of analysis that captures possible non-linear relationship among predictors and produces results that are easy applied by means of clinical decision rules. The classification tree selected the ROM of hip IR and SFA in McConnells model and isometric hip abductor torque in Arnos model as predictors of patellar rotation. CART selected the three predictor variables analyzed in this study. SFA and ROM interacted in a non-linear way and defined more clearly the occurrence of lateral patellar rotation. The hip abductors torque, when increased, lead to medial rotation. The cut-off values established for the variables can be used as clinical parameters to design interventions to reduce the rotation of the patella. The results demonstrate that there is a nonlinear interaction between the proximal and distal segments of the kinetic chain inaltering the position of the patella in the frontal plane. In addition, these data indicate that the angles of McConnell and Arno provide complementary information, since different predictors were selected in the analyses.