PURPOSE: To track the regeneration process of lateral gastrocnemius due to a muscle laceration in rats, and to treatment with plateletrich plasma (PRP). METHODS: Ultrasound (40 MHz) images were used for measuring pennation angle (PA), muscle thickness (MT) and mean pixel intensity, along with claudication scores, of treated (PRPG) and non-treated (NTG) groups of rats. RESULTS: NTG showed a PA increase for the non-injured leg (p<0.05) and a tendency of MT to increase, whereas for PRPG there were no differences. There was a progressive reduction of the claudication score for the PRPG group throughout the entire period, with an immediate difference after seven days (p<0.05), whereas the NTG had a significant reduction only at day 28 (p<0.05). CONCLUSION: It was observed a compensatory hypertrophic response due to the overload condition imposed to healthy leg for NTG that did not occur in PRPG, suggesting an accelerated repair process of the injured leg due to treatment, anticipating its use.

Há, atualmente, na literatura, poucas pesquisas de confiabilidade e validação da quantificação de parâmetros de arquitetura muscular por ultrassonografia (US), relatando informações importantes como o erro típico da medida (ETM) e o coeficiente de correlação intraclasse (ICC). O objetivo do estudo foi aplicar a técnica de US para quantificar as medidas de comprimento da fibra (CF) e ângulo de penação (AP) dos músculos gastrocnêmios e determinar a confiabilidade e a reprodutibilidade dessas medidas. Duas imagens de cada gastrocnêmio de 19 indivíduos jovens e saudáveis foram adquiridas com um equipamento de ultrassom modo-B (7,5MHz), em duas visitas. CF e AP foram medidos cinco vezes nas duas imagens de cada indivíduo, totalizando vinte medidas de cada parâmetro para cada participante. A confiabilidade do total das 760 medidas foi determinada através do coeficiente de variação (CV), ICC e ETM. O CV do CF variou de 1,67 a 4,44% e do AP de 3,8 a 11,62%. Todos os ICC se encontram no intervalo de grande confiabilidade, com exceção do valor referente à medida interdias do AP do gastrocnêmio medial (0,67). Os dois valores mais altos de ETM (3,1º e 3,7º) correspondem aos dois valores inferiores do ICC (0,67 e 0,83), referentes às medidas repetidas interdias dos gastrocnêmios. As medidas de CF dos gastrocnêmios medial e lateral apresentaram ETM de 2,17mm e 2,25mm, respectivamente. Os resultados obtidos demonstraram que a metodologia utilizada para medição de CF e AP realizada em imagens de ultrassom apresentou alta confiabilidade.

There are few studies in the literature concerning the reliability and validity of the quantification of muscle architecture parameters using ultrasound that also report important information such as typical error of measurement (TEM) and intraclass correlation coefficient (ICC). The aim of this study was to use ultrasound imaging to quantify fiber length (FL) and pennation angle (PA) of the gastrocnemius muscle and to determine the reliability and reproducibility of these measurements. Two images of each gastrocnemius of 19 young healthy subjects were acquired using ultrasound equipment (7.5 MHz), in two visits. FL and PA were measured five times on each image, for a total of twenty measurements of each parameter. The overall reliability of the 760 measurements was determined through coefficients of variation (CV), ICC and TEM. The CV of FL ranged from 1.67 to 4.44% and from 3.8 to 11.62% for the PA. All ICC were within the high reliability range, with the exception of the between-visits PA value of the medial gastrocnemius (0.67). The two highest TEM values (3.1º and 3.7º) correspond to the two lowest ICC values (0.67 and 0.83), referring to repeated between-visit measurements of the medial and lateral gastrocnemius. FL measurements of the medial and lateral gastrocnemius had a TEM of 2.17 and 2.25 respectively. The results showed that ultrasound-based measurement of FL and PA exhibits high reliability.