No abstract

Objective: The aim of this study was to elucidate the activities of the hip flexor muscles during straight leg raising (SLR) in healthy subjects. We also investigated the activities of these muscles during SLR with deep flexion, abduction, and external rotation. Methods: The ten dominant right legs of ten male volunteers were analyzed in this study. Twelve SLR motion tasks were performed; these comprised combinations of hip flexion at 30°, 45°, and 60°; abduction at 0° and 20°; and external rotation at 0° and 30°. The activities of the psoas major (PM) and iliacus (IL) were measured using fine-wire electrodes, whereas the activities of the rectus femoris, sartorius, adductor longus, and tensor fasciae latae muscles were measured using surface electrodes. The percentage of the maximal voluntary isometric muscle contraction (%MVC) during SLR was calculated for each muscle and used for data analyses. The Friedman test and the Wilcoxon signed-rank test were performed for statistical analyses. The significance level was set at P <0.05. Results: The %MVCs for the PM and IL at 60° flexion were significantly larger than those at 30° or 45° flexion. Moreover, for a constant hip flexion, the %MVC values for the PM and IL showed no significant changes when hip abduction and external rotation were added. For the other muscles, the %MVC values showed no significant change with increasing hip flexion with or without added abduction and external rotation. Conclusion: Our findings suggest that subjects who perform SLR of up to 60° mainly activate the PM and IL at larger hip flexion angles, whereas the other muscles included in the analysis do not contribute greatly to increased flexion angles during SLR.

Purpose: To investigate morphological changes in the infrapatellar fat pad (IPFP) during active knee extension using ultrasonography. Methods: IPFP deformity from 30∘ knee flexion to full extension was recorded using ultrasonography. IPFP thickness and patellar tendon-tibial angle were evaluated on 26 healthy knees in the first session and nine knees in the second session. Intra-rater and inter-rate reliability were evaluated using coefficient of variation (CV) and intraclass correlation coefficient (ICC) of types (1, 3) and (2, 3), respectively. Absolute reliability was assessed using the standard error of measurement (SEM). Changes in the patellar tendon-tibial angle and IPFP thickness were analyzed using paired [Formula: see text]-test. Results: At each knee angle, ICC (1, 3) was [Formula: see text] for the patellar tendon-tibial angle and IPFP thickness (CV [Formula: see text]). Compared to 30∘ knee flexion, the patellar tendon-tibial angle increased significantly from 33.3∘ to 38.9∘ ([Formula: see text]). The IPFP thickness significantly increased from 4.4[Formula: see text]mm to 5.3[Formula: see text]mm with active knee extension ([Formula: see text]), without overlap of the 95% CI of SEM. For inter-rater reliability, ICC (2, 3) was [Formula: see text] for each variable (CV [Formula: see text]). Conclusions: Increased IPFP thickness during active knee extension indicates IPFP deformity in the anterior interval. Ultrasonography may help evaluate morphological changes and estimate IPFP scarring.