A study on the shape change of the rectus femoris muscle with knee flexion / 体力科学

Since the rectus femoris muscle is associated with trauma and disorders such as muscle strain, it is often a target for evaluation and treatment. However, in many studies, measurement results were obtained from only a part of the rectus femoris muscle and used as a representative value without considering the differences across the muscle. The rectus femoris muscle may change shape with knee flexion because the structure is complicated; it has an intramuscular tendon. The purpose of this study was to assess the changes in shape of the rectus femoris muscle during flexion of the knee joint in different directions. Twelve lower limbs of 12 male university students were analyzed. The rectus femoris muscle was divided into eight parts, and short-axis images were taken with an ultrasonic diagnostic imaging device at the knee joint; in extension; flexion at 30 °, 60 °, 90 °, and 120 °; muscle thickness; muscle width; and cross-sectional area. It was suggested that the thickness of the rectus femoris muscle increased from “A” to “F” due to knee flexion, and that this increase occurred because of stretching at the same site. In “G,” there was no difference between the angle conditions; conversely, in “H,” the muscle thickness decreased due to knee flexion. It should also be noted that D and E have the greatest muscle thickness when measuring in the knee flexion position.

Tibial Torsion and Knee Varus Angle: Are These Aetiologies of Hallux Valgus?

OBJECTIVE: The purpose of this study is to evaluate that knee deformity (varus or valgus) due to osteoarthritis of the knee and tibial torsion could be aetiologies of hallux valgus. METHODS: Forty-nine patients (43 females, six males; mean patient age, 69.88±6.12 years) before total knee arthroplasty for advanced primary osteoarthritis were recruited. All deformities were of the left knee. Preoperative torsional computed tomography, anteroposterior (AP) and lateral weight-bearing foot radiographs, AP and lateral weight-bearing knee radiographs, and long-leg standing AP views were obtained for each patient. The correlations between foot angle and knee varus angle or tibial torsion angle were examined. RESULTS: There was no significant correlation between knee varus angle and foot angle. Similarly, there was no significant relationship between tibial torsional angle and foot angle, except talocalcaneal angle (TCA)-lateral (r=0.28). No significant relationships were found between TCA-AP and (1–2 intermetatarsal angle [IMA] and hallux valgus angle [HVA]), or between TCA-lateral and (1–2 IMA and HVA). CONCLUSION: No significant correlations were found between the knee anatomical axis (knee varus angle) and foot angle or between the tibial torsional angle and foot angle. Tibial torsion and knee varus angle were not aetiologies for hallux valgus.

Development of Tibiofemoral Angle in Korean Children

This study was performed to identify the chronological changes of the knee angle or the tibiofemoral angles in normal healthy Korean children. Full-length anteroposterior view standing radiographs of 818 limbs of 452 Korean children were analyzed. The overall patterns of the chronological changes in the knee angle were similar to those described previously in western or Asian children, but the knee angle development was delayed, i.e., genu varum before 1 yr, neutral at 1.5 yr, increasing genu valgum with maximum a value of 7.8 degrees at 4 yr, followed by a gradual decrease to approximately 5-6 degrees of genu valgum of the adult level at 7 to 8 yr of age. These normative data on chronological changes of knee angles should be taken into consideration when evaluating lower limb alignment in children.

Emg-angle relationship during maximum voluntary movement / 体力科学

The purpose of this study is to investigate the relationship between joint angle and EMG activity concerning the human knee joint and hamstring muscles. Ten healthy males participated in this study. They performed maximum voluntary isokinetic knee flexion in the flexion angle range of 0° to 120° in a prone position on a table. The EMG activities of the semitendinosus, semimembranosus, long and short heads of the biceps femoris muscles were detected by bipolar fine wire electrode, and were integrated at knee flexion range intervals of 15° from 0° to 120°. After three months, the same examination was performed with the same subjects to confirm the reliability of this study. Results showed the mean peak isokinetic torque was attained from a 15° to 45° knee flexion angle. The EMG activities of the hamstring muscles varied with changes in the knee flexion angle. The integrated EMG of the semitendinosus, semimembranosus and short head of the biceps femoris muscles in-creased gradually as the knee flexion angle was increased from 0° to 105°. The peak integrated EMG of these three muscles was attained between 90° and 105° knee flexion in both trials. On the other hand, the peak integrated EMG of the long head of the biceps femoris muscle was largest at a knee angle ranging from 15° to 30°. Peak integrated EMG decreased when the knee flexion angle increased in both trials. These results show that the electromyographic activity of agonist muscles during maximum voluntary movement varied with the change of muscle length or joint angle. Therefore, it was considered that the relationship between joint torque and joint angle is influenced not only by the sarcomere length and the moment arm but also muscle activities of agonist muscles, even if the movement is performed with maximum effort.