Intra- and Inter-rater Reliabilities of Measurements of Iliopsoas Thickness in Hip Flexion

Abstract

To investigate the intra-and inter-rater reliabilities of measurements of the iliopsoas thickness, and the change in iliopsoas thickness due to hip flexion. [Participants and Methods] The participants were 13 healthy young males. Iliopsoas thickness was measured in hip flexion of 0, 15, 30, 45 and 60 degrees at the center of the groin area using sonography. The intra-and inter-rater reliabilities of measurements of iliopsoas thickness were calculated, and the iliopsoas thickness was compared among the hip flexion positions. [Results] When hip joint flexion was 45˚ or less, both the intra-and inter-rater reliabilities of measurements of the iliopsoas thickness were high. Systematic bias was not found at any of the hip flexion angles. The iliopsoas thickness increased with hip flexion. [Conclusion] Highly reproducible data can be obtained by measuring iliopsoas thickness at hip flexion of 45˚ or less. However, as the thickness of the iliopsoas thickness changes with hip flexion, making it necessary to consider the hip flexion angle when measuring it.

Relationship between iliopsoas muscle thickness and hip angle during squats in different pelvic positions

“…Kinugasa 16) reported that the crosssectional area of the muscle decreases with muscle elongation because the muscle has a constant volume; conversely, the cross-sectional area of the muscle is likely to increase as the muscle adopts a shortened position. In our previous study 15) , it was also shown that increasing the hip angle passively between 0 and 60° increased the muscle thickness of the iliopsoas muscle. The angle of hip flexion during squatting in the present study was within the range of our previous study 15) , which might have resulted in changes in muscle thickness due to the shortening limb position of the iliopsoas muscle.…”

“…In our previous study 15) , it was also shown that increasing the hip angle passively between 0 and 60° increased the muscle thickness of the iliopsoas muscle. The angle of hip flexion during squatting in the present study was within the range of our previous study 15) , which might have resulted in changes in muscle thickness due to the shortening limb position of the iliopsoas muscle. However, in the present study, the correlation between ΔIT and ΔJA of the hip joint was not observed in NP and PP, but only in AP.…”

“…The iliopsoas muscle was imaged using an ultrasound machine ((LOGIQ e, GE Healthcare Japan, Tokyo, Japan) with a linear probe (10 MHz) in B mode. The ultrasound probe was applied to measure the iliopsoas muscle according to the methodology of our previous study 15) , and the measurement area was the center of the inguinal region at the midpoint of the line connecting the anterior superior iliac spine to the pubic symphysis. Markings were applied to the pre-identified measurement areas to keep them constant, and the iliopsoas muscle was imaged by touching those areas with the probe (Fig.…”