[Purpose] This study assessed the reliability and validity of an ultrasound-based imaging method for measuring the interspinous process distance in the lumbar spine using two different index points. [Subjects and Methods] Ten healthy males were recruited. Five physical therapy students participated in this study as examiners. The L2–L3 interspinous distance was measured from the caudal end of the L2 spinous process to the cranial end of the L3 spinous process (E-E measurement) and from the top of the L2 spinous process to the top of the L3 spinous process (T-T measurement). Intraclass correlation coefficients were calculated to estimate the relative reliability. Validity was assessed using a model resembling the living human body. [Results] The reliability study showed no difference in intra-rater reliability between the two measurements. However, the E-E measurement showed higher inter-rater reliability than the T-T measurement (Intraclass correlation coefficients: 0.914 vs. 0.725). Moreover, the E-E measurement method had good validity (Intraclass correlation coefficients: 0.999 and 95% confidence interval for minimal detectable change: 0.29 mm). [Conclusion] These results demonstrate the high reliability and validity of ultrasound-based imaging in the quantitative assessment of lumbar interspinous process distance. Of the two methods, the E-E measurement method is recommended.

[Purpose] The intra- and inter-examiner reliabilities of lumbar interspinous process distances measured by ultrasound imaging were examined. [Subjects and Methods] The subjects were 10 males who had no history of orthopedic diseases or dysfunctions. Ten lumbar interspinous images from 360 images captured from 10 subjects were selected. The 10 images were measured by nine examiners. The lumbar interspinous process distance measurements were performed five times by each examiner. In addition, four of the nine examiners measured the distances again after 4 days for test-retest analysis. In statistical analysis, the intraclass correlation coefficient was used to investigate relative reliability, and Bland-Altman analysis was used to investigate absolute reliability. [Results] The intraclass correlation coefficients (1, 1) for intra-examiner reliability ranged from 0.985 to 0.998. For inter-rater reliability, the intraclass correlation coefficient (2, 1) was 0.969. The intraclass correlation coefficients (1, 2) for test-retest reliability ranged from 0.991 to 0.999. The Bland-Altman analysis results indicated no systematic error. [Conclusion] The results indicate that ultrasound measurements of interspinous process distance are highly reliable even when measured only once by a single person.

[Purpose] The purpose of this study was to examine the reliability and validity of measurements of hip extensor muscle strength using a handheld dynamometer (HHD) with subjects in a sitting position. In doing so, we also aimed to establish a modified method of measurement for patients with flexion contractures in the trunk and lower extremities. [Subjects and Methods] In 20 healthy males, hip extensor muscle strength was measured using a handheld dynamometer in sitting, prone, and standing positions by contracting the hip extensor muscle isometrically with the knee flexed at 90 degrees. For each position, we investigated the relative and absolute reliability and validity of the measurements, and compared muscle strength between the different positions. [Results] The reliability and validity of measurements were highest in the sitting position and higher in both the sitting and standing positions as compared with those in the prone position. [Conclusion] Our findings suggest that measurements taken in a sitting position are accurate in assessing hip extensor muscle strength and would be applicable to patients with flexion contractures in the trunk and lower extremities.

The effects of different postures on the static flexion relaxation phenomenon were compared using electromyography, to clarify whether the angles for the activation and relaxation of the spinal muscles are different. [Subjects and Methods] Thirty healthy males maintained several different trunk inclination angles while standing and sitting. The muscle activities were measured and compared among the different postures and the different trunk angles: 0, 10, 20, 30, 40, 50, 60, and maximum forward leaning. The thoracic and lumbar erector spinae, multifidus, gluteus maximus, and biceps femoris were the target muscles. [Results] Muscle activities increased with increasing forward inclination angle, but at low inclination angles in the sitting position, the activities of the multifidus and erector spinae were constant. Between the postures, trunk muscle activities became significantly lower in the sitting position than in the standing position with increasing inclination. [Conclusion] Compared to standing, muscle activities at low inclination angles have low, constant values.

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