An investigation of the reproducibility of ultrasound measures of abdominal muscle activation in patients with chronic non-specific low back pain

Abstract

Ultrasound (US) measures are used by clinicians and researchers to evaluate improvements in activity of the abdominal muscles in patients with low back pain. Studies evaluating the reproducibility of these US measures provide some information; however, little is known about the reproducibility of these US measures over time in patients with low back pain. The objectives of this study were to estimate the reproducibility of ultrasound measurements of automatic activation of the lateral abdominal wall muscles using a leg force task in patients with chronic low back pain. Thirty-five participants from an existing randomised, blinded, placebo-controlled trial participated in the study. A reproducibility analysis was undertaken from all patients using data collected at baseline and after treatment. The reproducibility of measurements of thickness, muscle activation (thickness changes) and muscle improvement/deterioration after intervention (differences in thickness changes from single images made before and after treatment) was analysed. The reproducibility of static images (thickness) was excellent (ICC 2,1 = 0.97, 95% CI = 0.96-0.97, standard error of the measurement (SEM) = 0.04 cm, smallest detectable change (SDC) = 0.11 cm), the reproducibility of thickness changes was moderate (ICC 2,1 = 0.72, 95% CI 0.65-0.76, SEM = 15%, SDC 41%), while the reproducibility of differences in thickness changes from single images with statistical adjustment for duplicate measures was poor (ICC 2,1 = 0.44, 95% CI 0.33-0.58, SEM = 21%, SDC = 66.5%). Improvements in the testing protocol must be performed in order to enhance reproducibility of US as an outcome measure for abdominal muscle activation.

Reliability of real-time ultrasound measurement of transversus abdominis thickness in healthy trained subjects

“…These parameters are regarded quick and easy to obtain, non-invasive indicators of the TrA performance which is crucial for stability and control of the lumbar spine [2,3]. Authors conclude that US measurement of TrA thickness generally shows acceptable reliability in healthy persons [6][7][8][9][10][11][12][13][14][15][16] and patients with low back pain [12,[17][18][19][20][21][22]. Results concerning TrA thickness change are still contradictory or unclear.…”

“…For measurements taken on the same day Costa et al [20] showed moderate intra-rater reliability, Kiesel et al [12] reported good intra-rater reliability, Koppenhaver et al [21] showed excellent intra-rater and good to excellent inter-rater reliability, and results from Mannion et al [19] ranged from poor to excellent.…”

“…Only three studies [16,20,21] have investigated the reliability of TrA thickness change over time. Costa et al [20], using single measurements, reported poor betweenday reliability, whereas Koppenhaver et al [21] provide evidence for moderate to good reliability using averaged outcomes of two repeated measurements.…”

“…Costa et al [20], using single measurements, reported poor betweenday reliability, whereas Koppenhaver et al [21] provide evidence for moderate to good reliability using averaged outcomes of two repeated measurements. In turn, Jhu et al [16] demonstrated moderate to good reliability, which was further improved by means of compensation for motion of the array.…”

Relationships between Sit-Ups and Abdominal Flexion Strength Tests and the Thickness of Each Abdominal Muscle

“…The thickness of rectus abdominis was measured as the maximal width of a point 4-cm transverse from the navel, excluding tendinous intersections. Because the other three parts have overlapping organizations, they were measured at the same position (Ferreira, Ferreira, & Hodges, 2004;Leonardo, Chris, Jane, Paul, & Debra, 2009). We measured two thirds of line drawn horizontally from the height of the navel perpendicular to a vertical axillary line (Figure 4).…”