Diaphragm Muscle Thickness in 4 Different Positions in Patients With Low Back Pain Compared to Healthy Individuals:...

This study aimed to investigate the changes in the thickness of the diaphragm muscle during 4 different postures in individuals with and without chronic low back pain (LBP) using transcostal rehabilitative ultrasound imaging.

This cross-sectional study was conducted on 56 participants, including 28 patients with nonspecific chronic LBP (14 males and 14 females) and 28 individuals without LBP (14 males and 14 females), aged 20 to 45 years. Diaphragm thickness and diaphragm thickness fraction (DTF) of the right hemidiaphragm were assessed via B-mode ultrasound in supine, sitting, standing, and straight leg raised (SLR) positions in different respiratory phases, including inspiration, expiration, and deep inspiration.

In each group, diaphragm thickness was found to be different among supine, SLR, sitting, and standing positions in all respiratory phases (P < .001). The difference in diaphragm thickness between the LBP and non-LBP groups was more obvious in the SLR position (P = .035). Moreover, groups differed significantly in DTF in SLR, sitting, and standing positions (P < .001).

Increased load on the lumbar region caused by elevating the lower limb and posing more upright postures resulted in a thicker diaphragm. Based on the results, the SLR position reflected the differences in diaphragm thickness between the study groups more efficiently than other positions, which might be attributed to impaired load transfer through the lumbopelvic region in individuals with back pain. Furthermore, DTF seemed to be more sensitive compared to the thickness measurement for the identification of differences between patients with LBP and healthy individuals.