Objectives: The aim of this study was to provide a metric description of acupuncture points BL25 and BL26, to investigate their relation to individual anatomical landmarks and structures, and to identify anatomical structures that are involved in needle manipulation during de qi.
Design: Fifty-eight (58) white patients with low-back pain received 107 needlings that were documented using computed tomography (CT).
Outcome measures: For each patient, the body-mass index (BMI) and the interscapular distance were measured. Using the CT scan, the following parameters were assessed: thickness of the soft tissue layer, distance of the puncture site and the needle tip to the vertebral line, distance of the needle tip to the body surface and the intermuscular space, and the needle depth in muscle tissue.
Results: The mean distance from the puncture site to the vertebral line was 3.5 +/- 0.5 cm for BL25 and 3.4 +/- 0.4 cm for BL26. The distance of the needle tip to the vertebral line was similar (3.4 +/- 0.5 cm for BL25 and 3.2 +/- 0.4 cm for BL26). The mean distance of the needle tip to the body surface was 4.1 +/- 0.9 cm at BL25 and 3.9 +/- 0.8 cm at BL26. The majority of the needle tips were located in the intermuscular region between the erector spinae and the transversospinal muscles. There was a significant correlation between the interscapular distance and the thickness of the soft tissue layer with the BMI at both acupuncture points. Nearly all parameters correlated with the BMI. At BL26, correlations between the distance of needle to the vertebral line and the BMI were not statistically significant but the scatter plots indicate a positive dependency.
Conclusions: The results of this study show an association between de qi and needle location within the intermuscular septa. BL25 and BL26 are located as clusters in and around the intermuscular region of the erector spinae and the transversospinal muscles, with a distance to the vertebral line of 3.49 +/- 0.58 cm and 3.32 +/- 0.53 cm, respectively. Using proportional methods is relevant for the success of acupuncture therapy.