Effect of dry needling on lumbar muscle stiffness in patients with low back pain: A double blind, randomized controlled trial using shear wave elastography

Abstract

Background: Dry needling treatment focuses on restoring normal muscle function in patients with musculoskeletal pain; however, little research has investigated this assertion. Shear wave elastography (SWE) allows quantification of individual muscle function by estimating both resting and contracted muscle stiffness.

Objective: To compare the effects of dry needling to sham dry needling on lumbar muscle stiffness in individuals with low back pain (LBP) using SWE.

Methods: Sixty participants with LBP were randomly allocated to receive one session of dry needling or sham dry needling treatment to the lumbar multifidus and erector spinae muscles on the most painful side and spinal level. Stiffness (shear modulus) of the lumbar multifidus and erector spinae muscles was assessed using SWE at rest and during submaximal contraction before treatment, immediately after treatment, and 1 week later. Treatment effects were estimated using linear mixed models.

Results: After 1 week, resting erector spinae muscle stiffness was lower in individuals who received dry needling than those that received sham dry needling. All other between-groups differences in muscle stiffness were similar, but non-significant.

Conclusion: Dry needling appears to reduce resting erector spinae muscle following treatment of patients with LBP. Therefore, providers should consider the use of dry needling when patients exhibit aberrant stiffness of the lumbar muscles.

Keywords: Dry needling; elastography; low back pain; muscle; ultrasound.

Figure 1.

The erector spinae muscle bulk, the iliac crest, and targeted level (e.g. L4 in photo) spinous process were all marked on the must symptomatic side prior to imaging. (Top) To image the erector spinae muscles, the transducer was centered on the paraspinal muscle bulk with the transducer oriented parallel to the spine. (Bottom) To image the lumbar multifidus, the transducer was rotated approximately 20º and tilted approximately 10º medially toward the targeted level facet joint.

Figure 2.

The shear wave elastography (SWE) box, which overlays the B-mode ultrasound image, gives a visual color-coded image based on regional tissue stiffness (Young’s modulus) within the box. Young’s modulus was later converted to shear modulus (kilopascals- kPa).

Figure 3.

Dry needling techniques. (Top) For the lumbar multifidus muscle, needles were inserted approximately 1.5 cm lateral to the spinous process at the most symptomatic side and segmental level in a posterior to anterior direction with a slight inferior-medial angle (approximately 2º) to the depth of the lumbar lamina. (Bottom) For the erector spinae muscles, the needle was inserted just lateral to the paraspinal muscle bulk (approximately 5–10 cm lateral to the spinous process) in a lateral to medial direction toward the spinous process.

Figure 4.

Flow of participant recruitment and exclusion. Abbreviation: SLR, Straight Leg Raise Test; ODI, Oswestry Disability Index.

Figure 5.

Comparisons in shear modulus (in kilopascals- kPa) of the erector spinae muscle between participants that received dry needling and sham dry needling before treatment (baseline), immediately after treatment (post-needle), and at 1-week follow-up. Error bars denote 95% confidence intervals. *Statistically significant difference at 1-week after adjusting for baseline values.