2012 Annual Conference

Su, Jonathan

Center for Physical Therapy Research, U.S. Army-Baylor University Doctoral Program in Physical Therapy, Fort Sam Houston, TX, USA

Although dry needling is increasingly used in the treatment of patients with low back pain (LBP), evidence for its efficacy is mixed and limited by our current understanding of the physiologic mechanisms involved. The purpose of this study is to determine if dry needling facilitates lumbar multifidus (LM) muscle function in patients with LBP and if such facilitation is associated with clinical improvement.

Sixty-six volunteers with mechanical LBP (38 men, 28 women, age = 41.3±9.2 years, body mass index = 28.8±4.9 kg/m², months since initial LBP onset = 57.5±83.3 months) were recruited and completed the study.

Pre-treatment data was collected from questionnaires, history and physical examination, and rehabilitative ultrasound imaging (RUSI) of the LM muscles at levels L4/5 and L5/S1 on the symptomatic side. RUSI measurements of rested and contracted LM muscle thickness were collected with the LM at rest and during a sub-maximal contraction elicited by a contralateral arm lift maneuver. Treatment then consisted of dry needling to the bilateral LM muscles at levels L3/4, L4/5, and L5/S1. Post-treatment RUSI measurements of the LM were collected immediately following dry needling treatment and after one week. Repeat questionnaires and physical examination data were also collected at the 1-week follow-up. Percent change in LM thickness (contracted-rest/rest) was calculated for each time point at the most painful side and lumbar segment as determined by pain algometry. Participants were dichotomized based on whether or not they experienced clinical improvement after one week, defined as at least a 30% improvement on the Oswestry Disability Index (ODI).

A 2x3 mixed-model analysis of variance (ANOVA) was conducted for group (improved vs. not improved) by time (pre-treatment, post-treatment, and 1-week follow-up) followed by pairwise post-hoc analysis.

Main effects of time and group were non-significant. However, statistically significant group by time interactions were found overall (p = 0.048) and between post-treatment and 1-week follow-up measures (p = 0.03). Participants that experienced clinical improvement exhibited a mean 36.3% increase in LM thickness change relative to baseline compared to a mean 30.2% decrease in participants whom did not experience clinical improvement.

Only participants with LBP who experienced clinical improvement demonstrated improved LM muscle contraction one week after dry needling treatment. Future research should investigate the effects of dry needling on long-term clinical improvement and on muscle function in patients with other neuro-musculoskeletal conditions.

Understanding a mechanism that mediates the clinical benefits of dry needling may help clinicians more effectively use this treatment intervention in patients with LBP.