In this prospective study, eligible subjects with chronic non specific low back pain and asymptomatic volunteers will undergo a research dynamic ultrasound exam of the lower back before and after a massage technique.

The overall aim of the present research is to develop ultrasonographic parameters that characterize the geometrical, the mechanical and tissue characteristic properties of the thoracolumbar fascia, and to explore the effect of a massage therapy technique on these parameters.

In this prospective proof of concept study, eligible subjects with chronic non specific low back pain and asymptomatic volunteers will undergo a research dynamic ultrasound (US) exam of the thoracolumbar fascia (TLF) of the lower back. A musculoskeletal radiologist will perform the US exams consisting of a series of 5 dynamic scans of both the right and left paraspinal muscles, obtained during 15 degrees of passive flexion of the lower body using a motorized table.

Following the US exam, the group of patients and the group of volunteers will be respectively randomized to receive either a standardized massage technique intervention or a sham technique. The US exam will be repeated after the intervention.

Ultrasound image segmentation will be performed by two independent observers and inter-rater variability will be assessed. Post-processing of the US recordings will include assessment of geometrical (thickness), mechanical (percent shear strain between the TLF and the epimysium-muscle complex) and tissue ultrastructure features (the mean intensity μ, the scatterer clustering parameter α and the structure parameter κ of the echo envelope). These features will be compared between patients and volunteers and between the intervention groups.

Inclusion Criteria:

Patient group:

• Presenting with chronic low back and/or referred pain (non specific pattern) above or just below the gluteal fold of at least 3/10 on a numerical pain rating scale (NRS), for at least 6 months;
• Pain is present at least 50% of the time during the day;

Asymptomatic group:

• No history of low back pain or any other chronic pain limiting activities of daily living or work.

Exclusion Criteria:

• History of back surgery;
• History of severe back or low extremity injury;
• Back pain attributable to a specific, recognizable, known pathology (i.e.: infection, tumor, fracture, spinal stenosis, sciatica etc.);
• Corticosteroid medication intake or corticosteroid injection in the lumbar spine in the previous 3 months;
• Pregnancy.