The purpose of the Thoraco-Lumbar Fascial Mobility (TLFM) study is to use ultrasound to measure the movement of connective tissue in the low back area of individuals with chronic low back pain (lasting more than 1 year). This study will compare baseline measurements, measurements after a single high velocity low amplitude spinal manipulation (HVLA-SM) and after a course of up to 16 HVLA-SM.

The investigators will conduct a single arm pilot (proof-of-concept) clinical trial. Approximately 30 participants with self-reported chronic low-back pain (LBP), defined as pain for ≥ 1-year in duration and pain on at least ½ of the days in the past 6-months, will be enrolled.

This trial will consist of two separate enrollment phases. Phase 1 consists of enrollment at baseline followed by 3 separate ultrasound measurements. Phase 1 ends after a 4-week no treatment run-in phase.

Phase 2 begins twice-weekly HVLA-SM treatments to the thoracolumbar region for 8-weeks. Two ultrasound imaging evaluations will occur at visit 1 (pre and post-treatment). Pre-treatment ultrasound evaluations will be obtained at 4-weeks and 8-weeks.

The primary outcome is shear strain (adjacent tissue layer mobility measured with ultrasound) at the level of the lumbar L2-L3 vertebrae bilaterally. Ultrasound measures will be obtained with a Terason t3000 system using a 12L5 linear array probe with 10 MHz setting. Because shear strain may differ between sexes, we will attempt to recruit equal numbers of male and female participants.

Inclusion:

1. Adults between 21 and 65 years
2. LBP of ≥ 1-yr duration with at least ½ of days with pain over the prior 6-months
3. Able to understand study procedures and willing to sign informed consent document
4. Willing to forgo any manual therapy for LBP for the initial 4-week study period
5. Willing to forgo any manual therapy for LBP other than study treatments during the 8-week treatment period
6. Able to tolerate and safely receive study procedures

Exclusion Criteria:

1. Chiropractic care or other manual therapy for at least 90 days prior to baseline visit
2. Unable to visualize necessary tissue layers using musculoskeletal ultrasound
3. Weight above 350 lbs
4. Unable to tolerate or safely receive study procedures
5. Need for referral
6. Unable or unwilling to comply with study procedures
7. Current or planned pregnancy (self-reported) within the study timeframe
8. Any prior surgery to the thoracolumbar region
9. Needing a proxy
10. Connective tissue disorder such as Marfan and Ehlers-Danlos syndrome

This is a proof of concept study. No data will be available for sharing.

Data analysis will be performed by blinded personnel. As a single group trial involving a manual therapy, participant and provider blinding is not feasible.