Abstract: This study evaluates the effect of paravertebral spinal injection (PSI), utilizing both subjective and objective assessments in chronic low back pain (LBP) associated with facet joint arthrosis over a one-month duration. Subjective questionnaires included the Visual Analogue Scale (VAS) for pain, Oswestry Disability Index, Health Survey SF-12, and the short Falls Efficacy Scale International (FES-I). Objective assessments included in-clinic gait and timed-up-and-go (TUG) tests using wearable sensors, as well as 48-hour daily physical activity (DPA) monitored using a chest-worn tri-axial accelerometer. Subjective and objective measures were performed prior to treatment, immediately after the treatment, and one-month afterthe treatment. Eight LBP patients were recruited for this study (mean age = 54±13 years, body mass index = 31.41±6.52 kg/m2, 50% males). Results show significant decrease in pain (~55%, p<0.05) and disability (Oswestry scores, ~21%, p<0.05). In-clinic gait and TUG were also significantly improved (~16% and ~18% faster walking and shorter TUG, p<0.05); however, DPA (including percentage of physical activities (walking and standing) and the number of steps) showed no significant change after PSI (p>0.25; effect size≤0.44). We hypothesize that DPA may continue to be truncated by conditioned fear-avoidance, a psychological state that may prevent increase in daily physical activity to avoid pain.