Ultrasound-assessed segmental lumbar motion and clinical outcomes following spinal manipulation: a randomized, controlled pilot study

Objective To determine if spinal manipulation (SM) leads to measurable changes in ultrasound-assessed segmental lumbar motion (SLM) compared with a sham intervention and to evaluate short-term effects on pain, trunk flexion, perceived recovery, and disability.Methods Forty-four adults with low back pain (LBP) were randomly assigned to receive either lumbar SM or a sham intervention. SLM was assessed using diagnostic ultrasound imaging by measuring distances between adjacent lumbar spinous processes (L1–L5) in the fully flexed position before and immediately after the intervention. Pain, trunk flexion, perceived improvement, and disability were assessed using the Numeric Pain Rating Scale, Oswestry Disability Index, Finger-to-Floor Test, and Global Rating of Change. Mixed-design analyses of variance were used to evaluate group-by-time effects for all outcomes.Results No significant group-by-time interaction was found for ultrasound-assessed SLM (F (1,42)=0.001, p = 0.972) or finger-to-floor distance (F (1,42)=0.91, p = 0.347), indicating no differential change between groups. For current pain intensity, a significant group-by-time interaction was observed (F (2,84) = 4.39, p = 0.015), with greater reductions in the SM group. Disability also improved more in the SM group (F (1,42) = 12.38, p = 0.001). No significant group-by-time interaction was found for perceived improvement (F (1,42)=0.62, p = 0.434).Conclusion Lumbar SM produced significant short-term improvements in pain and disability compared with the sham manipulation, but these effects were not accompanied by a significant between-group increase in ultrasound-assessed SLM. These pilot findings suggest that immediate segmental motion changes are unlikely to explain the short-term clinical effects following SM in individuals with LBP.Clinical Trailas Registration no NCT06294132 (clinicaltrial.gov).