Intra-observer reliability study of lumbar segmental measurements utilizing ultrasonography

Spinal Manipulative Therapy (SMT) benefits LBP patients, but its mechanism is not well documented. One hypothesis indicates that SMT restores interspinal movements. Ultrasound measurement (UM) of spinous process separation (SPS) assesses the intersegmental movements. We used the test-retest reliability of UM between the L3, L4, L5, and S1 spinous processes on fifteen asymptomatic volunteers while lying prone on a chiropractic table. The participants then walked around for over 5 minutes, and ultrasound images were reperformed prone. UM identified the tips of the spinous processes and distances between L3-L4, L4-L5, and L5-S1. Reliability was assessed using intra-class correlation coefficient (ICC). ICC values of SPS measurements were 0.982 for L3-L4, 0.992 for L4-L5, and 0.997 for L5-S1. Rootmean square difference between the two measures were 0.35mm for L5-S1, 0.36mm for L4-L5, and 0.57mm for L3-L4. This study found UM to be reliable in measuring interspinous distance.