Predicting the Vertebral Body Position Based on Palpated Spinous Process Position

Palpation is an essential skill of manual therapy. Clinical techniques of physical therapy usually assume that the movement direction of palpating spinous process (SP) is the direction of the vertebral body center (VBC). This study investigated the distance [SP–projected VBC (PVBC)] between the surface palpation of the five SPs and the radiographically projected vertebral center locations (PVBC) on the skin of the lumbar spine in 37 patients with low back pain (LBP). The measurement of SP–PVBC was intended to describe if palpation on SPs could explain the positions of the VBC. The SP–PVBC distance was the greatest at L1 (35.9 mm) and the smallest at L4 (15.1 mm). The predictive analysis investigated the relationships between SP–PVBC and the geometric measurements of the lumbar anatomical structures. The geometric characteristics of the lumbar spine affected the SP–PVBC distance in different levels, with the R2 values from 0.66–0.89, except 0.38 in the L4 level. Increases in the SP inclination as well as vertebral inclinations, and increases in the SP height (SPH) were factors that were found to be significantly related to the SP–PVBC distance (p < 0.05). The results indicate that the orientation of the VBC and the SP may not be the same, and tilting and rotation of the vertebrae may occur when applying manual techniques through SPs. Physical therapists need to be aware that the tilting or rolling effect of vertebrae may not be avoidable once the treatment is done via palpation on SPs