Variations of spinous and transverse process length in the human lumbar spine

Some manual therapy schools of thought rely on palpation of vertebral position via bony processes prior to the application of directional manual interventions. It is feasible that malformation or asymmetry of the spinous processes (SPs) or transverse processes (TPs), if unknown, may influence the outcome of a diagnostic palpatory exam and the application of directional manual interventions. This study provides morphometric data for the lumbar spine, to assess the occurrence of length differences in lumbar SPs and TPs occurring between the right and left sides.

The lumbar processes were measured bilaterally in 16 adult cadaveric specimens, 9 females and 7 males ranging in age from 68 to 89 years. A measurable difference in SP length, defined as ≥ 0.1 cm, was found in 72.4% of the population, and for TP lengthin 90.6% of the population. A mean SP length difference of 0.2 ± 0.2 cm and a mean TP length difference of 0.4 ± 0.3 cm were observed. Process length was longer on average for males, and the magnitude of process length difference increased with age.

These results indicate that a finding of a clinical positional fault of a vertebra through palpatory exam may be flawed.