Studies of spinal biomechanics typically do not focus on the contributions to range of motion (ROM) of the primary components of the spinal canal, dura, arachnoid, pia, spinal cord, nerve roots, ligaments, and vessels. We sought to determine the stability offered by these soft tissues in vitro.Material and Methods:
Human cadaveric segments were tested intact, after osteoligamentous destabilization, and after transection of T8-9 spinal canal components. Specimens were induced into flexion, extension, axial rotation, and lateral bending using nonconstraining, nondestructive pure moment while tracking motion response stereophotogrammetrically. The range of motion (ROM) was compared in each condition after adjusting for soft tissue creep.
After spinal canal element transection, ROM increased in all directions (mean 4.7%). This increase was most pronounced during lateral bending (p = 0.055). The cumulative ROM from all directions of loading showed a statistically significant mean increase of 3.3% (p = 0.040).
Sectioning of canal elements was found to cause a measurable increase in ROM. Although nonviable tissues were tested, living tissues are also likely to contribute to spinal stability.