Three-dimensional analysis of the movement of lumbar spinal nerve roots in nonsimulated and simulated adhesive conditions.
METHODS
Biomechanical analysis of the movement of the lumbar spinal nerve roots (NRs).


OBJECTIVE
The characteristics of the movement of lumbar spinal NRs corresponding to the change of posture were three-dimensionally analyzed in nonsimulated and simulated adhesion conditions using a porcine model.


BACKGROUND
There is a paucity of data on the movement of NRs.


METHODS
Thirty two NRs of four pig cadavers were investigated. (study 1) Two tantalum beads were sutured on respective NRs from L3 to L6. Five beads were put into each bony structure as reference points. The porcine body was put on the cage designed for three-dimensional radiostereometric analysis. Two oblique radiographs were simultaneously taken at flexion, neutral, and extension. (study 2) After study 1, either L4 NR was ligated onto the adjacent bone to mimic monoradicular adhesion. Radiographs were taken in the same manner. The movements of the beads on NRs relative to immobile standard points in each vertebra were analyzed.


RESULTS
The movement of NRs was characterized as a combination of stretching/slackening and pendulum motion. The distance that NRs were stretched/slackened, the excursion, and the angles that NRs moved were: 0.39 +/- 0.29 mm, 1.81 +/- 0.63 mm, and 10.46 +/- 5.93 degrees (in nonadhesion), and 0.30 +/- 0.20 mm, 1.02 +/- 0.50 mm, and 7.13 +/- 3.79 degrees (in simulated adhesion), respectively.


CONCLUSIONS
Adhesion might play a part in the pathogenesis of lumbar spinal disorders because mechanical irritation secondary to stretching/slackening and pendulum motion might be concentrated at the distal part of NRs, adjacent to adhesion site, which has less cerebrospinal fluid and is close to dorsal root ganglion.
Miyamoto
Hiroshi
H
Queen's University, Kingston, Canada. hm0617@med.kobe-u.ac.jp
Dumas
Genevieve A
GA
Wyss
Urs P
UP
Ryd
Leif
L
D000818:Animals; D001696:Biomechanical Phenomena; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000294:innervation*; D008954:Models, Biological; D011859:Radiography; D012399:Rotation; D013126:Spinal Nerve Roots / Q000502:physiology*; D013552:Swine