Significance of fixation of the vertebral column for spinal cord injury experiments.
METHODS
Thoracic spinal cord transections were performed in adult rats. The animals were divided into two groups, with or without internal fixation of the involved vertebral column. Histologic and immunohistochemical studies were performed to compare the effect of internal fixation of the vertebral column.


OBJECTIVE
To find out the aspects and extent of beneficial effects of vertebral column fixation for spinal cord repair.


BACKGROUND
Vertebral column fixation is a routine procedure in clinical spinal cord surgery. Paradoxically, most, if not all, animal spinal cord experiments seem to have ignored the importance of vertebral column fixation. During trunk movements, the vertebral column flexes to different directions, accompanied by bending of the spinal cord. Following spinal cord lesions, with frequent bending of the cord there will be repeated bleeding, inflammation, and other pathologic processes at the lesion site. Thus, the healing process will be hampered. The severity of the damages that will be brought about by bending of the cord is, to a certain degree, unpredictable. There will be rather big individual variations in injury and repair among the same type of experiments, rendering quantification and conclusion difficult.


METHODS
Adult Sprague-Dawley rats were used. The thoracic spinal cord was transected. Strong stainless steel wires were used for internal fixation of the vertebral column. The histology of the horizontal sections of the spinal cord segment, which included the lesion site, was examined at the 14th postoperative day. The volumes of the secondary degeneration and meningeal scar, the gap between the borders of the proximal and distal stumps of the transected spinal cord, the thickness of the meningeal scar, the astrocytic reaction, and the abundance of regenerating nerve fibers at the lesion site were compared between the vertebral column fixed and nonfixed groups. Whenever possible, the results were evaluated quantitatively.


RESULTS
In all these aspects, the internally fixed group was consistently far better than the unfixed group. The quantitative analyses were as follows (fixed/unfixed): 1)volume of secondary degeneration: 1.07 +/- 0.20/1.81 +/- 0.43 mm3 (P < 0.01); 2) volume of meningeal scar: 2.38 +/- 0.55/4.34 +/- 1.40 mm3 (P < 0.05); 3) distance between cord stumps: 1.38 +/- 0.34/2.35 +/- 0.79 mm (P < 0.05); 4) the mean thinnest dimension of the meningeal scar: 0.90 +/- 0.43/1.98 +/- 0.85 mm (P < 0.05).


CONCLUSIONS
Vertebral column fixation is a crucial procedure for spinal cord animal experiments.
Liu
Fei
F
Institute of Neurosciences, The Fourth Military Medical University, Xi'an, PR China.
Luo
Zhuo-Jin
ZJ
You
Si-Wei
SW
Jiao
Xi-Ying
XY
Meng
Xiao-Mei
XM
Shi
Ming
M
Wang
Chun-Ting
CT
Ju
Gong
G
D000818:Animals; D001253:Astrocytes / Q000378:metabolism / Q000473:pathology; D002921:Cicatrix / Q000473:pathology; D004195:Disease Models, Animal; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis; D007150:Immunohistochemistry; D016268:Internal Fixators; D016900:Neurofilament Proteins / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D013116:Spinal Cord / Q000473:pathology*; D013119:Spinal Cord Injuries / Q000473:pathology / Q000517:prevention & control*; D013123:Spinal Fusion / Q000295:instrumentation; D013124:Spinal Injuries / Q000473:pathology / Q000601:surgery*; D013131:Spine / Q000601:surgery*
D005904:Glial Fibrillary Acidic Protein; D016900:Neurofilament Proteins