The Journal of Bone and Joint Surgery, Vol 76, Issue 4 540-548, Copyright © 1994 by Journal of Bone and Joint Surgery, Inc
The biological and biomechanical effects of irradiation on anterior spinal bone grafts in a canine model
SE Emery, MS Brazinski, A Koka, JS Bensusan and S Stevenson
Department of Orthopaedics, Case Western Reserve University, Cleveland, Ohio 44106.
We evaluated the effects of irradiation on the healing of anterior
vertebral strut grafts with use of a canine model. Through a left
thoracotomy, a partial corpectomy of the seventh thoracic vertebra and
autogenous iliac strut-grafting from the sixth to the eighth thoracic
levels were performed in twenty-two adult beagles. Four groups were
established: Group I (control) received no irradiation, Group II received
preoperative irradiation, Group III received postoperative irradiation that
began on the third postoperative day, and Group IV received postoperative
irradiation that began on the twenty-first postoperative day. The
irradiation protocol was five treatments of 500 centigray three times a
week for a total of 2500 centigray. Fluorochromes were administered at
regular intervals postoperatively. The beagles were killed three months
postoperatively, and non-destructive biomechanical testing was done to
evaluate the stiffness of the construct. The quality of healing at the
junctions of the graft with the sixth and eighth thoracic vertebrae, the
degree of revascularization of the graft, and the amount of new-bone
formation were evaluated histologically. Statistical evaluation of the
biomechanical data revealed no significant difference in the stiffness of
the construct between Groups I, II, and IV. The specimens from Group III
were significantly less stiff than those from Group I (the control group)
in torsion (p = 0.03) and left lateral bending (p = 0.04) and than those
from Group II in flexion (p = 0.02) and left lateral bending (p =
0.005).(ABSTRACT TRUNCATED AT 250 WORDS)