Effect of recombinant human bone morphogenetic protein-2 in an experimental model of spinal fusion in a radiated area.
METHODS
An animal model of posterolateral intertransverse process spine fusion was used.


OBJECTIVE
To investigate whether recombinant human bone morphogenetic protein-2 (rhBMP-2) can overcome the adverse effects of radiation treatment (RT) on spine fusion.


BACKGROUND
Spinal metastases are common. Some of these patients are candidates for spinal cord decompression and vertebral reconstruction; however, radiation has significant adverse effects on bone healing.


METHODS
A posterolateral fusion model was used with rhBMP-2 or iliac crest bone graft (ICBG). Eighty one-year-old rabbits were divided into eight groups: 1) RT 14 days before surgery, rhBMP-2; 2) RT 14 days before surgery, ICBG; 3) RT 2 days after surgery, rhBMP-2; 4) RT 2 days after surgery, ICBG; 5) RT 14 days after surgery, rhBMP-2; 6) RT 14 days after surgery, ICBG; 7) no RT, rhBMP-2; 8) no RT, ICBG. Animals were killed approximately 35 days after surgery. Manual palpation was the definitive test of fusion. Biomechanical and histologic assessments were also performed.


RESULTS
All rhBMP-2 groups had significantly greater fusion rates versus respective ICBG control groups: 1 (86%) versus 2 (0%) (P = 0.005), 3 (100%) versus 4 (0%) (P < 0.0001), 5 (100%) versus 6 (0%) (P < 0.0001), and 7 (100%) versus 8 (60%) (P = 0.003). Stiffness and ultimate strength did not differ significantly between the experimental and control groups. Histologic assessment confirmed new bone formation in the fusion masses from rhBMP-2 groups.


CONCLUSIONS
Use of rhBMP-2 produced a significantly greater rate of fusion compared with ICBG in a previously radiated area in an animal model, without the morbidity of ICBG harvesting and without the risk of inadvertently using autograft contaminated by micrometastases.
Ames
Christopher P
CP
Comprehensive Spine Center, Department of Neurological Surgery, University of California, San Francisco School of Medicine, San Francisco, CA 94143-0112, USA. amesc@neurosurg.ucsf.edu
Smith
Justin S
JS
Preul
Mark C
MC
Crawford
Neil R
NR
Kim
Grace E
GE
Nottmeier
Eric
E
Chamberlain
Robert
R
Speiser
Burton
B
Sonntag
Volker K H
VK
Dickman
Curtis A
CA
D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D016025:Bone Transplantation / Q000000981:diagnostic imaging / Q000379:methods; D006801:Humans; D008159:Lumbar Vertebrae / Q000187:drug effects* / Q000528:radiation effects* / Q000601:surgery; D011817:Rabbits; D011859:Radiography; D011994:Recombinant Proteins / Q000494:pharmacology*; D013123:Spinal Fusion / Q000379:methods*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta