Anterior cervical interbody fusion with rhBMP-2 and tantalum in a goat model.
BACKGROUND
Tricortical autogenous iliac crest has long served as the gold standard for arthrodesis after cervical discectomy. The added morbidity resulting from bone graft harvest may be eliminated by the use of a biocompatible synthetic bone graft substitute with osteoconductive abilities, and when used with an osteoinductive agent, such as recombinant bone morphogenic protein (rhBMP)-2, it may facilitate arthrodesis similar to autograft.


OBJECTIVE
To determine by radiographic and histologic analysis whether tantalum with and without rhBMP-2 can facilitate bony ingrowth and arthrodesis in an animal model.


METHODS
Single-level anterior cervical discectomy and fusion was performed using a tantalum bone graft substitute with and without rhBMP-2 in a previously established goat model for anterior cervical fusion.


METHODS
Eight goats underwent single-level anterior cervical discectomy and stabilization with a porous tantalum implant. There were four goats in each experimental group. Group A underwent anterior cervical stabilization with tantalum alone, whereas in Group B rhBMP-2 was added to the tantalum implant. The goats were sacrificed at 12 weeks, and their cervical spines were removed for histologic and radiological analysis.


RESULTS
Only one of four goats in Group A had any bony ingrowth into the tantalum. Three of four goats in Group B demonstrated bony ingrowth. The average extent of bony ingrowth at the perimeter of the tantalum in Group A was 2.5% compared with 12.5% in Group B. Similarly, the volume of bony ingrowth within the tantalum was 2.5% in Group A and 10% in Group B. The difference was not statistically significant.


CONCLUSIONS
The data in this pilot study suggest that tantalum may function as a synthetic osteoconductive bone graft substitute. The addition of rhBMP-2 may facilitate osteoinduction within a synthetic osteoconductive implant. The sample size in this study was too small for statistical significance. The present animal model as used in this study was inadequate for cervical arthrodesis where rigid implant fixation is desired.
Department of Orthopaedic Surgery, William Beaumont Hospital, 3535 West Thirteen Mile Road, Royal Oak, MI 48073, USA.
K S
KS
Sidhu
T D
TD
Prochnow
P
P
Schmitt
J
J
Fischgrund
S
S
Weisbrode
H N
HN
Herkowitz
D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D018786:Bone Substitutes / Q000494:pharmacology*; D002574:Cervical Vertebrae / Q000166:cytology / Q000000981:diagnostic imaging / Q000601:surgery*; D017586:Diskectomy; D006041:Goats; D016348:Osseointegration; D011859:Radiography; D011994:Recombinant Proteins / Q000494:pharmacology; D013123:Spinal Fusion / Q000379:methods*; D013635:Tantalum / Q000494:pharmacology*; D016212:Transforming Growth Factor beta
D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D018786:Bone Substitutes; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D013635:Tantalum