Use of autogenous bone graft compared with RhBMP in high-risk patients: a comparison of fusion rates and time to fusion.
METHODS
A retrospective study.


OBJECTIVE
To evaluate whether recombinant human bone morphogenetic protein (rhBMP-2) can improve fusion rates and time to fusion in high-risk patients when compared with autograft in lumbar posterolateral fusion.


BACKGROUND
The use of rhBMP-2 in the general population for posterolateral fusion has resulted in relatively good reported outcomes; however, it is currently considered "off-label" use. Few studies, however, have determined the outcomes of rhBMP-2 when used in patients with numerous risk factors for a pseudarthrosis.


METHODS
One hundred ninety-five patients were divided into 4 groups depending on fusion material and the presence/absence of fusion-related risk factors for nonunions; group A was defined as rhBMP-2 used in the presence of high-risk factors (FRRF), group B was defined as rhBMP-2 used in the absence of FRRF, group C was defined as autograft used in the presence of FRRF, and group D was defined as autograft used in the absence of FRRF. The time to fusion, fusion rate were compared between each group.


RESULTS
The time to fusion was significantly faster in group B than in group D in patients with no history of smoking (P<0.05), hypertension (P<0.01), or other significant comorbidity (P<0.05). The time to complete fusion was also significantly faster in group B than in group D in patients under the age of 65 (P<0.05), patients undergoing primary surgery (P<0.05), single-level surgery (P<0.01), no smoking history (P<0.05), no diabetes mellitus (P<0.01), no hypertension (P=0.001), no osteoporosis (P<0.01), and no significant comorbidity (P<0.01). Although the fusion rate was higher in group B than in group D, with the exception of sex and single-level surgery, there were no significant differences between groups B and D. Although initial fusion mass and time to solid fusion was faster in group A than in group C, there were no significant differences between groups A and C. In addition, fusion rates were higher in group C than in group A, looking at all factors except revision surgery, but the differences were not statistically significant.


CONCLUSIONS
With relative low dosage of rhBMP-2 compared with the dose used in Food and Drug Administration trial, in patients without fusion-related risk factors, rhBMP-2 may lead to acceptable fusion rates and faster fusion time when compared with autograft. Therefore, rhBMP-2 may serve as an acceptable alternative to autogenous bone graft in patients without fusion-related risk factors undergoing instrumented posterolateral lumbar fusions. When compared with patients with fusion-related risk factors, the use of rhBMP-2 was comparable with autograft but was not sufficient to overcome all aspects of the weakened osteoinductive capacity encountered in patients with these risk factors.
Department of Orthopaedic Surgery, University of California, Los Angeles, CA, USA.
Kwang-Bok
KB
Lee
Jared S
JS
Johnson
Kyung-Jin
KJ
Song
Cyrus E
CE
Taghavi
Jeffrey C
JC
Wang
D000328:Adult; D000368:Aged; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage*; D016025:Bone Transplantation / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D011994:Recombinant Proteins / Q000008:administration & dosage; D012307:Risk Factors; D013123:Spinal Fusion / Q000379:methods*; D013997:Time Factors; D014182:Transplantation, Autologous; D016896:Treatment Outcome
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D011994:Recombinant Proteins