Influence of rhBMP-2 on the healing patterns associated with allograft interbody constructs in comparison with autograft.
METHODS
A prospective, nonblinded, multicenter study.


OBJECTIVE
To determine the patterns of allograft incorporation and new bone formation after ALIF using stand-alone threaded cortical allograft dowels with either autograft or rhBMP-2.


BACKGROUND
Accelerated healing patterns of allograft dowels have been reported in an animal study and a small human study of ALIF with rhBMP-2 and bone dowels.


METHODS
We enrolled and randomly assigned 131 patients with lumbar spondylosis who were undergoing single-level ALIF with allograft dowels to either the investigational group who received rhBMP-2 (79 patients) or the control group who received autologous bone graft (52 patients). Independent radiologists used plain radiographs and computed tomography scans to evaluate fusion. Allograft incorporation was assessed using a modified Bridwell-Lenke scale, and changes in bone density within the adjacent vertebral bodies were monitored.


RESULTS
At 12 months, all investigational patients had radiographic evidence of new bone formation and incorporation of the allografts into the adjacent vertebral endplates; there were no changes in fusion status at 24 months. Fusions were documented in 89% of patients in the control group at 12 months. The percentage declined to 81.5% at 24 months with 10% of the patients in the autograft group showing incomplete healing and 11% having no healing of the allograft dowels. On CT scans, 14 of the investigational patients (14 of 79; 18%) developed a transient, localized area of bone remodeling within the vertebral body adjacent to the allograft dowel. All were healed by 24 months. The transient appearance of these zones had no effect on clinical outcomes. No patient in the control group developed bone remodeling zones.


CONCLUSIONS
We think that the use of rhBMP-2 is a promising method of facilitating allograft dowel incorporation and new bone formation in patients undergoing ALIF with allograft dowels.
Wilderness Spine Services, Hughston Clinic, Columbus, GA 31909, USA. jkb66@knology.net
J Kenneth
JK
Burkus
Harvinder S
HS
Sandhu
Matthew F
MF
Gornet
D000328:Adult; D000368:Aged; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage*; D016025:Bone Transplantation / Q000379:methods*; D017586:Diskectomy / Q000379:methods; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000601:surgery / Q000637:transplantation*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010012:Osteogenesis; D011446:Prospective Studies; D011859:Radiography; D011994:Recombinant Proteins / Q000008:administration & dosage*; D013128:Spinal Osteophytosis / Q000000981:diagnostic imaging / Q000601:surgery*; D016212:Transforming Growth Factor beta / Q000008:administration & dosage*; D014182:Transplantation, Autologous / Q000379:methods; D014184:Transplantation, Homologous / Q000379:methods; D016896:Treatment Outcome
D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2