Use of recombinant human bone morphogenetic protein-2 as an adjunct in posterolateral lumbar spine fusion: a prospective CT-scan analysis at one and two years.
BACKGROUND
This study determines whether recombinant human bone morphogenetic protein-2 (rhBMP-2) (12 mg at the rate of 1.5 mg/mL) delivered on an absorbable collagen sponge with an added bulking agent can increase posterolateral lumbar spine fusion success rates and decrease time for fusion with autogenous bone grafts.


METHODS
A prospective, single institution, clinical case-matched, radiographic, cohort study was undertaken. A total of 52 patients underwent posterolateral lumbar arthrodesis with pedicle screw instrumentation. The experimental group (n=41) underwent placement of Iliac crest bone graft (ICBG) with InFUSE (12 mg/level at the rate of 1.5 mg/mL). The control group (n=11) consisted of sex-matched patients, consecutively collected over the same time period with an instrumented posterolateral arthrodesis and ICBG placed in the intertransverse space.


METHODS
Thin-cut (2 mm) axial, coronal, and sagittal reconstructions were blindly evaluated for evidence of bridging bone and cortication of the fusion mass by 3 separate reviewers. Fusions were graded and an overall score was given to the quality of the fusion mass.


RESULTS
Fifty patients (ICBG alone n=11; ICBG/rhBMP-2 n=39) were available for CT evaluation at 2-year follow-up. An overall 97% (68/70 levels; Definite+Probably Fused) fusion rate in the rhBMP-2 group was achieved as compared to the 77% fusion rate (17/22 levels) in the ICBG alone group (P<0.05). In the rhBMP-2 group, 92% of the patients (36/39 patients) received an overall excellent subjective fusion rating as compared to 27% (3/11) in the control group (P<0.05). There was no computed tomographic evidence of soft-tissue ossification, dural ossification, or laminar bone regrowth in any patient.


CONCLUSIONS
The adjunctive use of rhBMP-2 and ICBG seems to be safe and results in significantly larger and more consistent posterolateral fusion masses.
Singh
Kern
K
Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA. Kernsingh@gmail.com
Smucker
Joseph D
JD
Gill
Sanjitpal
S
Boden
Scott D
SD
D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000627:therapeutic use*; D016022:Case-Control Studies; D017024:Chemotherapy, Adjuvant; D015331:Cohort Studies; D008137:Longitudinal Studies; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000601:surgery*; D011379:Prognosis; D011446:Prospective Studies; D011859:Radiography; D011994:Recombinant Proteins / Q000627:therapeutic use; D016037:Single-Blind Method; D013123:Spinal Fusion / Q000379:methods*; D013168:Spondylolisthesis / Q000000981:diagnostic imaging* / Q000628:therapy*; D016212:Transforming Growth Factor beta / Q000627:therapeutic use*; D016896:Treatment Outcome
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta