22 - The Effect of rhBMP-2 in one-level PLIF...

#22 The Effect of rhBMP-2 in one-level PLIF

Biologic Therapies

Poster Presented by: J. Michielsen

Author(s):

J. Michielsen (1)
J. Sys (2)

(1) University Hospital of Antwerp, Antwerp, Belgium
(2) Sint Blasius Hospital, Dendermonde, Belgium

Abstract

Introduction: In this prospective randomized controlled trial, our objective was to assess both the clinical and radiological effect of recombinant human bone morphogenic protein (rhBMP-2) on an absorbable collagen carrier (inductos™) in instrumented posterior lumbar interbody fusion (PLIF) with polyetheretherketone (PEEK) cages (Telamon™).

Materials and Methods: Forty patients were recruited for the study fulfilling strict entry requirements and were randomized with a 1:1 ratio. Patients completed the Oswestry Disability Index (ODI), the Short-Form 36 (SF-36), and the Visual Analogue Score (VAS) preoperatively and postoperatively at 3, 6, 12, and 24 months, respectively. CT-scans of the fused segment with reconstructions in both the coronal and the sagital plane were taken postoperatively at 3, 6, and 12 months, respectively. Posterior stabilisation was achieved with pedicle screws and interbody fusion was aimed at with PEEK cages, filled with 8 mg of rhBMP-2 in the study group and autologous bone in the control group.

Results: Baseline demographic data showed no statistical difference between groups, except that the BMI was higher in the study group. There were no significant clinical differences (VAS, ODI, and SF-36) between the 2 groups at each time interval. At 3 months, end plate resorption was noted around the cages filled with rhBMP-2 in all patients. No cage migration nor subsidence were observed. Bridging Trabecular Bone Scale scores and bone density measures were significantly lower in the study group at 3, 6, and 12 months.

Osteolysis and ectopic bone formation occurred in 36,8% of the study group and did not occur in the control group. This did not result in radicular symptoms, however.

At 2 years, CT-scans showed osseous healing with no difference between groups. There were no revision procedures.

Conclusion: End plate resorption, osteolysis, and ectopic bone formation were frequently noted in posterior lumbar interbody fusion with cages, filled with rhBMP-2 on an absorbable collagen carrier. However, this did not result in clinical differences or a decrease in fusion rate when compared to cages filled with autograft bone. CT-graphic findings suggest that dosage determination, carrier improvement, and eventual sealing of the product in the disc space need further attention.