Ryan William Kaliney MD, Presenter: Nothing to Disclose

Michael Gregory Fox MD, Abstract Co-Author: Nothing to Disclose

Vincent Arlet MD, Abstract Co-Author: Nothing to Disclose

Jonathan Mason MD, Abstract Co-Author: Nothing to Disclose

Cree Michael Gaskin MD, Abstract Co-Author: Research Consultant, DePuy Mitek, Inc Research grant, DePuy Mitek, Inc Royalties, Oxford University Press Royalties, Thieme Medical Publishers, Inc Royalties, Lippincott Williams & Wilkins

Francis H. Shen MD, Abstract Co-Author: Nothing to Disclose

To evaluate the effects of recombinant bone morphogenetic protein-2 (rhBMP-2) on transforaminal lumbar interbody fusion (TLIF) utilizing allografts by comparing radiographic outcomes of TLIF performed with and without rhBMP-2 in the intervertebral disc space.

63 vertebral levels (49 patients) which underwent TLIF by a single surgeon during a two year period were retrospectively assembled. Levels were grouped into those in which rhBMP-2 was used in the intervertebral disc space (Group A: 32 patients, 38 levels) and those in which no rhBMP-2 was used (Group B: 17 patients, 25 levels). Postoperative follow-up radiographs were reviewed by two radiologists, assessing for endplate erosion, allograft subsidence, allograft migration, new bone formation, and bridging bone by consensus. Endplate erosion was graded as “none to mild” or “moderate to severe.” The other measures were scored as present or absent. Statistical analysis was performed using Chi-square test.

Preliminary results demonstrate moderate to severe endplate erosion in 16% (6/38) of Group A levels as compared to 4% (1/25) of Group B (p = 0.15). Similarly, allograft migration and subsidence were more common in Group A (11% and 18%) than B (0% and 8%, p = 0.09 and 0.24). Group A demonstrated a greater percentage of new bone formation (84%) than Group B (38%, p = 0.13). At 53%, bridging bone was observed more often in Group A as compared to 25% in Group B (p = 0.02).

Endplate osteolysis attributed to rhBMP-2 in interbody fusion has been documented in the orthopedic literature, but it has not been reported in the radiology literature to our knowledge. Though endplate osteolysis, allograft migration, and allograft subsidence were all seen more commonly on follow-up radiographs of TLIF levels with interbody rhBMP-2, statistically significant differences from the cohort of TLIF levels without rhBMP-2 were not observed. A greater sample size would likely achieve statistical significance. Such statistical significance was achieved in the correlation of rhBMP-2 usage and bridging bone formation. Our findings are likely attributed to rhBMP-2 causing an osteoclastic response prior to the intended osteoinductive response.

The usage of rhBMP-2 in lumbar interbody fusion likely results in radiographically apparent complications which have received minimal attention heretofore.

Kaliney, R, Fox, M, Arlet, V, Mason, J, Gaskin, C, Shen, F, Does the Use of Recombinant Bone Morphogenetic Protein-2 (rhBMP-2) Affect the Imaging Appearance Following Transforaminal Lumbar Interbody Fusion (TLIF) Utilizing Allograft?.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9009610.html