Clinical and radiographic correlation in the use of rhBMP2 for posterolateral lumbar spinal fusion'

1
Clinical and radiographic correlation in the use
of rhBMP-2 for posterolateral lumbar spinal
fusion.
Nauman Akhtar, MD Department of
Orthopedics Marc Underhill, MD Department of
Radiology Joseph Craig, MD Department of
Radiology Stephen Bartol, MD Department of
Orthopedics
2
Disclosure

• My disclosure is in the Final Program
• Book and in the AAOS database.
• In this study, the participants report no
  conflict of interest, conflict of commitment, or
  financial interest.

3
Objectives

• Determine the efficacy of rh-BMP2 (bone
  morphogenetic proteins) use in posterior spinal
  fusion surgery.
• Determine rh-BMP2s ability to influence complete
  fusion rates as determined by radiographic
  analysis.
• Determine risk factors that lead to
  pseudoarthrosis as determined by radiographic
  analysis.
• Explore clinical outcomes of patients after
  posterior lumbar fusion enhanced with rh-BMP2.

4
Study Design

• Retrospective review of prospectively collected
  outcomes data.
• 83 consecutive patients underwent posterior
  lumbar decompression and fusion
• All with autograft enhanced with bone
  morphogenetic protein

5
Methods Materials

• Total of 83 patients were initially evaluated, 63
  were included.
• All surgeries performed by single senior staff
  orthopaedic surgeon, Dr. Stephen Bartol.
• All patients underwent lumbar spine posterior
  decompression and fusion between 2003 - 2006.
• One to Seven levels, all with local autograft
  enhanced with rh-BMP2.
• Amount of rh-BMP2 utilized per level
• 1-2 Levels Small Package - 2.8mg
• 2-4 Levels Medium Package - 5.4mg
• 5 Levels Large Package - 8.4mg

6
Materials Methods

• Imaging
• Primarily AP and Lateral radiographs.
• Intermixed post operative CT /MRI
• Images interpreted by one senior staff,
  fellowship trained musculoskeletal radiologist.

7
Materials Methods

• Clinical Outcome Measures
• Oswestry Scores
• Back and Leg Pain Scores
• Evaluated at Pre-Op, 2-5 weeks, 6 weeks-2 months,
  3-5 months, 6-11 months, 1 year.
• Comorbidities Evaluated
• ASA Score
• Diabetes
• Smoking
• BMI

8
Methods Materials

• Exclusions
• 20/83- 2 groups
• 10/83
• 1 Poor post operative imaging.
• 5 patients with prior fusion surgery in the
  region in question.
• 4 patients entirely lost to follow up
• 10/83
• Bilateral incomplete fusion, but less than 1 year
  worth of imaging follow up.
• Expected average fusion rates at HFHS posterior
  fusion rates 12 months

9
Methods Materials

• Patient Population
• 23 male patients
• Age range 34 75, mean 55.4 years of age.
• 40 female patients
• Age range 34 84, mean 63 years of age.

10
Methods Materials

• Radiographic Fusion
• Determined to be solid if bridging bone with
  confluent trabeculation was evident between the
  transverse processes.

11
Methods Materials

• Result groups
• Complete fusion
• All levels involved with bilateral fusion

12
Methods Materials

• Result groups
• Partial fusion
• All levels fused on a single side.
• Scattered levels fused on opposite side.

13
Methods Materials

• Result groups
• Pseudoarthrosis
• Bilateral non- fusion
• At least 1 year post op.

14
Results
15
Results

• 51 Complete Fusion
• Average Time to Complete Fusion 306.24 Days
• Average Time to Fusion of Individual Sides
  283.06 days
• 16.1 faster than with out rh-BMP2
• Assuming 1 year expected fusion rate.
• 2/ 63 patients demonstrated pseudoarthrosis
• Both patients were smokers, however 54 of our
  total patients were smokers.
• 2 level fusion, 4 level fusion.

16
Results

• 2/63 rate of pseudoarthrosis yields a 98.6
  fusion rate.
• Rates for fusion in other studies with autograft
  alone
• 83.2, Jorgenson SS et al, Spine 1994
• 83, Carreon LY et al, Spine 2005
• 88, Angevine et al, Spine 2007

17
Days to Fusion Per Level
Days to Fusion
Number of Levels
18
Oswestry and VAS Scores
19
Conclusions

• rhBMP-2 is useful in aiding posterior fusion of
  the spine.
• As the number of levels increase, the average
  time to fusion also increases.
• Rate of pseudoarthrosis is significantly
  different with rh-BMP2 than fusion rates with
  autograft alone.
• Oswestry pain and functional scores seem to
  correlate with radiographic assessment of fusion.
• Smoking may be a risk factor to pseudoarthrosis,
  however not statistically in this study.

20
References

• 1.)Bone morphogenetic proteins basic concepts
• Setti S. Rengachary, M.D.
• Neurosurg Focus 13(6) Article 2, 2002
• 2.)A Comparison of Single-Level Fusions With and
  Without Hardware
• Mark Lorenz, MD, Michael Zindrick, MD, Paul
  Schwaegler, MD, et. Al
• Department of Orthopaedics and Rehabilitation,
  Loyola Univ. Medical Center
• Spine Vol 16, Number 8, Supplement 1991
• 3.)Correlation of Radiologic Assessment of Lumbar
  Spine Fusions with Surgical Exploration.
• Brodshym MD, Kovalsky, MD, Khalil MD
• Texas Institute for Spinal Disorders, Houston
  Texas, Baylor Medical College
• Spine, Volume 16, Number 6, Supplement 1991
• 4.)Developemental Abnormalities at the
  Lumbosacral Juncture Causing Pain and Disability
• Hibbs, M.D. F.A.C.S., and Swift MD
• New York Orthopaedic Dispensary and Hospital,
  New York
• Surgery, Gynecology, and Obstetrics pages
  604-612
• 5.)Effect of Regional Gene Therapy with Bone
  Morphogenetic Protein-2-Producing Bone Marrow
  Cells on Spinal Fusion in Rats
• Wang, MD, Kanim, MA, Yoo, BA, Campbell PhD,
  Berk, MD, Lieberman,MD
• Department of Orthopaedic Surgery, Univ. of
  California at Los Angles
• The Journal of Bone and Joint Surgery (American)
  85905-911 (2003)

21
References

• 6.)Effects of Spinal Instrumentation on Fusion of
  the Lumbosacral Spine
• Schwab, MD, Nazarian, MD, Mahmud, MD, Michelsen,
  MD
• Spine Volume 20, Number 18, pp 2023-2028 (1995)
• 7.)Evaluation of Lumbar Spine Fusion, Plain
  Radiogrpahs Versus Direct Surgical Exploration
  and Observation
• Kant, MD, Daum, MD, Dean, MD, Uchida, MS
• Spine Volume 20, Number 21, pp 2313-2317 (1995)
• 8.)Experimental Spinal Fusion with Use of
  Recombinant Human Bone Morphogenetic Protein 2
• Itoh, MD, Ebara, MD, Kamimura MD, Tateiwa, MD,
  Kinoshita MD, Yuzawa MD, Takaoka, MD
• Spine. 24 (14) 1402, July 15, 1999
• 9.)Lumbar Fusion With and Without Pedicle Screw
  Fixation Comments on a Prospective, Randomized
  Study
• Angevine, Peter D. MD, MPH Dickman, Curtis MD
  McCormick, Paul MD, MPH
• Spine 32 (13), 1 June 2007, pp 1466-1471
• 10) Higher costs with spinal fusion helpers
• OR Manager, Volume 22 No. 2, February 2006.