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Anterior Cervical Arthrodesis & Pseudarthrosis

Anterior Cervical Arthrodesis & Pseudarthrosis. Diagnosis and Treatment. Sanjay Jatana, MD February 25, 2011. Disclosures. FDA Device Status: Off-label use of InFuse discussed (Medtronic) Conflict of Interest: None Paid Consultant: Zimmer Hospital Agreement: Rose Spine Institute. OPTIONS.

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Anterior Cervical Arthrodesis & Pseudarthrosis

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  1. Anterior CervicalArthrodesis & Pseudarthrosis Diagnosis and Treatment Sanjay Jatana, MD February 25, 2011

  2. Disclosures • FDA Device Status: Off-label use of InFuse discussed (Medtronic) • Conflict of Interest: None • Paid Consultant: Zimmer • Hospital Agreement: Rose Spine Institute

  3. OPTIONS

  4. Background • Fusion • (-) motion • (-) lucency • (+) bony ingrowth • Pseudarthrosis • without detectable motion • with obvious motion • symptomatic vs. asymptomatic

  5. AR – 3 - LEVEL

  6. Is there a Problem? • Fusion Rates • One Level ACDF 93-95% • Two Level ACDF 70-75% (100%) • Three Level ACDF 50-60% Two & Three Level Fusion Rates UNACCEPTABLE

  7. Five FDA IDE Trial Data from Texas Back Institute of CDR v. ACF Guyer, R.D. et al., CSRS paper 65, 2010 • 127 patients (81 CDR, 46 ACF) • 12-60 month follow-up • (1) 1.2% reoperation in CDR (adj. segment) • (2) 4.3% reoperation in ACF (pseudo) • (1) 2.2% reoperation in ACF (adj. segment) • No difference between ACF v. CDR • Blood loss, op time, LOS, NDI

  8. Anterior Cervical Pseudarthrosis 67% symptomatic (28% asymptomatic for 2 years) 33% asymptomatic Re-operation : fusion: 19 Excellent, 1 Good Phillips, FM et al: Spine, 1997 Bohlman, HH., et. al: JBJS, 1993

  9. Pseudarthrosis of the Cervical Spine: A Comparison of Radiographic Diagnostic Measures • Solid Fusion (18), Pseudarthrosis (11) • Flexion-extension radiographs • Manual measurement technique • Cobb angle (IVM) • Distance between tips of spinous processes (SPD) • SPD BETTER in reliability, specificity & sensitivity • Pseudarthrosis: Greater than 2 mm difference in sp. process distance Cannada, LK, et al; SPINE, 28:46-51, 2003

  10. Radiographic Motion Thresholds Cobb Angle • Kimax QMA, medical metrics software • (accuracy: 0.5deg motion, 0.5mm translation) • FDA guideline: 4 degrees of motiondefines Pseudoarthrosis Hipp, JA, et al: SPINE, 2005

  11. MMI FDA Pseudoarthrosis Detection Failure Rate Guidelines are needed to define how much IVM should be of clinical concern. Dependence of Pseudoarthrosis Rate on the Threshold Used to Define Fusion

  12. Threshold Cervical Range-of-Motion Necessary to Detect Abnormal Intervertebral Motion in Cervical Spine Radiographs Hwang, H., Hipp, J.A., et. al., SPINE, 33:E261-7, 2008 Cadaver Study Need to Flex-Extend to a minimum range of 60 degrees before evaluation for instability in the sub-axial spine Center of rotation most sensitive in determining abnormal motion and potential injury

  13. Short Term Comparison of Cervical Fusion with Static and Dynamic Plating Using Computerized Motion Analysis Goldberg, G., Albert, T., et al., SPINE 32:E371-375, 2007 • Computerized evaluation of digital films can improve accuracy and reproducibility of analysis of AC Fusion. • Angular Threshold of 2 Degrees • Accuracy error of 0.5 degrees • Reproducibility error of 0.9 degrees • 2 Degrees allows for some natural motion at fusion • Dynamic plates = Static plates

  14. Fusion Rate Goldberg, G., Albert, T., et al., SPINE 32:E371-375, 2007 Short Term Comparison of Cervical Fusion with Static and Dynamic Plating Using Computerized Motion Analysis 2 level ACDF (Thomas Jefferson/Rothman Institute) ACDF/Static Plate/autograft: 87.8% per level ACDF/Dynamic Plate/allograft: 89.8% per level All pseudarthrosis patients were asymptomatic (10-13 months)

  15. Patient TT – C7 Stabilized C6-7 Rotation = 4.9º

  16. Patient TT – C6 Stabilized C6-7 Rotation = 4.9º; C5-6 Rotation = 1.1º

  17. Patient TT – C5 Stabilized C5-6 Rotation = 1.1º; C4-5 Rotation = 5.0º

  18. Patient TT – C4 Stabilized C4-5 Rotation = 5.0º

  19. Study Demographics • Symptomatic patients one year after ACDF who underwent PSF to address symptoms / pseudarthrosis • Pre-op CT scan, Radiographs with flexion/extension • Intra-operative findings to clarify pre-op data • Motion evaluated at the facet joints Ghiselli, Wharton, Hipp, Wong, Jatana., SPINE 2011

  20. Study • 2003 – 2005 • 24 levels, ACDF, minimum 1 year after surgery, with recurrent symptoms • Neck Pain, Radiculopathy • Age 35-69 • One 1 level, four 2 level, five 3 level • Diagnostic Imaging, X-rays, CT scan, posterior spinal fusion

  21. Methods • Inter-vertebral motion (IVM) at fusion level • Quantification by medical metrics (Kimax QMA software) • CT scan reviewed by neuro-radiologist • Intra-operative motion noted at facet joints • Correlation between findings, CT scan and motion analysis reviewed

  22. Results • 13/24 levels pseudarthrosis (intraoperative) • 7/13 less than 2 degrees of IVM (0-7.2 degrees) • 11/24 levels with fusion, IVM range 0 – 0.9 degrees • CT scan 9/13 (+) pseudarthrosis

  23. Statistical Analysis

  24. 4 Degree Threshold • Study suggests a high PPV • Low sensitivity (23%) • ie: miss pseudarthrosis with < 4 degrees of motion • At 1 degree • Sensitivity higher (77%)

  25. CT scan • NPV is 73% • Subject to Type I, II errors

  26. Anterior Cervical Fusion Assessment Buchwowski, J.M., et al., SPINE 33:11, 1185-91, 2008 • 14 patients • CT, MRI, X-rays & Intra-operative findings • Kappa values • 0.67 X-rays • 0.81 CT Scan • 0.48 MRI • CT scan agrees the best with intra-operative findings but not 100%

  27. Conclusion 2008 • Symptomatic pseudarthrosis in the cervical spine can exhibit less than 2 degrees of IVM • No agreement - Current radiographic methods to diagnose pseudoarthrosis. • The 4 degree angular motion threshold accepted by the FDA maybe too high. • Threshold at less then 2 degrees yields the higher sensitivity, specificity, PPV and NPV Ghiselli, Jatana, Wharton, CSRS, 2007

  28. Key Points Ghiselli, Wharton, Hipp, Wong, Jatana., SPINE 2011 Quantitative Motion Analysis (QMA) is an effective tool to diagnose cervical pseudarthrosis. Combining QMA with CT increases the NPV in diagnosing pseudarthrosis. Current thresholds for pseudarthrosis need to be redefined as they lack specificity.

  29. ACDF : The Landscape • Fusion rates decrease as levels fused increase • Multi-level disease forces ant/post surgery • Same day, staged, later date • Cervical deformity forces ant/post surgery • Arthroplasty for multilevel disease not approved • Who knows if it ever will • Stand alone laminectomy / laminoplasty / foraminotomy • limitations

  30. “Improve the Environment” • Don’t Fuse • Laminectomy • Laminoplasty • Multilevel arthroplasty • Anterior Corpectomy/Discectomy • Accept pseudoarthrsis rate and address as needed • Mechanical – Plate, Screw designs • Biological – Bone, Cells, BMP’s

  31. RhBMP-2 REFERENCES • Williams, B.J., CSRS paper #20, 2010 • Pradan, B. et al., CSRS 2006, poster 26 (Delamarter) • Alexander, G.A., et al., CSRS 2007, paper 7 • Shen, H.X., et al., CSRS 2007, poster 14 • Bae, H., et al., CSRS 2007, poster 21 • Miller, C. et al., CSRS 2007, paper 17 (Delamarter) • Singh, K. et al., CSRS 2007, paper 52 rhBMP-2 and repeat surgery • Allen, T.R. et al., SPINE 2007, 32:26, 2996-3006 rhBMP-2, osteomyelitis • Pradhan, B.et al., CSRS 2004, paper 31 (Delamarter) • Patel,V., et al., CSRS 2004, paper41 (Delamarter) • Smucker, J.D. et al., CSRS 2005, paper 50 • Smucker, J.D. et al., SPINE 31, 2006 • Longley, C.L. et al. CSRS 2005, paper 7 • Bae, H.W. et al., CSRS 2005, poster 23 (Delamarter) • Burd, T.A. et al., CSRS 2006, paper 37 • Sheilds et al. SPINE 31: 2006

  32. Comparison of the Incidence of Complications of Anterior Cervical Fusion with and without BMP: A Report of the Scoliosis Research Society Morbidity and Mortality Committee Williams, B.J., CSRS paper #20, 2010 • 2004-7, 5184 Cases, BMP used in 622 (12%) • Superficial & deep infection, dysphagia, mortality • 373 revisions (7.2%), BMP used in 107 (29%) • Stat signif. Results • Overall complication rate 5.8% v. 2.4% • Overall infection rate 2.1% v. 0.4% • Deep infection rate 1.2% v. 0.2%

  33. POSITIVE • RhBMP-2 use in the neck works • Increase fusion rates • Decrease pseudoarthrosis rates • Decrease rate repeat surgery ? • Cost is high

  34. Shen, H.X. et al., CSRS 2007 (Riew,D) • Pseudoarthrosis in rhBMP-2 augmented multilevel ACF • 127 cases, minimum 2 year follow up • Fibular allograft and plate fixation • 3 level - 77pts 4% • 4 level - 32pts 16% • 5 level - 8pts 17% • Lowest level C6-7 - 14pts, C7-T1 - 2pts • @6 mo. 10/16pts asymptomatic, @12 mo. 6/10pts fused • Nonunion rate = 13.4% @ 6 mo. 8.7% @ 1 year • Factors: revision surgery, age>50 (smoking, DM not signif. stat) • “Long lever arm overwhelms the biologic advantage of BMP”

  35. EJ – 6mo, 1year

  36. BMP Issues • Heterotopic Bone Formation • Neural Irritation • Soft Tissue Swelling • Seroma/Hematoma • Immunologic footprint

  37. 2-LEVEL Fusion

  38. AR – 3 - LEVEL PSF

  39. PB – Myelopathy

  40. PB - MRI

  41. PB – Lami/Laminoplasty/PSF

  42. Anterior Cervical Fusion • Pseudarthrosis rates vary • Patients may be asymptomatic for a long time • No agreed upon radiographic criteria • Probably underestimated • Need to follow patients that have possible pseudarthrosis longer than one year • Treatment Options not perfect • Revision anterior fusion • Posterior spinal fusion • BMP use in the neck is OFF-LABEL • Not 100% successful • Higher complications

  43. Sanjay Jatana, MD Gary Ghiselli, MD David A. Wong, MD Scott A. Bainbridge, MD C. Deno Pappas, MD denverspine.com jatanaspine.com

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