Transcript Diagnosis - Jatana Spine
Anterior Cervical Arthrodesis & Pseudarthrosis
Diagnosis and Treatment
Disclosures
FDA Device Status: Off-label use of InFuse discussed (Medtronic) Conflict of Interest: None Paid Consultant: Zimmer Hospital Agreement: Rose Spine Institute
OPTIONS
Background
Fusion (-) motion (-) lucency (+) bony ingrowth Pseudarthrosis without detectable motion with obvious motion symptomatic vs. asymptomatic
AR – 3 - LEVEL
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
Five FDA IDE Trial Data from Texas Back Institute of CDR v. ACF 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 Guyer, R.D. et al., CSRS paper 65, 2010
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
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
Radiographic Motion Thresholds Cobb Angle
Kimax QMA, medical metrics software (accuracy: 0.5deg motion, 0.5mm translation) FDA guideline: 4 degrees of motion defines Pseudoarthrosis Hipp, JA, et al: SPINE, 2005
Failure Rate
Pseudoarthrosis Detection
Guidelines are needed to define how much IVM should be of clinical concern.
MMI FDA
Dependence of Pseudoarthrosis Rate on the Threshold Used to Define Fusion
Threshold Cervical Range-of-Motion Necessary to Detect Abnormal Intervertebral Motion in Cervical Spine Radiographs 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 Hwang, H., Hipp, J.A., et. al., SPINE, 33:E261-7, 2008
Short Term Comparison of Cervical Fusion with Static and Dynamic Plating Using Computerized Motion Analysis 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 Goldberg, G., Albert, T., et al., SPINE 32:E371-375, 2007
Fusion Rate
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) 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
Patient TT – C7 Stabilized
C6-7 Rotation = 4.9º
Patient TT – C6 Stabilized
C6-7 Rotation = 4.9º; C5-6 Rotation = 1.1º
Patient TT – C5 Stabilized
C5-6 Rotation = 1.1º; C4-5 Rotation = 5.0º
Patient TT – C4 Stabilized
C4-5 Rotation = 5.0º
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
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
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
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
Statistical Analysis
Sensitivity Specificity PPV 4 Degree QMA threshold 1 Degree QMA threshold CT Scan CT Scan + 1 Degree QMA
23%
77% 69% 85% 100% 100% 100% 100% 100% 100% 100% 100% NPV 52%
79% 73%
85%
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%)
CT scan
NPV is 73% Subject to Type I, II errors
Anterior Cervical Fusion Assessment
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% Buchwowski, J.M., et al., SPINE 33:11, 1185-91, 2008
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
Key Points
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.
Ghiselli, Wharton, Hipp, Wong, Jatana., SPINE 2011
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
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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
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
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 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% Williams, B.J., CSRS paper #20, 2010
POSITIVE
RhBMP-2 use in the neck works Increase fusion rates Decrease pseudoarthrosis rates Decrease rate repeat surgery ?
Cost is high
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)
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Long lever arm overwhelms the biologic advantage of BMP
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EJ – 6mo, 1year
BMP Issues
Heterotopic Bone Formation Neural Irritation Soft Tissue Swelling Seroma/Hematoma Immunologic footprint
2-LEVEL Fusion
AR – 3 - LEVEL PSF
PB – Myelopathy
PB - MRI
PB – Lami/Laminoplasty/PSF
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
Sanjay Jatana, MD Gary Ghiselli, MD David A. Wong, MD Scott A. Bainbridge, MD C. Deno Pappas, MD