6/13/2014. Cervical Disc Arthroplasty (CDA) preserves motion

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1 6/13/2014 Joseph R. O Brien, MD, MPH Associate Director of Spine Surgery, GWUH Associate Professor of Orthopaedic Surgery and Neurosurgery Department of Orthopaedic Surgery The George Washington University School of Medicine Cervical Disc Arthroplasty (CDA) preserves motion Is superior to Anterior Discetomy and Fusion (ACDF) with regard to complications and adjacent segment degeneration Will prove to be durable in the long term ACDF is tried and true Disc arthroplasty represents the siren song of technological advance 1

2 6/13/ Complication rate equal or less than ACDF 2. Long-term durability 3. Equal or better in terms of lasting relief compared with ACDF 4. Reduce the incidence of adjacent level degeneration 5. Ease of implantation 6. Acceptable cost FM. Phillips, S.R. Garfin, MD. Cervical Disc Replacement. Spine, 30 (17S), pp S27 S33; Patients single level disc replacement 3% operative complication rate Patients multi-level disc replacement 2.18% re-operation rate 2 Comparable to ACDF rate: 0.95% to 3.8% based on metaanalysis 3 1. Goffin J, et al. Spine 2003;28: Pimenta, et al. Spine 2007; 32: Villavicencio AT. Spine J Mar-Apr;7(2): Epub 2006 ACDF: incidence as high as 21.3% at 2 years 1 CDA may have decreased esophageal pressure due to decreased retraction 2 CDA has no anterior profile compared to plate with ACDF 4 Prospective, randomized study on dysphagia with CDA (18mos): 2.2% CDA v. 4.5% ACDF 4 1. Riley, LH, et al. Spine 2005; 30: Tortolani, PJ J Spinal Disord Tech; 2006; 19; Villavicencio AT. Spine J Mar-Apr;7(2): Epub Datta, J. Proceedings of the NASS 21st Annual Meetings / Spine Journal 6 (2006) 1S 161S 2

3 6/13/ patients single level / 44 bi-level No device failures or explantations at 2 years/ 1 year for either group patients Survivorship at 3 years 94.5% 2 Long term data pending 1. Goffin J, et al. Spine 2003;28: Pimenta, et al. Spine 2007; 32: in vitro spine stimulator and in vivo in goat / chimpanzee models Wear debris produced 1.2 mg/million cycles 10 million cycles/ 0.75% weight loss of the prosthesis Device heights decreased by 0.02mm/million cylcles Comparison: ACDF plates had more metallic debris and inflammation Anderson et al., Spine % for single level arthroplasty at 2 years 96% for bi-level arthroplasty at 1 year 93% for multi-level arthroplasties at 3 years Comparable to ACDF: 93% 3, 96% 4, 94% 5, 93% 6 1. Goffin J, et al. Spine 2003;28: Pimenta, et al. Spine 2007; 32: Riley LH, et al. J Neurosurg. 30: , Gore, et al. Spine 9: , Brodke DS and Zdeblick TA. Spine 17;10S: S , Klein GR, Vaccaro AR, Albert TJ. Spine 25;7: ,

4 6/13/2014 Biomechanical data on intra-discal pressure adjacent to ACDF 1 : 48% increase in proximal level 125% increase in distal level 1. Dmitriev, AE. Et al. Spine 2005; 30: patients in prospective, randomized multicenter trial 1.1% (3 operations) in CDA 2 above, 1 below 3.4% (11 operations) in ACDF 3 above, 7 below, 1 above/below Returned to work average 16 days sooner in CDA group 1. Mummaneni, Burkus, Haid, Traynelis, Zdeblick. J Neurosurg Spine 6: , Patients should be informed that there is an approximately one in four chance of new disease developing at another level in the first ten years after an anterior cervical arthrodesis. We believe that this risk is related to the natural history of cervical spondylosis rather than to a failure of the operative technique and that it is probably unaffected by the operative management. Most of our patients in whom symptomatic adjacent-segment disease developed did not respond to non operative management, but the new symptoms usually resolved after anterior cervical decompression and arthrodesis 1 50 % of people have cervical spondylosis by age 50 2, but do 25% of 50 year olds need an ACDF? Hilibrand, A, et al. J Bone Joint Surg Am. 1999;81: Kellgren, J. H., et al. Ann. Rheumat. Dis., 17: ,

5 6/13/2014 It doesn t make sense ACDF alters biomechanics in vitro and in vivo How many extra levels are Fused because of spondylosis??? Perspective through other comparisons Knee Arthrodesis since Sir Charnley had 99% success and 99% fusion rate 2 TKA v. Knee arthrodesis 3 SF-36 similar in the two groups. Fusion group higher global score Arthrodesis had a better pain score Arthrodesis patients were more likely to be sucidial 1. Lexer E.. Surg Gynecol Obstet. 1908;6: Charnley J. Arthrodesis of the knee. Clin Orthop. 1960;18: Benson ER, et al. Orthopedics. 1998;21:

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7 Cervical TDA Biomaterials/Wear Debris Wellington K. Hsu, MD Clifford C. Raisbeck Distinguished Professor of Orthopaedic Surgery Director of Research, NMH Musculoskeletal Institute Department of Orthopaedic Surgery Department of Neurological Surgery Northwestern University Feinberg School of Medicine 6/16/2014 Chicago, IL Entity Consulting Advisory Board Speaker s Bureau Research Grant Medtronic X Stryker X Pioneer/RTI X Depuy-Synthes X AONA X Lifenet X Globus X Bioventus X Wellington K. Hsu, MD Spinesmith X Graftys Clifford C. Raisbeck X Distinguished Professor of Orthopaedic Surgery Zimmer Director of Research, NMH X Musculoskeletal Institute LSRS Department of X Orthopaedic Surgery X CSRS Department of X Neurological Surgery OREF Northwestern University Feinberg School of Medicine X 6/16/2014 Disclosures Chicago, IL Referendum on TDA Many FDA-approved implants ACDF not a perfect surgery Potential Advantages Improve clinical outcomes Retain range of motion Reduce ASD 1

8 Theoretical rationale Implants retain motion at the index level Metal-on-polethylene articulations provide safe wear Motion is good 6/16/2014 What is the effect from the biomaterials??? Points of Interest Basic Design Considerations/Concepts Biomaterials Articulating surfaces Wear Debris Endplate Incorporation 2

9 Design Considerations Past experience with Hip Knee Shoulder Goal: Creation of Artificial joint Safe Stable Durable Biomechanically sound Design Considerations Cervical spine with unique considerations Bone stock is limited IVD as a contributor to spinal stability by resotring balance to anterior and middle columns (unlike TJA) Stability dependent on intact ligament structure Must work with dorsal facet articulations Expected lifespan longer than hip/knee prostheses (30-50 yrs) 3

10 Basic design concepts Fixed or single-axis of motion Ball-and-socket Prodisc-C Prevent translation during rotation Variable axis of motion Coupled translation with rotation during motion Ball-and-trough Prestige ST Biomaterials Important considerations Durability Incidence of fatigue / fracture Wear characteristics Stiffness, biocompatibility, resistance to corrosion MRI-compatible materials Biomaterials Stainless steel Most inexpensive Widely available Less compatibility Imaging artifacts concerns Alloys include iron, carbon, chromium, nickel, molybdenum Prestige ST Cobalt-chromium alloy Contains molybdenum Improved mechanical properties Highest young s modulus and hardness Excellent long-term wear profiles MRI quality worse than titanium alloys Prodisc-C and PCM 4

11 Biomaterials Titanium Biocompatible, inert Promote ingrowth of bone Titanium oxidizes to form TiO2 on surface Resistance to corrosion Best imaging artifact profile Pure titanium has inferior fatigue performance, stress notching, brittle nature Alloys improve upon characteritstics Prestige LP, Bryan Metal versus PE Metal-on-metal reduced wear rates with smaller debris particles compared to metal-on-pe Wear particles greater in number Systemic effect Surface Articulation Polyethlyene Ultra High-Molecular Weight Polyethylene Low friction when compared to metals Conventional UHMWPE Decreases wear rate in vitro Highly cross-linked UHMWPE Created through electron-beam irradiation Not yet used in cervical TDA In TJA, threshold of thickness that prevents catastrophic failure (6-8 mm) Not yet defined in TDA 5

12 Surface Articulation Polycarbonate-polyurethane Excellent biocompatibility Better viscoelastic properties than UHMWPE Wear resistance similar to UHMWPE Used in lumbar dynamic pedicle screw devices and cervical arthroplasty (Bryan) Potential for decreased inflammatory reaction PEEK, silicon, polyvinyl alcohol, ceramic (ceramic-metal alloys) Wear particles Debris is created by all devices having a bearing surface Wear particles are bioactive Can activate macrophages and production of cytokines (PG-3, IL-1, IL- 6, TNF-α) Inflammatory effect compared to TJA is unknown Nano-sized particles may be more biologically active than others Dose of debris appears to be important - No osteolysis seen - New onset clicking - Areas of necrotic debris 6

13 Reviewed published reports of explanted cervical artificial discs 9 articles 17 devices Metallic and polymeric debris common Inflammatory cells frequently present in surrounding tissues 4 patients with hypersensitivity to metal Conclusion: cervical disc implants consistently associated with metallic debris and inflammation 7

14 Endplate Incorporation Most TDA implants have bone-implant interface that is titanium Similar modulus of elasticity to bone Faster incorporation Bryan (titanium porous coating) ProDisc-C, CerviCore (plasma-sprayed surface) Hydroxyapatite also used Lumbar disc arthroplasty (NuNec) SB Charite PCM combines titanium with HA with 3- layer coating Unique considerations to cervical TDA Differences in biomaterials used Beware of metal-on-metal articulations Long-term implications of wear debris unknown 8

15 Wellington K. Hsu, MD Clifford C. Raisbeck Distinguished Professor Director of Research Department of Orthopaedic Surgery Department of Neurological Surgery Northwestern University Feinberg School of Medicine 9

16 6/12/2014 Latest Controversy around Adjacent Segment Disease ACDF vs CDR Louis G. Jenis, MD Boston Spine Group Associate Chair, Orthopaedic Surgery Newton Wellesley Hospital Clinical Associate Professor, Orthopaedic Surgery Tufts University School of Medicine Newton, MA Disclosures Consulting / product training Stryker Spine NuVasive Royalties Stryker Spine Breakaway Imaging Definitions Post arthrodesis adjacent segment pathology Adjacent segment degeneration (ASDeg) Development of new radiographic degenerative changes adjacent to a surgical fusion Absence of symptomatology Adjacent segment disease (ASDis) New degenerative changes adjacent to a fusion accompanied by symptoms Neurocompressive pathology - radiculopathy / myelopathy Neck pain related to biomechanical instability Controversial - pain 1

17 6/12/2014 Etiology Controversy ASDeg / ASDis related to natural history of age-related changes or biomechanically-induced following anterior cervical fusion Natural history Boden, et al, - 63 asymptomatic subjects MRI <40yo - 14% - - >40yo 28% Matsumoto, et al, asymptomatic subjects Linear increase in degenerative findings Adjacent level disc injury Needle localization Adjacent level ossification disease (ALOD) Sagittal alignment Boden, et al, JBJS 72A: , 1990; Matsumoto, et al, Spine 35:36-42, 2010 Etiology Controversy Fusion need critically consider ASDeg / ASDis Wide variability reported 9-17% ASDis / 1.5 4% annual incidence Cho, Riew JAAOS 21:3-11, 2013 Controversy Fusion Xia, et al - systematic review of literature Prevalence of adjacent segment pathology up to studies = 34,716 patients Lawrence, et al, - predicting the risk of ASDeg Systematic review studies - 4 retrospective / 1 database total of % / year 11-12% at 5 years 16-38% at 10 years 33% at 17 years Reoperation rate - 0.8% / year Risk Factors Age less than 60 at time of ACDF Fusion adjacent to C5C6 or C6C7 Preexisting spondylosis / HNP Etiology Xia, et al, Spine 38: , 2013; Lawrence, et al, Spine 37:s52-64,

18 6/12/2014 ACDF vs CDR Is CDR a viable alternative? Symptoms / stability / surgical technique Some clinical parameters CDR better? Question remains - effect on ASDeg / ASDis? Numerous designs Several clinical trials IDE regulated by FDA Noninferiority design Does CDR reduce incidence? ACDF vs CDR CDR vs ACDF Cho, Riew JAAOS 21:3-11, 2013 ACDF vs CDR CDR vs ACDF Nunley, et al, - 3 prospective RCT 113 CDR / 57 ACDF 1 or 2 level month f/u (median 38 month) Nunley, et al, Spine 37: ,

19 6/12/2014 ACDF vs CDR CDR vs ACDF Maldonado, et al, 190/208 patients minimum 3 year f/u 105 ACDF / 85 CDR Equivalent clinical outcomes ASDeg 10.5% ACDF / 8.8% CDR (P=0.72) Maldonado, et al, Eur Spine J 20:s , 2011 ACDF vs CDR CDR vs ACDF Park, et al, Retrospective cross-sectional study 22 patients CDR / 21 patients ACDF 5 year F/U MRI / CT / Radiographs ASDeg Demographically similar significant improvements VAS / NDI Radiographic fusion % ACDF / 4.5% CDR ACDF % / CDR 50% Park, et al, Eur Spine J 22: , 2013 ACDF vs CDR CDR vs ACDF Coric, et al, Bryan / Kineflex CDR 41 CDR / 33 ACDF single level 86% minimum 4 years f/u average 72 months (48 108) 4.9% adjacent level reoperation in CDR VS 3.0% ACDF Coric, et al, JNS 18:36-42,

20 6/12/2014 ACDF vs CDR Summary No clear evidence that ACDF increases incidence ASDeg / ASDis Short term studies comparing CDR Index level clinical outcomes comparable significant difference in preventing clinical symptoms from adjacent level pathology Small sample sizes 5 6 year maximum f/u THANK YOU 5

21 Biomechanical and Surgical Techniques for TDR Ronald A. Lehman, Jr., M.D. Professor of Orthopaedic Surgery Professor of Neurological Surgery Cervical and Pediatric and Adult Deformity Washington University School of Medicine St. Louis, MO 7 th Annual Cervical Spine Research Society Course Feb 20-22, 2014, St. Louis, MO Many Current Choices Goals of arthroplasty: preservation of motion cervical kinematics Surgeon must consider: biomechanics at the surgical level device design instruments for implantation surgical technique Upadhyaya et al J NSG Spine 2012

22 Fixation Modes of Various Implants Theoretical COR Initial Fixation Puttlitz et al. NCNA 2005 Technique Considerations Lateral Uncinate Lehman A wider and more thorough uncinate process and osteophyte resection is necessary when a TDR is performed in patients with myelopathy (and even in patients with spondylotic radiculopathy) than in a fusion. If the decompression is inadequate, continued motion across the segment may lead to recurrence of symptomatic spondylosis; in contrast, after cervical fusion procedures, osteophytes often regress once a solid fusion has been obtained

23 Most Important for TDR- Reference the Midline Adequate Decompression Decompression Considerations Anterior Inferior Aspect of Cephalad Body ACDF/Corpectomy Take off anterior osteophytes Take off anterior inferior lip Allows better visualization Better access for decompression Better surface area for screw placement & bone graft sizing TDRs Prestige Remove Ant osteophytes Recess anterior aspect of VB Bryan Remove Ant osteophytes Do NOT remove Anterior Lip ProDisc-C Remove Ant osteophytes Minimal burr work

24 Prestige TDR Pearls and Pitfalls Preop T2 MRI 21 yo Div I Wrestler Several Stingers Profound Weakness Prestige Surgical Technique Decompress disc herniation Caspar pins & anterior osteophytes

25 Prestige Placement Guide and Trial Final Implant placement Postop Prestige Returned to Div I Wrestling Postop Prestige 28 yo Special Forces Soldier Midline Good Posterior Placement

26 Prestige 3 year Postop Prestige Hybrid Osteolysis Bryan TDR Pearls and Pitfalls

27 Preop MRI C5/6 and 6/7 HNP Axial T2 C 6/7 C 5/6 Caution with Internal Distractor Device for Bryan vs. ProDisc-C Easy to violate spinal canal Rely on Internal Distractor

28 Bryan Surgical Technique Adequate lateral Dissection Bryan TDR Caspar Pin Placement Pins parallel and far from endplate 2-Level Sx, Place pin midpoint VB Internal Distractor Place posterior ring apophysis Distract under Fluoro; Ext distract

29 Place Trial and Cutter Assess with Fluoro Place Posterior Mill with distraction Bryan Trialing Disc decompression After Milling HNP Implant Placement Check grooves after Milling Partially Distract to Place TDR

30 Confirm with AP and Lat in OR Perfect Lateral Assess Rotation Implants in Place C6/7 C6/7 and C5/6 C6 Final Fluoro Images

31 2-level ACDFs decrease C4-T1 ROM 2-level Pro Disc-C increases overall ROM ACDF/ProDisc-C hybrid ROM operative levels ~ same as intact Regarding adjacent-level ROM 2-level ACDF increases ROM 2-level ProDisc-C and hybrid ACDF/PPs~NO significant change COR Parameters based on Placement Device placed per Guidelines Resultant 1.1 deg Ant to Preop Device too Anterior ProDisc-C Pearls and Pitfall

32 Caspar Pins and Trial Placement Further from Endplate Internal Distraction then External Distraction thru Caspar pins ProDisc-C Wide Decompression Trial in Place Final Trial AP and Lat

33 ProDisc C Final Steps Caudal Milling Implant in Place Final Fluoro AP and Lat Pitfalls

34 ProDisc-C Hybrid N.B. Implant in Flexion Immediate Postop 1 Year Follow Up 1 Year Postop Operative Flexion/Extension Extension (Splinting) Flexion Do NOT get Fooled by Intraoperative Fluoroscopy

35 Anatomic Midline Less Reliance on AP Fluoroscopy Postoperative Films ProDisc-C Heterotopic Ossification Ext? Too Wide HO

36 Thank You