Update on Cervical Disc Update on Cervical Disc ArthroplastyArthroplasty

Brian Su, MDBrian Su, MD

John Ratliff, MDJohn Ratliff, MD

Associate ProfessorAssociate Professor

Departments of Neurosurgery and Orthopedic Spine Departments of Neurosurgery and Orthopedic Spine SurgerySurgery

Thomas Jefferson UniversityThomas Jefferson University

Almost all published after 2001Almost all published after 2001 34 in last year (2 prospective RCT)34 in last year (2 prospective RCT)

Becoming a billion dollar businessBecoming a billion dollar business

CDR mandates a critical lookCDR mandates a critical look Background Background Analysis of IDE studies of FDA cleared CDRAnalysis of IDE studies of FDA cleared CDR

Bottom line resultsBottom line results How they compare to previous studiesHow they compare to previous studies

CDR for myelopathyCDR for myelopathy Adjacent level disease and longest available follow Adjacent level disease and longest available follow

upup CPT coding changesCPT coding changes

BackgroundBackground

First clinical report of CDR First clinical report of CDR Bristol-Cummins Bristol-Cummins

22 implanted for myelopathy in 22 implanted for myelopathy in endstage cervical diseaseendstage cervical disease

Evolved into Prestige I, II, and ST Evolved into Prestige I, II, and ST (Medtronic)(Medtronic)

Current CDRCurrent CDR As of 7/2009 FDA approved CDRAs of 7/2009 FDA approved CDR

Prestige ST (Medtronic)Prestige ST (Medtronic) Bryan (Medtronic)Bryan (Medtronic) ProDisc-C (Synthes)ProDisc-C (Synthes)

Several others under IDESeveral others under IDE

All IDE StudiesAll IDE Studies Controls: Allograft and plateControls: Allograft and plate 2 year FU2 year FU Radiculopathy or myelopathy from Radiculopathy or myelopathy from single-level single-level

diseasedisease Exclusion criteriaExclusion criteria

Marked spondylosis/Facet joint arthrosisMarked spondylosis/Facet joint arthrosis <2 º motion at index segment<2 º motion at index segment >50% disc space collapse>50% disc space collapse Segmental instability (>3 mm translation)Segmental instability (>3 mm translation) Cervical kyphosisCervical kyphosis

Prestige ST IDEPrestige ST IDE

Prestige ST stainless steel Prestige ST stainless steel metal on metal ball and trough metal on metal ball and trough articulationarticulation

CDR (276 pts) vs. ACDF (265 CDR (276 pts) vs. ACDF (265 pts) for single level diseasepts) for single level disease

Prestige ST IDEPrestige ST IDE

NDI better in CDR group up to 3 mo onlyNDI better in CDR group up to 3 mo only Collar use?Collar use?

No difference in SF 36, neck or arm pain, or No difference in SF 36, neck or arm pain, or return to work statusreturn to work status

In 2007 became first CDR FDA approvedIn 2007 became first CDR FDA approved

Prestige ST IDEPrestige ST IDE

CDR (27 pts) vs ACDF (28 pts) CDR (27 pts) vs ACDF (28 pts) 2 yr FU; no difference between groups 2 yr FU; no difference between groups

Only one other clinical studyOnly one other clinical study First RCT of CDRFirst RCT of CDR

Bryan IDEBryan IDE

Polyurethane nucleus between titanium shellPolyurethane nucleus between titanium shell CDR (242 pts) vs. ACDF (221 pts)CDR (242 pts) vs. ACDF (221 pts) Better SF-36 score and arm pain relief at 1 Better SF-36 score and arm pain relief at 1

yr for CDR not significant at 2 yrsyr for CDR not significant at 2 yrs

Bryan IDEBryan IDE Lower neck pain score for CDR at all time Lower neck pain score for CDR at all time

pointspoints

Bryan IDEBryan IDE Lower NDI score for CDR at all time pointsLower NDI score for CDR at all time points

Difference may not be clinically significantDifference may not be clinically significant

Bryan IDEBryan IDE Earlier return to work at 1.5 and 3 months Earlier return to work at 1.5 and 3 months

in CDR group but not at 2 yrsin CDR group but not at 2 yrs RTW 13 days sooner in CDR groupRTW 13 days sooner in CDR group

Bryan IDEBryan IDE 2 other studies on Bryan CDR neither with 2 other studies on Bryan CDR neither with

control groupcontrol group

ProDisc-C IDEProDisc-C IDE

Metal on UHMWPE with CoCrMo Metal on UHMWPE with CoCrMo alloy and midline keelalloy and midline keel

CDR (103 pts) vs. ACDF (106 pts)CDR (103 pts) vs. ACDF (106 pts) No differences in any clinical No differences in any clinical

outcome measures at 1 or 2 yrsoutcome measures at 1 or 2 yrs

IDE ProDisc-CIDE ProDisc-C

Significant differences at 2 yrs in favor of CDRSignificant differences at 2 yrs in favor of CDR Secondary surgeries Secondary surgeries

9% ACDF vs 2% CDR9% ACDF vs 2% CDR More patients on narcotics More patients on narcotics

19% ACDF vs 10% CDR 19% ACDF vs 10% CDR Unblinded surgeon discretion used to Unblinded surgeon discretion used to

prescribe further treatmentsprescribe further treatments

IDE Pro-Disc CIDE Pro-Disc C 2 other studies on Pro-Disc C2 other studies on Pro-Disc C

Bertagnoli et al (no control group)Bertagnoli et al (no control group) Nabhan et al prospective RCT vs ACDFNabhan et al prospective RCT vs ACDF

Conflict of Interest Conflict of Interest

Adjacent to FusionAdjacent to Fusion

PCM Disc: Unconstrained CoCr and UHMWPE press fitPCM Disc: Unconstrained CoCr and UHMWPE press fit Adjacent to prior fusion (26 pts) vs. primary CDR (126 pts)Adjacent to prior fusion (26 pts) vs. primary CDR (126 pts) Part of IDE study even though no ACDF control groupPart of IDE study even though no ACDF control group

Adjacent to FusionAdjacent to Fusion No differences in improvement in NDI and No differences in improvement in NDI and

VAS scores between two groupsVAS scores between two groups

ROMROM Preserving ROM ↓ adjacent IDP/facet forces?Preserving ROM ↓ adjacent IDP/facet forces? 3 IDE studies with 3 IDE studies with 7º ROM at treated 7º ROM at treated

segmentsegment 15% of patients with ↓ ROM or ankylosis15% of patients with ↓ ROM or ankylosis

Adjacent Level DiseaseAdjacent Level Disease Prevention of ALD is main focus of CDRPrevention of ALD is main focus of CDR

Hilibrand et al repeatedly referenced in CDR Hilibrand et al repeatedly referenced in CDR papers regarding adjacent level diseasepapers regarding adjacent level disease

Adjacent Level DiseaseAdjacent Level Disease

2.9%/yr symptomatic adjacent level disease2.9%/yr symptomatic adjacent level disease

In agreement with progression in non-fusion In agreement with progression in non-fusion procedures procedures ((Henderson 1983 NeurosurgeryHenderson 1983 Neurosurgery))

Adjacent Level DiseaseAdjacent Level Disease

Only 1 clinical study on ALD in CDR vs fusionOnly 1 clinical study on ALD in CDR vs fusion Bryan vs. Affinity cageBryan vs. Affinity cage 2 yr FU2 yr FU

Patients from separate RCT trialsPatients from separate RCT trials Cohort of patients 6 yrs apartCohort of patients 6 yrs apart

Adjacent Level DiseaseAdjacent Level Disease

7% symptomatic in fusion group vs 0% in CDR 7% symptomatic in fusion group vs 0% in CDR Radiographs not blindedRadiographs not blinded Posterior osteophytes not includedPosterior osteophytes not included Not CDR vs ACDFNot CDR vs ACDF

Long Term ResultsLong Term Results

Potential Potential 7 yr FU 7 yr FU of first RCT CDR not reportedof first RCT CDR not reported

Future ProblemsFuture Problems

MRI imaging may be impossible in some MRI imaging may be impossible in some devicesdevices Sekhon, Duggal, et al. Spine 32: 2007Sekhon, Duggal, et al. Spine 32: 2007 Non-titanium devices make MRI imaging Non-titanium devices make MRI imaging

impossible due to artifactimpossible due to artifact PCM, Prodisc CPCM, Prodisc C

Could not visualize either the operated upon Could not visualize either the operated upon nor adjacent levelsnor adjacent levels

With titanium devices, imaging was feasibleWith titanium devices, imaging was feasible

SummarySummary 3 CDR currently approved 3 CDR currently approved Know indications/exclusion criteriaKnow indications/exclusion criteria IDE studies show early benefit but for the most IDE studies show early benefit but for the most

part equivalent to ACDFpart equivalent to ACDF Bryan CDR less neck pain and NDI at 2 yrsBryan CDR less neck pain and NDI at 2 yrs

CDR ok for myelopathy and adjacent to fusionCDR ok for myelopathy and adjacent to fusion Benefits in ↓ ALD promisingBenefits in ↓ ALD promising

No published reports longer than 2 yr FU No published reports longer than 2 yr FU

Natural history is unclearNatural history is unclear Adjacent segment Adjacent segment

disease importantdisease important

Arthroplasty rapidly Arthroplasty rapidly evolvingevolving

Long term impact of Long term impact of cervical arthroplasty cervical arthroplasty remains unclearremains unclear

ConclusionConclusion