1. Update on Cervical Disc Arthroplasty
Brian Su, MD
John Ratliff, MD
Associate Professor
Departments of Neurosurgery and Orthopedic Spine Surgery
Thomas Jefferson University

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

4. Becoming a billion dollar business

5. CDR mandates a critical look
Background
Analysis of IDE studies of FDA cleared CDR
Bottom line results
How they compare to previous studies
CDR for myelopathy
Adjacent level disease and longest available follow up
CPT coding changes

6. Background First clinical report of CDR Bristol-Cummins
22 implanted for myelopathy in endstage cervical disease
Evolved into Prestige I, II, and ST (Medtronic)

7. Current CDR As of 7/2009 FDA approved CDR Several others under IDE
Prestige ST (Medtronic)
Bryan (Medtronic)
ProDisc-C (Synthes)
Several others under IDE

8. All IDE Studies Controls: Allograft and plate 2 year FU
Radiculopathy or myelopathy from single-level disease
Exclusion criteria
Marked spondylosis/Facet joint arthrosis
<2 º motion at index segment
>50% disc space collapse
Segmental instability (>3 mm translation)
Cervical kyphosis

9. Prestige ST IDE
Prestige ST stainless steel metal on metal ball and trough articulation
CDR (276 pts) vs. ACDF (265 pts) for single level disease

10. Prestige ST IDE NDI better in CDR group up to 3 mo only Collar use?
No difference in SF 36, neck or arm pain, or return to work status
In 2007 became first CDR FDA approved

11. Prestige ST IDE Only one other clinical study First RCT of CDR
CDR (27 pts) vs ACDF (28 pts)
2 yr FU; no difference between groups

12. Bryan IDE Polyurethane nucleus between titanium shell
CDR (242 pts) vs. ACDF (221 pts)
Better SF-36 score and arm pain relief at 1 yr for CDR not significant at 2 yrs

13. Bryan IDE
Lower neck pain score for CDR at all time points

14. Bryan IDE Lower NDI score for CDR at all time points
Difference may not be clinically significant

15. Bryan IDE
Earlier return to work at 1.5 and 3 months in CDR group but not at 2 yrs
RTW 13 days sooner in CDR group

16. Bryan IDE
2 other studies on Bryan CDR neither with control group

17. ProDisc-C IDE Metal on UHMWPE with CoCrMo alloy and midline keel
CDR (103 pts) vs. ACDF (106 pts)
No differences in any clinical outcome measures at 1 or 2 yrs

18. IDE ProDisc-C Significant differences at 2 yrs in favor of CDR
Secondary surgeries
9% ACDF vs 2% CDR
More patients on narcotics
19% ACDF vs 10% CDR
Unblinded surgeon discretion used to prescribe further treatments

19. IDE Pro-Disc C 2 other studies on Pro-Disc C
Bertagnoli et al (no control group)
Nabhan et al prospective RCT vs ACDF

20. Conflict of Interest

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

22. Adjacent to Fusion
No differences in improvement in NDI and VAS scores between two groups

23. ROM Preserving ROM ↓ adjacent IDP/facet forces?
3 IDE studies with  7º ROM at treated segment
 15% of patients with ↓ ROM or ankylosis

24. Adjacent Level Disease
Prevention of ALD is main focus of CDR
Hilibrand et al repeatedly referenced in CDR papers regarding adjacent level disease

25. Adjacent Level Disease
2.9%/yr symptomatic adjacent level disease
In agreement with progression in non-fusion procedures (Henderson 1983 Neurosurgery)

29. Adjacent Level Disease
Only 1 clinical study on ALD in CDR vs fusion
Bryan vs. Affinity cage
2 yr FU
Patients from separate RCT trials
Cohort of patients 6 yrs apart

30. Adjacent Level Disease
7% symptomatic in fusion group vs 0% in CDR
Radiographs not blinded
Posterior osteophytes not included
Not CDR vs ACDF

31. Long Term Results
Potential 7 yr FU of first RCT CDR not reported

32. Future Problems MRI imaging may be impossible in some devices
Sekhon, Duggal, et al. Spine 32: 2007
Non-titanium devices make MRI imaging impossible due to artifact
PCM, Prodisc C
Could not visualize either the operated upon nor adjacent levels
With titanium devices, imaging was feasible

33. Summary 3 CDR currently approved Know indications/exclusion criteria
IDE studies show early benefit but for the most part equivalent to ACDF
Bryan CDR less neck pain and NDI at 2 yrs
CDR ok for myelopathy and adjacent to fusion
Benefits in ↓ ALD promising
No published reports longer than 2 yr FU

34. Conclusion Natural history is unclear
Adjacent segment disease important
Arthroplasty rapidly evolving
Long term impact of cervical arthroplasty remains unclear