This may be useful information for the many EDSers who are faced with cervical disc fusions.
For single-level cervical disease with radiculopathy, implanting a prosthetic cervical disc provides a slight advantage over discectomy and fusion, researchers said this week at the Congress of Neurological Surgeons.
They based their conclusions on a meta-analysis of three randomized multicenter trials comparing implantation of various artificial discs to anterior cervical discectomy and fusion (ACDF).
Both procedures had excellent two-year results, according to senior researcher Dr. Praveen V. Mummaneni, from the University of California, San Francisco. But the replacement discs preserved sagittal motion and resulted in better neurological outcomes and less need for reoperation.
Getting the procedures paid for is likely to be a challenge, however, because insurance companies are still reluctant to reimburse for them.
The three trials each tested a different artificial disc. Two are from Medtronic (Medtronic Sofamor Danek, Memphis, TN — the Prestige ST Cervical Disc System and the Bryan Cervical Disc prosthesis — and the other, the ProDisc-C Total Disc Replacement System, is from Synthes Spine (Paoli, PA).
The ProDisc-C Total Disc Replacement system and the Prestige Cervical Disc System received FDA approval in 2007; the Bryan Cervical Disc received premarket approval on May 12, 2009. At this point, Medicaid, Medicare and many private insurers still claim there's insufficient clinical evidence to support medical efficacy.
The cohort presented this week — 1,213 patients with symptomatic, single-level cervical disc disease — is "the largest ever seen" in a study of treatment for this disease, said Dr. Mummaneni.
Overall, 621 patients received artificial cervical discs and 592 patients had ACDF, with 94% of the arthroplasty group and 87% of the ACDF group followed for two years.
"Sagittal motion was maintained in all three trials," said Dr. Mummaneni. In the arthroplasty group, segmental sagittal motion averaged 7.26 degrees preoperatively and 8.14 degrees after two years. At that point, the ACDF patients had a fusion rate of 95%. The analysis did not compare the various devices to each other.
The arthroplasty patients did not differ significantly from the ACDF patients in neck disability index, short-form-36 mental component subscore, short-form-36 physical component subscore, or intensity or frequency of pain in the arm or neck as measured by a visual analogue scale.
But the arthroplasty group enjoyed better neurological success (p=0.006) and a lower rate of secondary surgeries (p= 0.018). When analyzed using a fixed effects model, the reoperation rate for adjacent level disease was lower for the arthroplasty group as well (p=0.026).
The studies were too different from each other in their definitions of adverse events to compare this criterion, said Dr. Mummaneni.
Asked to comment, Dr. Michael Groff from Cambridge, MA said he was especially intrigued by the lower rate of adjacent level diseases with arthroplasty. Dr. Groff is chief of the neurosurgical spine service at Beth Israel Deaconess Medical Center in Boston.
The premise for disc replacement is that although single-level fusion doesn't appear to reduce global mobility of the spine, it may increase pressure on and movement of adjacent disc segments, leading to their degeneration. Replacing the degenerated discs with artificial ones is intended to reduce that risk.
Laird Harrison • Reuters Health Information © 2010