Spinal arthroplasty has been on the cutting edge of spine technology and technique development for the past decade. While some surgeons rushed to adapt the new technology as an alternative to fusion, others waited to see whether these procedures delivered on the promise of better outcomes.
Short-term data shows cervical spinal arthroplasty could deliver the same — potentially better — outcomes than spinal fusion for appropriately indicated patients. Still, many surgeons in the field have held out for long-term data, which is just beginning to roll in.
"In the properly selected patients, cervical disc replacement is at least as beneficial as fusion," says Todd Albert, MD, President of Rothman Institute in Philadelphia. "The long term data generally shows as favorable results. In some studies the outcomes appear better than fusion. Also a small number of studies have suggested a higher re-operation rate in the fusion group. These findings will lower one barrier to usage in properly indicated patients."
An article published in an early 2014 edition of The Spine Journal examined the ProDisc II from Synthes and followed patients for five to 10 years. Among the 181 patients, researchers found:
• Highly significant improvements in baseline visual analog scale and Oswestry disability index scores at all levels postoperatively.
• VAS scores had a slight deterioration from 48 months onward
• Patient satisfaction remained stable, with 63.6 percent reporting high satisfaction and 22.7 percent reporting satisfactory outcomes.
• There was a complication rate of 14.4 percent.
• Incidence of revision for general or device-related complications was 7.2 percent.
• Two-level replacements also demonstrated significant VAS and ODI scores over baseline, but those results were significantly inferior to one-level cases.
A 2013 study published in Spine examining the ProDisc-C at 13 different treatment sites compared cervical disc replacement with spinal fusion. The researchers found:
• After five years, patients who underwent TDR had a 97.1 percent probability of no secondary procedures, compared with 85.5 percent for ACDF patients.
• No reoperations in TDR patients were due to implant breakage or device failure.
• Pseudarthrosis was the most common reason for reoperation at the index level among ACDF patients.
• Recurrent neck pain and/or arm pain was the most common reason for reoperation at the adjacent level for both groups.
• Only 2.9 percent of TDR patients had reoperations within five years of the initial surgery, compared with 14.5 percent of the ACDF patients.
Similar studies with new devices on the market will make an impact on the future of the procedure. In 2012, the U.S. Food and Drug Administration approved two cervical total disc replacement devices. A 2013 Research and Markets analysis predicted non-fusion procedures will gain popularity and adoption in coming years, and surgeons will begin exploring motion preservation technologies due to physical restrictions and degeneration of adjacent segments that spinal fusion can cause.
"All discs approved now have ranges of motion most compatible with flexion/extension, lateral bending," says Dr. Albert. "Future approved discs will hopefully have compliance/cushioning to more closely recapitulate the normal disc."
Some surgeons are performing cervical disc arthroplasties in the outpatient ambulatory surgery center setting. Richard Wohns, MD, founder of NeoSpine in the Puget Sound Area, Wash., published an article describing the cost-effectiveness of outpatient cervical disc arthroplasty in Surgical Neurology International in 2010. The article reviewed 26 patients who underwent outpatient cervical disc arthroplasty and found 100 percent of patients improved after the surgery and no postoperative complications.
The cost of outpatient single-level cervical disc arthroplasty was 62 percent less than outpatient single-level anterior cervical discectomy with fusion using allograft and plate. The arthroplasty procedure cost 84 percent less in the outpatient ASC than inpatient hospital setting.
Despite the potential for positive outcomes with cervical disc arthroplasty, reimbursement remains a barrier for many surgeons and patients.
"Some insurers still will not cover disc replacement despite the excellent and high-quality data demonstrating its safety and efficacy," says Dr. Albert.
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