Better 5-Year Results With Cervical Arthroplasty Than Fusion

CHICAGO, Illinois — Patients who underwent cervical disc arthroplasty had improved clinical outcomes and segmental vertebral motion at 5 years, according to new research. In addition, neck disability was better after arthroplasty than after anterior cervical discectomy and fusion.

"Our 5-year data show cervical disc arthroplasty is as good as or better than discectomy with fusion," said principal investigator J. Kenneth Burkus, MD, an orthopaedic surgeon at the Hughston Clinic in Columbus, Georgia. In fact, "disc arthroplasty could certainly be considered the gold standard for single-level cervical degenerative disc disease," he said.

Dr. Burkus explained that the device used for the arthroplasty — the Prestige ST cervical disc system (Medtronic Sofamor Danek) — "does not have a drop-off or failure rate up to 5 years, and 5 years is considered a significant milestone for hip and knee replacement."

His team conducted the multicenter prospective randomized exemption study comparing arthroplasty with anterior cervical discectomy and fusion. He presented the findings here at the American Academy of Orthopaedic Surgeons 2013 Annual Meeting.

The study involved 541 patients treated at 32 sites from October 2003 to August 2004. Five-year outcomes for 271 of these patients were published previously (J Neurosurg Spine. 2010;13:308-318).

All patients underwent anterior cervical discectomy to treat single-level cervical disc disease. They were randomly assigned to receive either disc replacement (n = 276) or fusion with an allograft anterior cervical plate (n = 265). Demographic characteristics, including mean age, were similar in the 2 groups.

Five-year follow-up data were available for 219 patients in the arthroplasty group and 188 in the control group, Dr. Burkus reported.

Table. Mean Neck Disability Index Scores During 5-Year Follow-up Period

Follow-up Assessment	Arthroplasty Group Score	Control Group Score	P value
2 years	35.4	33.9	ns
3 years	36.3	31.3	.008
5 years	38.2	33.8	.014

The rates of maintenance or improvement in neurologic status (motor function, sensory function, and reflex) were significantly higher in the arthroplasty group than in the control group at all 3 follow-up assessments (P = .025).

Arm and neck pain improved in both groups, and there was no statistically significant between-group difference.

No patients in the arthroplasty group required revision surgery to adjust the implant configuration or supplemental fixation to place additional spinal devices, other than an external bone growth stimulator, Dr. Burkus reported, whereas a few patients in the control group did. This difference was statistically significant at 5 years.

Table. Mean 5-Year Outcomes

Outcome	Arthroplasty Group	Control Group	P Value
Neurologic status success (%)	92.2	85.7	.025
Revision surgery (n)	0	6	.013
Supplemental fixation (n)	0	5	.028

Fewer surgical procedures were required to repair adjacent segment disease in the arthroplasty group than in the control group, although the difference was not statistically significant.

"We have not proved that arthroplasty eliminates adjacent segment disease, but it looks promising," Dr. Burkus told Medscape Medical News.

Five years after arthroplastic surgery, range of motion was preserved — average angular motion was 6.7°— and there was no migration.

The fact that range of motion was preserved and reoperation was less frequent in the arthroplasty group than in the control group treated with the current gold-standard surgery is important, said session comoderator Ronald Lehman, MD, who was asked by Medscape Medical News to comment on the findings.

"It really could change practice," said Dr. Lehman, who is from the Walter Reed National Military Medical Center in Bethesda, Maryland.

It will be important to determine whether cervical disc replacement reduces adjacent segment disease, which is the reason "most of us perform cervical disc arthroplasty," Dr. Lehman explained.

The US Food and Drug Administration approved the artificial cervical disc in 2007, but a 7-year postoperative follow-up is required. Dr. Burkus said they expect to report the 7-year data next year.

This study was funded by Medtronic Sofamor Danek. Dr. Burkus reports receiving research funding, speaker fees, and consulting fees from Medtronic; and receiving royalties unrelated to the Prestige system. Dr. Lehman has disclosed no relevant financial relationships.

American Academy of Orthopaedic Surgeons (AAOS) 2013 Annual Meeting: Abstract 159. Presented March 20, 2013.