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Patients needed fewer index level reoperations after CDR vs ACDF
Patients treated with the cervical disc replacement device retained 7º mean angular motion through the 7-year follow-up, according to study results.
Patients who underwent cervical disc replacement returned to work 20 days earlier than similar patients who were fused, according to recently presented data.
Mark E. Shaffrey, MD, FAANS, FACS, presented findings at the Spine Summit 2015: CNS/AANS Section on Disorders of the Spine & Peripheral Nerves Annual Meeting. In the study, outcomes of 280 patients were compaere to who received the Medtronic Prestige LP cervical disc replacement to historical controls treated with anterior cervical discectomy and fusion (ACDF).
The researchers found patients who underwent cervical disc replacement (CDR) returned to work at 40 postoperative days compared to 60 postoperative days for the patients who were fused. According to Shaffrey, other findings showed similar success with treatment between the groups at long-term follow-up, including resolution of arm pain.
CDR improvement similar to ACDF
After the disc replacement surgery, patients had mean angular motion at the target level that was maintained at 7.5° at 24 months and 6.9° at 84 months, according to the findings.
For disc replacement patients, “the mean angular motion measurements at the target level were approximately 7º and, of course, the ACDF did its job as well, with minimum motion over a period of 7 years,” Shaffrey said.
Mark E. Shaffrey
The analysis of the study data for the patients who received the investigational prosthesis and for the patients who underwent fusion was done independently at Vanderbilt University. The historical controls were from a different study with the same inclusion and exclusion criteria, he said.
Neck and arm pain scores improve
The Neck Disability Index (NDI), one key factor looked at in the study, was greater than or equal to 30 points at baseline and it improved 15 points from preoperative. About 86.1% of CDR patients in the cohort experienced a 15 point improvement compared to 80.1% in the ACDF cohort, according to the study abstract.
“You can see there was a difference between the investigational arm and the control arm, but overall what we saw was a probability of noninferiority at 100%,” Shaffrey said when he discussed the NDI results.
In addition, investigators found the CDR patients experienced greater improvement in arm pain, which was a mean of 41 points, compared with a 37.2 point mean improvement in arm pain in the ACDF patients.
Revisions studied long-term
One advantage of the long-term follow-up from this study, according to Shaffrey, was it shed light on outcomes, such as revisions and reoperations, which are not yet available in other studies of CDR procedures.
“We looked at revisions, which were a modification of original device, for instance putting in a longer screw in a plate, device removal both electively and necessary removals, supplemental fixations and reoperations, which would include things like foraminotomies at the same level or adjacent level. And, what we saw was a difference overall in the percentage of patients that required index levels reoperations — approximately 11% for the ACDF group and approximately 6.5% for the investigational arm,” Shaffrey said.
CDR improvements
He noted there were some small, but not statistically significant, differences between the groups, including heterotopic ossification bridging bone that increased by about 10% through the last follow-up.
“We do not know how that affects the device performance,” Shaffrey said.
The investigators concluded patients in the CDR cohorts reported significant improvements from baseline up to 84 months after surgery, which were comparable to the outcomes in an ACDF cohort. – by Susan M. Rapp and Robert Linnehan
- Reference:
- Shaffrey ME, et al. Oral paper #106. Presented at: Spine Summit 2015: CNS/AANS Section on Disorders of the Spine & Peripheral Nerves Annual Meeting; March 4-7, 2015; Phoenix.
- For more information
- Mark E. Shaffrey, MD, FAANS, FACS, can be reached at University of Virginia School of Medicine, Department of Neurosurgery, PO Box 800212, Charlottesville, VA 22908; email: mes8c@virginia.edu.
Disclosure: Shaffrey reports no relevant financial disclosures.
Perspective
Back to TopCongratulations to Dr. Shaffrey and colleagues for adding to the growing literature supporting cervical disc replacement as a viable, if not preferable, alternative to fusion in appropriately selected patients. They have presented a 7-year follow-up of a level 1 investigational device exemption study with fairly robust follow-up. On all outcome measures, arthroplasty was either comparable or superior to fusion out to 7 years. This has been repeated in multiple studies, both in the United States and outside the United States. As has been shown elsewhere, quicker return to normal function is seen in the arthroplasty group compared to fusion. In this particular study, median return to work time was 40 days compared with 60 days.
Scott L. Blumenthal
What I would have liked to have seen in this study are two other issues important to the field of arthroplasty in the cervical spine: the incidence and the degree of heterotopic ossification, particularly as it relates to range of motion. In addition, what is not reported, is the incidence of adjacent segment disease and a comparison of the rates of both same-segment and adjacent-segment surgery between the groups.
Again, congratulations to the authors and we look forward to more data on this low-profile, non-keeled next generation device.