Study: Artificial cervical disc safe, effective for degenerative cervical radiculopathy
Use of an artificial cervical disc from Spinal Kinetics LLC in the treatment of degenerative cervical radiculopathy was safe, effective and noninferior compared with anterior cervical discectomy and fusion, according to published results.
Frank M. Phillips, MD, and colleagues compared 160 patients with single-level symptomatic degenerative cervical radiculopathy undergoing cervical total disc replacement with the M6-C Artificial Cervical Disc to a matched subset of 189 patients who underwent anterior cervical discectomy and fusion (ACDF). Researchers performed pain and function, quality of life, safety, neurologic and radiographic assessments of motion. Composite clinical success at 24 months was considered the primary clinical endpoint.
Results showed significant improvements in patient-reported outcomes at all time points over baseline in both groups. Patients in the artificial cervical disc group also had significant improvement in overall SF-36 physical component score and neck and arm pain scores vs. the ACDF group, according to results. Researchers found similar improvements in composite clinical success and mean neck disability index between the two groups. At 24 months relative to baseline, researchers noted significantly fewer patients in the artificial cervical disc group used pain medication or opioids. Results showed patients in the artificial cervical disc group maintained range of motion, while the groups had comparable subsequent surgical interventions, dysphagia rates and series adverse events.
“This study adds to the body of literature supporting the value of cervical disc replacement relative to ACDF in appropriately selected patients. Previous FDA-approved artificial discs have ball-and-socket designs, which are unable to match the natural disc kinematics,” Phillips told Healio Orthopedics. “The M6, with its annular-nuclear design, uniquely provides cushioning, as well as graded resistance to motion, much more closely mimicking the function of a natural disc. The study confirms superiority of the M6 disc for numerous study endpoints and also showed significantly greater reduction in use of opioids at 2 years when compared to ACDF.”
Perspective
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The study by Frank M. Phillips, MD, and colleagues discusses a new cervical total disk replacement device, the M6-C. This new device has a non-articulating surface with a compressible viscoelastic nuclear core and an annular structure designed to replicate the structure and 6° of motion of the native disc. This study compared the M6-C with anterior cervical discectomy and fusion for single-level radiculopathy. The primary endpoint was composite clinical success. This study demonstrated non-inferiority of the M6-C to anterior cervical discectomy and fusion. Both procedures showed significant improvements in patient-reported outcomes at all time points over baseline. Composite clinical success and mean NDI improvements were similar. What was unusual is the reduced opioid use in the M6-C patients at 2 years.
Heterotopic ossification was seen in 89 of 150 patients in the M6-C group (17 of 150 with grade 3 or 4 heterotopic ossification). Heterotopic ossification has been shown to progress with time in many other studies. Lastly, there was no data on adjacent segment disease at 2 years, as this is usually negligible at this time point.
The M6-C mimics spinal kinematics better than other total disc replacement devices and shows significant promise compared to other devices. The critical issue will be: Does the improved kinematics translate to less adjacent segment disease and will the heterotopic ossification rates remain low? A single-level anterior cervical discectomy and fusion remains one of the most successful operations in spine surgery and the bar to surpass it remains high.
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