7 Year Outcome Comparing Cervical Disc Arthroplasty vs ACDF

Mark Shaffrey, MD discussed the long-term outcome of the Prestige^® LP Cervical Disc (Medtronic Sofamor Danek, Inc., Memphis, TN) versus anterior cervical discectomy (ACDF) and fusion (ie, plated fusion with allograft). Of particular interest, as Dr. Shaffrey brought out, “is the durability of the treatment.”
This was a prospective study with 20 investigational sites comparing 265 historically-controlled ACDF patients in a prior cervical investigational device exemption study.The cervical artificial disc (CAD) is described as a low-profile, ball-in-trough device that allows some anterior/posterior translation with flexion and extension. A titanium plasma spray on the disc’s surface allows for bony ingrowth. The artificial disc is made from a titanium-ceramic alloy that offers favorable imaging.  

About the Study
This was a prospective study with 20 investigational sites comparing 265 historically-controlled ACDF patients in a prior cervical investigational device exemption study. There were 280 investigational patients.

Inclusion criteria:

• Single-level radiculopathy and/or myelopathy
• C3-C7
• Herniated disc, spondylosis
• Pre-operative Neck Disability Index (NDI) ≥ 30
• Six weeks failed nonoperative treatment
• ≥ 18 years of age

Exclusion critera:

• More than one level requiring surgery
• Fused level adjacent to index level
• Previous surgery at the index level
• Instability
• Deformity
• Facet joint pathology
• > 50% disc space collapse
• Osteoporosis

Results
Patient follow up at 84 months (7 years) was 75.0% in the CDA group and 68.7% in the ACDF group. In both groups, improvement in preoperative NDI and SF-36 were achieved by 1.5 months and maintained to 84 months.

Dr. Shaffrey asked and answered, “Did the device do its job over a period of seven years? It did. The mean angular motion measurements at the target level were approximately 7%, and of course the ACDF did its job as well with minimal motion over a period of seven years.”  With the neurologic status of success, the percent of patients who experienced maintenance or improved postoperative status based on motor function, sensory function, and reflexes—there was a significant difference between CAD and ACDF groups.

With regard to secondary surgeries, Dr. Shaffrey commented, “We looked at revisions, which are a modification of the original device; for instance, putting in a longer screw in a plate; device removal, both electively and necessary removal; supplemental fixations; and reoperations, which would include things like foraminotomies at the level or adjacent level. And what we saw was a difference overall in the percentage of patients who require index level reoperations; approximately 11% for the ACDF [group] and approximately 6.5% for the investigational arm [CAD].”