At 10-year follow-up 19 of 22 (86.4%) of patients had data available in the investigational group (Figure 3). In the control group all 23 of 25 (92.0%) of patients were available for assessment. NDI scores were followed preoperatively and at routine postsurgical intervals (Figure 4). At the final follow up of 120 months, the NDI for the arthroplasty group was 8 (8.05) and that for the arthrodesis group was 15 (15.48) (Table 2), a statistically significant difference favoring the arthroplasty cohort (P = 0.0485). Both groups achieved and maintained improvement in comparison with their preoperative NDI baseline score of 50 (P < 0.0001).
VAS neck pain scores were similar in the presurgical groups, 7.5 arthrodesis and 7.2 arthroplasty. Both groups demonstrated sustained postsurgical, statistically significant improvement in these scores in comparison with their presurgical state over the follow-up intervals including the 7- and 10-year assessments (Figure 5). At the 7-year follow-up VAS neck was 2.71 for arthrodesis and 0.9 for arthroplasty (Table 1). At this interval, there was a significant difference between the two groups favoring arthroplasty (P = 0.0146). At the final 10-year, these assessments were 1.5 for arthrodesis and 1.3 for arthroplasty (Table 2). There was no-significant difference between these two groups at the final 10-year interval with respect to VAS neck pain (P = 0.6958).
VAS arm pain scores were also similar in the presurgical groups, 7.0 arthrodesis and 7.8 arthroplasty. Both groups demonstrated sustained postsurgical, statistically significant improvement in these scores in comparison with their presurgical state over the follow-up intervals including the 7- and 10-year assessments (Figure 6). At the 7-year follow-up VAS arm was 1.88 for arthrodesis and 0.45 for arthroplasty (Table 1). At this interval, there was a significant difference between the two groups, favoring the arthroplasty cohort (P = 0.0322). At the 10-year assessment, scores were 0.74 arthrodesis and 0.84 arthroplasty (Table 2). There was no-significant difference between these two groups at the final 10-year interval with respect to VAS arm pain (P = 0.8564).
Reoperations were examined at 10 years. In the arthroplasty cohort, two patients (9%) required operative interventions, one patient at an adjacent level, and a second patient at a nonadjacent level. The single patient initially randomized to fusion who received an arthroplasty did not require a reoperation. In the arthrodesis cohort, eight patients (32%) required reoperation. Two patients required multiple reoperations for a total of 11 operative events (11/25 = 44%). Six patients required an operative event at an adjacent level. None of the patients in our center's experience required a reoperation at the index surgical level.
Ten total patients required reoperation in this investigation overall (21%). Two patients in the arthroplasty group (9%) were later treated with additional cervical spine procedures. One patient underwent an ACDF at a nonadjacent level (two levels from the index arthroplasty site). The second patient was treated with an adjacent level arthrodesis. Eight patients in the arthrodesis group (32%) were later treated with additional cervical spine procedures, two patients of whom required multiple reoperations. Four patients required a single-level adjacent fusion. One patient underwent a secondary arthrodesis at a nonadjacent level. One patient underwent a posterior laminectomy at a nonindex and nonadjacent level. Two patients underwent multiple adjacent level fusions (one above and one below the index segment in separate operative and clinical events). One of these multiadjacent segment patients later required a posterior arthrodesis for pseudoarthrosis. Surgical survivorship of the prosthesis as defined by the metric of patient reoperation was 90.90% representing two reoperations in 22 total patients. By this same metric, arthrodesis surgical survivorship was 68.0% represented by the eight reoperations in 25 total patients. This difference was not a statistically significant finding (P = 0.05551).
A chart review was accomplished to assess the extent of our data availability and understand anomalies with data collection and reporting. Five patients were identified who were not available for 10-year follow up. Of these patients, one patient was deceased and four patient had failed to respond for further data collection and analysis and were “lost” to follow up for patient care and data collection. Three patients were converted intraoperatively from the randomized arthroplasty to ACDF. Intraoperative judgments of the operating surgeon appeared to play a substantial role in conversion of these patients to arthrodesis. One patient had enough degeneration of the index operative level that the disc-space could not be properly prepared with the disc preparation and milling tools. A second patient's disc space was anatomically too small to accommodate the smallest arthroplasty size available for implantation. The third patient's intervention was converted to arthrodesis secondary to inadequate visualization of the index operative level at C6-C7 and preparation and insertion of the arthroplasty device was felt to be inappropriate from a safety perspective. None of these patients required a reoperative event at any point during their 10-year follow up.
Anterior cervical discectomy and fusion demonstrates positive patient outcomes and high success rates with respect to fusion at the index surgical site.1 Cervical disc arthroplasty is an alternative to this procedure and data for many of these devices has been collected via US FDA IDE trials over a number of postsurgical intervals.9–15 Beyond the initial 24-month outcomes, longer-term data has also been published demonstrating favorable outcomes with both arthrodesis and arthroplasty.16–20 Our single-site data has been collected as part of the greater experience with the BRYAN device.9
We demonstrate success of cervical arthrodesis and arthroplasty over long-term 7- and 10-year intervals. Both groups demonstrated sustained improvements from presurgical baseline as assessed by NDI, and VAS arm and neck pain scores. The degree of this improvement compares favorably with former nonrandomized European clinical trials of this same device.21 Investigations of alternative arthroplasty devices have also demonstrated improvement with both of these techniques over time with similar outcome measures. At the final 120-month outcome the arthroplasty device did compare favorably with arthrodesis with respect to NDI, suggesting an advantage in the arthroplasty cohort with respect to this clinical outcome measure.
Although a rapid return to work and index safety of arthroplasty provided an early argument for in comparison with arthrodesis,9 the difference in reoperation rates is notable over the longer-term. A 32% reoperation rate in the arthrodesis cohort is inline with the 10-year predicted rate discussed in the landmark adjacent segment data published by Hilibrand el al.3 Their investigation suggested a rate of 2.9% per annum, a figure which mirrors our 10-year data very closely. In contrast, the 9% reoperation rate in the arthroplasty group at 10 years is suggestive of preservation of the adjacent levels to a degree not provided by arthrodesis at this interval. Longer-term investigations, including this cohort have been previously suggested to be critical to understanding the advantages of arthroplasty in this regard secondary to the altered mechanics of arthrodesis6,7 in contrast to arthroplasty. This advantage with respect to reoperation rate appears to be present in 7-year multicenter outcomes as reported in a randomized prospective investigation reported by Janssen et al,20 who noted a statistically significant (P = 0.0201) difference reoperation rate of 7% and 18% (arthroplasty vs. arthrodesis). These mechanical advantages do not appear to be at the expense of baseline outcomes with continued motion at the index surgical segment. This investigation supplements the effectiveness of arthrodesis in longer-term outcomes, and provides additional prospective data for a “gold standard” surgery.
There are weaknesses in this investigation. All patients in our dataset reached 10-year follow-up, yet data from the five patients (three investigational, two control) who were not examined might have altered our conclusions. It may be that subsets of single-center data do not ultimately reflect the longer-term results of the multicenter experience. Finally, the conclusions made with respect to adjacent segment degeneration, though consistent with prior investigations,3 may not be fully reflective of the characteristics of cervical aging.
Investigational trials are not-inclusive of all patients who may be eligible for a surgical intervention, and exclude patients who would either benefit from or have a poor-outcome with either an investigational device or the study control. This trial represents a narrow patient cohort of single-level disc concerns. Our single-center represents a second subset. Finally, of the 62 patients screened as eligible at our center 15 were excluded (15/62 = 24.2%): 10 patients were excluded by the sponsor as being ineligible (10/62 = 16.1%), and five patients withdrew secondary to follow-up requirements (5/62 = 8.1%). It is possible that conclusions reached in this investigation are not representative of the positive and/or negative outcomes that may be achieved in broad clinical. Although it is interesting to draw a parallel to the data collected by Hilibrand et al.3 and our 10-year reoperation rate, the data reflected in the Hilibrand et al. cohort is potentially far more surgically diverse than our dataset.
Three patients required intraoperative conversion from the randomized intervention (arthroplasty) to ACDF. A variety of factors may lead to such a decision such as: difficulty with implant sizing, imaging challenges related to device location or patient soft-tissue artifact, difficulty with implant seating/placement, intraoperative instability or failure of primary device fixation, failure of bone/disc preparation tools, challenges with device centering or anterior-posterior alignment, bone fracture/structural integrity, neurological decompression needs, and a variety of other surgeon, patient, or anesthesia driven factors. It is notable that these conversions were a deviation from the intended randomization and may have intrinsically changed the patient reported outcomes. However, of the three patients in question who were treated with arthrodesis instead of arthroplasty, all were available for 10-year follow up and none went on to reoperation during the course of their 10-year follow up. The single patient initially randomized to fusion who received an arthroplasty was also available for all follow-ups over the entire 10-year interval. This patient also had an excellent clinical outcome and was not one of the two arthroplasty patients who required a reoperation. Although all four of these patients appeared to have similar 10-year outcomes these deviations in treatment could either reflect negatively or positively on the outcome of arthrodesis or arthroplasty, and should be considered in the interpretation of this dataset.
A variety of investigations have been undertaken and described since the initiation of this FDA IDE trial. Data from investigations into arthroplasty at multiple levels is now becoming available.22 In addition, the mechanics and outcomes of arthroplasty adjacent to an arthrodesis are now being investigated.23,24 Facet degenerative change is not addressed with cervical disc arthroplasty and may serve as another opportunity for intervention. Novel bearing surfaces may address imaging artifact issues and may be coupled with simplified implantation techniques to create a more consistent experience for surgeons and patients. It will be important to compare this data with that collected from other arthroplasty trials over time. There may be arthroplasty design characteristics that prove to be more favorable with time. It is encouraging to find that the longer-term examinations of this technique appear to offer distinct advantages in comparison with arthrodesis.
* At 7- and 10-year follow up, both single-level arthrodesis and arthroplasty demonstrate sustained improvement in comparison to presurgical patient baseline outcome metrics.
* Cervical arthroplasty demonstrates greater improvement in NDI at 10-years in comparison with cervical arthrodesis.
* At 10-year follow-up the reoperation rate in the arthroplasty cohort of this investigation is lower but not statistically different (9%) than that observed in the arthrodesis cohort (32%) (P = 0.05551).
1. Bohlman HH, Emery SE, Goodfellow DB, et al. Robinson anterior cervical discectomy and arthrodesis for cervical radiculopathy. Long-term follow-up of one hundred and twenty-two patients. J Bone Joint Surg Am
2. Emery SE, Fisher JR, Bohlman HH. Three-level anterior cervical discectomy and fusion: radiographic and clinical results. Spine
3. Hilibrand AS, Carlson GD, Palumbo MA, et al. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am
4. Goffin J, van Loon J, Van Calenbergh F, et al. Long-term results after anterior cervical fusion and osteosynthetic stabilization for fractures and/or dislocations of the cervical spine. J Spinal Disord
5. Goffin J, Geusens E, Vantomme N, et al. Long-term follow-up after interbody fusion of the cervical spine. J Spinal Disord Tech
6. Eck JC, Humphreys SC, Lim TH, et al. Biomechanical study on the effect of cervical spine fusion on adjacent-level intradiscal pressure and segmental motion. Spine
7. Fuller DA, Kirkpatrick JS, Emery SE, et al. A kinematic study of the cervical spine before and after segmental arthrodesis. Spine
8. Brodke DS, Zdeblick TA. Modified Smith-Robinson procedure for anterior cervical discectomy and fusion. Spine
9. Heller JG, Sasso RC, Papadopoulos SM, et al. Comparison of BRYAN cervical disc arthroplasty with anterior cervical decompression and fusion: clinical and radiographic results of a randomized, controlled, clinical trial. Spine
10. Hisey MS, Bae HW, Davis R, et al. Multi-center, prospective, randomized, controlled investigational device exemption clinical trial comparing Mobi-C Cervical Artificial Disc to anterior discectomy and fusion in the treatment of symptomatic degenerative disc disease in the cervical spine. Int J Spine Surg
11. Phillips FM, Lee JY, Geisler FH, et al. A prospective, randomized, controlled clinical investigation comparing PCM cervical disc arthroplasty with anterior cervical discectomy and fusion. 2-year results from the US FDA IDE clinical trial. Spine (Phila Pa 1976)
12. Mummaneni PV, Burkus JK, Haid RW, et al. Clinical and radiographic analysis of cervical disc arthroplasty compared with allograft fusion: a randomized controlled clinical trial. J Neurosurg Spine
13. Gornet MF, Burkus JK, Shaffrey ME, et al. Cervical disc arthroplasty with PRESTIGE LP disc versus anterior cervical discectomy and fusion: a prospective, multicenter investigational device exemption study. J Neurosurg Spine
2015; Epub ahead of print.
14. Murrey D, Janssen M, Delamarter R, et al. Results of the prospective, randomized, controlled multicenter Food and Drug Administration investigational device exemption study of the ProDisc-C total disc replacement versus anterior discectomy and fusion for the treatment of 1-level symptomatic cervical disc disease. Spine J
15. Vaccaro A, Beutler W, Peppelman W, et al. Clinical outcomes with selectively constrained SECURE-C cervical disc arthroplasty: two-year results from a prospective, randomized, controlled, multicenter investigational device exemption study. Spine (Phila Pa 1976)
16. Hisey MS, Bae HW, Davis RJ, et al. Prospective, Randomized Comparison of Cervical Total Disk Replacement Versus Anterior Cervical Fusion: Results at 48 Months Follow-up. J Spinal Disord Tech
17. Delamarter RB, Murrey D, Janssen ME, et al. Results at 24 months from the prospective, randomized, multicenter Investigational Device Exemption trial of ProDisc-C versus anterior cervical discectomy and fusion with 4-year follow-up and continued access patients. SAS J
18. Zigler JE, Delamarter R, Murrey D, et al. ProDisc-C and anterior cervical discectomy and fusion as surgical treatment for single-level cervical symptomatic degenerative disc disease: five-year results of a Food and Drug Administration study. Spine (Phila Pa 1976)
19. Sasso RC, Anderson PA, Riew KD, et al. Results of cervical arthroplasty compared with anterior discectomy and fusion: four-year clinical outcomes in a prospective, randomized controlled trial. J Bone Joint Surg Am
20. Janssen ME, Zigler JE, Spivak JM, et al. ProDisc-C total disc replacement versus anterior cervical discectomy and fusion for single-level symptomatic cervical disc disease: seven-year follow-up of the prospective randomized U.S. Food and Drug Administration Investigational Device Exemption Study. J Bone Joint Surg Am
21. Goffin J, Van Calenbergh F, van Loon J, et al. Intermediate follow-up after treatment of degenerative disc disease with the Bryan Cervical Disc Prosthesis: single-level and bi-level. Spine
22. Davis RJ, Kim KD, Hisey MS, et al. Cervical total disc replacement with the Mobi-C cervical artificial disc compared with anterior discectomy and fusion for treatment of 2-level symptomatic degenerative disc disease: a prospective, randomized, controlled multicenter clinical trial: clinical article. J Neurosurg Spine
23. Phillips FM, Allen TR, Regan JJ, et al. Cervical disc replacement in patients with and without previous adjacent level fusion surgery: a prospective study. Spine (Phila Pa 1976)
24. Gandhi AA, Kode S, DeVries NA, et al. Biomechanical analysis of cervical disc replacement and fusion using single level, two level and hybrid constructs. Spine (Phila Pa 1976)
Keywords:Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
arthrodesis; arthroplasty; cervical; disc; fusion; outcomes; prospective; randomized