The surgical treatment of cervical radiculopathy is still

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1 SPINE Volume 43, Number 6, pp E365 E372 ß 2018 Wolters Kluwer Health, Inc. All rights reserved. Surgical Treatment of Cervical Radiculopathy Meta-analysis of Randomized Controlled Trials Gabriel Gutman, MD,,y Derek H. Rosenzweig, PhD, z and Jeff D. Golan, MD, FRCS(c),y Study Design. Meta-analysis of published randomized controlled trials (RCTs). Objective. To determine whether anterior cervical discectomy and fusion (ACDF), cervical disc replacement (CDR), or minimally invasive posterior cervical foraminotomy (MI-PCF) provides the best outcomes for patients with symptomatic singlelevel, single-side, and cervical radiculopathy. Summary of Background Data. The surgical treatment of cervical radiculopathy is still controversial. ACDF has been widely used as a gold standard. CDR has evolved and become a motion-preserving alternative with a potentially lower incidence of adjacent segment disease. However, both techniques require anterior neck dissection that carries a potential for serious morbidity. MI-PCF is a motion-preserving technique that can be performed with minimal invasiveness but has not gained universal acceptance. Methods. Electronic database search for RCTs comparing the efficacy and effectiveness of ACDF, CDR, and MI-PCF was performed. Meta-analysis was done for secondary surgical procedures and adverse events. Results. A total of 358 studies were retrieved, of which four RCT reports met the inclusion criteria for this study. Three studies present clinical data comparing ACDF and CDR, and one study presents data comparing ACDF and MI-PCF. Available data from the RCTs analyzed concluded that ACDF, CDR, and MI-PCF result in significant improvements in relevant symptoms, clinical, and functional outcomes in patients with single-level, single side cervical radiculopathy refractory to nonoperative treatment. CDR had the lowest percentage of secondary surgical procedures (P ¼ ) whereas MICPF had the lowest percentage of adverse events (P < ). From the Department of Neurosurgery, Jewish General Hospital, Montreal, Quebec, Canada; y Department of Neurosurgery, McGill University, Montreal, Quebec, Canada; and z Department of Surgery, McGill University, Montreal, Quebec, Canada. Acknowledgment date: March 22, First revision date: June 12, Acceptance date: June 16, The manuscript submitted does not contain information about medical device(s)/drug(s). No funds were received in support of this work. No relevant financial activities outside the submitted work. Address correspondence and reprint requests to Jeff D. Golan, MD, FRCS(c), Department of Neurosurgery, Division of Neurosurgery, Jewish General Hospital, Montreal, QC, Canada; jgolan@jgh.mcgill.ca DOI: /BRS Conclusion. All three techniques are effective in treating cervical radicular symptoms. MI-PCF has the lowest rate of adverse events whereas CDR has the lowest rate of secondary procedures. There is insufficient evidence to show which technique is the most effective and provides the longest-lasting symptom relief. Key words: anterior cervical discectomy and fusion, cervical disc arthroplasty, cervical radiculopathy, minimally invasive posterior cervical foraminotomy, spine surgery. Level of Evidence: 1 Spine 2018;43:E365 E372 The surgical treatment of cervical radiculopathy is still controversial. Since the late 1950s, anterior cervical discectomy and fusion (ACDF), originally described by Cloward 1 and Smith and Robinson, 2 has been used by many surgeons as a gold standard. 3,4 Despite reports of high fusion rates after ACDF, 3 6 the association with adjacent segment degeneration has increased to about 3% to 8% per year over the past decade. 4,7,8 In addition, problems such as loss in intervertebral disc height or pseudarthrosis may occur Cervical disc replacement (CDR) has evolved since its introduction in the 1980 s and become an alternative. 12 Data from randomized controlled trials (RCT s) have indicated that CDR is challenging the gold standard of ACDF, whereby CDR is reporting a lower amount of secondary surgeries and medication use. 13,14 Nonetheless, the nature of both surgeries presents the potential for access related complications Minimally invasive motion-preserving techniques have therefore become popular alternatives. 20,21 Posterior cervical foraminotomy (PCF) is a motion-preserving technique that was first described by Spurling and Scoville 22 in It can be performed using advanced minimally invasive techniques with promising results. 21,23,24 The goal of this updated systematic review and meta-analysis is to determine which of these three techniques provides the best clinical, functional, and radiological outcomes, with the least adverse effects, for patients with symptomatic single-level, single-side, cervical radiculopathy that failed conservative treatment. MATERIALS AND METHODS One author (GG) conducted the literature search. A search strategy was devised in consultation with members of the McGill University Epidemiology department to find the Spine E365

2 TABLE 1. Inclusion and Exclusion Criteria for Article Selection Type of study Randomized controlled trials Population Intervention Reported outcomes Inclusion Criteria 18-years old Failed conservative treatment Symptomatic single level, single side pathology from C2-T1. Clinically and MRI correlated Single level ACDF (either by plate, cage, autograft, allograft, or a combination) and CDR or MI-PCF are directly compared. Clinical, functional, and radiological parameters. Minimum 12-month follow-up Primary: Arm pain on a visual analogue scale (VAS) Adverse Effects Revision surgery Secondary: Neck-related functional status (NDI). Neurological. Patient satisfaction. Radiological signs of fusion (bridging of trabecular or cortical bones, or both, absence of detectable movement on flexion extension lateral radiographs, absence of lucencies around the cage or disc prosthesis) Global health status Exclusion Criteria Prospective trials, retrospective trials, cohort studies, expert opinion Patients less than 18-years old Myelopathy, infection, inflammatory spinal arthritis, radiotherapy of the cervical spine region. Previous surgery at the index level. highest level of evidence possible on the subject. This search was used in the electronic databases PubMed, OVID Medline, OVID Embase, and Cochrane library for RCT s about ACDF, CDR, and minimally invasive PCF (MI-PCF) reporting surgical outcomes in cervical radiculopathy. All available literature published between January 1996 and November 15, 2016 was reviewed. All RCTs that matched the inclusion criteria (Table 1) investigating the efficacy of ACDF, CDR, and MI-PCF for cervical radiculopathy were included. Extracted data included: study design (inclusion and exclusion criteria, method of randomization, blinding (patient, practitioner, analyst), study period, and duration of follow-up), characteristics of the study population (e.g., number of participants, age, sex, baseline scores of the outcome measures described in Table 1), characteristics of the intervention (technique and type of implant used), duration of follow-up (and follow-up moments), and sponsorship of the trial (e.g., industry sponsored). Meta-analysis was performed where possible. In an effort to obtain unpublished data, we attempted to contact the authors of the different trials. We used the revised Cochrane risk of bias tool for randomized trials (RoB 2.0) 25 to assess the risk of bias of the studies included in the review. RESULTS Systematic Review The literature search yielded 358 titles. There were no additional records from other sources. After deduplication process, 248 titles and abstracts were reviewed. Two hundred and thirty-three studies were excluded [studies that compared the same type of surgery with different implants or bone graft, studies that did not match the inclusion criteria (patients with cervical myelopathy), or abstracts that belonged to conference presentations/proceedings]. Fifteen full articles were assessed for eligibility. Eleven of them were excluded with one being a double publication. Seven studies included the same data that is reported in more recent studies with longer follow-ups. One study did not report outcomes, one study included two-level surgeries, and one study included patients with myelopathy. In the current review, we include three RCTs presenting clinical data comparing ACDF and CDR and one RCT presenting data comparing ACDF and MI-PCF. The flow of this systematic review is presented in Figure 1. Meta-analysis For the Neck Disability Index (NDI) and the Visual Analog Scale (VAS) arm measures, two of the three studies reported data. One reported adjusted differences with 95% confidence interval (CI). 14 The second provided only crude means with standard deviations. 26 For VAS neck, NDI, operative time, and blood loss, three of the four studies reported data of which two of them provided only means. 24,27 In consequence, meta-analyses for all the above measures could not be performed. However, meta-analysis was done for secondary surgical procedures and adverse events. CDR had the lowest percentage of secondary surgical procedures (P ¼ ) whereas MI-CPF had the lowest percentage of adverse events (P < ), as indicated in Tables 2 and 3. We contacted the corresponding authors of all the articles regarding their data that was unclear or insufficient to be included in our meta-analysis. We failed to obtain clarification or unpublished data from the authors using the addresses provided in the articles. The available data E366 March 2018

3 Identification # 358 of records identified through database searching # 0 of additional records identified through other sources Screening #248 of records after duplicates removed #248 of records screened #233 of records excluded Figure 1. Flow chart of the study selection. The schematic diagram shows the identification, screening, and eligibility criteria that resulted in the included studies for review and meta-analysis. Eligibility Included #15 of full-text articles assessed for eligibility #4 of studies included in qualitative synthesis #11 of full-text articles excluded: #1 duplicate. #7 Same data patients. #1 didn t report outcomes. #1 included two-levels surgery #1 included patients with myelopathy abstracted from these studies are summarized in Table 4. 14,24,26,27 Below we present the main findings in each of these studies. The article by Ruetten et al 24 reports the results of the comparison between cervical discectomies in full-endoscopic posterior foraminotomy technique with the conventional microsurgical anterior decompression and fusion. ACDF was performed using a microscope. A polyether ether ketone (PEEK) cage was used as an intervertebral implant without additional ventral plating. MI-PCF was performed with the patient in prone position, with the cervical spine delordosated. The head was fixed in place with tape. The procedure was done as a full-endoscopic uniportal technique. Two hundred patients with a mean age of 43-years old were randomized in an open way, (as they may identify the procedure) one hundred to each group, and the randomization assignment was made by alternation in the order of presentation. This technique of randomization presents itself with a high risk of bias. 25 The clinical outcomes and adverse events were reported for 175 patients, with up to 2 years of followup. Two patients that were allocated originally to the fusion group received MI-PCF. No intention to treat analysis was performed. Of the 25 dropout cases, 10 underwent revision surgery with conventional ACDF. It is unclear why they were considered as dropouts. Clinical outcomes were reported as mean values without standard deviations which precluded estimation of effects that can be used in a meta-analysis with any degree of confidence. The authors concluded that MI-PCF has the advantage of being an economical procedure because of short operation time, rapid rehabilitation, no operationrelated neck pain, reduced bleeding, and reduced risk of access-related complications. They consider the technique described to be a sufficient and safe supplement within the spectrum of conventional procedures. Although the results are encouraging, the overall risk of bias in the study is high. 25 The study by Nabhan et al 26 is a RCT assessing adjacentsegment mobility after CDR as compared to ACDF in 20 patients with a mean age of 43-years old with radiculopathy after 1 year of follow-up. ACDF was performed with a PEEK cage filled with Tribone 80 (Stryker Howmedia GmbH, Gewerbeallee 18, Mulheim, Germany), and a titanium alloy plate. CDR was performed with the ProDisc-C disc replacement implant (DePuy Synthes Spine, Raynham, MA). Each group consisted of 10 patients and was randomized by drawing cards in sealed envelopes. The authors did not provide any information as to whether patients were TABLE 2. Secondary Surgical Procedures MI-PCF CDR ACDF P Yes No Total Percentage ACDF indicates anterior cervical discectomy and fusion; CDR, cervical disc replacement; MI-PCF, minimally invasive posterior cervical foraminotomy. TABLE 3. Adverse Events MI-PCF CDR ACDF P Yes No Total Percentage < ACDF indicates anterior cervical discectomy and fusion; CDR, cervical disc replacement; MI-PCF, minimally invasive posterior cervical foraminotomy. Spine E367

4 TABLE 4. Randomized Controlled Trials 14,24,26,27 Sample ACDF MI-PCF Author (yr) Number Age, yrs Sex Number Age, yrs Sex Follow-up, Complications Outcomes Conclusions mo Ruetten 100 Mean age: 43 34% male 100 Mean age: et al % male 24 Reinterventions ACDF: Persistent arm pain (3) revisions (4.7% revision rate). Implant failure (1). MIPCF: Persistent arm pain (3) revisions (6.7% revision rate). Adverse events ACDF: transient dysphagia (3), surface hematoma (1), scar distortion (1). MIPCF: transient dermatoma-related hyperesthesia (3). Significant reduction of neck and arm pain in both groups (P< 0.001). Neurologic deficits were significantly (P< 0.001) reduced in both groups when the patient s history of pain was less than 10 days. The MIPCF group return to work faster (19 days) than the ACDF group (34 days) (P < 0.01) MIPCF has the advantages of economical procedure thanks to short operation time, rapid rehabilitation, no operation-related neck pain, reduced bleeding, reduced risk of access-related complications; maintained mobility. Author Number CDR Number ACDF Follow Up, mo Complications Outcomes Conclusions Age, yrs Age, yrs Nabhan No complications and no et al 26 revisions ROM of treated segment: segmental motion was significantly higher in the prosthesis group in comparison to fusion for extension (P¼0.02) and axial rotation (P¼0.013). It was not significantly different between both groups for bending (P ¼ 0.06) ROM of adjacent segment: segmental motion shows a slightly higher segmental motion for all three axes in the fusion group, but without significant difference for any direction (extension, axial rotation and bending) In both groups, NDI for neck pain decreased significantly and VAS arm pain improved significantly. There was no significant difference between both groups in pain relief for neck and arm pain. No significant difference of the segmental motion of the adjacent level either treated with prostheses or fusion, 1 year after surgery. Clinical results did also show no significant difference in pain relief between both groups. E368 March 2018

5 TABLE 4 (Continued) Author Number CDR Number ACDF Follow Up, mo Complications Outcomes Conclusions Age, yrs Janssen Reinterventions et al secondary surgical procedures had been performed in 19 (18%) of the 106 patients in the ACDF group compared with 7 secondary surgical procedures in 7 (7%) of the 103 patients in the CDR group (P ¼ ). The mean cumulative function of risk for secondary surgery was approximately 3.7 times higher in the ACDF group than in the CDR group (P ¼ ). Adverse Events There were no significant differences between groups with regard to any category of adverse event or with regard to the proportion of patients with any adverse event at all (P ¼ ). Coric et al Reinterventions There were 3 reoperations (7.3%) at index (n ¼ 1; 2.4%) or adjacent levels (n¼2; 4.9%) in the CDR group. There was 1 reoperation (3.0%) in the ACDF group at the adjacent level and none (0%) at the index level. Adverse Events One patient in the CDR group (2.4%) had persistent swallowing difficulties and underwent scar revision surgery. Age, yrs All outcomes (NDI, VASarm, VASneck, SF-36) except for the SF-36 general health domain were improved, compared with the preoperative status, and maintained at seven years (P < 0.05). Both groups reported a high level of satisfaction at 7 years (P ¼ ). The rates of neurologic success were 88% and 89% in the CDR and ACDF groups, respectively. 11% of patients in the CDR group had bone bridging on radiographs with loss of motion at the index level. The mean flexionextension ROM at the index was in the CDR compared to in the ACDF group (P < ). Mean NDI and VAS neck scores improved significantly by 6 weeks after surgery and remained significantly improved by minimum 48-month follow-up (p < 0.001) Postoperative mean ROM in CDR group was higher than preoperatively (8.68 vs 8.28) Postoperative mean ROM in ACDF group was significantly reduced compared with preoperatively (0.28 vs 7.68). There were no cases of CDR implant failure or reoperations for failed fusions. Both ACDF and CDR result in significant long-term improvements in relevant symptoms and clinical, functional, and health related general health outcomes in patients with single level cervical DDD refractory to nonoperative treatment. However, CDR was associated with a lower risk of secondary surgery at both the index and adjacent vertebral levels. Both ACDF and CDR result in excellent clinical long-term outcomes as a surgical treatment for cervical radiculopathy that failed conservative treatment. ACDF was associated with a lower risk of reoperation at both the index and adjacent vertebral levels. ACDF indicates anterior cervical discectomy and fusion; CDR, cervical disc replacement; MI-PCF, minimally invasive posterior cervical foraminotomy; NDI, Neck Disability Index; ROM, range of motion; VAS, Visual Analog Scale. Spine E369

6 blinded to the treatment. The authors concluded that there was no significant difference of the segmental motion of the adjacent level either treated with prostheses or with fusion, 1 year after surgery. Clinical results reported by VAS for arm pain and NDI also did not show a significant difference in pain relief between both groups. The bias arising from the randomization process for this study presented some concerns 25 (unsealed allocation envelopes may be opened, translucent envelopes may be held against a bright light to reveal the contents.) The study by Janssen et al 14 is a report from the US Food and Drug Administration (FDA) Investigational Device Exemption (IDE) multicenter RCT for the ProDisc-C usage. A noninferiority design with a 1:1 randomization was used. A contract research organization using a fixed randomization blocking method of four assignments per block generated the allocations and executed at each site with use of opaque and sealed envelopes. The patient remained blinded to the randomization until the surgery was completed. Two hundred and nine patients were randomized and treated (106 ACDF; mean age 43 yrs, 103 CDR; mean age 42 yrs). ACDF was performed with allograft bone and anterior cervical plating. At 7-years follow-up, there was a followup rate of 92% in both groups. The authors concluded that both ACDF and CDR result in significant long-term improvements in relevant symptoms and clinical, functional, and health-related general outcomes in patients with single level cervical degenerative disc disease (DDD) refractory to nonoperative treatment. However, CDR was associated with a lower risk of secondary surgery at both the index and adjacent vertebral levels. The bias arising from the randomization process for this study is low. 25 The study by Coric et al 27 is a report from a subgroup analysis of patients with radiculopathy at a single institution that belong to two separate RCT s of the US FDA IDE: Bryan Disc, Medtronic Inc. and Kineflex C, 31 SpinalMotion, 32 Inc. Seventy-four patients were enrolled and randomly assigned to undergo CDR with either Bryan Disc or Kineflex C (41 patients, mean age 49.5 yrs) or ACDF using structural corticoancellous allograft and an anterior plate (33 patients, mean age 49.3 yrs). Sixty-three patients (86.3%) with minimum of 4 years of follow-up were available for the analysis. Interestingly, the reoperation rate for index and adjacent level was higher in the CDR than in ACDF group (2.4% and 4.9% vs. 0% and 3%, respectively). The authors concluded that both CDR and ACDF showed excellent clinical outcomes that were maintained in the long-term follow-up (average 6 yrs) and are viable surgical options for the treatment of single level cervical radiculopathy. The randomization process for the Kineflex C 31 study is not reported, and therefore there are some concerns when assessing the risk of bias. 25 On the other hand, for the Bryan Disc 32 study, the sponsor centrally generated the randomization, using a fixed block size of 4. Each site was responsible for the stratification. Because the investigators and patients remained blinded through confirmation of eligibility and informed consent, there is a low risk of bias. 25 DISCUSSION This is the first descriptive systematic review and metaanalysis that attempts to identify the best level I evidence available to document which surgical treatment, between CDR, ACDF, and MI-PCF, offers the best outcomes for patients with single-level, single-side cervical radiculopathy that failed conservative treatment. When we planned this study, we expected to retrieve more than four RCTs reporting clinical outcomes in patients that underwent one of the above-mentioned treatments for cervical radiculopathy. Most of the available RCTs comparing ACDF and CDR included patients with myelopathy and were excluded from the current study. Up to the date of this literature search, only one study reported outcomes comparing MI- PCF and ACDF, 24 and there are no studies comparing either CDR with MI-PCF or the three techniques together. The studies reviewed in this report found no statistical evidence of differences in clinical outcomes between the three groups. The main difference in the outcome of MI-PCF and CDR compared to fusion is preservation of spine mobility at the index level. However, at this time the evidence does not support that preservation of segmental mobility provides better clinical outcomes than fusion by preventing adjacent level degeneration and disease. In the study of Ruetten, 24 revision rates were similar in both groups. On the other hand, when combining the data for the meta-analysis, the MI-PCF group experienced the lowest rate of adverse events. Nabhan 26 concluded that there is no difference in adjacent segmental mobility between ACDF and CDR at 1-year follow-up. Still, it is possible that longer follow-up times might drive different conclusions. In another study by Janssen, 14 there were significantly less secondary surgical procedures in the arthroplasty group at 7-years follow-up. Nevertheless, surgeon bias in terms of the decision for adjacent-level fusion extension in patients with ACDF may have played a role. The subgroup analysis of radiculopathy patients from the US FDA IDE trial reported by Coric 27 had lower reoperation rate in the ACDF group than in the CDR group as compared with the other US FDA IDE trial. 14 This difference might be related to implant design and/or patient characteristics from both studies. There are several limitations to our study. First, there is discrepancy between the reporting length of follow-up among the different RCTs reviewed. Second, it is possible that there are unreported differences between the disc herniation location, degree of degeneration, and the baseline neck pain between the population sample of each study. Third, we were unable to perform meta-analysis for important and relevant variables like NDI, VAS, surgery time, and blood loss because of methodological and reporting deficiencies in the studies. CONCLUSION MI-PCF avoids the access-related potential morbidities of the anterior approach and the need for device implantation. In consequence, this technique has the lowest rate of adverse events. However, at this time, there is not enough evidence to support which of the presented treatments is the most E370 March 2018

7 effective. Future studies should be designed to compare MI- PCF, CDR, and ADCF together and report change scores and change score variance in accordance with RTC guidelines to strengthen credibility of conclusions. Key Points Surgical treatment of cervical radiculopathy is controversial, and it remains unclear whether ACDF, CDR, or MI-PCF is best. A meta-analysis of the literature is performed to compare outcomes following ACDF, CDR, and MI-PCF. All three techniques are effective in treating cervical radicular symptoms. MI-PCF has the lowest rate of adverse events whereas CDR has the lowest rate of secondary procedures. Acknowledgments The authors would like to thank Ms. Jachynte Touchette, librarian, for her advice during the literature search and Mr. Abbas Kezouh, statistician, for the statistics and members of the McGill University epidemiology department for their guidance during the study. References 1. Cloward RB. The anterior approach for removal of ruptured cervical disks. 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Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am 1999;81: Ishihara H, Kanamori M, Kawaguchi Y, et al. Adjacent segment disease after anterior cervical interbody fusion. Spine J 2004;4: Brown MD, Malinin TI, Davis PB. A roentgenographic evaluation of frozen allografts versus autografts in anterior cervical spine fusions. Clin Orthop Rel Res 1976; Samartzis D, Shen FH, Goldberg EJ, et al. Is autograft the gold standard in achieving radiographic fusion in one-level anterior cervical discectomy and fusion with rigid anterior plate fixation? Spine (Phila Pa 1976) 2005;30: Suchomel P, Barsa P, Buchvald P, et al. Autologous versus allogenic bone grafts in instrumented anterior cervical discectomy and fusion: a prospective study with respect to bone union pattern. Eur Spine J 2004;13: Cummins BH, Robertson JT, Gill SS. Surgical experience with an implanted artificial cervical joint. 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8 32. 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 (Phila Pa 1976) 2009;34: Burkus JK, Traynelis VC, Haid RW Jr, et al. Clinical and radiographic analysis of an artificial cervical disc: 7-year follow-up from the Prestige prospective randomized controlled clinical trial: clinical article. J Neurosurg Spine 2014;21: Sasso WR, Smucker JD, Sasso MP, et al. Long-term clinical outcomes of cervical disc arthroplasty: a prospective, randomized, controlled trial. Spine (Phila Pa 1976) 2016;42: Hisey MS, Zigler JE, Jackson R, et al. Prospective, randomized comparison of one-level Mobi-C cervical total disc replacement vs. anterior cervical discectomy and fusion: results at 5-year followup. Int J Spine Surg 2016;10: Phillips FM, Geisler FH, Gilder KM, et al. Long-term outcomes of the US FDA IDE prospective, randomized controlled clinical trial comparing pcm cervical disc arthroplasty with anterior cervical discectomy and fusion. Spine (Phila Pa 1976) 2015;40: Vaccaro A, Beutler W, Peppelman W, et al. Clinical outcomes with selectively constrained SECURE-C cervical disc arthroplasty: twoyear results from a prospective, randomized, controlled, multicenter investigational device exemption study. Spine (Phila Pa 1976) 2013;38: E372 March 2018