Prospective, randomized multicenter study of cervical arthroplasty versus anterior cervical discectomy and fusion: 5-year results with a metal-on-metal artificial disc

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>Seven cervical total disc replacement (TDR) devices have received FDA approval since 2006. These devices represent a heterogeneous assortment of implants made from various biomaterials with different biomechanical properties. The majority of these devices are composed of metallic endplates with a polymer core. In this prospective, randomized multicenter study, the authors evaluate the safety and efficacy of a metal-on-metal (MoM) TDR (Kineflex|C) versus anterior cervical discectomy and fusion (ACDF) in the treatment of single-level spondylosis with radiculopathy through a long-term (5-year) follow-up.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>An FDA-regulated investigational device exemption (IDE) pivotal trial was conducted at 21 centers across the United States. Standard validated outcome measures including the Neck Disability Index (NDI) and visual analog scale (VAS) for assessing pain were used. Patients were randomized to undergo TDR using the Kineflex|C cervical artificial disc or anterior cervical fusion using structural allograft and an anterior plate. Patients were evaluated preoperatively and at 6 weeks and 3, 6, 12, 24, 36, 48, and 60 months after surgery. Serum ion analysis was performed on a subset of patients randomized to receive the MoM TDR.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>A total of 269 patients were enrolled and randomly assigned to undergo either TDR (136 patients) or ACDF (133 patients). There were no significant differences between the TDR and ACDF groups in terms of operative time, blood loss, or length of hospital stay. In both groups, the mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the 60-month follow-up (both p &lt; 0.01). Similarly, VAS pain scores improved significantly by 6 weeks and remained significantly improved through the 60-month follow-up (both p &lt; 0.01). There were no significant changes in outcomes between the 24- and 60-month follow-ups in either group. Range of motion in the TDR group decreased at 3 months but was significantly greater than the preoperative mean value at the 12- and 24-month follow-ups and remained significantly improved through the 60-month period. There were no significant differences between the 2 groups in terms of reoperation/revision surgery or device-/surgery-related adverse events. The serum ion analysis revealed cobalt and chromium levels significantly lower than the levels that merit monitoring.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>Cervical TDR with an MoM device is safe and efficacious at the 5-year follow-up. These results from a prospective randomized study support that Kineflex|C TDR as a viable alternative to ACDF in appropriately selected patients with cervical radiculopathy.</jats:p><jats:p>Clinical trial registration no.: NCT00374413 (clinicaltrials.gov)</jats:p></jats:sec>

Long‐term Results Comparing Cervical Disc Arthroplasty to Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta‐Analysis of Randomized Controlled Trials

“…. Nine studies were adequately randomized, but 1 study did not provide detailed information of randomization, and 1 study failed to achieve adequate randomization. Only 4 studies provided a clear statement regarding avoiding allocation concealment.…”

“…The patients were informed immediately after surgery about the type of surgical procedure they had been underwent, and care providers were aware of which kind of surgery was to be performed during surgery. Almost all the studies described the dropout rate and 2 studies with a follow‐up rate below 70% were considered as having high risk of bias. All included studies were scored above seven and were rated as having low risk of bias.…”

“…Of all the parameters identified for meta‐analysis, 6 studies compared overall success and NDI success, 7 studies compared neurological success, 3 studies compared radiological success, 7 studies compared NDI score, 5 studies compared neck pain score, 4 studies compared arm pain score , 5 studies compared SF‐36 PCS, 4 studies compared SF‐36 MCS, 8 studies compared any AE, 4 studies compared serious AE, 6 studies compared device/surgery‐related AE and symptomatic ASD, 2 studies compared radiological superior and inferior ASD, 8 studies compared total secondary surgeries and secondary surgeries at the index level, 9 studies compared secondary surgeries at the adjacent level, 2 studies compared work status, 4 studies compared patients’ satisfaction rate, and 2 studies compared patients’ recommendation rate.…”

“…Among them, 2 studies 45,47 were partial results of multicenter RCT and 8 studies [39][40][41][42][43][44]46,48 included duplicated data for publication. Ultimately, 11 articles [28][29][30][31][32][33][34][35][36][37][38] involving 3505 patients (CDA/ACDF: 1913/1592) were included in this meta-analysis. There are 923 male and 990 female patients in the CDA group and 791 male and 801 female patients in the ACDF group.…”

“…The basic characteristics of the included studies and patients are summarized in Table 1. Among them, 8 studies [28][29][30][32][33][34]36,38 compared single-level CDD, 1 study 31 compared two-level CDD, and 2 studies 35,37 compared both single-level and two-level CDD independently.…”