Prospective, randomized, multicenter study of cervical arthroplasty: 269 patients from the Kineflex|C artificial disc investigational device exemption study with a minimum 2-year follow-up

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Cervical total disc replacement (CTDR) represents a relatively novel procedure intended to address some of the shortcomings associated with anterior cervical discectomy and fusion (ACDF) by preserving motion at the treated level. This prospective, randomized, multicenter study evaluates the safety and efficacy of a new metal-on-metal CTDR implant (Kineflex|C) by comparing it with ACDF in the treatment of single-level spondylosis with radiculopathy.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The study was a prospective, randomized US FDA Investigational Device Exemption (IDE) pivotal trial conducted at 21 centers across the US. The primary clinical outcome measures included the Neck Disability Index (NDI), visual analog scale (VAS) scores, and a composite measure of clinical success. Patients were randomized to CTDR using the Kineflex|C (SpinalMotion, Inc.) cervical artificial disc or ACDF using structural allograft and an anterior plate.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>A total of 269 patients were enrolled and randomly assigned to either CTDR (136 patients) or to ACDF (133 patients). There were no significant differences between the CTDR and ACDF groups when comparing operative time, blood loss, length of hospital stay, or the reoperation rate at the index level. The overall success rate was significantly greater in the CTDR group (85%) compared with the ACDF group (71%) (p = 0.05). In both groups, the mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the 24-month follow-up (p &lt; 0.0001). Similarly, the VAS pain scores improved significantly by 6 weeks and remained significantly improved through the 24-month follow-up (p &lt; 0.0001). The range of motion (ROM) in the CTDR group decreased at 3 months but was significantly greater than the preoperative mean at 12- and 24-month follow-up. The ROM in the ACDF group was significantly reduced by 3 months and remained so throughout the follow-up. Adjacent-level degeneration was also evaluated in both groups from preoperatively to 2-year follow-up and was classified as none, mild, moderate, or severe. Preoperatively, there were no significant differences between groups when evaluating the different levels of adjacent-level degeneration. At the 2-year follow-up, there were significantly more patients in the ACDF group with severe adjacent-level radiographic changes (p &lt; 0.0001). However, there were no significant differences between groups in adjacent-level reoperation rate (7.6% for the Kineflex|C group and 6.1% for the ACDF group).</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Cervical total disc replacement allows for neural decompression and clinical results comparable to ACDF. Kineflex|C was associated with a significantly greater overall success rate than fusion while maintaining motion at the index level. Furthermore, there were significantly fewer Kineflex|C patients showing severe adjacent-level radiographic changes at the 2-year follow-up. These results from a prospective, randomized study support that Kineflex|C CTDR is a viable alternative to ACDF in select patients with cervical radiculopathy.</jats:p></jats:sec>

Reoperation After Cervical Disc Arthroplasty Versus Anterior Cervical Discectomy and Fusion: A Meta-analysis

“…Supplemental material is available with the online version of CORR 1 .). Finally, 12 eligible RCTs were included in our systematic review and meta-analysis [5,8,10,22,30,34,35,37,38,[42][43][44]. The study selection is shown in the PRISMA flowchart (Fig.…”

“…During the past decade, the cervical disc arthroplasty has emerged as an alternative to fusion and has been shown to provide the pain relief and functional improvements similar or superior to those of anterior cervical discectomy and fusion in FDA Investigational Device Exemption clinical trials [5,8,10,22,30,32,35,38,44]. Owing to its biomechanical advantages, the cervical disc arthroplasty may be associated with less adjacent-segment degeneration.…”

“…Some FDA Investigational Device Exemption trials and a retrospective study have suggested that patients who underwent cervical disc arthroplasty had fewer reoperations than those treated with anterior cervical discectomy and fusion [5,10,22,31,38,44]. However, two other FDA Investigational Device Exemption trials showed that the secondary surgical procedures were not significantly different between the two groups at 24 months [8,19] and longer-term followups [35]. Notably, a higher frequency of reoperation in the cervical disc arthroplasty group (8%) compared with the anterior cervical discectomy and fusion group (2%) was documented in a retrospective study based on the US Nationwide Inpatient Sample database [28].…”

Cervical canal stenosis and adjacent segment degeneration after anterior cervical arthrodesis

“…The development of adjacent segment degeneration (ASD) following anterior cervical decompression and fusion (ACDF) is well reported in the literature [4][5][6][7][8][9][10][11][12][13][14][15]. Within the past few decades, both in vivo and in vitro biomechanical evidence suggest that arthrodesis may augment stress on the unfused adjacent levels [16][17][18][19][20][21].…”

CORR Insights®: Reoperation After Cervical Disc Arthroplasty Versus Anterior Cervical Discectomy and Fusion: A Meta-analysis

“…Further subanalyses of the dataset may have the potential to answer specific questions regarding details of decision making and radiographic criteria with which to make intervention decisions. Cervical disc replacement has the potential to be an excellent long-term intervention in this patient subset with these answers and further innovation to improve upon the devices available [1,3].…”