A long-term study of the use of PCM cervical disk (Nuvasvie) arthroplasty indicates that its clinical outcomes are superior to those produced by anterior cervical discectomy and fusion (ACDF).
Led by Frank M Phillips, Midwest Orthopaedics at Rush University Medical Center, Chicago, USA, and published ahead-of-print by Spine, the published article is a long-term follow-up on the earlier results from the prospective, multicentre, randomised clinical trial which reported on the two-year outcomes of the PCM cervical disk. The authors note that, following PCM patients and ACDF controls out to seven years, this study represents “the longest reported follow-up in the US cervical arthroplasty investigational device exemption (IDE) trials to date”.
The PCM cervical disk has been suggested as a motion-preserving alternative to an ACDF procedure, which in fusing the affected portion of the spine reduces motion.
The trial focused on the use of the PCM disk in patients with symptomatic single-level degenerative spondylosis between C3-C4 and C7-T1 with or without prior cervical fusion. Patients with single-level cervical spondylosis and radiculopathy with or without myelopathy and unresponsive to non-operative treatment were enrolled. The per protocol patient sample at five years included 293 patients (163 PCM, 130 ACDF). Adverse events and secondary surgeries are reported on the cohorts through current follow-up, which include 110 patients (68 PCM, 42 ACDF) at seven years.
At five years postoperative, all patient-reported outcomes—neck and arm pain visual analogue score (VAS), neck disability index (NDI), general health (SF-36 physical and mental component scores: PCS, MCS)—were significantly improved from baselines in both groups. However, “mean scores were significantly better in the PCM group for NDI (p=0.001), neck pain (p=0.002), general health (PPCS=0.014; PMCS=0.004), and patient satisfaction (p=0.005)”, according to Phillips et al.
At five years, 73.7% of the PCM group reported clinically significant improvement of ≥15% in PCS scores compared to 56.7% the ACDF group (p=0.004), while 46.2% of the PCM group reported clinically significant improvement in MCS scores compared to 54.3% of the ACDF group (p=0.189). Mean patient satisfaction VAS scores were 86.9 and 78.3 for the PCM and ACDF groups, respectively (p=0.005), and 88.8% of PCM patients said they were “very” or “moderately” satisfied compared with 78.7% of those in the ACDF group.
PCM patients trended toward fewer two-to-seven-year device-related serious adverse events (1/214, 0.5% PCM; 2/190, 1.1% ACDF) and secondary surgeries (7/211, 3.3% PCM; 14/290, 7.6% ACDF). Adjacent level degeneration was radiographically more frequent after ACDF (33.1% PCM, 50.9% ACDF; p=0.006), and, was the primary indication for the increase in late-term secondary surgeries after ACDF.
Phillips and colleagues write that across multiple trials, improvements in patient-reported outcomes are shown following both techniques, fusion and arthroplasty. However, some clinical measures indicate the superiority of cervical arthroplasty. “Notably, lower mean neck disability index scores and greater percentage of neck disability index success rates are consistently reported for arthroplasty over fusion across all US IDE trials,” they write. Discounting the effects of patient euphoric bias given the longer follow-up time, these findings suggest that “cervical arthroplasty may have a protective effect against accelerated adjacent level degeneration, which may translate to patient-reported assessment of pain-related function.”