Acrylic cages are good alternatives to bone graft and PEEK in anterior cervical discectomy and fusion


A study published ahead-of-print by the Journal of Spinal Disorders and Techniques suggests that novel acrylic cages, composed of polymethylmethacrylate (PMMA) and methacrylate, are as clinically effective as PEEK cages and bone graft in promoting fusion following an anterior cervical discectomy (ACDF).

The study authors, led by Majid Reza Farrokhi, Shiraz Neuroscience Research Center, Shiraz University of Medical Sciences, Shiraz, Iran, designed an acrylic cage to use in ACDF procedures, as, although there are many options for restoring physiologic disc height and enhancing spinal fusion, they believed that “the ideal device, which would provide immediate structural support and subsequent osteointegration and stability, has not been identified yet,” and use of existing devices can result in cage subsidence, migration or failure.


The prospective, single-blind randomised controlled clinical study enrolled a total of 64 patients who were randomly allocated to undergo ACDF either with acrylic interbody fusion cage filled with bone substitute (n=32) or PEEK cage (n=32). Nurick’s grading was used for quantifying the neurological deficit. Clinical and radiological outcome was assessed preoperatively, immediately after surgery, and subsequently at two, six and 12 months follow up using Odom’s criteria and dynamic radiographs (flexion-extension) and computed tomography scans, respectively.

The authors report that there was a statistically significant improvement in the clinical outcomes of the acrylic cage group compared with the PEEK cage group (mean difference: -0.438, 95% confidence interval -0.807 to -0.068; p=0.016). There was a statistically significant difference in disk space height increase between the two groups at the six- and twelve-month follow-up. The acrylic cage achieved higher fusion rate than the PEEK cage (96.9% vs 93.8%). Intervertebral angle demonstrated a significant difference among the two treated groups throughout the follow-up period. The authors also found that their acrylic cage was significantly cheaper (US$100) than the PEEK alternative (US$800).

Farrokhi et al write that “Clinical improvement, disk spacing height, intervertebral angle and fusion rate in the patients of the acrylic cage group was better than the PEEK cage group.” They conclude that an acrylic cage “can be a good, safe and economical alternative compared to commercially available PEEK cages in ACDF at 12-month follow-up.

Alex Vaccaro, incoming Editor-in-Chief of the Journal of Spinal Disorders and Techniques, told Spinal News International that “The PEEK cage costs eight times more than the acrylic cage, but it did not lead to an improvement in fusion rates or clinical outcomes. While physicians should always strive to provide the best available healthcare to their patients, understanding the scarcity of healthcare resources is also critical. When two products offer equivalent outcomes, surgeons must consider the economics of each treatment when deciding which is best for their patients.”