3D-Printed PEEK Implants in Cervical Spondylotic Myelopathy

Early results from a study using patient-specific 3D-printed PEEK implants in the surgical treatment of cervical spondylotic myelopathy (CSM) were presented by Matthew W. Colman, MD. While traditional reconstructive options, including anterior cervical corpectomy with fusion and anterior cervical discectomy and fusion are effective, Dr. Colman noted, “it is clinically demanding to adjust the size of vertebral body replacement (VBR) cages to the defect without compromising the endplate integrity, increasing the risk of subsidence. Dr. Colman is Assistant Professor at Rush University Medical Center in Chicago, IL and specializes in spine surgery and musculoskeletal oncology.

While traditional reconstructive options are effective, Dr. Colman noted, “it is clinically demanding to adjust the size of vertebral body replacement (VBR) cages to the defect without compromising the endplate integrity". Photo Source:123RF.com.In his presentation at the 17^th Annual Meeting of the International Society for the Advancement of Spine Surgery (ISASS17), Dr. Colman presented data on 12 patients who underwent surgery using a patient-specific, custom-made VBR using a polyetherehterketone (PEEK) 3D-printed implant. Noting the technical design demands in adjusting the size and shape of existing implants, 3D printing offers spine surgeons the ability to develop patient-specific implants. Dr. Colman described the process of developing the patient-specific VBR cages, beginning with an extensive preoperative imaging analysis through the 3D-printing in PEEK, to implantation.

Five of the 12 patients in this retroprospective study underwent single-level corpectomy (n=4 at C4, n=1 at C5), and the remaining 7 underwent two-level corpectomy (n=2 at C4-C5, n=5 at C5-C6). Radiological data was collected preoperatively, and at routine postoperative intervals of 3, 12 and 24 months.

Immediate postoperative data is available for 8 of the 12 patients, and 7 patients have been followed for an average of 6 months (ranging from 1.5 to 12 months). Data from the most recent follow-up noted improvements of anterior, posterior and medial heights (1.9mm, 1.7mm, and 1.4mm, respectively), representing improvements of 4%, 4% and 5% (respectively), with no observation of severe subsidence (defined as >3mm). There was an average 96.3% agreement with the plan in terms of height restoration.

Additional clinical outcomes noted improvement in European Myelopathy Scores from 12.25 to 15.25 and modified Japanese Orthopedic Association’s scores from 11.62 to 15.37, with recovery rates of 54.75% and 74.97%, respectively. Both C2-C7 and corpectomy angles were both maintained. Visual analogue scores (VAS) for neck pain decreased from 6.63 to 3.25, and VAS arm pain decreased from 5.25 to 2.75. The neck disability index decreased from 46.63% to 23.87%. No revisions have been reported.

Surgeons utilizing the custom-made 3D-printed VBR implant noted that it offers an easier and safer surgery, requiring no intra-operative adjustments. Dr. Colman also noted that patient-reported outcomes were excellent, although they were not included in this study. Theoretically, he noted that the use of custom-made VBR implants may enable shorter operative times, as a result of precision alignment planning. As an aside, he noted the benefits of treating patients earlier in the course of their disease, before they have begun a cycle of pharmacologic pain management. 

The radiological and clinical outcomes from this initial single-center study were good and are encouraging. Future studies involving a larger patient cohort, and with longer follow-up to assess fusion, are warranted.