Clinical and radiographic outcomes using third-generation bioactive glass as a bone graft substitute for multi-level anterior cervical discectomy and fusion—a retrospective case series study

Background: Bioactive glasses have unique bone forming properties that have been used as a bone graft substitute for anterior cervical discectomy and fusions (ACDFs). Bone graft substitutes are used for achieving fusion while simultaneously avoiding donor site morbidity of iliac crest autograft. In this study, our principal intention is to assess the clinical and radiographic outcomes in patients with multi-level cervical disc disease undergoing ACDF using a third-generation bioactive glass as a bone graft substitute. Methods: A retrospective case series study was performed of patients who underwent primary multi-level instrumented fusions for degenerative cervical disc disease with bioactive glass bone graft substitute between May 2016 and December 2017 by a single fellowship-trained spine surgeon. All patients were treated with a porous PEEK interbody spacer and with a third-generation bioactive glass synthetic bone graft substitute. Patients were assessed pre-operatively, immediately following surgery, and at 3, 6, 12, and 24 months. Accepted standard outcome measures were applied to evaluate preoperative and postoperative metrics, including Visual Analog Scale neck pain and arm pain, and Neck Disability Index. Dynamic lateral radiographs were used to assess sagittal alignment, disc space height, arthrodesis status, osseous integration, and implant migration. Sagittal plane angulation was measured by Cobb’s criteria. Results: Thirty-nine patients underwent multi-level instrumented fusions: seventeen (43%) were two-level; 12 (31%) were three-level; 9 (23%) were four-level; and 1 (3%) was five-levels. All patients were followed for a minimum of 6 months for mean of 16.0 months (range, 6 to 36 months); none were lost to follow-up. Significant improvements from preoperative scores in Neck Disability Index scores as well as neck and arm visual analog scale pain scores were realized. All patients either maintained or improved their neurological status. Radiographically, all patients were fused by 6 months postoperatively and showed improvement in fusion segment lordosis (Pre-Post and Pre-Final P<0.001), C2-C7 lordosis angle (Pre-Post and Pre-Final P<0.001), T1 slope (Pre-Post P=0.01, Pre-Final P=0.07) and maintenance of disc height (Post-Final P=0.02). There were no adverse events, infections, or reoperations. Conclusions: Third-generation bioactive glass synthetic graft is a viable alternative to allograft or autograft in the setting of multi-level instrumented fusions for achieving improved clinical and radiographic outcomes.