Comparative Analysis of Bioactive Glass Utilization in Patients Undergoing Anterior Lumbar Interbody Fusion

Introduction: Bioactive glass is an implant material often utilized in dentistry and fracture repair to enhance osteogenesis and angiogenesis and promote bone healing. Being synthetic in nature, it is customizable and has lower risks of infection and immune rejection than allografts. The use of bioactive glass implant in spinal fusion surgeries is relatively new, with few studies having evaluated its efficacy compared to traditional grafts such as allografts and autografts with demineralized bone matrix (DBM). In this study, we compared patients who underwent anterior lumbar interbody fusion (ALIF) with the use of bioactive glass versus those with other implants.

Methods: We retrospectively selected 47 consecutive patients who underwent ALIF with either bioactive glass implants (N=31) or other forms of implants that were standardized and utilized autograft local bone with DBM (N=16). Fusion status was evaluated using serial CT axial images and graded on a 1-4 scale, with 1 being complete fusion with remodeling and trabeculae present, 2 being incomplete fusion and remodeling but with intact graft without radiolucency, 3 being intact graft but with radiolucency present at the top and bottom of the graft, and 4 being no fusion and having collapse/resorption of the graft. Exclusion criteria included lack of imaging follow-up, tumor, and infection.

Results: Descriptive and univariate statistical analyses revealed significant differences only in pre-operative lumbar lordosis (p=0.0099) and operation time (p=0.049), suggesting otherwise comparable baseline features of the two patient groups. Propensity score matching between the cohorts and two multivariate models, one adjusting for covariates and another for all baseline variables, demonstrated a faster rate of fusion in the bioactive glass group compared to the non-bioactive glass group (p=0.0000078, β=-1.8; p=0.0039, β=-1.8) at 1.5 years of follow-up. None of the patients have pseudarthrosis.

Conclusion : Patients who received bioactive glass grafts have a significantly increased rate of fusion compared to other graft types. This stays true even after correcting for baseline characteristics, level of fusion, and length of follow-up.