Rate of Bone Union After Surgery With Stand-alone Fibergraft

Lumbar interbody fusion is an established procedure for patients with lumbar degenerative conditions and spondylolisthesis, with symptoms of pain, radiculopathy, and/or myelopathy. Completion of fusion, ie, union, of an intended motion segment remains a desirable endpoint of spinal fusion, supported by the observations that pseudoarthrosis, ie, nonunion, following spinal fusion is correlated with poorer patient outcomes.

Iliac crest bone autograft is considered the gold standard for spinal fusion with excellent fusion rates and clinical outcomes. However, its clinical use has been restricted due to limited availability of harvestable bone, donor-site morbidity, increased surgical time, and the need for additional surgical staff and associated costs. As a result, there has been great interest in the search for bone graft substitutes to replace or reduce the amount of autograft, which will lower the risks associated with the harvesting procedure while still providing a favorable environment for a solid fusion. A wide range of synthetic bone grafts have been explored, including ceramics, bioactive glasses, and polymer-based compounds.

Although bioactive glasses have been used in spinal fusion for three decades, literature on them is dispersed over the wide array of bioactive glasses investigated and numerous small clinical studies. There is marked variability in these studies in terms of the patient population, indications, procedures performed, single- vs multi-level procedures, types of bioactive glasses, use of autografts, duration of follow-up (FU), and methods to determine fusion status. It is therefore difficult to draw conclusions on the optimal bioactive glass for a particular application. Nonetheless, the current literature suggests that bioactive glasses may be effective as bone graft extenders when combined with autograft to promote spinal fusion, yielding at least noninferior fusion rates when compared with autograft alone. There is limited data regarding the effectiveness of bone glasses as standalone bone graft substitutes or in interbody fusion procedures.

This single-center study to be conducted at the St. Maartenskliniek, the Netherlands, aims to address this knowledge gap. Since 2023, the hospital has consistently used Fibergraft Bioactive Glass (BG) Putty, a product from the FIBERGRAFTTM Bioactive Bone Graft Substitute family (Johnson & Johnson MedTech), as standalone cage fillers for anterior lumbar interbody fusion (ALIF) and extreme lateral interbody fusion (XLIF). This provides an opportunity for a case series to determine the fusion rate for bioactive glass as a standalone bone graft substitute in lumbar interbody fusion.

Inclusion criteria

• Adults ≥ 18 years old
• Diagnosed with the following lumbar spine disorders: foraminal nerve root compression, isthmic spondylolisthesis, and short-segment (1-2 levels) deformity.
• Undergone primary surgery of ALIF or XLIF using titanium cages filled with standalone Fibergraft and with the following criteria fulfilled (ie, the index surgery):

• ALIF (up to 2 levels) as either standalone (ie, no posterior procedure) or as an anterior first procedure with posterior procedure as a second procedure.
• XLIF (up to 2 levels) as an anterior first procedure with posterior procedure as a second procedure.
• Consenting to have CT scans taken to allow assessment of fusion status at 12-24 months post index surgery

• This criterion is applicable to patients who have not undergone revision surgery.
• For patients who have undergone revision surgery due to any reason other than nonunion, which typically occurs within 1 year of the index surgery, this criterion is only applicable if it is possible to obtain the CT scan within 12-24 months of the index surgery. If no CT scan can be taken during this window, the patient does not need to undergo the CT scan; in such cases, the CT scan that has been taken as part of the standard of care before the revision surgery will be retrospectively retrieved to assess the fusion status at the time of the revision surgery.
• This criterion is not applicable to patients who underwent revision surgery due to nonunion, which typically occurs 1 year after the index surgery; these patients do not need to undergo the CT scan. In such cases, the CT scan that has been taken as part of the standard of care before the revision surgery will also be retrospectively retrieved to assess and grade the fusion status at the time of the revision surgery.
• Ability to provide informed consent according to the IRB/EC defined and approved procedures

Exclusion criteria

• Revision surgery
• Standalone XLIF
• Posterior lumbar interbody fusion
• Diagnosis of fractures, malignancies, ankylosing spondylitis, or acute cauda equina syndrome
• Diagnosis of Parkinson's disease
• Body mass index > 35kg/m2