A Prospective Study of the Safety and Efficacy of Transforaminal Lumbar Interbody Fusion with InQu Bone Graft Extender with 12-month Radiographic and Clinical Outcomes

Objective: Bone graft extenders are frequently used in spinal surgery as an adjunctive tool to achieve bony fusion. Synthetic bone graft extenders have been developed in order to avoid the time and morbidities associated with harvesting iliac crest autograft. Different types of synthetic bone graft extenders have been developed including both ceramic and polymer-based grafts. There is little literature on the efficacy of polymer-based synthetic bone graft extenders. We sought to study the effectiveness of a specific polymer-based synthetic bone graft extender, InQu, in achieving fusion in transforaminal lumbar interbody fusion.

Methods: This study was a prospective multicenter study which enrolled 21 patients with grade 1 spondylolisthesis and/or degenerative disc diseases and were treated with transforaminal lumbar interbody fusion with the use of InQu bone graft extender. We collected pre-and post-operative patient-reported outcomes at 12-months, using Visual analog score (VAS)-back, VAS-right leg, VAS-left leg, and Oswestry Disability Index v2.0. Interbody fusion was subjectively evaluated on CT-scan by using a previously described fusion scoring system.

Results: All patients reported significant improvement in all four self-reported data scores from preoperative to 12-month follow up (all p<0.0001). A large majority (90%) of the patients at our center had a fusion score suggesting a lack of radiographic fusion as seen on CT at 12-month follow-up.

Conclusion: While the use of InQu provided significant improvements in clinical outcome measures, the lack of radiographic fusion seen on CT at 12-months in the majority of our patients was less than expected and is a concerning trend. We will continue to follow our cohort of patients to investigate the long-term clinical effects.