Background:There are no reports of the fusion rates of iliac crest bone graft combined with other bone extenders in Extreme Lateral Interbody Fusion (XLIF) surgery.

Objective: To investigate the fusion rates of different bone grafting materials and their combinations in patients who underwent XLIF surgery.

Material and Method: This retrospective study included patients who underwent XLIF at Siriraj Hospital (Bangkok, Thailand) during the 2015-2018 study period. Demographic, clinical, surgical, and radiographic data were collected, recorded, and analyzed. Bone graft fusion was defined as either bone graft bridging in interbody cage on CT scan, or <5 degrees of movement on lateral flexion-extension radiographs.

Results: Fifty-six patients (total 71 levels of spinal fusion) were included. Iliac crest bone graft (ICBG) was used in 11 levels; recombinant human bone morphogenetic protein type 2 (rhBMP-2) was used in 37 levels; and, iliac crest bone graft with bone extenders [either ß-tricalcium phosphate (ß-TCP) or demineralized bone matrix (DBM)] was used in 23 levels. These 4 bone grafting material groups were evaluated for fusion status by plain radiography on lumbar spine flexion and extension or on computer tomography scan at the 1-year follow-up. The fusion rate was 100%, 97.3%, 94.4%, and 80.0% in the ICBG group, the rhBMP-2 group, the ICBG+ß-TCP group, and the ICBG+DBM group, respectively. However, no statistically significant difference was observed among the 4 evaluated bone grafting materials.

Conclusion: ICBG with ß-TCP can be used in XLIF surgery with a result similar to that found in ICBG and rhBMP-2. ICBG with ß-TCP grafting is lower cost compared to ICBG and rhBMP-2, and has lower donor site morbidity due to less harvested bone graft compared to ICBG alone. The results of this study confirmed XLIF surgery to be a technique with a high fusion rate (95.8%).

Keywords: Extreme Lateral Interbody Fusion, fusion rate, bone graft substitutions, bone morphologic protein type 2