A Longitudinal Study on the Growth of Fusion Mass in Posterior Spinal Fusion with Advance High-resolution Peripheral Quantitative Computed Tomography – Preliminary Findings.

Introduction: Various means have been attempted to enhance osteogenesis of posterior spinal fusion (PSF) surgery. Stem cells treatment and biophysical intervention have been shown to enhance PSF. Before optimizing the treatment effect, it is necessary to understand the temporal and spatial pattern of osteogenesis during the PSF. With the advanced high-resolution peripheral quantitative computed tomography (HR-pQCT), the fusion mass can be monitored with relatively smaller number of animals. Objective: The study used HR-pQCT and image analysis program to depict the temporal and spatial pattern of osteogenesis in rabbit PSF model with bioceramic, osteogenic cells, and low-intensity pulsed ultrasound(LIPUS). Materials and Methods: Eight rabbits undergone standardized posterior spinal fusion surgery with mesenchymal stem cells were randomly divided into 2 groups with or without LIPUS treatment. The animals were followed at week 1,4,10 with HR-pQCT to depict the bone formation at the fusion site qualitatively and quantitatively. Results: Bone formation was not limited to the transverse processes at the fusion site but also around and within the implanted material. The bone mineral content of the fusion mass in LIPUS treated animal enhanced by 15–20%. Different pattern of bone formation was observed in LIPUS treated animal. Conclusion: HR-pQCT is a feasible and non-invasive method allowing the uncoverage of important, new information of bone microstructure in spinal fusion sequentially. The LIPUS can enhance the bone formation in the implant of posterior spinal fusion. Significance: The new HR-pQCT monitor enables better understanding of the biology mechanism and sequence of bony fusion in vivo for further research in enhancement of spinal fusion. [ABSTRACT FROM AUTHOR]