Bone remodeling is a crucial process in lumbar interbody fusion (LIF), a surgical procedure used to treat conditions such as degenerative disc disease and spinal instability. Here’s an overview of how bone remodeling impacts the success of LIF:
Bone remodeling in lumbar interbody fusion is vital for achieving long-term success, involving complex interactions between cells and graft material. Managing influencing factors can improve outcomes and ensure a successful fusion.
A study proposes a numerical approach for simulating bone remodeling in lumbar interbody fusion (LIF). It employs a topology optimization method to drive the remodeling process and uses a pixel function to describe the structural topology and bone density distribution. Unlike traditional approaches based on strain energy density or compliance, this study adopts von Mises stress to guide the remodeling of LIF. A novel pixel interpolation scheme associated with stress criteria is applied to the physical properties of the bone, directly addressing the stress shielding effect caused by the implanted cage, which significantly influences the bone remodeling outcome in LIF. Additionally, a boundary inverse approach is utilized to reconstruct a simplified analysis model. To reduce computational cost while maintaining high structural resolution and accuracy, the Scaled Boundary Finite Element Method (SBFEM) is introduced. The proposed numerical approach successfully generates results that closely resemble human lumbar interbody fusion 1).
The fusion rate in spinal surgery may vary in relation to the technique, and it remains unknown which surgical technique provides the best fusion rate and surgical outcomes. Lee et al., aimed to compare radiological and surgical results between three surgical techniques used for lumbar interbody fusión.
Seventy-seven patients diagnosed with degenerative lumbar spinal stenosis including spondylolytic lumbar spondylolisthesis. Patients were divided into three groups according to the surgical technique: anterior lumbar inter-body fusion (ALIF, n = 26), transforaminal lumbar inter-body fusion (TLIF, n = 21), and posterior lumbar inter-body fusion (PLIF, n = 30). Various radiological parameters were measured including fusion rates.
Significant changes after surgery were observed in the ALIF group for the percentage of vertebral body slippage, anterior disc height, posterior disc height, segmental, and segmental ROM. The fusion rate on CT scan at the final follow-up was 69.2% in the ALIF, 72.7% in the TLIF, and 64.3 % in the PLIF. The cage subsidence rate 2 years after surgery was 15.4% in the ALIF, 38.1% in the TLIF, and 10% in the PLIF.
ALIF was associated with better restoration of segmental lordosis. The fusion rate on CT scan and with segmental ROM did not differ between the three groups. TLIF was associated with a better post op VAS. PLIF showed the lowest cage subsidence rate. Therefore, it looks difficult to tell which surgical technique is better between the three groups as well as all the surgical procedures being equivocal in terms of fusion rate and outcomes 2).