Search

Abstract Background Oblique lateral lumbar fusion (OLIF) is widely used in spinal degeneration, deformity and other diseases. The purpose of this study was to investigate the biomechanical differences between two different shapes of OLIF cages on whether to add posterior internal fixation system, using finite element analysis. Methods A complete three-dimensional finite element model is established and verified for L3–L5. Surgical simulation was performed on the verified model, and the L4–L5 was the surgical segment. A total of the stand-alone group (Model A1, Model B1) and the BPSF group (Model A2, Model B2) were constructed. The four OLIF surgical models were: A1. Stand-alone OLIF with a kidney-shaped Cage; B1. Stand-alone OLIF with a straight cage; A2. OLIF with a kidney-shaped cage + BPSF; B2. Stand-alone OLIF with a straight cage + BPSF, respectively. The differences in the range of motion of the surgical segment (ROM), equivalent stress peak of the cage (ESPC), the maximum equivalent stress of the endplate (MESE) and the maximum stress of the internal fixation (MSIF) were compared between different models. Results All OLIF surgical models showed that ROM declines between 74.87 and 96.77% at L4–L5 operative levels. The decreasing order of ROM was Model A2 > Model B2 > Model A1 > Model A2. In addition, the ESPC and MESE of Model A2 are smaller than those of other OLIF models. Except for the left-bending position, the MSIF of Model B2 increased by 1.51–16.69% compared with Model A2 in each position. The maximum value of MESE was 124.4 Mpa for Model B1 in the backward extension position, and the minimum value was 7.91 Mpa for Model A2 in the right rotation. Stand-alone group showed significantly higher ROMs and ESPCs than the BPSF group, with maximum values of 66.66% and 70.59%. For MESE, the BPSF group model can be reduced by 89.88% compared to the stand-alone group model. Conclusions Compared with the traditional straight OLIF cage, the kidney-shaped OLIF cage can further improve the stability of the surgical segment, reduce ESPC, MESE and MSIF, and help to reduce the risk of cage subsidence.

Abstract Purpose To compare the clinical efficacy of oblique lateral interbody fusion (OLIF) combined with unilateral (UPSF) and bilateral pedicle screw internal fixation (BPSF) in patients with osteoporosis. Methods Clinical data of 57 patients who underwent single-segment OLIF surgery with a clear diagnosis of osteoporosis from December 2018 to May 2021 were retrospectively analyzed, of which 27 patients underwent OLIF + UPSF and 30 patients underwent OLIF + BPSF. Surgical technique-related indexes were recorded, including operative time, operative blood loss and postoperative hospital stay; clinical outcome-related indexes included postoperative complications, Visual analogue scale (VAS) and Oswestry disability index (ODI) at preoperative, 1 week, 1 month, 3 months, and 12 months postoperative follow-up; and imaging outcome-related indexes included the measurement of preoperative and postoperative segmental lordosis (SL), and observation of the degree of cage subsidence and bone graft fusion. Results The surgery was successfully performed in 57 patients, and there was no statistical difference in operative blood loss and postoperative hospital stay between UPSF group and BPSF group (P > 0.05). In terms of operative time, there was a significant difference (UPSF group: 92.30 ± 11.03 min, BPSF group: 119.67 ± 16.41, P 0.05). At 1 year postoperatively, the rate and degree of cage subsidence was higher in the UPSF group than in the BPSF group (P