Objective To evaluate the biomechanical properties of the bilateral pedicle screw(BPS)and bilateral modified cortical bone trajectory screw(BMCS)fixation techniques in the posterior lumbar interbody fusion(PLIF)model of the L4-5 segment.Methods Finite element models of the L1-S1 lumbar spine were established using three cadaveric lumbar spine specimens.BPS-BPS(TT at the L4-5 segment),BPS-BMCS(TT at the L4 segment and MCBT at the L5 segment),BMCS-BPS(MCBT at the L4 segment and TT at the L5 segment),and BMCS-BMCS(MCBT at the L4-5 segment)were implanted into the finite element model.The range of motion(ROM)at the L4-5 segment and the peak von Mises stress on the internal fixation system,cage,and connecting rods were compared under bending,extension,flexion,and rotation conditions with a 400 N load and 7.5 N·m torque.Results The BMCS-BPS group showed lower ROM and von Mises stress on the cage,internal fixation system,and connecting rods under rotational conditions than the BPS-BPS,BPS-BMCS,and BMCS-BMCS groups.The BPS-BMCS and BMCS-BPS groups had significantly reduced ROM of the L4-5 segment under bending and rotational conditions compared with the BPS-BPS group,and significantly decreased ROM under rotational conditions compared with the BMCS-BMCS group.The BPS-BMCS and BMCS-BPS groups had a significantly reduced risk of cage subsidence under bending conditions compared with the BPS-BPS group,and under rotational conditions compared with the BMCS-BMCS group.The BPS-BMCS and BMCS-BPS groups had a significantly reduced risk of connecting rod fractures under bending and rotational conditions compared with the BPS-BPS and BMCS-BMCS groups.This enhanced the stability of the internal fixation system.Conclusions PLIF combined with the BPS-BMCS and BMCS-BPS fixation techniques can provide better stability for the internal fixation system and vertebral body as well as a lower risk of cage subsidence and connecting rod fracture during bending and rotation in the human body.This would improve the success rate of surgery and recovery effect of patients.

Objective To evaluate the biomechanical properties of the bilateral pedicle screw(BPS)and bilateral modified cortical bone trajectory screw(BMCS)fixation techniques in the posterior lumbar interbody fusion(PLIF)model of the L4-5 segment.Methods Finite element models of the L1-S1 lumbar spine were established using three cadaveric lumbar spine specimens.BPS-BPS(TT at the L4-5 segment),BPS-BMCS(TT at the L4 segment and MCBT at the L5 segment),BMCS-BPS(MCBT at the L4 segment and TT at the L5 segment),and BMCS-BMCS(MCBT at the L4-5 segment)were implanted into the finite element model.The range of motion(ROM)at the L4-5 segment and the peak von Mises stress on the internal fixation system,cage,and connecting rods were compared under bending,extension,flexion,and rotation conditions with a 400 N load and 7.5 N·m torque.Results The BMCS-BPS group showed lower ROM and von Mises stress on the cage,internal fixation system,and connecting rods under rotational conditions than the BPS-BPS,BPS-BMCS,and BMCS-BMCS groups.The BPS-BMCS and BMCS-BPS groups had significantly reduced ROM of the L4-5 segment under bending and rotational conditions compared with the BPS-BPS group,and significantly decreased ROM under rotational conditions compared with the BMCS-BMCS group.The BPS-BMCS and BMCS-BPS groups had a significantly reduced risk of cage subsidence under bending conditions compared with the BPS-BPS group,and under rotational conditions compared with the BMCS-BMCS group.The BPS-BMCS and BMCS-BPS groups had a significantly reduced risk of connecting rod fractures under bending and rotational conditions compared with the BPS-BPS and BMCS-BMCS groups.This enhanced the stability of the internal fixation system.Conclusions PLIF combined with the BPS-BMCS and BMCS-BPS fixation techniques can provide better stability for the internal fixation system and vertebral body as well as a lower risk of cage subsidence and connecting rod fracture during bending and rotation in the human body.This would improve the success rate of surgery and recovery effect of patients.

Objective: To evaluate the clinical value of suprapubic Trocar puncture lithotripsy in the treatment of benign prostatic hyperplasia and bladder stones. Methods: From February 2016 to August 2018, 60 patients with benign prostatic hyperplasia and bladder stones in the Second Hospital of Pujiang County were randomly selected.The patients were divided into transurethral prostatic bipolarplasma electrotomy group(control group, 30 cases) and transurethral prostatic bipolar excision procedure combined with suprapubic Trocar puncture cystinolithotomy group(study group, 30 cases) according to the operation methods.The operation time, stone extraction time, removal of bladder fistula time, catheter extraction time, success of one stone extraction, postoperative complications of the two groups were statistically analyzed. Results: The operation time, stone removal time, bladder fistula removal time and catheter removal time of the study group were significantly shorter than those of the control group(t=6.965, 4.541, 3.365, 3.306, all P<0.05). The success rate of the first stone extraction in the study group was 100.0%(30/30), which was significantly higher than 86.7%(26/30) in the control group (χ²=12.83, P<0.05). The incidence rate of postoperative complications in the study group was 10.0%(3/30), which was significantly lower than 23.3%(7/30) in the control group(χ²=13.34, P<0.05). Conclusion Suprapubic Trocar puncture lithotripsy has high value in the treatment of benign prostatic hyperplasia and bladder stones.