EDITORIAL

<p>To make comparisons among the different modes for each strain gauge, each strain was normalized with respect to the average among the fixation modes. The average and standard deviation of the seven specimens are plotted.</p

Finite Element Analysis of a New Pedicle Screw-Plate System for Minimally Invasive Transforaminal Lumbar Interbody Fusion

<div><p>Purpose</p><p>Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is increasingly popular for the surgical treatment of degenerative lumbar disc diseases. The constructs intended for segmental stability are varied in MI-TLIF. We adopted finite element (FE) analysis to compare the stability after different construct fixations using interbody cage with posterior pedicle screw-rod or pedicle screw-plate instrumentation system.</p><p>Methods</p><p>A L3–S1 FE model was modified to simulate decompression and fusion at L4–L5 segment. Fixation modes included unilateral plate (UP), unilateral rod (UR), bilateral plate (BP), bilateral rod (BR) and UP+UR fixation. The inferior surface of the S1 vertebra remained immobilized throughout the load simulation, and a bending moment of 7.5 Nm with 400N pre-load was applied on the L3 vertebra to recreate flexion, extension, lateral bending, and axial rotation. Range of motion (ROM) and Von Mises stress were evaluated for intact and instrumentation models in all loading planes.</p><p>Results</p><p>All reconstructive conditions displayed decreased motion at L4–L5. The pedicle screw-plate system offered equal ROM to pedicle screw-rod system in unilateral or bilateral fixation modes respectively. Pedicle screw stresses for plate system were 2.2 times greater than those for rod system in left lateral bending under unilateral fixation. Stresses for plate were 3.1 times greater than those for rod in right axial rotation under bilateral fixation. Stresses on intervertebral graft for plate system were similar to rod system in unilateral and bilateral fixation modes respectively. Increased ROM and posterior instrumentation stresses were observed in all loading modes with unilateral fixation compared with bilateral fixation in both systems.</p><p>Conclusions</p><p>Transforaminal lumbar interbody fusion augmentation with pedicle screw-plate system fixation increases fusion construct stability equally to the pedicle screw-rod system. Increased posterior instrumentation stresses are observed in all loading modes with plate fixation, and bilateral fixation could reduce stress concentration.</p></div

Maximum Von Mises stresses on the longitudinal connector (rod/plate).

<p>LB: left lateral bending; RB: right lateral bending; LR: left axial rotation; RR: right axial rotation.</p

Transforaminal lumbar interbody fusion model.

<p>(A) L4-5 right side facetectomy, (B) PEEK cage and bone graft was placed after partial discectomy.</p

Stress nephogram of the intervertebral graft and posterior instrumentation on the right side under flexion.

<p>Grey color region indicated the over 70 MPa Von Mises stresses distribution. Cage and bone graft were showed on the left and the posterior instrumentations were showed on the right.</p

Material property and mesh type of spinal components and implants.

<p>Material property and mesh type of spinal components and implants.</p

Finite element model of fixation modes.

<p>Five finite element models with L3-S1 after right sided TLIF. UP, unilateral pedicle screw-plate fixation; UR, unilateral pedicle screw-rod fixation; BP, bilateral pedicle screw-plate fixation; BR, bilateral pedicle screw-rod fixation; UP+UR, unilateral pedicle screw-plate supplemented with pedicle screw-rod fixation.</p

Maximum Von Mises stresses on intervertebral graft.

<p>LB: left lateral bending; RB: right lateral bending; LR: left axial rotation; RR: right axial rotation.</p

Image_1_USP10 is a potential mediator for vagus nerve stimulation to alleviate neuroinflammation in ischaemic stroke by inhibiting NF-κB signalling pathway.tif

BackgroundVagus nerve stimulation (VNS) has a protective effect on neurological recovery in ischaemic stroke. However, its underlying mechanism remains to be clarified. Ubiquitin-specific protease 10 (USP10), a member of the ubiquitin-specific protease family, has been shown to inhibit the activation of the NF-κB signalling pathway. Therefore, this study investigated whether USP10 plays a key role in the protective effect of VNS against ischemic stroke and explore its mechanism.MethodsIschaemic stroke model was constructed by transient middle cerebral artery occlusion (tMCAO) in mice. VNS was performed at 30 min, 24hr, and 48hr after the establishment of tMCAO model. USP10 expression induced by VNS after tMCAO was measured. LV-shUSP10 was used to establish the model with low expression of USP10 by stereotaxic injection technique. The effects of VNS with or without USP10 silencing on neurological deficits, cerebral infarct volume, NF-κB pathway activation, glial cell activation, and release of pro-inflammation cytokines were assessed.ResultsVNS enhanced the expression of USP10 following tMCAO. VNS ameliorated neurological deficits and reduced cerebral infarct volume, but this effect was inhibited by silencing of USP10. Activation of the NF-κB pathway and the expression of inflammatory cytokines induced by tMCAO were suppressed by VNS. Moreover, VNS promoted the pro-to-anti-inflammatory response of microglia and inhibited activation of astrocytes, while silencing of USP10 prevented the neuroprotective and anti-neuroinflammatory effects of VNS.ConclusionUSP10 is a potential mediator for VNS to alleviate neurological deficits, neuroinflammation, and glial cell activation in ischaemic stroke by inhibiting NF-κB signalling pathway.</p

Range of motion values at L4-L5 in intact and instrumentation models.

<p>Range of motion values at L4-L5 in intact and instrumentation models.</p