Early Fusion Status After Posterior Lumbar Interbody Fusion With Cortical Bone Trajectory Screw Fixation or Traditional Trajectory Screw Fixation

A retrospective analysis of prospectively collected data.The aim was to examine whether posterior lumbar interbody fusion with cortical bone trajectory screw fixation (CBT-PLIF) is inferior to PLIF using traditional trajectory screw fixation (TT-PLIF) regarding early fusion status and whether the titanium-coated polyetheretherketone (PEEK) cage (TP cage) improves early fusion status compared with the same shape pure PEEK cage (P cage).We recently reported that the fusion rate was relatively lower after CBT-PLIF than after TT-PLIF, although no significant difference was found and that compared with the carbon PEEK cage, the TP cage significantly reduced the incidence of vertebral endplate cysts (cyst signs) and slightly improved the early fusion rate at 1 year after CBT-PLIF.The subjects were 37 patients undergoing TT-PLIF using P cages (TT-P group), 24 patients undergoing CBT-PLIF using P cages (CBT-P group), 32 patients undergoing TT-PLIF using TP cages (TT-TP group), and 20 patients undergoing CBT-PLIF using TP cages (CBT-TP group). On multiplanar reconstruction computed tomography at 6 months after surgery, cyst signs were evaluated and classified into diffuse or local cysts. Early fusion status was assessed using both dynamic plain radiographs and multiplanar reconstruction computed tomography at 1-year postoperatively.The incidence of the diffuse cyst was 27.0% in the TT-P group, 29.2% in the CBT-P group, 25.0% in the TT-TP group and 25.0% in the CBT-TP group (P>0.05). The early fusion rate was 75.7% in the TT-P group, 75.0% in the CBT-P group, 71.9% in the TT-TP group and 75.0% in the CBT-TP group (P>0.05).These results indicate that CBT-PLIF resulted in the equivalent early fusion status to TT-PLIF and that compared with the same shape P cage, the TP cage did not improve early fusion status after both TT-PLIF and CBT-PLIF.