Direction-changeable cage reduces X-ray exposure in treating isthmic lumbar spondylolisthesis: a retrospective study

In spite of a variety of designs for the lumbar interbody fusion cage, there is no consensus on the optimal design so far. Different cage designs may cause different extent of X-ray exposure to visualize the cage positon intraoperatively. In this study, we retrospectively evaluated the X-ray exposure and clinical outcomes of the direction-changeable cage in transforaminal lumbar interbody fusion (TLIF). The patients were divided into the direction-changeable cage group (group A, n=79) and non-direction-changeable cage group (group B, n=84). Intraoperative implantation duration, cage position adjustment times, implantation fluoroscopy times, fluoroscopy exposure time of cage implantation, Oswestry Disability Index (ODI) and visual analogue scale (VAS) scores were recorded before and after operation at the last follow-up. CT scanning was performed to evaluate lumbar fusion. All the patients underwent single-level TLIF and were followed up for 12 to 18 months. In the group A, intraoperative implantation duration, cage position adjustment times, implantation fluoroscopy times, and fluoroscopy exposure time of cage implantation were 6.7 ± 3.6 min, 1.2 ± 0.4 times, 2.5 ± 0.6 times, 7.84 ± 1.83 s, retrospectively. In the group B, these parameters were 11.5 ± 5.9 min, 2.6 ± 1.3 times, 5.8 ± 1.7 times, and 15.31 ± 5.16 s retrospectively, which were higher than those in the non-direction-changeable cage group with statistical significance (P<0.05). In terms of ODI and VAS scores, there was no statistical difference between the two groups before or after operation at the last follow-up (P>0.05). Regarding to the complications, there were 4 cases (4.49%) in the group A, with 3 cases of non-union and 1 case of dural laceration. Eight cases (10.53%) showed complications in the group B, with 7 cases of non-union and 1 case of infection. There was a significant difference between the groups in terms of the complication rate (P<0.05). In conclusion, the direction-changeable cage has merits like lower radiation exposure and fewer complications compared to the non-direction-changeable cage in treating isthmic lumbar spondylolisthesis. Both cages could yield equal clinical outcomes.