Risk Factors And Clinical Efficacy Of Cage Subsidence After Single Level Transforaminal Lumbar Interbody Fusion

Objective: This study was to analyze and discuss the clinical risk factors and clinical efficacy after transforaminal lumbar interbody fusion(TLIF) for treating single level lumbar disc herniation and lumbar spondylolisthesis. Meanwhile, the study was to provide clinical reference value for preventing cage subsidence.Methods: According to the inclusion criteria and exclusion criteria, a series of patients who underwent TLIF with PEEK cage in our department were evaluated retrospectively between May 2011 and May 2014. All patients were divided into subsidence group(≥2mm) and non-subsidence group(<2mm) based on the threshold value of intervertebral space height(2mm). The age, gender, related data of operation were recorded. Intervertebral space height and segmental angle were measured on the preoperative and postoperative iconography according to the metrical software. The oswestry disability index(ODI) and visual analogue scale(VAS) was used to evaluate the clinical efficacy.Results: There was a total of 107 patients with 12~47 months follow up in the study. Of all these patients, there were 36 patients in subsidence group and 71 patients in non-subsidence group. There was no significant difference between subsidence group and non-subsidence group about gender, age, course of disease and time of follow up(p > 0.05). The L4/5 level, preoperative intervertebral space height, postoperative intervertebral space height, postoperative segmental angle were risk factors of cage subsidence through univariate analysis(p <0.05). Preoperative intervertebral space height(OR=2.209,95%CI=1.39~3.509), postoperative intervertebral space height(OR=1.915,95%CI=1.252~2.929) and corrected intervertebral space height(OR=1.805, 95%CI=1.133~2.876) were risk factors of cage subsidence through logistic regression(p<0.05). There was no significant difference between subsidence group and non-subsidence group about ODI and VAS(p>0.05).Conclusion: 1. Transforaminal lumbar interbody fusion can obtain favourable clinical efficacy for treating the lumbar disc herniation and lumbar spondylolisthesis.2. Cage subsidence is affected by many factors after transforaminal lumbar interbody fusion. The L4/5 level, preoperative intervertebral space height, postoperative intervertebral space height, corrected intervertebral space height and postoperative segmental angle are important risk factors in our study. However, preoperative intervertebral space height, postoperative intervertebral space height and corrected intervertebral space height are important and independent risk factors relatively. Over distraction of intervertebral space height may increase the risk of cage subsidence.3. Cage subsidence is a common complication after transforaminal lumbar interbody fusion. However, cage subsidence does not have influence on clinical efficacy.