ABSTRACT
Objective To investigate the relationship between clinical efficacy and cage subsidence,and to identify the risk factors of cage subsidence after transforaminal lumbar interbody fusion (TLIF) in treating single level lumbar disc herniation and lumbar spondylolisthesis.Methods According to the inclusion/exclusion criteria,a series of 107 patients who underwent TLIF with polyetheretherketone (PEEK) cage in our department were evaluated retrospectively between May 2011 and May 2014.Intervertebral space height and segmental angle were measured on the preoperative and postoperative iconography according to the metrical software.All patients were divided into cage subsidence group (cage subsidence ≥ 2 mm) and cage non-subsidence group (cage subsidence ＜ 2 mm) based on the threshold value of intervertebral space height via X-ray.The Oswestry disability index (ODI) and visual analogue scale (VAS) was used to evaluate the clinical efficacy.Univariate analysis and logistic regression analysis were performed to identify the potential risk factors.Results Of all 107 patients,thirty-six patients (15 males and 21 females)aged 52.61 ± 13.82 years were divided into in the cage subsidence group with an average follow-up duration 26.33±7.66 months,seventy-one patients aged 53.80± 14.94 years,28 males and 43 females in the cage non-subsidence group,were followed-up for 23.82±8.95 months.There was no significant difference between cage subsidence group and cage non-subsidence group in gender,age,course of disease and time of follow-up (P＞ 0.05).The average 2.79±0.78 mm (range 2.02-5.53 mm) subsidence was observed in cage subsidence group.The preoperative intervertebral space height,postoperative intervertebral space height,postoperative segmental angle were related to cage subsidence by univariate analysis (P ＜ 0.05).Postoperative intervertebral space height [OR=1.864,95％CI(1.207,2.879) mm] was the risk factor of cage subsidence by logistic regression (P ＜ 0.05).There was no significant difference between cage subsidence group and cage non-subsidence group in ODI and VAS (P ＞ 0.05).Conclusion Cage subsidence is affected by the preoperative intervertebral space height,postoperative intervertebral space height,and postoperative segmental angle.Postoperative intervertebral space height is the independent risk factor of cage subsidence.Over distraction of intervertebral space height could increase the risk of cage subsidence.