ObjectiveTo compare the effectiveness and imaging features between implanting single and double Cage into intervertebral body through unilateral transforaminal lumbar interbody fusion (TLIF). MethodsThe clinical data were collected and analyzed from 104 patients who underwent unilateral TLIF between January 2013 and October 2014, who were divided into 2 groups:single Cage was implanted into intervertebral body in 64 cases (76 segments) in traditional group, and double Cage was implanted into intervertebral body in 56 cases (70 segments) in reformative group. There was no significant difference in age, gender, bone mineral density, operation segments between 2 groups (P>0.05). The visual analogue scale (VAS), Oswestry disability index (ODI), and Japanese Orthopedic Association (JOA) scores were used to evaluate the effectiveness; the area of intervertebral bone-graft, fusion rate, height of intervertebral space, and the number of Cage subsidence were measured by CT scan. ResultsAll the patients were followed up 12.85 months on average (range, 9-15 months). The VAS, ODI, and JOA scores were significantly improved at each time point after operation when compared with preoperative values (P<0.05), and no significant difference was found between 2 groups (P>0.05) except VAS and ODI at 12 months after operation (P<0.05). However, the area of intervertebral bone-graft in reformative group[(5.94±1.17) cm2] was significantly larger than that in traditional group[(4.81±0.97) cm2] at 7 days after operation (t=-6.365, P=0.000). At 3 and 12 months after operation, the fusion rate was respectively 84.2% and 92.1% in traditional group and was respectively 88.6% and 94.3% in reformative group. Although the height of intervertebral space were increased when compared with preoperative height, the incidence rates of Cages subsidence in traditional group were 44.74% and 47.37% respectively at 3 and 12 months after operation and were significantly higher those that in reformative group (11.43% and 14.29% respectively) (P<0.05). In addition, the height difference between affected side and normal side in traditional group was significantly larger than that in reformative group (P<0.05). ConclusionBoth single and double Cage implanted into the intervertebral body through unilateral TLIF have good effectiveness. However, double Cage implanted into intervertebral body may hold the height of intervertebral space, reduce the incident rate of Cage subsidence, and prevent sagittal imbalance.
ObjectiveTo summarize the advances in research on Cage subsidence following lumbar interbody fusion, and provide reference for its prevention.MethodsThe definition, development, clinical significance, and related risk factors of Cage subsidence following lumbar interbody fusion were throughout reviewed by referring to relevant domestic and doreign literature in recent years.ResultsAt present, there is no consensus on the definition of Cage subsidence, and mostly accepted as the disk height reduction greater than 2 mm. Cage subsidence mainly occurs in the early postoperative stage, which weakens the radiological surgical outcome, and may further damage the effectiveness or even lead to surgical failure. Cage subsidence is closely related to the Cage size and its placement location, intraoperative endplate preparation, morphological matching of disk space to Cage, bone mineral density, body mass index, and so on.ConclusionThe appropriate size and shape of the Cage usage, the posterolateral Cage placed, the gentle endplate operation to prevent injury, the active perioperative anti-osteoporosis treatment, and the education of patients to control body weight may help to prevent Cage subsidence and ensure good surgical results.
ObjectiveTo investigate the correlation between CT value and Cage subsidence in patients with lumbar degenerative disease treated with stand-alone oblique lumbar interbody fusion (OLIF). MethodsThe clinical data of 35 patients with lumbar degenerative diseases treated with stand-alone OLIF between February 2016 and October 2018 were retrospectively analyzed. There were 15 males and 20 females; the age ranged from 29 to 81 years, with an average of 58.4 years. There were 39 operative segments, including 32 cases of single-segment, 2 cases of double-segment, and 1 case of three-segment. Preoperative lumbar CT was used to measure the CT values of the axial position of L1 vertebral body, the axial and sagittal positions of L1-4 vertebral body, surgical segment, and the axial position of upper and lower vertebral bodies as the bone mineral density index, and the lowest T value was recorded by dual-energy X-ray absorptiometry. The visual analogue scale (VAS) and Oswestry disability index (ODI) scores were recorded before operation and at last follow-up. At last follow-up, the lumbar interbody fusion was evaluated by X-ray films of the lumbar spine and dynamic position; the lumbar lateral X-ray film was used to measure the subsidence of the Cage, and the patients were divided into subsidence group and nonsubsidence group. The univariate analysis on age, gender, body mass index, lowest T value, CT value of vertebral body, disease type, and surgical segment was performed to initially screen the influencing factors of Cage subsidence; further the logistic regression for multi-factor analysis was used to screen fusion independent risk factors for Cage subsidence. The receiver operating characteristic (ROC) curve and area under curve (AUC) were used to analyze the CT value and the lowest T value to predict the Cage subsidence. Spearman correlation analysis was used to determine the correlation between Cage subsidence and clinical results. Results All the 35 patients were followed up 27-58 months, with an average of 38.7 months. At last follow-up, the VAS and ODI scores were significantly decreased when compared with preoperative scores (t=32.850, P=0.000; t=31.731, P=0.000). No recurrent lower extremity radiculopathy occurred and no patient required revision surgery. Twenty-seven cases (77.1%) had no Cage subsidence (nonsubsidence group); 8 cases (22.9%) had at least radiographic evidence of Cage subsidence, the average distance of Cage subsidence was 2.2 mm (range, 1.1-4.2 mm) (subsidence group). At last follow-up, there was 1 case of fusion failure both in the subsidence group and the nonsubsidence group, there was no significant difference in the interbody fusion rate (96.3% vs. 87.5%) between two groups (P=0.410). Univariate analysis showed that the CT value of vertebral body (L1 axial position, L1-4 axial and sagittal positions, surgical segment, and upper and lower vertebral bodies axial positions) and the lowest T value were the influencing factors of Cage subsidence (P<0.05). According to ROC curve analysis, compared with AUC of the lowest T value [0.738, 95%CI (0.540, 0.936)], the AUC of the L1-4 axis CT value was 0.850 [95%CI (0.715, 0.984)], which could more effectively predict Cage subsidence. Multivariate analysis showed that the CT value of L1-4 axis was an independent risk factor for Cage subsidence (P<0.05). Conclusion The CT value measurement of the vertebral body based on lumbar spine CT before stand-alone OLIF can predict the Cage subsidence. Patients with low CT values of the lumbar spine have a higher risk of Cage subsidence. However, the Cage subsidence do not lead to adverse clinical results.