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.
ObjectiveTo investigate the clinical results and complication prevention of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in the treatment of single-segment severe lumbar spinal stenosis (LSS).MethodsThe clinical data of 112 patients with severe LSS treated with MIS-TLIF between January 2010 and January 2017 were retrospectively analyzed. There were 43 males and 69 females, aged 52-81 years, with an average age of 65.3 years. The disease duration ranged from 4 to 126 months, with an average of 10.5 months. Clinical manifestations: 104 cases of low back pain, 91 cases of nervous intermittent claudication of both lower limbs, 21 cases of unilateral nerve root pain and/or numbness, and 5 cases of cauda equina nerve injury. The 112 cases were all severe central spinal stenosis, including 32 cases with lateral recess stenosis, 20 cases with foramen stenosis, 9 cases with ossification of ligamentum flavum, 38 cases with disc herniation; 14 cases with two complications and 5 cases with three. Stenosis segment: L3, 4 in 6 cases, L4, 5 in 89 cases, and L5, S1 in 17 cases. Surgical methods included bilateral decompression through bilateral approach (60 cases), bilateral decompression through unilateral approach (15 cases), and unilateral decompression (37 cases). The operation time, intraoperative blood loss, visual analogue scale (VAS) score of low back pain and leg pain, Oswestry disability index (ODI) score, fusion rate, and surgical complications were recorded. At last follow-up, the lumbar fusion was evaluated by Bridwell method, grades Ⅰ and Ⅱ were expressed as fusion.ResultsThe operation time was 83-186 minutes (mean, 126.8 minutes), and the intraoperative blood loss was 65-630 mL (mean, 163.1 mL). All the 112 patients were followed up 25-49 months, with an average of 35.1 months. The VAS score of low back pain and leg pain and ODI score at each time point after operation were significantly improved when compared with preoperative scores (P<0.05). There was no significant difference between the VAS score of low back pain and leg pain and ODI score at the other time points except 1 month after operation (P<0.05). At last follow-up, 2 cases of cauda equina nerve injury recovered and 3 cases partially recovered. According to Bridwell classification criteria, 58 cases were grade Ⅰ, 47 cases were grade Ⅱ, and 7 cases were grade Ⅲ. The fusion rate was 93.8%. Perioperative complications included 5 cases of incision complications (superficial infection in 3 cases, hematoma formation in 2 cases), 19 cases of internal fixator complications (intraoperative end plate fracture in 8 cases, fusion cage sinking in 11 cases at last follow-up), and 15 cases of neurological complications (dural sac tear in 10 cases, transient neurological symptoms of lower extremities aggravated in 5 cases). Conclusion MIS-TLIF treatment of single-level severe LSS can achieve good clinical results, while there is a risk of serious complications. Full understanding of the clinical and imaging features of the disease and reasonable and careful operation are helpful to control the occurrence of cauda equina nerve damage.