Objective:To evaluate the effect of oblique lateral interbody fusion (OLIF) combined with posterior fixation on segmental alignment in the treatment of degenerative spondylolisthesis (DS).Methods:The clinical data of 40 patients with DS who underwent OLIF combined with posterior fixation from July 2017 to December 2019 were retrospectively analyzed. There were 7 males and 33 females, aged 45-81 years, with an average age of 65.7±9.06 years. The total number of slip segments was 43, including 37 levels at L 4, 5, 5 levels at L 3, 4, and 1 level at L 2, 3. According to the decompression methods, the patients were divided into two groups. 22 patients with 23 levels were treated with direct decompression combined with laminectomy, and 18 patients with 20 levels were treated with indirect decompression without laminectomy. All patients underwent preoperative and intraoperative imaging examination. The disc height (DH), slip ratio (SR) and segmental lordosis (SL) were measured by preoperative CT and intraoperative fluoroscopy images. One-way repeated measures ANOVA was used to compare the radiographic parameters of the segmental alignment prior to cage implantation, following cage insertion and posterior fixation. Bonferroni test was used to compare the radiographic parameters between groups. Results:In the OLIF combined with the posterior fixation, there were statistically significant differences in the radiographic parameters of segmental alignment at different stages of operation [DH ( F=147.786, P<0.001) , SR ( F=83.754, P<0.001) , SL ( F=38.296, P<0.001) ]. DH increased from 7.99±1.39 mm to 11.69±1.72 mm ( P<0.001), SR decreased from 10.67%±4.67% to 8.66%±4.50% ( P=0.001) and SL increased from 7.26°±2.73° to 7.85°±2.30° ( P=0.425). After combined posterior fixation, SR further decreased from 8.66%±4.50% to 2.07%±4.00% ( P<0.001), SL further increased from 7.85°±2.30° to 10.72°±3.08° ( P<0.001), and DH had no significant change ( P=1.000). There was no significant difference in radiographic parameters between the direct decompression group and the indirect decompression group when prior to cage implantation, following cage insertion and following posterior fixation, respectively. Conclusion:OLIF combined with posterior fixation in the treatment of DS can further reduce the slip rate of patients with lumbar degenerative spondylolisthesis and increase the lordosis angle of the surgical segment. At the same time, the direct decompression combined with laminectomy has no significant effect on the segmental alignment.

Objective:To explore the long-term clinical efficacy and complications of modified spinous process splitting laminoplasty using coralline hydroxyapatite (SLAC).Methods:The patients who underwent SLAC surgery in this hospital from 2005.5 to 2011.7 were included retrospectively. The perioperative data were collected and followed up. A total of 165 cases were included. Among them, there were 115 males and 50 females; the average age was 56.5±11.4 years (range: 26-84 years), and the average follow-up period was 136.5±23.2 months (range: 108-182 months). The modified Japanese Orthopedic Association (mJOA) score, the neck disability index (NDI) score were used to evaluate the clinical symptoms of patients, and follow-up imaging to observe the changes in cervical spine curvature and mobility.Results:In terms of functional score: mJOA score increased from 11.4±2.9 before surgery to 15.0±1.8 in the early postoperative period but dropped to 14.0±2.5 at the last follow-up ( F=77.096, P<0.001), and NDI score decreased from 19.2%±14.4% before surgery to 13.0%±15.0% in the early postoperative period, but it rose to 14.0%±14.9% at the last follow-up ( F=6.915, P<0.001). The improvement rate of mJOA was 63.5% (early postoperatively) and 50.8% (last follow-up). Regarding the curvature of the cervical spine, the C 2-C 7 Cobb angle decreased from 14.8°±9.1° before surgery to 11.1°±10.5°, and it was maintained at the last follow-up (11.0°±10.1°) ( F=1.083, P=0.342). The cervical spine range of motion decreased significantly, mainly because the Cobb angle in the flexion position decreased from -19.8°±13.6° before the operation to -3.7°±10.6° at the last follow-up ( P<0.001). Seventy-two patients (44.0%) had complications after operation. Six patients (3.6%) developed neurological symptoms aggravated during follow-up, and their mJOA decreased by more than 3 points. 62 patients (37.6%) developed axial symptoms, of which 7 cases were relieved early (within 6 months post-op), 55 patients had persisted symptom and 17 cases (10.3%) remained painful. C 5 nerve root palsy occurred in 10 cases (6.1%) after the operation, 9 cases resolved within two years and the last patient did not resolve. Conclusion:SLAC surgery can effectively alleviate the patient's neurological symptoms and maintain long-term efficacy and cervical lordosis. The occurrence of persistent axial symptoms and the loss of cervical flexion range are long-term complications after SLAC surgery.

Objective:To explore the factors affecting changes of disc angle (ΔDA) during oblique lateral interbody fusion (OLIF) and establish a predictive model of ΔDA.Methods:This retrospective study included 119 patients with 174 segments undergoing OLIF procedures between July 2017 and August 2019 in Beijing Jishuitan Hospital. 45 males and 74 females with an average age of 62.1±9.8 years (33-86 years) were included. The lordotic cages were all 6 degrees. Radiographic parameters included preoperative and postoperative disc angle (DA), disc height (DH), ΔDA on flexion-extension views (ΔDA-FE), cage location and cage inclination. Pearson correlation coefficient and machine-learning techniques were utilized to identify factors related to ΔDA. Based on machine leaning techniques, ten-fold cross-validation for model training and validation were used to develop a predictive linear model for ΔDA.Results:The average ΔDA was 3.9°±4.8° with preoperative disc angle (preoperative DA) of 5.3°±5.0°. The average change of posterior DH (ΔPDH) was 3.1±2.1 mm with preoperative posterior DH of 6.6±1.9 mm. The average change of anterior DH was 6.1±3.2 mm. Pearson correlation analysis showed a significant negative correlation between ΔDA and preoperative DA ( r=-0.713, P<0.001), cage location ( r=-0.183, P=0.016), and ΔDA-FE ( r=-0.153, P=0.044). PDH changes were significantly negatively correlated with preoperative PDH ( r=-0.444, P<0.001) and positively correlated with cage location ( r=0.218, P=0.004). ΔDA was 10.8°±3.2° for negative preoperative DA (indicating kyphotic), 5.0°±3.7° for preoperative DA between 0° and 6°, and 1.0°±4.1° for preoperative DA>6°. A predictive model was developed using ten-fold cross-validation, resulting in the formula ΔDA=7.9°-0.8×preoperative DA ( R=0.707, MAE=2.837). Conclusion:Disc angle changes in OLIF primarily depend on the preoperative disc angle, secondly on cage location. The predicting model based on machine-learning techniques using preoperative disc angle facilitates preoperative planning for OLIF procedures.

Objective To compare the clinical outcomes between oblique lumbar interbody fusion(OLIF)and transforaminal lumbar interbody fusion(TLIF)for patients with degenerative spondylolisthesis during 2-year follow-ups.Methods Patients with symptomatic degenerative spondylolisthesis who underwent OLIF(46 cases)and TLIF(45 cases)between July 2017 and September 2020 with 2-year follow-ups were retrospectively reviewed.One level or two-level lumbar fusion were included.The primary outcomes were Visual Analogue Scale(VAS)and Oswestry Disability Index(ODI)at 2 years after surgery.The secondary outcomes included radiographic parameters,fusion rate,cage subsidence rate,and permanent nerve injury rate.Results No significantly different changes were noted in VAS-back[2(2,3)vs.2(2,2),P=0.943],VAS-leg[2(2,2)vs.2(2,2),P=0.988],and ODI[17％(10％,22％)vs.14％(10％,22％),P=0.417]between the OLIF group and the TLIF group,respectively.Greater restoration of disc height and segmental lordosis were obtained in the OLIF group[mean,(11.9±1.5)mm and 15.7°±7.2°]than in the TLIF group[mean,(9.2±2.0)mm and 12.5°±5.9°]at postoperative 2-year(P＜0.001 and P=0.029).The subsidence rate was lower in the OLIF group than in the TLIF group[19.6％(9/46)vs.40.0％(16/40),P=0.037].The fusion rates at postoperative 2-year were 93.5％(43/46)in the OLIF group and 87.5％(35/40)in the TLIF group,having no significant difference(P=0.562).The rates of permanent nerve injury were similar between the two groups[4.3％(2/46)vs.6.7％(3/45),P=0.980]at postoperative 2-year.Conclusion Short segment OLIF doesn't show better clinical outcomes and fusion rate than TLIF for degenerative spondylolisthesis,except for greater disc height restoration,greater segmental lordosis,and lower subsidence rate at postoperative 2-year.