Risk factors and clinical significance of posterior slip of the proximal vertebral body after lower lumbar fusion

BACKGROUND Adjacent segment disease(ASD)after fusion surgery is frequently manifests as a cranial segment instability,disc herniation,spinal canal stenosis,spondylolisthesis or retrolisthesis.The risk factors and mechanisms of ASD have been widely discussed but never clearly defined.AIM To investigate the risk factors and clinical significance of retrograde movement of the proximal vertebral body after lower lumbar fusion.METHODS This was a retrospective analysis of the clinical data of patients who underwent transforaminal lumbar interbody fusion surgery between September 2015 and July 2021 and who were followed up for more than 2 years.Ninety-one patients with degenerative lumbar diseases were included(22 males and 69 females),with an average age of 52.3 years(40-73 years).According to whether there was retrograde movement of the adjacent vertebral body on postoperative X-rays,the patients were divided into retrograde and nonretrograde groups.The sagittal parameters of the spine and pelvis were evaluated before surgery,after surgery,and at the final follow-up.At the same time,the Oswestry Disability Index(ODI)and Visual Analogue Scale(VAS)were used to evaluate the patients’quality of life.RESULTS Nineteen patients(20.9%)who experienced retrograde movement of proximal adjacent segments were included in this study.The pelvic incidence(PI)of the patients in the retrograde group were significantly higher than those of the patients in the nonretrograde group before surgery,after surgery and at the final follow-up(P<0.05).There was no significant difference in lumbar lordosis(LL)between the two groups before the operation,but LL in the retrograde group was significantly greater than that in the nonretrograde group postoperatively and at the final follow-up.No significant differences were detected in terms of the|PI–LL|,and there was no significant difference in the preoperative lordosis distribution index(LDI)between the two groups.The LDIs of the retrograde group were 68.1%±11.5%and 67.2%±11.9%,respectively,which were significantly lower than those of the nonretrograde group(75.7%±10.4%and 74.3%±9.4%,respectively)(P<0.05).Moreover,the patients in the retrograde group had a greater incidence of a LDI<50%than those in the nonretrograde group(P<0.05).There were no significant differences in the ODI or VAS scores between the two groups before the operation,but the ODI and VAS scores in the retrograde group were significantly worse than those in the nonretrograde group after the operation and at the last follow-up,(P<0.05).CONCLUSION The incidence of posterior slippage after lower lumbar fusion was approximately 20.9%.The risk factors are related to a higher PI and distribution of lumbar lordosis.When a patient has a high PI and insufficient reconstruction of the lower lumbar spine,adjacent segment compensation via posterior vertebral body slippage is one of the factors that significantly affects surgical outcomes.

A Flat Sagittal Spinal Alignment Is Common among Young Patients with Lumbar Disc Herniation

Background: Recent studies suggest a correlation between spinal sagittal alignment and different types of lumbar pathologies due to different load patterns on the lumbar spine. The main objective of this study was to investigate the preoperative spinal sagittal alignment in young patients (Methods: Information regarding preoperative clinical examinations was collected from the patient medical charts. Preoperative MRI examinations were used to classify lumbar types according to four sagittal spinal alignment groups (1: a long thoracic kyphosis, 2: a flat back, 3: a normal spine and 4: an increased thoracic kyphosis). Other MRI findings were also noted. Classification of lumbar types was performed independently by three spine surgeons. To compare two sample proportions the 2-sample z-test was performed. Results: The distribution of lumbar curve types was: Type 1, 17% (9 patients);Type 2, 62% (33 patients);Type 3, 17% (9 patients) and Type 4, 4% (2 patients). The distribution of operated levels was: L3 - L4, 2% (1 patient);L4 - L5, 47% (25 patients);L5 - S1, 42% (22 patients) and L4 - L5 + L5 - S1, 9% (5 patients). Conclusions: A majority of the young patients (62%) that underwent surgery due to herniated disc in the lumbar spine were classified as Type 2 indicating a flat back. Future studies are needed to increase the knowledge about spinopelvic sagittal alignment and the correlation to spinal pathologies.

Evaluation of lordosis recovery after lumbar arthrodesis and its clinical impact

Background Posterior lumbar arthrodesis has become a widely used therapeutic option to correct sagittal imbalances in patients suffering from degenerative lumbar conditions.However,in western Africa,there is no study have reported long-term outcome of posterior lumbar arthrodesis.The aim of this study was to investigate the relationship between the restoration of adequate lordosis and the patient’s postoperative quality of life.Method The study was retrospective.From January 2012 to December 2019,80 patients who underwent posterior lumbar arthrodesis for lumbar degenerative diseases were included with a mean follow-up of 43.2 months.Mean age was 50.8 years(SD=12.2).Preoperative and postoperative patients'symptoms were assessed by the visual analog scale(VAS),Oswestry Disability Index(ODI),and 12-item Short Form(SF-12).Pre-and post-operative radiographic evaluation included lumbar lordosis measured(LLm),pelvic incidence(PI),sacral slope(SS),and pelvic stilt(PS).Theoretical lumbar lordosis(LLt)was defined by the following:LL=0.54×PI+27.6.Data analysis was done using the statistical software"R."The risk of error was 5%(p<0.05).Result The mean pelvic incidence was 57.23°.There was no statistically significant difference between preoperative and postoperative lumbar lordosis(p=0.2567).There was no statistical difference between preoperative and post-operative PI-LL(p=0.179).There was a statistically significant difference between the pre and postoperative clinical scores(p<0.001).Statistical analysis showed a correlation between recovery of lumbar lordosis and improvement in physical component of SF-12(PCS)(p<0.05)and lumbar and radicular VAS(p<0.05)for the subgroup of narrow lumbar spine.There was a statistical relationship between the restoration of lumbar lordosis and improvement in PCS(p=0.004)and VAS(p=0.003)for the subgroup of isthmic lysis spondylolisthesis.Discussion The root decompression performed in most patients could explain the clinical improvement regardless of recovery of lordosis.The failure to consider spinal parameters and sagittal balance of patients in the surgery could explain no restoration of lumbar lordosis.Our study had limitations inherent to its retrospective character such as the classic selection bias.Conclusion Satisfactory correction of spinopelvic alignment may improve long-term clinical signs.