Current incidence of adjacent segment pathology following lumbar fusion versus motion-preserving procedures: a systematic review and meta-analysis of recent projections

Identification of Autophagy-Related Genes Involved in Intervertebral Disc Degeneration by Microarray Data Analysis

BACKGROUND

Nucleus pulposus cells survive in a hypoxic, acidic, nutrient-poor, and hypotonic microenvironment. Consequently, they maintain low proliferation and undergo autophagy to protect themselves from cellular stress. Therefore, we aimed to identify autophagy-related biomarkers involved in intervertebral disc degeneration pathogenesis.

METHODS

Autophagy-related differentially expressed genes were derived from the intersection between the public GSE147383 microarray data set to identify differentially expressed genes and online databases to identify autophagy-related genes. Furthermore, we assessed their biological functions with gene annotation and enrichment analysis in the Metscape portal. Then, the STRING database and Cytoscape software allowed inferring a protein-protein interaction (PPI) network and identifying hub genes. In addition, to predict transcription factors that may regulate the hub genes, we used the GeneMANIA website. Finally, the competing endogenous RNA prediction tools and Cytoscape were also used to construct an mRNA-miRNA-lncRNA network.

RESULTS

A total of 123 autophagy-related differentially expressed genes were identified, they were mainly involved in phosphoinositide 3-kinase-Akt signaling, autophagy animal, and apoptosis pathways. Nine were identified as hub genes (PTEN, MYC, CTNNB1, JUN, BECN1, ERBB2, FOXO3, ATM, and FN1) and 36 transcription factors were associated with them. Finally, an autophagy-associated competing endogenous RNA network was constructed based on the 9 hub genes.

CONCLUSIONS

Nine hub genes were identified and a network of competing endogenous RNA associated with autophagy was established. They can be used as autophagy-related biomarkers of intervertebral disc degeneration and for further exploration.

Determining a relative total lumbar range of motion to alleviate adjacent segment degeneration after transforaminal lumbar interbody fusion: a finite element analysis

BACKGROUND

A reduction in total lumbar range of motion (ROM) after lumbar fusion may offset the increase in intradiscal pressure (IDP) and facet joint force (FJF) caused by the abnormally increased ROM at adjacent segments. This study aimed to determine a relative total lumbar ROM rather than an ideal adjacent segment ROM to guide postoperative waist activities and further delay adjacent segment degeneration (ASD).

METHODS

An intact L1-S1 finite element model was constructed and validated. Based on this, a surgical model was created to allow the simulation of L4/5 transforaminal lumbar interbody fusion (TLIF). Under the maximum total L1-S1 ROM, the ROM, IDP, and FJF of each adjacent segment between the intact and TLIF models were compared to explore the biomechanical influence of lumbar fusion on adjacent segments. Subsequently, the functional relationship between total L1-S1 ROM and IDP or total L1-S1 ROM and FJF was fitted in the TLIF model to calculate the relative total L1-S1 ROMs without an increase in IDP and FJF.

RESULTS

Compared with those of the intact model, the ROM, IDP, and FJF of the adjacent segments in the TLIF model increased by 12.6-28.9%, 0.1-6.8%, and 0-134.2%, respectively. As the total L1-S1 ROM increased, the IDP and FJF of each adjacent segment increased by varying degrees. The relative total L1-S1 ROMs in the TLIF model were 11.03°, 12.50°, 12.14°, and 9.82° in flexion, extension, lateral bending, and axial rotation, respectively.

CONCLUSIONS

The relative total L1-S1 ROMs after TLIF were determined, which decreased by 19.6-29.3% compared to the preoperative ones. Guiding the patients to perform postoperative waist activities within these specific ROMs, an increase in the IDP and FJF of adjacent segments may be effectively offset, thereby alleviating ASD.

Vertebral Bone Quality Score as a Predictor of Adjacent Segment Disease After Lumbar Interbody Fusion

BACKGROUND AND OBJECTIVE

With lumbar spine fusion being one of the most commonly performed spinal surgeries, investigating common complications such as adjacent segment disease (ASD) is a high priority. To the authors' knowledge, there are no previous studies investigating the utility of the preoperative magnetic resonance imaging-based vertebral bone quality (VBQ) score in predicting radiographic and surgical ASD after lumbar spine fusion. We aimed to investigate the predictive factors for radiographic and surgical ASD, focusing on the predictive potential of the VBQ score.

METHODS

A single-center retrospective analysis was conducted of all patients who underwent 1-3 level lumbar or lumbosacral interbody fusion for lumbar spine degenerative disease between 2014 and 2021 with a minimum 12 months of clinical and radiographic follow-up. Demographic data were collected, along with patient medical, and surgical data. Preoperative MRI was assessed in the included patients using the VBQ scoring system to identify whether radiographic ASD or surgical ASD could be predicted.

RESULTS

A total of 417 patients were identified (mean age, 59.8 ± 12.4 years; women, 54.0%). Eighty-two (19.7%) patients developed radiographic ASD, and 58 (13.9%) developed surgical ASD. A higher VBQ score was a significant predictor of radiographic ASD in univariate analysis (2.4 ± 0.5 vs 3.3 ± 0.4; P < .001) and multivariate analysis (odds ratio, 1.601; 95% CI, 1.453-1.763; P < .001). For surgical ASD, a significantly higher VBQ score was seen in univariate analysis (2.3 ± 0.5 vs 3.3 ± 0.4; P < .001) and served as an independent risk factor in multivariate analysis (odds ratio, 1.509; 95% CI, 1.324-1.720; P < .001). We also identified preoperative disk bulge and preoperative existence of adjacent segment disk degeneration to be significant predictors of both radiographic and surgical ASD. Furthermore, 3-level fusion was also a significant predictor for surgical ASD.

CONCLUSION

The VBQ scoring system might be a useful adjunct for predicting radiographic and surgical ASD.

Therapeutic factors and biomaterial-based delivery tools for degenerative intervertebral disc repair

Intervertebral disc degeneration (IDD) is the main cause of low back pain (LBP), which significantly impacts global wellbeing and contributes to global productivity declines. Conventional treatment approaches, encompassing conservative and surgical interventions, merely serve to postpone the advancement of IDD without offering a fundamental reversal. Consequently, there is an urgent demand for an effective approach to prevent the progression of IDD. Recent investigations focusing on the treatment of IDD utilizing diverse bioactive substances integrated within various biomaterials have exhibited promising outcomes. Various bioactive substances, encompassing conventional small molecule drugs, small molecule nucleic acids, and cell therapies, exhibit distinct capacities for repairing IDD. Additionally, various biological material delivery systems, such as nano micelles, microspheres, and hydrogels, possess diverse biological and release characteristics. Consequently, these diverse materials and drugs hold promise for advancing the treatment of IDD. This article aims to provide a concise overview of the IDD process and investigate the research advancements in biomaterials and bioactive substances for IDD treatment, delving into their mechanisms.

Adjacent segment degeneration after posterolateral lumbar fusion: results and complications of posterior revision surgery

BACKGROUND

Lumbar fusion is an important technique for the treatment of degenerative pathologies. Adjacent segment degeneration is a known complication after lumbar fusion that causes significant morbidity. Our objective was to evaluate the demographics, risk factors, type of surgery, and surgical complications in patients who underwent reoperation through a posterior route due to adjacent segment degeneration.

METHODS

We performed a retrospective analysis of all patients who underwent instrumented posterolateral fusion in the lumbar spine for the treatment of degenerative diseases from January 2000 to December 2015 at a single institution. Patients who developed symptomatic adjacent segment degeneration requiring a second surgery were noted and compared with patients who did not develop adjacent segment degeneration.

RESULTS

A total of 750 patients with degenerative pathologies who underwent fusion with instrumentation were identified. Forty-five patients (6%) required a second surgery for symptomatic adjacent segment degeneration. The average onset of adjacent segment degeneration symptoms after fusion was 5.89 years. Adjacent segment degeneration occurred above the level of fusion in 40 cases and below in 5 cases. The risk factor identified in our series was L5-S1 fusion. The main complication seen after the second surgery was infection in 5 cases (11%).

CONCLUSIONS

This study identifies the L5-S1 fusion as a possible risk factor for adjacent segment degeneration. Reoperation through a posterior route is a therapeutic option but is associated with considerable morbidity. Further studies are necessary to elucidate this pathology and the best options for its management.

Reoperation rate after fusion and non-fusion surgery for degenerative lumbar spine disease

INTRODUCTION

The number of reoperations increases with the growing number of operations performed.

METHODS

The clinical material included a group of 2194 patients treated surgically due to degenerative disease of the lumbar spine; we selected a total of 332 patients who were reoperated, and the indications for reoperation were analysed.

RESULTS

The percentage of patients operated due to adjacent segment disease in the group of patients with stabilization was on average 8.9%.

CONCLUSIONS

Indications for stabilizing or preservation of the mobility of the operated segment should provide for the nature of the lesions, and anatomical and surgical conditions.

Long-term adjacent segment degeneration at average 21-year follow-up of posterior instrumented fusion for adolescent idiopathic scoliosis

INTRODUCTION

Posterior instrumented fusion for progressive adolescent idiopathic scoliosis (AIS) is generally considered to have good outcomes, but very long-term reviews are rare. Data on adjacent segment degeneration (ASD) following posterior instrumented thoracic fusion for AIS are lacking. The primary aim was to assess the incidence of ASD and to correlate this with radiographic measures and patient-reported outcome measures (PROMs). The secondary aim was to assess maintenance of curve correction at very long-term follow-up.

METHODS

This single-surgeon consecutive case series of 47 AIS patients was identified from a prospectively collated dataset. As the primary outcome, ASD was assessed radiographically using the Mimura grading system. Pulmonary function tests and PROMs were assessed along with secondary radiographic outcome measures.

RESULTS

Radiographic follow-up was achieved in 77% (36/47) of patients at an average of 21 years (range, 16.5-26.5 years) after surgery. Radiographic evidence of ASD was seen in 64%. PROMs showed a mean Oswestry disability index of 12.1% with an overall Scoliosis Research Society 22 score averaging at 3.7 out of 5. The Coronal Cobb Angle was corrected from an average of 57° preoperatively to 19° immediately postoperatively, deteriorating to 22° at final review, maintaining a 61% curve correction.

CONCLUSIONS

Radiographic evidence of ASD was found in 64% of the cohort. The patient-reported outcome measures were good, with few limitations to activities.

Medium and long-term radiographic and clinical outcomes of Dynesys dynamic stabilization versus instrumented fusion for degenerative lumbar spine diseases

BACKGROUND

Dynesys stabilization (DS) is utilized to preserve mobility at the instrumental segments and prevent adjacent segment pathology in clinical practice. However, the advantages of DS method in medium and long-term follow-up remain controversial.

OBJECTIVE

To compare the radiographic and clinical outcomes between DS and instrumented fusion in the treatment of degenerative lumbar spine disease with or without grade I spondylolisthesis with a minimum follow-up period of 2 years.

METHODS

We conducted a comprehensive search of PubMed, EMBASE, Cochrane, and Web of Science databases, Chinese National Knowledge Databases, and Wanfang Database for potentially eligible articles. Clinical outcomes were assessed in terms of VAS and ODI scores, screw loosening and breakage, and surgical revision. Radiographic outcomes were assessed in terms of postoperative range of movement (ROM) and disc heigh. Moreover, adjacent segment degeneration (ASDeg) and adjacent segment disease (ASDis) were evaluated.

RESULTS

Seventeen studies with 1296 patients were included in the meta-analysis. The DS group was associated with significantly lower postoperative VAS scores for low-back and leg pain, and lower rate of surgical revision than the fusion group. Moreover, the Dynesys group showed significantly less ASDeg than the fusion group but showed no significant advantage over the fusion group in terms of preventing ASDis. Additionally, the ROM at the stabilized segments of the fusion group decreased significantly and that at the adjacent segments increased significantly compared with those of the DS group.

CONCLUSION

DS showed comparable clinical outcomes and provided benefits in preserving the motion at the stabilized segments, thus limiting the hypermobility at the adjacent segments and preventing ASDeg compared with the fusion method in degenerative disease with or without grade I spondylolisthesis.

Adjacent Segment Vertebral Body Bone Density Changes as Measured By Hounsfield Units After Lumbar Spine Fusion

OBJECTIVE

We sought to evaluate Hounsfield units (HU) at the adjacent segment after single-level transforaminal lumbar interbody fusion (TLIF) with preoperative and postoperative computed tomography scans.

METHODS

We performed a retrospective study on a series of patients who underwent L4-5 TLIF, from 2007 to 2017, by 3 spine surgeons at our institution. One-hundred and forty-three total patients were identified, and 41 patients with minimum 1-year follow-up met inclusion criteria. HU values were measured on preoperative and postoperative computed tomography at the adjacent L3 segment and at L1 as a control arm. Lumbar lordosis, pelvic tilt, pelvic incidence, sacral slope, and sagittal vertical axis were also collected preoperatively and postoperatively.

RESULTS

Mean preoperative HU value at L3 did not differ from the postoperative value (134.11 ± 47.14 mg/cm³ vs. 141.21 ± 55.14 mg/cm³, P = 0.34). Similarly, the mean preoperative HU value at the L1 control level region of interest did not differ from the postoperative value (150.17 ± 53.91 mg/cm³ vs. 145.78 ± 58.34 mg/cm³, P = 0.634). The interrater reliability of HU measurements was satisfactory with a resulting intraclass correlation coefficient of 0.76.

CONCLUSIONS

As measured by HU, we did not observe a change in bone density or other signs of adjacent segment disease at the L3 vertebral body 12 months after L4-5 TLIF. Spinopelvic parameters were not shown to be correlated with HU changes.

Proximal junctional kyphosis is a compensation for post-operative negative C2-FH in ASD patients: a cross-sectional study

BACKGROUND

Recent studies have found that C2-FH is close to 0 cm in both standing and sitting position for asymptomatic adults. We hypothesize that the thoracic spine may compensate with PJK when the immediate post-operative C2-FH was not ideally restored in adult spinal deformity (ASD).

METHODS

The inclusion criteria were as follows: ASD patients over 45 years old; Cobb angle > 30°; with posterior spinal correction surgery; at least 2 years follow-up. C2-FH was defined as the distance between the femoral heads to the C2 vertical line. All participants were divided into two groups according to the occurrence of PJK at the last follow-up: PJK group and non-PJK group.

RESULTS

68 ASD patients, with a minimum follow-up of 2.5 years, were included. PJK was found in 24 patients (35.3%) while the rest 44 patients remained no sagittal malalignment. Immediately post-operative C2-FH showed significant difference between PJK group and non-PJK group (p = 0.015). However, at the last follow-up, C2-FH showed no significant difference between PJK and non-PJK group and the mean value of C2-FH in both groups was approximately - 1 cm, indicating that ASD patients could develop various compensatory mechanisms to maintain sagittal global balance. The AUC was 0.84 (95%CI 0.68-0.97), indicating the well effectiveness of ROC curve and cut-off value in predicting occurrence of PJK in ASD patients. Based on the ROC curve, the optimal cut-off value of C2-FH as indicators for occurrence of PJK was - 42.3 mm.

CONCLUSION

Immediate postoperative negative global malalignment (C2-FH < - 42.3 mm) may predict proximal junctional kyphosis in ASD patients. The normal value of C2-FH, - 1 cm, may be the target of global sagittal compensation, and PJK is a compensatory mechanism.

TRIAL REGISTRATION

2021-LCYJ-DBZ-05, 2021.07, Retrospective study.

Impact of heterotopic ossification following lumbar total disk replacement: a systematic review

Background context

Lumbar total disc replacement (TDR) is an alternative to lumbar fusion in the treatment of lower back pain and reduces the risk of adjacent segment degeneration. Heterotopic ossification (HO) has been identified as a common complication following lumbar TDR.

Purpose

This systematic review aims to determine the prevalence, risk factors and clinical and radiological impact of HO following lumbar TDR.

Study Design

Systematic Review.

Methods

MEDLINE, Scopus, PubMed and Cochrane Central were searched for articles that referred to lumbar TDR and HO. The hits were assessed against inclusion and exclusion criteria. Data from each included study was extracted and analysed with respect to the study aims.

Results

Twenty-six studies were included in this review and the pooled prevalence of HO was estimated to be between 13.2% (participants) and 15.3% (vertebral levels). TDR clinical outcomes were not found to be reduced by HO and there was insufficient data to identify a given impact upon radiological outcomes. Age and follow up time were identified as potential risk factors for HO.

Conclusions

This review was hampered by inconsistencies in the reporting of HO across the studies. We therefore recommend that a set of guidelines should be produced to aid future researchers and reduce the risk of bias.

Lee L. Adjacent segment pathology of the cervical spine: A case report

Adjacent segment pathology (ASP) refers to degenerative changes at segments immediately contiguous to previous spinal fusion. Its pathophysiology is hypothesized as being possibly due to altered biomechanical stresses on adjacent levels following spinal fusion or due to patient propensity to develop progressive degenerative change. This case report describes a 61-year-old female who presented with neck pain and cervical radiculopathy attributed to an anterior cervical discectomy and spinal fusion performed for degenerative disc disease 30 years earlier. ASP was seen on magnetic resonance imaging (MRI) and radiograph. Treatment consisted of cervical manipulation, soft-tissue mobilization, flexion-distraction decompression, and therapeutic ultrasound to release restriction and restore muscle strength. Following 34 sessions of chiropractic intervention, her symptoms were resolved. Patients with ASP will have ongoing shared care between general practitioners and secondary or tertiary care pain units. This report aims to build a shared understanding from the wider vision of ASP and help primary practitioners to manage ASP effectively.

A comparison of long-term efficacy of K-rod-assisted non-fusion operation and posterior lumbar interbody fusion for single-segmental lumbar disc herniation

K-rod-assisted non-fusion surgery for the treatment of lumbar disc herniation has been proven to have short-term clinical efficacy. Meanwhile, its long-term effects have not been examined. To observed the long-term clinical efficacy of K-rod-assisted non-fusion operation, this study retrospectively analyzed 22 patients with lumbar disc (L4/5) herniation who underwent K-rod-assisted non-fusion operation (n = 13) or PLIF (n = 9). They were followed-up for more than 5 years. The operation times and blood loss were significantly reduced in the K-rod group compared to the PLIF group. At the last follow-up, the clinical outcomes of the K-rod group were improved compared to those of the PLIF group as observed by the VAS score, JOABPEQ, and ODI. Imaging outcomes at the last follow-up indicated that the loss of height in the L3/4 and L5/S1 intervertebral space, the ROM of L3/4 and L5/S1, and the incidence of adjacent segment degeneration in the PLIF group were significantly higher than those in the K-rod group. According to Pfirrmann grading, Modic changes, and UCLA grading, the incidence of adjacent segment degeneration was 55.6% in the PLIF group and 15.4% in the K-rod group. Changes in spino-pelvic parameters between the two groups were as follows: pelvic index remained unchanged, pelvic tilt angle increased, and lumbar lordosis and sacral slope decreased. Therefore, compared to PLIF, single-segment lumbar disc herniation using K-rod-assisted non-fusion surgery resulted in better long-term clinical efficacy. Our results demonstrate that this procedure can delay adjacent segment degeneration after lumbar surgery.

Comparison of adjacent segment disease after minimally invasive versus open lumbar fusion: a minimum 10-year follow-up

OBJECTIVE

The object of this study was to compare, after a long-term follow-up, the incidence and features of adjacent segment disease (ASDis) following lumbar fusion surgery performed via an open technique using conventional interbody fusion plus transpedicular screw fixation or a minimally invasive surgery (MIS) using a tubular retractor together with percutaneous pedicle screw fixation.

METHODS

The authors conducted a retrospective chart review of patients with a follow-up period > 10 years who had undergone instrumented lumbar fusion at the L4-5 level between January 2004 and December 2010. The patients were divided into an open surgery group and MIS group based on the surgical method performed. Baseline characteristics and radiological findings, including factors related to ASDis, were compared between the two groups. Additionally, the incidence of ASDis and related details, including diagnosis, time to diagnosis, and treatment, were analyzed.

RESULTS

Among 119 patients who had undergone lumbar fusion at the L4-5 level in the study period, 32 were excluded according to the exclusion criteria. The remaining 87 patients were included as the final study cohort and were divided into an open group (n = 44) and MIS group (n = 43). The mean follow-up period was 10.50 (range 10.0-14.0) years in the open group and 10.16 (range 10.0-13.0) years in the MIS group. The overall facet joint violation rate was significantly higher in the open group than in the MIS group (54.5% vs 30.2%, p = 0.022). However, in terms of adjacent segment degeneration, there were no significant differences in corrected disc height, segmental angle, range of motion, or degree of listhesis of the adjacent segments between the two groups during follow-up. The overall incidence of ASDis was 33.3%, with incidences of 31.8% in the open group and 34.9% in the MIS group, showing no significant difference between the two groups (p = 0.822). Additionally, detailed diagnosis and treatment factors were not different between the two groups.

CONCLUSIONS

After a minimum 10-year follow-up, the incidence of ASDis did not differ significantly between patients who had undergone open fusion and those who had undergone MIS fusion at the L4-5 level.

[Degenerative lumbar spine stenosis: minimally invasive microsurgical methods of treatment]

Degenerative lumbar spine stenosis is one of the main causes of chronic pain and radiculopathy in advanced age people. Along with increase in average life expectancy, degenerative lumbar spine stenosis becomes the most common indication for spinal surgery. There is still no consensus regarding the most optimal surgical approach due to the variety of modern surgical methods. In recent years, minimally invasive spinal surgery has become a more advisable alternative to open surgery due to its advanced technical features combined with less soft tissue damage, lower risk of complications and shorter postoperative recovery.

A Minimally Invasive Technique Using Cortical Bone Trajectory Screws Assisted by 3D-Printed Navigation Templates in Lumbar Adjacent Segment Degeneration

Purpose

Revision surgery for adjacent segment degeneration (ASD) commonly requires exposing and removing the original fixation. To minimize trauma and to reduce the operation time and blood loss, we introduced a minimally invasive lumbar revision technique using cortical bone trajectory (CBT) screws assisted by three-dimensional (3D)-printed navigation templates.

Methods

From April 2017 to October 2019, 18 patients with ASD underwent revision surgery with CBT screws assisted by 3D-printed templates in our hospital. All surgical data, including the operation time, blood loss, and incision length, were recorded. We evaluated the clinical efficacy using the visual analog scale (VAS), the Oswestry Disability Index (ODI), and the Japanese Orthopedic Association (JOA) score. X-ray and computed tomography (CT) scans were used to evaluate the stability of CBT screw fixation, the accuracy of screws, and the fusion rate.

Results

The mean follow-up was 22.4±4.7 months (12–31 months). The VAS, ODI, and JOA scores were analyzed by SPSS 21.0 and showed significant improvement at 2 weeks and the last follow-up compared with preoperative data (P<0.05). Seventy-six CBT screws were inserted with navigation templates; 2 screws were Grade B, and the other screws were Grade 0 or A. Changes in intervertebral height showed good stability of CBT screw fixation (P>0.05). All the patients exhibited satisfactory fusion results.

Conclusion

Revision surgery for ASD with CBT screws assisted by 3D-printed navigation templates has satisfactory clinical efficacy with the advantages of a short operation time, a small incision, and less blood loss.

[Expression profile of intervertebral disc degeneration-specific genes: a transcriptome sequencing-based analysis]

OBJECTIVE

To identify new therapeutic targets for intervertebral disc degeneration (IDD) by analyzing gene variations in IDD.

OBJECTIVE

We analyzed surgical samples of intervertebral disc from 4 patients with IDD and 3 patients with non-IDD using RNA sequencing (RNA-seq) technology to identify significant differentially expressed genes (DEGs) in IDD. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were utilized for gene enrichment studies to acquire the key genes and signal pathways during IDD progression. The differential expressions of the identified genes in IDD were validated in clinical samples with qRT-PCR.

OBJECTIVE

The transcriptome profile revealed 512 significant DEGs, which were enriched in terms of keratinization, extracellular matrix (ECM) components, growth factor binding, and inflammatory chemotaxis in GO analysis. The top 10 terms of KEGG enrichment included amoebiasis, viral protein interaction with cytokine and cytokine receptor, ECM-receptor interaction, IL-17 signaling pathway, cytokine-cytokine receptor interaction, TNF signaling pathway, AGE-RAGE signaling pathway in diabetic complications, PI3K-Akt signaling pathway, chemokine signaling pathway and estrogen signaling pathway. Thirteen DEGs selected as the targets for qRT-PCR validation showed significant differential expressions in IDD (P < 0.001), and their expression trends were all consistent with the results of RNA-seq. Among these genes, 10 genes showed significant intergroup fold change (Log2FoldChange>1).

OBJECTIVE

ECM, growth factors, collagen components, inflammatory chemokines and such signal pathways as TNF-α and PI3K-Akt all have important contributions to IDD progression and may thus serve as new therapeutic targets for treatment of IDD.

Can Indirect Decompression Reduce Adjacent Segment Degeneration and the Associated Reoperation Rate After Lumbar Interbody Fusion? A Systemic Review and Meta-analysis

OBJECTIVE

We sought to assess and compare the rate of adjacent segment degeneration (ASDeg), adjacent segment disease, and related reoperations between patients who underwent lumbar interbody fusion surgery using indirect or direct decompression.

METHODS

On the basis of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic review and meta-analysis was performed to identify and analyze studies that compared the rate of ASDeg, adjacent segment disease, and related reoperations between indirect and direct decompression techniques. Indirect decompression included anterior lumbar interbody fusion, lateral lumbar interbody fusion, and oblique lateral interbody fusion, whereas direct decompression included posterior or transforaminal lumbar interbody fusion.

RESULTS

Seven studies including a total of 576 patients (indirect: 314; direct: 262) were identified. The pooled rates of ASDeg were 19.4% (45/232) and 34.9% (66/189) for indirect and direct decompression, respectively. A fixed-effects model showed 0.34 times lower odds of developing ASDeg in the indirect decompression group (odds ratio = 0.34, 95% confidence interval [CI] = 0.20, 0.57). The pooled incidence of reoperation was 2.5% (8/314) and 6.1% (16/262) for indirect and direct decompression, respectively. A fixed-effects model showed 0.40 times lower odds of reoperation from ASDeg in the indirect decompression group (odds ratio = 0.40, 95% CI = 0.18, 0.89). The pooled mean difference for the segmental lordosis angle was 1.80 degrees (95% CI = 0.74, 2.86) and 7.11 degrees (95% CI = 4.47, 9.74) for total lumbar lordosis angle, favoring indirect decompression.

CONCLUSIONS

Indirect decompression showed lower odds of developing ASDeg and undergoing reoperation for ASDeg after lumbar interbody fusion surgery in this meta-analysis. However, the limited number and quality of the included studies should be considered when interpreting the results.

Clinical and Radiographic Outcomes of Lateral Interbody Fusion for Adjacent Segment Degeneration

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Assessment of outcomes in patients undergoing lateral interbody fusion as part of the surgical treatment of adjacent segment deterioration after previous lumbar spine fusion.

METHODS

Adult patients with previous lumbar posterior spinal fusion who presented with adjacent segment degeneration and stenosis refractory to nonoperative treatment and who underwent lateral lumbar interbody fusion were retrospectively analyzed. Clinical and radiographic outcomes were assessed and comparisons made between preoperative baseline and postoperative values.

RESULTS

Thirty-six patients with symptomatic adjacent segment degeneration at 46 motion segments were included. Thirty (83.3%) of the 36 patients had complete relief of both preoperative lower extremity pain and back pain at the time of final follow-up. Six (16.7%) of the 36 patients had persistent pain, though in all 6 cases, the pain was less postoperatively than preoperatively. Oswestry Disability Index scores were improved significantly at final follow-up (P = .001). Compared with preoperative baseline parameters, initial and final postoperative radiographs had an increase in segmental lordosis (P < .001 and P < .001, respectively), increase in overall lumbar lordosis (P < .05 and P = .094, respectively), decrease in segmental coronal angulation (P = .63 and P < .01, respectively), decrease in overall coronal angulation (P = .063 and P = .009, respectively), and increase in intervertebral height (P < .001 and P < .001, respectively).

CONCLUSION

Lateral lumbar interbody fusion achieves favorable clinical and radiographic outcomes for the treatment of adjacent segment degeneration after previous lumbar fusion.

LEVEL OF EVIDENCE

4.