Risk Factors Associated With Revision Microdiscectomy or Subsequent Spinal Fusion Within Two Years of Index Lumbar Microdiscectomy

Spine 2025;50:1392–1399

This large retrospective study found that within two years of lumbar microdiscectomy, 5.5% required revision surgery and 6.6% required spinal fusion. Age 40–59, female sex, and at least one Charlson Comorbidity Index (CCI) comorbidity significantly increased the risk of subsequent fusion, but not revision microdiscectomy.

Revision microdiscectomy rates after index lumbar microdiscectomy were 3.5% at one year and 5.5% at two years.

Lumbar fusion rates were 2.9% at one year and 6.6% at two years after index surgery.

Age 40–59, female sex, and presence of at least one Charlson Comorbidity Index (CCI) comorbidity significantly increased risk of lumbar fusion, but not revision microdiscectomy.

Having ≥1 CCI comorbidity increased the likelihood of needing fusion by about 80%.

Specific comorbidities (e.g., congestive heart failure, peripheral/cerebrovascular disease, diabetes) were strong predictors for time-to-fusion.

Age, sex, and CCI score were not predictive of time-to-revision microdiscectomy.

Results suggest CCI may help identify patients at higher risk for spinal fusion after microdiscectomy.

Findings may guide surgeons in perioperative decision-making and patient counseling.

Which interbody device minimized nonunion, subsidence, and reoperation after anterior cervical discectomy and fusion?

J Neurosurg Spine 43:453–463, 2024

This meta-analysis found that allograft spacers in anterior cervical discectomy and fusion (ACDF) result in lower nonunion and revision rates compared to PEEK cages, with no significant difference in subsidence risk. Allograft offers enhanced fusion and minimizes revision without increasing subsidence.

• Allograft and PEEK cages are the most commonly used interbody spacers in anterior cervical discectomy and fusion (ACDF), replacing autograft due to lower donor site morbidity.

• This meta-analysis included 10 studies with 1462 patients comparing allograft and PEEK cages for ACDF, analyzing nonunion, subsidence, and reoperation rates.

• Allograft showed a significantly lower rate of nonunion than PEEK cages (OR 0.33, p = 0.01), indicating better fusion outcomes.

• Reoperation due to nonunion was significantly higher with PEEK cages compared to allograft (OR 0.28, p < 0.01), but overall reoperation rates for any cause were not significantly different.

• No significant difference was found in the incidence or amount of subsidence between allograft and PEEK cages.

• Allograft’s osteoconductive properties likely contribute to its higher fusion rate, while PEEK cages may lead to fibrous interface formation, reducing solid fusion.

• Meta-regression showed no significant effect of smoking, age, or number of fused levels on nonunion rates.

• Conclusion: Allograft is advantageous over PEEK cages in ACDF due to higher fusion rates and lower revision risk, without increasing subsidence

Early Voice and Swallowing Disturbance Incidence and Risk Factors After Revision Anterior Cervical Discectomy and Fusion Using a Multidisciplinary Surgical Approach

Neurosurgery 94:444–453, 2024

Dysphagia and vocal cord palsy (VCP) are common otolaryngological complications after revision anterior cervical discectomy and fusion (rACDF) procedures. Our objective was to determine the early incidence and risk factors of VCP and dysphagia after rACDF using a 2-team approach.

METHODS: Single-institution, retrospective analysis of a prospectively collected database of patients undergoing rACDF was enrolled from September 2010 to July 2021. Of 222 patients enrolled, 109 patients were included in the final analysis. All patients had prior ACDF surgery with planned revision using a single otolaryngologist and single neurosurgeon. MD Anderson Dysphagia Inventory and fiberoptic endoscopic evaluation of swallowing (FEES) were used to assess dysphagia. VCP was assessed using videolaryngostroboscopy.

RESULTS: Seven patients (6.7%) developed new postoperative VCP after rACDF. Most cases of VCP resolved by 3 months postoperatively (mean time-to-resolution 79 ± 17.6 days). One patient maintained a permanent deficit. Forty-one patients (37.6%) reached minimum clinically important difference (MCID) in their MD Anderson Dysphagia Inventory composite scores at the 2-week follow-up (MCID decline of ≥6), indicating new clinically relevant swallowing disturbance. Forty-nine patients (45.0%) had functional FEES Performance Score decline. On univariate analysis, there was an association between new VCPs and the number of cervical levels treated at revision (P = .020) with long-segment rACDF (≥4 levels) being an independent risk factor (P = .010). On linear regression, there was an association between the number of levels treated previously and at revision for FEES Performance Score decline (P = .045 and P = .002, respectively). However, on univariate analysis, sex, age, body mass index, operative time, alcohol use, smoking, and individual levels revised were not risk factors for reaching FEES Performance Score decline nor MCID at 2 weeks postoperatively.

CONCLUSION: VCP is more likely to occur in long-segment rACDF but is often temporary. Clinically relevant and functional rates of dysphagia approach 37% and 45%, respectively, at 2 weeks postoperatively after rACDF.

Failure of Internal Cerebrospinal Fluid Shunt: A Systematic Review and Meta-Analysis of the Overall Prevalence in Adults

World Neurosurg. (2023) 169:20-30

Reported rates of failures of internal cerebrospinal fluid shunt (ICSFS) vary greatly from less than 5% to more than 50% and no meta-analysis to assess the overall prevalence has been performed. We estimated the failure rate after ICSFS insertion and searched for associated factors.

METHODS: Six databases were searched from January 1990 to February 2022. Only original articles reporting the rate of adult shunt failure were included. Random-effects meta-analysis with a generalized linear mixed model method and logit transformation was used to compute the overall failure prevalence. Subgroup analysis and meta-regression were implemented to search for associated factors.

RESULTS: Of 1763 identified articles, 46 were selected, comprising 70,859 ICSFS implantations and 13,603 shunt failures, suggesting an accumulated incidence of 19.2%. However, the calculated pooled prevalence value and its 95% confidence interval (CI) were 22.7% (95% CI, 19.8e5.8). The CI of the different estimates did not overlap, indicating a strong heterogeneity confirmed by a high I 2 of 97.5% (95% CI, 97.1e97.8; P < 0.001; s 2 [ 0.3). Ninety-five percent prediction interval of shunt failure prevalence ranged from 8.75% to 47.36%. A meta-regression of prevalence of publication found a barely significant decreasing failure rate of about 2% per year (e2.11; 95% CI, e4.02 to e0.2; P [ 0.031).

CONCLUSIONS: Despite being a simple neurosurgical procedure, ICSFS insertion has one of the highest risk of complications, with failure prevalence involving more than 1 patient of 5. Nonetheless, all efforts to lower this high level of shunt failure seem to be effective.

Risk factors for reoperation after lumbar total disc replacement at short-, mid-, and long-term follow-up

DOI:https://doi.org/10.1016/j.spinee.2021.02.020

The reoperation rate following TDR (Total Disc replacement) has been established at short- and mid-term time points through the Food and Drug Administration Investigational Device Exemption (FDA IDE) trials. However, these trials include highly selected centers and surgeons with strict governance of indications. The utilization of TDR throughout the community needs further analysis.

PURPOSE

To identify the risk factors for lumbar spine reoperation in patients undergoing lumbar total disc replacement (TDR) at short-, mid-, and long-term follow-up.

STUDY DESIGN/SETTING

This study is a multi-center retrospective cohort study utilizing the New York Statewide Planning and Research Cooperative System database.

PATIENT SAMPLE

We identified 1,368 patients who underwent an elective primary lumbar TDR in New York State between January 1, 2005 and September 30, 2013.

OUTCOME MEASURES

The primary functional outcome of interest was lumbar reoperation, specifically the evaluation of independent risk factors for lumbar reoperation at a minimum of 2 years, with sub-analyses performed at 5 and ten years.

METHODS

International Classification of Diseases, Ninth revision codes were utilized to identify patients undergoing a primary lumbar TDR. We excluded patients with primary/revision lumbar fusion procedures and revision disc replacement procedures. Hospital academic status was determined by the Accreditation Council for Graduate Medical Education. Unique encrypted patient identifiers allowed for longitudinal follow-up for reoperation. Logistic regression models compared reoperation and no-reoperation cohorts, and were performed on sub-analyses for significant univariate predictors of reoperation.

RESULTS

Between January 2005 and September 2013, 1368 patients underwent a primary lumbar TDR. Reoperation occurred in 8.8% by 2 years, 15.8% by 5 years, and 19.5% by ten years. Diabetics were more likely to have reoperations (7.5% vs 3.8%, p=.013). Teaching hospitals experienced a decreased reoperation rate compared to nonteaching hospitals at 2-year (5.0% vs 10.5%, p=.002), 5-year (10.7% vs 17.9%, p=.002) and 10-year (11.7% vs 21.9%, p=.045) follow-up. Lumbar fusion was the most common reoperation (14.2%).

CONCLUSION

We identified an 8.8% reoperation rate after inpatient lumbar TDR at 2-years, 15.8% at 5-years, and 19.5% at 10-years. When stratifying by teaching status, reoperation rates at teaching centers align with those reported in FDA IDE studies. Diabetes was the only patient factor influencing reoperation rate. There is a growing consensus that lumbar TDR is a durable and appropriate surgical option for lumbar degenerative disc disease. Proper indications are crucial to obtaining good outcomes with lumbar TDR.

 

What Is the Fate of Pseudarthrosis Detected 1 Year After Anterior Cervical Discectomy and Fusion?

Spine 2018;43:E23–E28

Objective. To investigate the consequences and appropriate management of pseudarthrosis after anterior cervical discectomy and fusion (ACDF).

Summary of Background Data. Pseudarthrosis is a frequent complication of ACDF and causes unsatisfactory results. Little is known about long-term prognosis of detecting pseudarthrosis 1 year after ACDF.

Methods. Eighty-nine patients with a minimum 2-year followup were included. ACDF surgery using allograft and plating was performed: single-level in 51 patients, two-level in 26 patients, and three-level in 12 patients. Presence of pseudarthrosis was evaluated 1 year postoperatively and then the nonunion segments were re-evaluated 2 years postoperatively. Demographic data were assessed to identify the risk factors associated with pseudarthrosis. A visual analogue scale for neck/arm pain and the Neck Disability Index were analyzed preoperatively and at 1 and 2 years postoperatively.

Results. Pseudarthrosis was detected in 29 patients (32.6%) 1 year postoperatively: 15of 51 patients after single-level surgery, 9 of 26 patients after two-level surgery, and 5 of 12 patients after three-level surgery. Only eight patients showed persistent nonunion at 2 years: 3 of 15 patients after single-level surgery, 3 of 9 after two-level surgery, and 2 of 5 after three-level surgery. The remaining 21 patients (72.4%) achieved bony fusion 2 years postoperatively without any intervention. Patients who underwent two-level or three-level ACDF had a significantly higher pseudarthrosis rate than those who underwent single-level ACDF, with odds ratios of 1.844 and 3.147, respectively. The improvements in visual analogue scale for neck pain and Neck Disability Index scores in the persistent nonunion group were significantly lower than those in the final union group at 2 years.

Conclusion. Patients with pseudarthrosis detected 1 year postoperatively may be observed without any intervention because approximately 70% of them will eventually fuse by the 2-year point. Early revision could, however, be considered if the pseudarthrosis is associated with considerable neck pain after multilevel ACDF.

Level of Evidence: 3

Cervical Myelopathy After Cervical Total Disc Arthroplasty

Spine 2012 ; 37 : E624 – E628 

This article reports 2 cases in which the patients accepted revision surgery after cervical total disc arthroplasty (CTDA) because of iatrogenic neurological injury.

Summary of Background Data. CTDA has been increasingly investigated to treat cervical degenerative disc disease. However, there are limited reports focused on its complications, especially the neurological complications after the procedure.

Methods. A 52-year-old man underwent total disc arthroplasty for C5–C6, but immediately after surgery, he experienced paralysis of his upper and lower limbs. Radiographical images indicated residual compression to the spinal cord in the level of C5–C6. Another patient, a 60-year-old man, underwent total disc arthroplasty for C4–C5. Afterward, he experienced severe neck pain and paralysis of upper and lower limbs. He was unresponsive to conservative treatments; thus, a laminectomy was performed 3 months later. However, little improvement was observed. Radiographical images indicated kyphosis and spinal cord compression at the level of C4– C5. Furthermore, both cases showed a high signal in the spinal cord by T2-weighted magnetic resonance image, suggestive of spinal cord injuries.

Results. Revision surgeries were performed in both cases. Cervical implants were first removed by the anterior approach, and fusion was then performed after a complete decompression. Motor examination of the patient in case 1 showed grade 3 strength in both of his hands and feet 6 months after revision surgery. In case 2, the patient’s severe neck pain was resolved at the early postoperative stage. Motor examination showed grade 1 strength in both of his hands and feet 3 months after revision surgery.

Conclusion. On the basis of presented cases and other reports, the surgical goals in these patients were prioritized as follows: (1) safe and adequate neurological decompression and (2) establishment and maintenance of cervical sagittal balance. Moreover, a criterion for selecting patients undergoing CTDA needs to be established in order to reduce the occurrence of neurological complications associated with the procedure.