Effect of Lumbar Discectomy or Lumbar Decompression on Axial Back Pain: Results of a Meta-Analysis

World Neurosurg. (2023) 177:109-121

This meta-analysis evaluated the impact of lumbar disk herniation and lumbar spinal stenosis (LSS) on axial back pain and the extent of improvement of axial and radicular pain following lumbar decompression and discectomy surgery in patients with low back pain (LBP).

METHODS: A systematic search for published literature between January 2012 and January 2023 was made on PubMed, Google Scholar, and Cochrane library database on 31 st January 2023.

Original articles that included patients with lumbar disc herniation or LSS who underwent lumbar discectomy or lumbar decompression respectively were included in the study.

RESULTS: A total of 71 studies including 16,770 patients with LBP undergoing lumbar discectomy or decompression surgery were included in the metaanalysis. The pooled standard mean difference between postoperative and preoperative: Visual Analog Scale scores for leg pain was L5.14 with 95% confidence interval (CI): L6.59 to L3.69 (P-value [ 0) and for back pain was L2.90 with 95% CI: L3.79 to L2.01 (P value [ 0), Numerical pain Rating Scale for leg pain was L1.64 with 95% CI: L1.97 to L1.30 (P-value<0.01) and for back pain was L1.58 with 95% CI: L1.84 to L1.32 (P-value <0.01), Oswerty Disability Index score was L4.76 with 95% CI: L6.22 to L3.29 (P-value [ 0) and the Japanese Orthopaedic Association score was 3.45 with 95% CI: 0.02 to 6.88 (P value 0) at follow-up.

CONCLUSIONS: This meta-analysis provides evidence that lumbar discectomy and decompression are effective in improving axial LBP in patients with lumbar disk herniation and LSS.


Anterolateral versus posterior minimally invasive lumbar interbody fusion surgery for spondylolisthesis: comparison of outcomes from a global, multicenter study at 12-months follow-up

The Spine Journal 23 (2023) 1494−1505

Several minimally invasive lumbar interbody fusion techniques may be used as a treatment for spondylolisthesis to alleviate back and leg pain, improve function and provide stability to the spine. Surgeons may choose an anterolateral or posterior approach for the surgery however, there remains a lack of real-world evidence from comparative, prospective studies on effectiveness and safety with relatively large, geographically diverse samples and involving multiple surgical approaches.

PURPOSE: To test the hypothesis that anterolateral and posterior minimally invasive approaches are equally effective in treating patients with spondylolisthesis affecting one or two segments at 3months follow-up and to report and compare patient reported outcomes and safety profiles between patients at 12-months post-surgery.

DESIGN: Prospective, multicenter, international, observational cohort study.

PATIENT SAMPLE: Patients with degenerative or isthmic spondylolisthesis who underwent 1- or 2-level minimally invasive lumbar interbody fusion.

OUTCOME MEASURES: Patient reported outcomes assessing disability (ODI), back pain (VAS), leg pain (VAS) and quality of life (EuroQol 5D-3L) at 4-weeks, 3-months and 12-months follow-up; adverse events up to 12-months; and fusion status at 12-months post-surgery using X-ray and/or CT-scan. The primary study outcome is improvement in ODI score at 3-months. METHODS: Eligible patients from 26 sites across Europe, Latin America and Asia were consecutively enrolled. Surgeons with experience in minimally invasive lumbar interbody fusion procedures used, according to clinical judgement, either an anterolateral (ie, ALIF, DLIF, OLIF) or posterior (MIDLF, PLIF, TLIF) approach. Mean improvement in disability (ODI) was compared between groups using ANCOVA with baseline ODI score used as a covariate. Paired t-tests were used to examine change from baseline in PRO for both surgical approaches at each timepoint after surgery. A secondary ANCOVA using a propensity score as a covariate was used to test the robustness of conclusions drawn from the between group comparison.

RESULTS: Participants receiving an anterolateral approach (n=114) compared to those receiving a posterior approach (n=112) were younger (56.9 vs 62.0 years, p <.001), more likely to be employed (49.1% vs 25.0%, p<.001), have isthmic spondylolisthesis (38.6% vs 16.1%, p<.001) and less likely to only have central or lateral recess stenosis (44.9% vs 68.4%, p=.004). There were no statistically significant differences between the groups for gender, BMI, tobacco use, duration of conservative care, grade of spondylolisthesis, or the presence of stenosis. At 3-months follow-up there was no difference in the amount of improvement in ODI between the anterolateral and posterior groups (23.2 § 21.3 vs 25.8 § 19.5, p=.521). There were no clinically meaningful differences between the groups on mean improvement for back- and leg-pain, disability, or quality of life until the 12-months follow-up. Fusion rates of those assessed (n=158; 70% of the sample), were equivalent between groups (anterolateral, 72/88 [81.8%] fused vs posterior, 61/70 [87.1%] fused; p=.390).

CONCLUSIONS: Patients with degenerative lumbar disease and spondylolisthesis who underwent minimally invasive lumbar interbody fusion presented statistically significant and clinically meaningful improvements from baseline up to 12-months follow-up. There were no clinically relevant differences between patients operated on using an anterolateral or posterior approach.

Surgery Decreases Nonunion, Myelopathy, and Mortality for Patients With Traumatic Odontoid Fractures

Neurosurgery 93:546–554, 2023

Existing literature suggests that surgical intervention for odontoid fractures is beneficial but often does not control for known confounding factors.

OBJECTIVE: To examine the effect of surgical fixation on myelopathy, fracture nonunion, and mortality after traumatic odontoid fractures.

METHODS: We analyzed all traumatic odontoid fractures managed at our institution between 2010 and 2020. Ordinal multivariable logistic regression was used to identify factors associated with myelopathy severity at follow-up. Propensity score analysis was used to test the treatment effect of surgery on nonunion and mortality.

RESULTS: Three hundred and three patients with traumatic odontoid fracture were identified, of whom 21.6% underwent surgical stabilization. After propensity score matching, populations were well balanced across all analyses (Rubin’s B < 25.0, 0.5 < Rubin’s R < 2.0). Controlling for age and fracture angulation, type, comminution, and displacement, the overall rate of nonunion was lower in the surgical group (39.7% vs 57.3%, average treatment effect [ATE] = À0.153 [À0.279, À0.028], P = .017). Controlling for age, sex, Nurick score, Charlson Comorbidity Index, Injury Severity Score, and selection for intensive care unit admission, the mortality rate was lower for the surgical group at 30 days (1.7% vs 13.8%, ATE = À0.101 [À0.172, À0.030], P = .005) and at 1 year was 7.0% vs 23.7%, ATE = À0.099 [À0.181, À0.017], P = .018. Cox proportional hazards analysis also demonstrated a mortality benefit for surgery (hazard ratio = 0.587 [0.426, 0.799], P = .0009). Patients who underwent surgery were less likely to have worse myelopathy scores at follow-up (odds ratio = 0.48 [0.25, 0.93], P = .029).

CONCLUSION: Surgical stabilization is associated with better myelopathy scores at follow-up and causes lower rates of fracture nonunion, 30-day mortality, and 1-year mortality.

Complications associated with single-position prone lateral lumbar interbody fusion

J Neurosurg Spine 39:380–386, 2023

Lateral lumbar interbody fusion (LLIF) is a workhorse surgical approach for lumbar arthrodesis. There is growing interest in techniques for performing single-position surgery in which LLIF and pedicle screw fixation are performed with the patient in the prone position. Most studies of prone LLIF are of poor quality and without long-term followup; therefore, the complication profile related to this novel approach is not well known. The objective of this study was to perform a systematic review and pooled analysis to understand the safety profile of prone LLIF.

METHODS A systematic review of the literature and a pooled analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. All studies reporting prone LLIF were assessed for inclusion. Studies not reporting complication rates were excluded.

RESULTS Ten studies meeting the inclusion criteria were analyzed. Overall, 286 patients were treated with prone LLIF across these studies, and a mean (SD) of 1.3 (0.2) levels per patient were treated. The 18 intraoperative complications reported included cage subsidence (3.8% [3/78]), anterior longitudinal ligament rupture (2.3% [5/215]), cage repositioning (2.1% [2/95]), segmental artery injury (2.0% [5/244]), aborted prone interbody placement (0.8% [2/244]), and durotomy (0.6% [1/156]). No major vascular or peritoneal injuries were reported. Sixty-eight postoperative complications occurred, including hip flexor weakness (17.8% [21/118]), thigh and groin sensory symptoms (13.3% [31/233]), revision surgery (3.8% [3/78]), wound infection (1.9% [3/156]), psoas hematoma (1.3% [2/156]), and motor neural injury (1.2% [2/166]).

CONCLUSIONS Single-position LLIF in the prone position appears to be a safe surgical approach with a low complication profile. Longer-term follow-up and prospective studies are needed to better characterize the long-term complication rates related to this approach.

Anatomic trajectory for iliac screw placement adapts better to the morphological features of the pelvis of each individual than the S2 alar iliac screw

Acta Neurochirurgica (2023) 165:2607–2614

The iliac fixation (IF) through the S2 ala permits the minimization of implant prominence and tissue dissection. An alternative to this technique is the anatomic iliac screw fixation (AI), which considers the perpendicular axis to the narrowest width of the ileum and the width of the screw. The morphological accuracy of the iliac screw insertion of two low profile iliac fixation (IF) techniques is investigated in this study.

Methods Twenty-nine patients operated on via low profile IF technique were divided into two groups, those treated using 28 screws with the starting point at S2, and those treated with 30 AI entry point. Radiological parameters (Tsv-angle, Sag-Angle, Max-length, sacral-distance, iliac-width, S2-midline, skin-distance, iliac-wing, and PSIS distance) and clinical outcomes (early and clinic complications) were evaluated by two blinded expert radiologists, and the results were compared in both groups with the real trajectory of the screws placed.

Results Differences between ideal and real trajectories were observed in 6 of the 9 evaluated parameters in the S2AI group. In the AI group, these trajectories were similar, except for TSV-Angle, Max-length, Iliac-width, and distance to iliac-wing parameters. Moreover, compared with S2AI, AI provided better adaptation to the pelvic morphology in all parameters, except for sagittal plane angulation, skin distance, and iliac width.

Conclusions AI ensures the advantages of low profile pelvic fixation like S2AI, with a starting point in line with S1 pedicle anchors and low implant prominence, and moreover adapts better to the morphological features of the pelvis of each individual.

Comparison of minimally invasive decompression alone versus minimally invasive short-segment fusion in the setting of adult degenerative lumbar scoliosis:

J Neurosurg Spine 39:394–403, 2023

Patients with degenerative lumbar scoliosis (DLS) and neurogenic pain may be candidates for decompression alone or short-segment fusion. In this study, minimally invasive surgery (MIS) decompression (MIS-D) and MIS short-segment fusion (MIS-SF) in patients with DLS were compared in a propensity score–matched analysis.

METHODS The propensity score was calculated using 13 variables: sex, age, BMI, Charlson Comorbidity Index, smoking status, leg pain, back pain, grade 1 spondylolisthesis, lateral spondylolisthesis, multilevel spondylolisthesis, lumbar Cobb angle, pelvic incidence minus lumbar lordosis, and pelvic tilt in a logistic regression model. One-to-one matching was performed to compare perioperative morbidity and patient-reported outcome measures (PROMs). The minimal clinically important difference (MCID) for patients was calculated based on cutoffs of percentage change from baseline: 42.4% for Oswestry Disability Index (ODI), 25.0% for visual analog scale (VAS) low-back pain, and 55.6% for VAS leg pain.

RESULTS A total of 113 patients were included in the propensity score calculation, resulting in 31 matched pairs. Perioperative morbidity was significantly reduced for the MIS-D group, including shorter operative duration (91 vs 204 minutes, p < 0.0001), decreased blood loss (22 vs 116 mL, p = 0.0005), and reduced length of stay (2.6 vs 5.1 days, p = 0.0004). Discharge status (home vs rehabilitation), complications, and reoperation rates were similar. Preoperative PROMs were similar, but after 3 months, improvement was significantly higher for the MIS-SF group in the VAS back pain score (−3.4 vs −1.2, p = 0.044) and Veterans RAND 12-Item Health Survey (VR-12) Mental Component Summary (MCS) score (+10.3 vs +1.9, p = 0.009), and after 1 year the MIS-SF group continued to have significantly greater improvement in the VAS back pain score (−3.9 vs −1.2, p = 0.026), ODI score (−23.1 vs −7.4, p = 0.037), 12-Item Short-Form Health Survey MCS score (+6.5 vs −6.5, p = 0.0374), and VR-12 MCS score (+7.6 vs −5.1, p = 0.047). MCID did not differ significantly between the matched groups for VAS back pain, VAS leg pain, or ODI scores (p = 0.38, 0.055, and 0.072, respectively).

CONCLUSIONS Patients with DLS undergoing surgery had similar rates of significant improvement after both MIS-D and MIS-SF. For matched patients, tradeoffs were seen for reduced perioperative morbidity for MIS-D versus greater magnitudes of improvement in back pain, disability, and mental health for patients 1 year after MIS-SF. However, rates of MCID were similar, and the small sample size among the matched patients may be subject to patient outliers, limiting generalizability of these results.

Three-level ACDF versus 3-level laminectomy and fusion: are there differences in outcomes?

Neurosurg Focus 55(3):E2, 2023

OBJECTIVE The authors sought to compare 3-level anterior with posterior fusion surgical procedures for the treatment of multilevel cervical spondylotic myelopathy (CSM).

METHODS The authors analyzed prospective data from the 14 highest enrolling sites of the Quality Outcomes Database CSM module. They compared 3-level anterior cervical discectomy and fusion (ACDF) and posterior cervical laminectomy and fusion (PCF) surgical procedures, excluding surgical procedures crossing the cervicothoracic junction. Rates of reaching the minimal clinically important difference (MCID) in patient-reported outcomes (PROs) were compared at 24 months postoperatively. Multivariable analyses adjusted for potential confounders elucidated in univariable analysis.

RESULTS Overall, 199 patients met the inclusion criteria: 123 ACDF (61.8%) and 76 PCF (38.2%) patients. The 24-month follow-up rates were similar (ACDF 90.2% vs PCF 92.1%, p = 0.67). Preoperatively, ACDF patients were younger (60.8 ± 10.2 vs 65.0 ± 10.3 years, p < 0.01), and greater proportions were privately insured (56.1% vs 36.8%, p= 0.02), actively employed (39.8% vs 22.8%, p = 0.04), and independently ambulatory (14.6% vs 31.6%, p < 0.01). Otherwise, the cohorts had equivalent baseline modified Japanese Orthopaedic Association (mJOA), Neck Disability Index (NDI), numeric rating scale (NRS)–arm pain, NRS–neck pain, and EQ-5D scores (p > 0.05). ACDF patients had reduced hospitalization length (1.6 vs 3.9 days, p < 0.01) and a greater proportion had nonroutine discharge (7.3% vs 22.8%, p < 0.01), but they had a higher rate of postoperative dysphagia (13.5% vs 3.5%, p = 0.049). Compared with baseline values, both groups demonstrated improvements in all outcomes at 24 months (p < 0.05). In multivariable analyses, after controlling for age, insurance payor, employment status, ambulation status, and other potential clinically relevant confounders, ACDF was associated with a greater proportion of patients with maximum satisfaction on the North American Spine Society Patient Satisfaction Index (NASS) (NASS score of 1) at 24 months (69.4% vs 53.7%, OR 2.44, 95% CI 1.17–5.09, adjusted p = 0.02). Otherwise, the cohorts shared similar 24-month outcomes in terms of reaching the MCID for mJOA, NDI, NRS–arm pain, NRS–neck pain, and EQ-5D score (adjusted p > 0.05). There were no differences in the 3-month readmission (ACDF 4.1% vs PCF 3.9%, p = 0.97) and 24-month reoperation (ACDF 13.5% vs PCF 18.6%, p = 0.36) rates.

CONCLUSIONS In a cohort limited to 3-level fusion surgical procedures, ACDF was associated with reduced blood loss, shorter hospitalization length, and higher routine home discharge rates; however, PCF resulted in lower rates of postoperative dysphagia. The procedures yielded comparably significant improvements in functional status (mJOA score), neck and arm pain, neck pain–related disability, and quality of life at 3, 12, and 24 months. ACDF patients had significantly higher odds of maximum satisfaction (NASS score 1). Given comparable outcomes, patients should be counseled on each approach’s complication profile to aid in surgical decision-making.

Outcomes following anterior odontoid screw versus posterior arthrodesis for odontoid fractures

J Neurosurg Spine 39:196–205, 2023

Odontoid fractures can be managed surgically when indicated. The most common approaches are anterior dens screw (ADS) fixation and posterior C1–C2 arthrodesis (PA). Each approach has theoretical advantages, but the optimal surgical approach remains controversial. The goal in this study was to systematically review the literature and synthesize outcomes including fusion rates, technical failures, reoperation, and 30-day mortality associated with ADS versus PA for odontoid fractures.

METHODS A systematic literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines by searching the PubMed, EMBASE, and Cochrane databases. A random-effects meta-analysis was performed and the I 2 statistic was used to assess heterogeneity.

RESULTS In total, 22 studies comprising 963 patients (ADS 527, PA 436) were included. The average age of the patients ranged from 28 to 81.2 years across the included studies. The majority of the odontoid fractures were type II based on the Anderson-D’Alonzo classification. The ADS group was associated with statistically significantly lower odds to achieve bony fusion at last follow-up compared to the PA group (ADS 84.1%; PA 92.3%; OR 0.46; 95% CI 0.23–0.91; I 2 42.6%). The ADS group was associated with statistically significantly higher odds of reoperation compared to the PA group (ADS 12.4%; PA 5.2%; OR 2.56; 95% CI 1.50–4.35; I 2 0%). The rates of technical failure (ADS 2.3%; PA 1.1%; OR 1.11; 95% CI 0.52–2.37; I 2 0%) and all-cause mortality (ADS 6%; PA 4.8%; OR 1.35; 95% CI 0.67–2.74; I 2 0%) were similar between the two groups. In the subgroup analysis of patients > 60 years old, the ADS was associated with statistically significantly lower odds of fusion compared to the PA group (ADS 72.4%; PA 89.9%; OR 0.24; 95% CI 0.06–0.91; I 2 58.7%).

CONCLUSIONS ADS fixation is associated with statistically significantly lower odds of fusion at last follow-up and higher odds of reoperation compared to PA. No differences were identified in the rates of technical failure and all-cause mortality. Patients receiving ADS fixation at > 60 years old had significantly higher and lower odds of reoperation and fusion, respectively, compared to the PA group. PA is preferred to ADS fixation for odontoid fractures, with a stronger effect size for patients > 60 years old.

Postoperative Spinal Cerebrospinal Fluid-Venous Fistulas Associated With Dural Tears in Patients With Intracranial Hypotension or Superficial Siderosis

Neurosurgery 93:473–479, 2023

Postoperative spinal cerebrospinal fluid (CSF) leaks are common but rarely cause extensive CSF collections that require specialized imaging to detect the site of the dural breach.

OBJECTIVE: To investigate the use of digital subtraction myelography (DSM) for patients with extensive extradural CSF collections after spine surgery.

METHODS: A retrospective review was performed to identify a consecutive group of patients with extensive postoperative spinal CSF leaks who underwent DSM.

RESULTS: Twenty-one patients (9 men and 12 women) were identified. The mean age was 46.7 years (range, 17-75 years). The mean duration of the postoperative CSF leak was 3.3 years (range, 3 months to 21 years). MRI showed superficial siderosis in 6 patients. DSM showed the exact location of the CSF leak in 19 (90%) of the 21 patients. These 19 patients all underwent surgery to repair the CSF leak, and the location of the CSF leak could be confirmed intraoperatively in all 19 patients. In 4 (19%) of the 21 patients, DSM also showed a CSF-venous fistula at the same location as the postoperative dural tear.

CONCLUSION: In this study, DSM had a 90% detection rate of visualizing the exact site of the dural breach in patients with extensive postoperative spinal CSF leaks. The coexistence of a CSF-venous fistula in addition to the primary dural tear was present in about one-fifth of patients. The presence of a CSF-venous fistula should be considered if CSF leak symptoms persist in spite of successful repair of a durotomy.

Risk Factors for Adjacent Segment Disease in Short Segment Lumbar Interbody Fusion

Operative Neurosurgery 25:136–141, 2023

Adjacent segment disease (ASD) is a common problem after lumbar spinal fusions. Ways to reduce the rates of ASD are highly sought after to reduce the need for reoperation.

OBJECTIVE: To find predisposing factors of ASD after lumbar interbody fusions, especially in mismatch of pelvic incidence and lumbar lordosis (PI-LL).

METHODS: We conducted a retrospective cohort study of all patients undergoing lumbar interbody fusions of less than 4 levels from June 2015 to July 2020 with at least 1 year of follow-up and in those who had obtained postoperative standing X-rays.

RESULTS: We found 243 patients who fit inclusion and exclusion criteria. Fourteen patients (5.8%) developed ASD, at a median of 24 months. Postoperative lumbar lordosis was significantly higher in the non-ASD cohort (median 46.4°± 1.4°vs 36.9°± 3.6°, P < .001), pelvic tilt was significantly lower in the non-ASD cohort (16.0°± 0.66°vs 20.3°± 2.4°, P = .002), PI-LL mismatch was significantly lower in the non-ASD cohort (5.28°± 1.0°vs 17.1°± 2.0°, P < .001), and age-appropriate PI-LL mismatch was less common in the non-ASD cohort (34 patients [14.8%] vs 13 [92.9%] of patients with high mismatch, P < .001). Using multivariate analysis, greater PI-LL mismatch was predictive of ASD (95% odds ratio CI = 1.393-2.458, P < .001) and age-appropriate PI-LL mismatch was predictive of ASD (95% odds ratio CI = 10.8-970.4, P < .001).

CONCLUSION: Higher PI-LL mismatch, both age-independent and when adjusted for age, after lumbar interbody fusion was predictive for developing ASD. In lumbar degenerative disease, correction of spinopelvic parameters should be a main goal of surgical correction.

Effects of Sacral Slope Changes on the Intervertebral Disc and Hip Joint: A Finite Element Analysis

World Neurosurg. (2023) 176:e32-e39

Spinopelvic parameters are vital components that must be considered when treating patients with spinal disease. Several finite element (FE) studies have explored spinopelvic parameters such as sacral slope (SS) and the impact on the lumbar spine, although no study has examined the effect on the hip and sacroiliac joint (SIJ) on varying SS angles. Therefore, it is necessary to have a biomechanical understanding of the impact on the spinopelvic complex.

METHODS: An FE lumbar, pelvis, and femur model was created from computed tomography scans of a 55-year-old female patient with no abnormalities. Three models were created: a normal model (SS [ 26  ), a model with high SS (SS [ 30  ), and a model with low SS (SS [ 20  ). These models underwent loading for flexion, extension, lateral bending, and axial rotation. Range of motion (ROM), intradiscal pressures, hip joint, and SIJ contact stresses were analyzed.

RESULTS: The high SS model (SS [ 30  ) indicated the highest ROM in the L5-S1 (slip angle) level and the highest intradiscal pressures. The highest average hip and SIJ contact stresses were present in this model, although the low SS model (SS [ 20  ) in extension had the largest stresses for the hip and SIJ.

CONCLUSIONS: The results provide evidence that patients with higher SS may be more prone to increased ROM at the slip angle (L5-S1). In addition, patients with higher SS were shown to have higher contact stresses on the hip joint and SIJ, potentially leading to SIJ dysfunction. Clinically, correcting lumbar lordosis including SS is important; however, a high SS may have a negative impact on the intervertebral disc, SIJ, and hip joint.

Far lateral lumbar interbody fusion with unilateral pedicle screw fixation and double traversing cages using a biportal endoscopic technique

Acta Neurochirurgica (2023) 165:2165–2169

Transforaminal lumbar interbody fusion (TLIF) with a single cage and bilateral pedicle screw fixation results in decreased stability or increased risk of cage displacement Wang and Guo (Comput Methods Biomech Biomed Eng, 24(3):308–319, 6). We succeeded in inserting double traversing cages with unilateral pedicle screw fixation (UPSF) during far lateral TLIF using unilateral biportal endoscopy (UBE).

Method We attempted far lateral UBE-TLIF through two small incisions for degenerative lumbar spondylolisthesis with unilateral stenosis. With the help of novel instruments, far lateral UBE-TLIF with double traversing cages and UPSF was performed under tracheal intubation anaesthesia.

Conclusions We successfully performed far lateral UBE-TLIF with double traversing cages and UPSF. This procedure may be an alternative minimally invasive method for treating lumbar instability.

Comparison of Perioperative Complications After Anterior–Posterior Versus Posterior–Anterior–Posterior Cervical Fusion: A Retrospective Review of 153 Consecutive Cases

Neurosurgery 93:373–386, 2023

Although published data support the utilization of circumferential fusion to treat select cervical spine pathologies, it is unclear whether the posterior–anterior–posterior (PAP) fusion has increased risks compared with the anterior–posterior fusion.

OBJECTIVE: To evaluate the differences in perioperative complications between the 2 circumferential cervical fusion approaches.

METHODS: One hundred fifty-three consecutive adult patients who underwent single-staged circumferential cervical fusion for degenerative pathologies from 2010 to 2021 were retrospectively reviewed. Patients were stratified into the anterior–posterior (n = 116) and PAP (n = 37) groups. The primary outcomes assessed were major complications, reoperation, and readmission.

RESULTS: Although the PAP group was older (P = .024), predominantly female (P = .024), with higher baseline neck disability index (P = .026), cervical sagittal vertical axis (P = .001), and previous cervical operation rate (P < .00001), the major complication, reoperation, and readmission rates were not significantly different from the 360°group. Although the PAP group had higher urinary tract infection (P = .043) and transfusion (P = .007) rates, higher estimated blood loss (P = .034), and longer operative times (P < .00001), these differences were insignificant after the multivariable analysis. Overall, operative time was associated with older age (odds ratio [OR] 17.72, P = .042), atrial fibrillation (OR 158.30, P = .045), previous cervical operation (OR 5.05, P = .051), and lower baseline C1-7 lordosis (OR 0.93, P = .007). Higher estimated blood loss was associated with older age (OR 1.13, P = .005), male gender (OR 323.31, P = .047), and higher baseline cervical sagittal vertical axis (OR 9.65, P = .022).

CONCLUSION: Despite some differences in preoperative and intraoperative variables, this study suggests both circumferential approaches have comparable reoperation, readmission, and complication profiles, all of which are high.

Incidence and Risk Factor of Implant Dislocation After Cervical Disk Arthroplasty: A Retrospective Cohort Analysis of 756 Patients

Neurosurgery 93:330–338, 2023

Implant dislocation after cervical disk arthroplasty (CDA) is obviously a critical complication, but no information about the incidence and associated risk factor has been reported.

OBJECTIVE: To investigate the incidence and risk factor of implant dislocation after CDA by a retrospective cohort analysis.

METHODS: A retrospective review of a consecutive series of CDA performed between January 2009 and March 2021 at a single institution was conducted. Analyses of chart records and radiological data established the incidence and associated risk factor of implant dislocation after CDA. A Kaplan-Meier survival estimation of implant survival was performed.

RESULTS: A total of 756 consecutive patients were included in this analysis. Five patients (0.7%) had a migration and even dropout of the artificial disk. The overall cumulative survival rate of the implant reached approximately 99.3% of the 756 patients. Preoperative kyphosis was significantly related to implant dislocation (P = .016), with an odds ratio of 15.013.

CONCLUSION: The incidence of implant dislocation after CDA is as low as 0.7% or 5/756 patients. Preoperative kyphosis significantly increases the risk of postoperative implant dislocation by a factor of 15. The migrating implants could be revealed on radiographs as early as 0.9 to 1.4 months postoperatively and were revised to anterior cervical diskectomy and fusion within half a year. No new event of implant dislocation occurred half a year postoperatively. The overall cumulative survival rate of the implant reached 99.3% of the 756 patients. In conclusion, CDA remains a safe and reliable procedure.

Anterior-To-Psoas Approach Measurements, Feasibility, Non-Neurological Structures at Risk and Influencing Factors: A Bilateral Analysis From L1-L5 Using Computed Tomography Imaging

Operative Neurosurgery 25:52–58, 2023

Spinal fusion through the anterior-to-psoas (ATP) technique harbors several approach-related risks. We used abdominal computed tomography imaging to analyze the L1-L5 ATP fusion approach measurements, feasibility, degree of obstruction by non-neurological structures, and the influence of patient characteristics on ATP approach dimensions.

METHODS: The vascular window, psoas window, safe window, and incision line anterior and posterior margins for the ATP approach were measured on abdominal computed tomography imaging. The feasibility of approach and the presence of kidneys, ribs, liver, spleen, and iliac crests within the ATP approach were also measured. Correlation and regression models among radiographic measurements and patient age, height, weight, and body mass index (BMI) were analyzed as well as differences in approach measurements based on sex.

RESULTS: Safe window and incision line measurements were more accommodating for the left-sided vs right-sided ATP approach. At L4-5, the ATP approach was not feasible 18% of the time on the left side vs 60% of the time on the right side. The spleen was present 22%, 10%, and 3% of the time from L1-4, while the liver was present 56%, 30%, and 9% of the time. The iliac crests were not observed within ATP parameters. Patient age, height, weight, and BMI did not strongly correlate with approach measurements, although ATP dimensions did differ based on sex.

CONCLUSION: This study reports characteristics of the ATP approach including approach measurements, feasibility, non-neurological structures at risk, and influencing factors to approach measurements. While incision line measurements are larger for male patients compared with female patients at the lower lumbar levels, safe window sizes are similar across all levels L1-L5. The kidneys, ribs, spleen, and liver are potential at-risk structures during the ATP approach, although the iliac crests pose limited concern for ATP technique. Patient characteristics such as age, height, weight, and BMI do not markedly affect ATP approach considerations.

Long-Term Durability of Stand-Alone Lateral Lumbar Interbody Fusion

Neurosurgery 93:60–65, 2023

BACKGROUND: The long-term durability of stand-alone lateral lumbar interbody fusion (LLIF) remains unknown.

OBJECTIVE: To evaluate whether early patient-reported outcome measures after stand-alone LLIF are sustained on long-term follow-up.

METHODS: One hundred and twenty-six patients who underwent stand-alone LLIF between 2009 and 2017 were included in this study. Patient-reported outcome measures included the Oswestry Disability Index (ODI), EuroQOL-5D (EQ-5D), and visual analog score (VAS) scores. Durable outcomes were defined as scores showing a significant improvement between preoperative and 6-week scores without demonstrating any significant decline at future time points. A repeated measures analysis was conducted using generalized estimating equations (model) to assess the outcome across different postoperative time points, including 6 weeks, 1 year, 2 years, and 5 years.

RESULTS: ODI scores showed durable improvement at 5-year follow-up, with scores improving from 46.9 to 38.5 (P = .001). Improvements in EQ-5D showed similar durability up to 5 years, improving from 0.48 to 0.65 (P = .03). VAS scores also demonstrated significant improvements postoperatively that were durable at 2-year follow-up, improving from 7.0 to 4.6 (P < .0001).

CONCLUSION: Patients undergoing stand-alone LLIF were found to have significant improvements in ODI and EQ-5D at 6week follow-up that remained durable up to 5 years postoperatively. VAS scores were found to be significantly improved at 6 weeks and up to 2 years postoperatively but failed to reach significance at 5 years. These findings demonstrate that patients undergoing stand-alone LLIF show significant improvement in overall disability after surgery that remains durable at long-term follow-up.

Spinopelvic sagittal compensation in adult cervical deformity

J Neurosurg Spine 39:1–10, 2023

The objective of this study was to evaluate spinopelvic sagittal alignment and spinal compensatory changes in adult cervical kyphotic deformity.

METHODS A database composed of 13 US spine centers was retrospectively reviewed for adult patients who underwent cervical reconstruction with radiographic evidence of cervical kyphotic deformity: C2–7 sagittal vertical axis > 4 cm, chin-brow vertical angle > 25°, or cervical kyphosis (T1 slope [T1S] cervical lordosis [CL] > 15°) (n = 129). Sagittal parameters were evaluated preoperatively and in the early postoperative window (6 weeks to 6 months postoperatively) and compared with asymptomatic control patients. Adult cervical deformity patients were further stratified by degree of cervical kyphosis (severe kyphosis, C2–T3 Cobb angle ≤ −30°; moderate kyphosis, ≤ 0°; and minimal kyphosis, > 0°) and severity of sagittal malalignment (severe malalignment, sagittal vertical axis T3–S1 ≤ −60 mm; moderate malalignment, ≤ 20 mm; and minimal malalignment > 20 mm).

RESULTS Compared with asymptomatic control patients, cervical deformity was associated with increased C0–2 lordosis (32.9° vs 23.6°), T1S (33.5° vs 28.0°), thoracolumbar junction kyphosis (T10–L2 Cobb angle −7.0° vs −1.7°), and pelvic tilt (PT) (19.7° vs 15.9°) (p < 0.01). Cervicothoracic kyphosis was correlated with C0–2 lordosis (R = −0.57, p < 0.01) and lumbar lordosis (LL) (R = −0.20, p = 0.03). Cervical reconstruction resulted in decreased C0–2 lordosis, increased T1S, and increased thoracic and thoracolumbar junction kyphosis (p < 0.01). Patients with severe cervical kyphosis (n = 34) had greater C0–2 lordosis (p < 0.01) and postoperative reduction of C0–2 lordosis (p = 0.02) but no difference in PT. Severe cervical kyphosis was also associated with a greater increase in thoracic and thoracolumbar junction kyphosis postoperatively (p = 0.01). Patients with severe sagittal malalignment (n = 52) had decreased PT (p = 0.01) and increased LL (p < 0.01), as well as a greater postoperative reduction in LL (p < 0.01).

CONCLUSIONS Adult cervical deformity is associated with upper cervical hyperlordotic compensation and thoracic hypokyphosis. In the setting of increased kyphotic deformity and sagittal malalignment, thoracolumbar junction kyphosis and lumbar hyperlordosis develop to restore normal center of gravity. There was no consistent compensatory pelvic retroversion or anteversion among the adult cervical deformity patients in this cohort.

Transforaminal Lumbar Interbody Fusion Versus Posterolateral Fusion Alone in the Treatment of Grade 1 Degenerative Spondylolisthesis

Neurosurgery 93:186–197, 2023

Transforaminal lumbar interbody fusion (TLIF) and posterolateral fusion (PLF) alone are two operations performed to treat degenerative lumbar spondylolisthesis. To date, it is unclear which operation leads to better outcomes.

OBJECTIVE: To compare TLIF vs PLF alone regarding long-term reoperation rates, complications, and patient-reported outcome measures (PROMs) in patients with degenerative grade 1 spondylolisthesis.

METHODS: A retrospective cohort study using prospectively collected data between October 2010 and May 2021 was undertaken. Inclusion criteria were patients aged 18 years or older with grade 1 degenerative spondylolisthesis undergoing elective, single-level, open posterior lumbar decompression and instrumented fusion with ≥1-year follow-up. The primary exposure was presence of TLIF vs PLF without interbody fusion. The primary outcome was reoperation. Secondary outcomes included complications, readmission, discharge disposition, return to work, and PROMs at 3 and 12 months postoperatively, including Numeric Rating Scale-Back/Leg and Oswestry Disability Index. Minimum clinically important difference of PROMs was set at 30% improvement from baseline.

RESULTS: Of 546 patients, 373 (68.3%) underwent TLIF and 173 underwent (31.7%) PLF. Median follow-up was 6.1 years (IQR = 3.6-9.0), with 339 (62.1%) >5-year follow-up. Multivariable logistic regression showed that patients undergoing TLIF had a lower odds of reoperation compared with PLF alone (odds ratio = 0.23, 95% CI = 0.54-0.99, P = .048). Among patients with >5-year follow-up, the same trend was seen (odds ratio = 0.15, 95% CI = 0.03-0.95, P = .045). No differences were observed in 90-day complications (P = .487) and readmission rates (P = .230) or minimum clinically important difference PROMs.

CONCLUSION: In a retrospective cohort study from a prospectively maintained registry, patients with grade 1 degenerative spondylolisthesis undergoing TLIF had significantly lower long-term reoperation rates than those undergoing PLF.

Biportal endoscopic extraforaminal lumbar interbody fusion using a 3D‑printed porous titanium cage with large footprints: technical note and preliminary results

Acta Neurochirurgica (2023) 165:1435–1443

The aim of this study was to introduce biportal endoscopic extraforaminal lumbar interbody fusion (BE-EFLIF), which involves insertion of a cage through a more lateral side as compared to the conventional corridor of transforaminal lumbar interbody fusion. We described the advantages and surgical steps of 3D-printed porous titanium cage with large footprints insertion through multi-portal approach, and preliminary results of this technique.

Methods This retrospective study included 12 consecutive patients who underwent BE-EFLIF for symptomatic singlelevel lumbar degenerative disease. Clinical outcomes, including a visual analog scale (VAS) for back and leg pain and the Oswestry disability index (ODI), were collected at preoperative months 1 and 3, and 6 months postoperatively. In addition, perioperative data and radiographic parameters were analyzed.

Results The mean patient age, follow-up period, operation time, and volume of surgical drainage were 68.3 ± 8.4 years, 7.6 ± 2.8 months, 188.3 ± 42.4 min, 92.5 ± 49.6 mL, respectively. There were no transfusion cases. All patients showed significant improvement in VAS and ODI postoperatively, and these were maintained for 6 months after surgery (P < 0.001). The anterior and posterior disc heights significantly increased after surgery (P < 0.001), and the cage was ideally positioned in all patients. There were no incidences of early cage subsidence or other complications.

Conclusions BE-EFLIF using a 3D-printed porous titanium cage with large footprints is a feasible option for minimally invasive lumbar interbody fusion. This technique is expected to reduce the risk of cage subsidence and improve the fusion rate.

Crossing the cervicothoracic junction: an evaluation of radiographic alignment, functional outcomes, and patient-reported outcomes

J Neurosurg Spine 38:653–661, 2023

There is currently no consensus regarding the appropriate lower instrumented vertebra (LIV) for multilevel posterior cervical fusion (PCF) constructs between C7 and crossing the cervicothoracic junction (CTJ). The goal of the present study was to compare postoperative sagittal alignment and functional outcomes among adult patients presenting with cervical myelopathy undergoing multilevel PCF terminating at C7 versus spanning the CTJ.

METHODS A single-institution retrospective analysis (January 2017–December 2018) was performed of patients undergoing multilevel PCF for cervical myelopathy that involved the C6–7 vertebrae. Pre- and postoperative cervical spine radiographs were analyzed for cervical lordosis, cervical sagittal vertical axis (cSVA), and first thoracic (T1) vertebral slope (T1S) in two randomized independent trials. Modified Japanese Orthopaedic Association (mJOA) and Patient-Reported Outcomes Measurement Information System (PROMIS) scores were used to compare functional and patient-reported outcomes at the 12-month postoperative follow-up.

RESULTS Sixty-six consecutive patients undergoing PCF and 53 age-matched controls were included in the study. There were 36 patients in the C7 LIV cohort and 30 patients in the LIV spanning the CTJ cohort. Despite significant correction, patients undergoing fusion remained less lordotic than asymptomatic controls, with a C2–7 Cobb angle of 17.7° versus 25.5° (p < 0.001) and a T1S of 25.6° versus 36.3° (p < 0.001). The CTJ cohort had superior alignment corrections in all radiographic parameters at the 12-month postoperative follow-up compared with the C7 cohort: increase in T1S (ΔT1S 14.1° vs 2.0°, p < 0.001), increase in C2–7 lordosis (ΔC2–7 lordosis 11.7° vs 1.5°, p < 0.001), and decrease in cSVA (ΔcSVA 8.9 vs 5.0 mm, p < 0.001). There were no differences in the mJOA motor and sensory scores between cohorts pre- and postoperatively. The C7 cohort reported significantly better PROMIS scores at 6 months (22.0 ± 3.2 vs 11.5 ± 0.5, p = 0.04) and 12 months (27.0 ± 5.2 vs 13.5 ± 0.9, p = 0.01) postoperatively.

CONCLUSIONS Crossing the CTJ may provide a greater cervical sagittal alignment correction in multilevel PCF surgeries. However, the improved alignment may not be associated with improved functional outcomes as measured by the mJOA scale. A new finding is that crossing the CTJ may be associated with worse patient-reported outcomes at 6 and 12 months of postoperative follow-up as measured by the PROMIS, which should be considered in surgical decision-making. Future prospective studies evaluating long-term radiographic, patient-reported, and functional outcomes are warranted.

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