Is Upper Extremity or Lower Extremity Function More Important for Patient Satisfaction? An Analysis of 24-Month Outcomes from the QOD Cervical Spondylotic Myelopathy Cohort.

STUDY DESIGN: Retrospective analysis of a prospective, multicenter registry. OBJECTIVE: To assess whether upper or lower limb mJOA improvement more strongly associates with patient satisfaction after surgery for cervical spondylotic myelopathy (CSM). SUMMARY OF BACKGROUND DATA: The modified Japanese Orthopaedic Association (mJOA) is commonly used to assess functional status in patients with CSM. Patients present with upper and/or lower extremity dysfunction, and it is unclear whether improvement in one and/or both symptoms drives postoperative patient satisfaction. METHODS: This study utilizes the prospective Quality Outcomes Database (QOD) CSM data set. Clinical outcomes included mJOA and North American Spine Society (NASS) satisfaction. The upper limb mJOA score was defined as upper motor plus sensory mJOA, and the lower limb mJOA as lower motor plus sensory mJOA. Ordered logistic regression was used to determine whether upper or lower limb mJOA was more closely associated with NASS satisfaction, adjusting for other covariates. RESULTS: Overall, 1141 patients were enrolled in the QOD CSM cohort. In all, 780 had both preoperative and 24-month mJOA scores, met inclusion criteria, and were included for analysis. The baseline mJOA was 12.1±2.7, and postoperatively, 85.6% would undergo surgery again (NASS 1 or 2, satisfied). Patients exhibited mean improvement in both upper (baseline:3.9±1.4 vs. 24 mo:5.0±1.1, P<0.001) and lower limb mJOA (baseline:3.9±1.4 vs. 24 mon:4.5±1.5, P<0.001); however, the 24-month change in the upper limb mJOA was greater (upper:1.1±1.6 vs. lower:0.6±1.6, P<0.001). Across 24-month NASS satisfaction, the baseline upper and lower limb mJOA scores were similar (pupper=0.28, plower=0.092). However, as satisfaction decreased, the 24-month change in upper and lower limb mJOA decreased as well (pupper<0.001, plower<0.001). Patients with NASS scores of 4 (lowest satisfaction) did not demonstrate significant differences from baseline in upper or lower limb mJOA (P>0.05). In ordered logistic regression, NASS satisfaction was independently associated with upper limb mJOA improvement (OR=0.81; 95% CI: 0.68-0.97; P=0.019) but not lower limb mJOA improvement (OR=0.84; 95% CI: 0.70-1.0; P=0.054). CONCLUSIONS: As the magnitude of upper and lower mJOA improvement decreased postoperatively, so too did patient satisfaction with surgical intervention. Upper limb mJOA improvement was a significant independent predictor of patient satisfaction, whereas lower limb mJOA improvement was not. These findings may aid preoperative counseling, stratified by patients' upper and lower extremity treatment expectations. LEVEL OF EVIDENCE: Level-III.

Reciprocal changes in sagittal spinal alignment after L5-S1 anterior lumbar interbody fusion.

OBJECTIVE: Degenerative diseases of the lumbar spine decrease lumbar lordosis (LL). Anterior lumbar interbody fusion (ALIF) at the L5-S1 disc space improves segmental lordosis, LL, and sagittal balance. This study investigated reciprocal changes in spinopelvic alignment after L5-S1 ALIF. METHODS: A retrospective chart review identified patients who underwent L5-S1 ALIF with or without posterior fixation at a single institution (November 1, 2016-October 1, 2021). Changes in pelvic tilt, sacral slope, proximal LL (L1-L4), distal LL (L4-S1), total LL (L1-S1), segmental lordosis, pelvic incidence-LL mismatch, thoracic kyphosis, cervical lordosis, and sagittal vertical axis were measured on preoperative and postoperative radiographs. RESULTS: Forty-eight patients were identified. Immediate postoperative radiographs were obtained at a mean (SD) of 17 (20) days after surgery; delayed radiographs were obtained 184 (82) days after surgery. After surgery, patients had significantly decreased pelvic tilt (15.71° [7.25°] vs 17.52° [7.67°], p=0.003) and proximal LL (11.86° [10.67°] vs 16.03° [10.45°], p<0.001) and increased sacral slope (39.49° [9.27°] vs 36.31° [10.39°], p<0.001), LL (55.35° [13.15°] vs 51.63° [13.38°], p=0.001), and distal LL (43.17° [9.33°] vs 35.80° [8.02°], p<0.001). Segmental lordosis increased significantly at L5-S1 and decreased significantly at L2-3, L3-4, and L4-5. Lordosis distribution index increased from 72.55 (19.53) to 81.38 (22.83) (p<0.001). CONCLUSIONS: L5-S1 ALIF was associated with increased L5-S1 segmental lordosis accompanied by pelvic anteversion and a reciprocal decrease in proximal lumbar lordosis. These changes may represent a reversal of compensatory mechanisms, suggesting an overall relaxation of spinopelvic alignment after L5-S1 ALIF.

Impact of Self-Reported Loss of Balance and Gait Disturbance on Outcomes following Adult Spinal Deformity Surgery.

Background: The objective of this study was to evaluate if imbalance influences complication rates, radiological outcomes, and patient-reported outcomes (PROMs) following adult spinal deformity (ASD) surgery. Methods: ASD patients with baseline and 2-year radiographic and PROMs were included. Patients were grouped according to whether they answered yes or no to a recent history of pre-operative loss of balance. The groups were propensity-matched by age, pelvic incidence-lumbar lordosis (PI-LL), and surgical invasiveness score. Results: In total, 212 patients were examined (106 in each group). Patients with gait imbalance had worse baseline PROM measures, including Oswestry disability index (45.2 vs. 36.6), SF-36 mental component score (44 vs. 51.8), and SF-36 physical component score (p < 0.001 for all). After 2 years, patients with gait imbalance had less pelvic tilt correction (-1.2 vs. -3.6°, p = 0.039) for a comparable PI-LL correction (-11.9 vs. -15.1°, p = 0.144). Gait imbalance patients had higher rates of radiographic proximal junctional kyphosis (PJK) (26.4% vs. 14.2%) and implant-related complications (47.2% vs. 34.0%). After controlling for age, baseline sagittal parameters, PI-LL correction, and comorbidities, patients with imbalance had 2.2-times-increased odds of PJK after 2 years. Conclusions: Patients with a self-reported loss of balance/unsteady gait have significantly worse PROMs and higher risk of PJK.

Factors Associated with the Maintenance of Cost-Effectiveness at 5 Years in Adult Spinal Deformity Corrective Surgery.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To evaluate factors associated with the long-term durability of cost-effectiveness (CE) in ASD patients. BACKGROUND: A substantial increase in costs associated with the surgical treatment for adult spinal deformity (ASD) has given precedence to scrutinize the value and utility it provides. METHODS: We included 327 operative ASD patients with 5-year (5 Y) follow-up. Published methods were used to determine costs based on CMS.gov definitions and were based on the average DRG reimbursement rates. Utility was calculated using quality-adjusted life-years (QALY) utilizing the Oswestry Disability Index (ODI) converted to Short-Form Six-Dimension (SF-6D), with a 3% discount applied for its decline with life expectancy. The CE threshold of $150,000 was used for primary analysis. RESULTS: Major and minor complication rates were 11% and 47% respectively, with 26% undergoing reoperation by 5 Y. The mean cost associated with surgery was $91,095±$47,003, with a utility gain of 0.091±0.086 at 1Y, QALY gained at 2 Y of 0.171±0.183, and at 5 Y of 0.42±0.43. The cost per QALY at 2 Y was $414,885, which decreased to $142,058 at 5 Y.With the threshold of $150,000 for CE, 19% met CE at 2 Y and 56% at 5 Y. In those in which revision was avoided, 87% met cumulative CE till life expectancy. Controlling analysis depicted higher baseline CCI and pelvic tilt (PT) to be the strongest predictors for not maintaining durable CE to 5 Y (CCI OR: 1.821 [1.159-2.862], P=0.009) (PT OR: 1.079 [1.007-1.155], P=0.030). CONCLUSIONS: Most patients achieved cost-effectiveness after four years postoperatively, with 56% meeting at five years postoperatively. When revision was avoided, 87% of patients met cumulative cost-effectiveness till life expectancy. Mechanical complications were predictive of failure to achieve cost-effectiveness at 2 Y, while comorbidity burden and medical complications were at 5 Y.

What is the effect of preoperative depression on outcomes after minimally invasive surgery for adult spinal deformity? A prospective cohort analysis.

OBJECTIVE: Depression has been implicated with worse immediate postoperative outcomes in adult spinal deformity (ASD) correction, yet the specific impact of depression on those patients undergoing minimally invasive surgery (MIS) requires further clarity. This study aimed to evaluate the role of depression in the recovery of patients with ASD after undergoing MIS. METHODS: Patients who underwent MIS for ASD with a minimum postoperative follow-up of 1 year were included from a prospectively collected, multicenter registry. Two cohorts of patients were identified that consisted of either those affirming or denying depression on preoperative assessment. The patient-reported outcome measures (PROMs) compared included scores on the Oswestry Disability Index (ODI), numeric rating scale (NRS) for back and leg pain, Scoliosis Research Society Outcomes Questionnaire (SRS-22), SF-36 physical component summary, SF-36 mental component summary (MCS), EQ-5D, and EQ-5D visual analog scale. RESULTS: Twenty-seven of 147 (18.4%) patients screened positive for preoperative depression. The nondepressed cohort had an average of 4.83 levels fused, and the depressed cohort had 5.56 levels fused per patient (p = 0.267). At 1-year follow-up, 10 patients still reported depression, representing a 63% decrease. Postoperatively, both cohorts demonstrated improvement in their PROMs; however, at 1-year follow-up, those without depression had statistically better outcomes based on the EQ-5D, MCS, and SRS-22 scores (p < 0.05). Patients with depression continued to experience higher NRS leg scores at 1-year follow-up (3.63 vs 2.22, p = 0.018). After controlling for covariates, the authors found that depression significantly impacted only 1-year follow-up MCS scores (ß = 8.490, p < 0.05). CONCLUSIONS: Depressed and nondepressed patients reported similar improvements after MIS surgery, except MCS scores were more likely to improve in nondepressed patients.

Development of a modified frailty index for adult spinal deformities independent of functional changes following surgical correction: a true baseline risk assessment tool.

PURPOSE: To develop a simplified, modified frailty index for adult spinal deformity (ASD) patients dependent on objective clinical factors. METHODS: ASD patients with baseline (BL) and 2-year (2Y) follow-up were included. Factors with the largest R2 value derived from multivariate forward stepwise regression were including in the modified ASD-FI (clin-ASD-FI). Factors included in the clin-ASD-FI were regressed against mortality, extended length of hospital stay (LOS, > 8 days), revisions, major complications and weights for the clin-ASD-FI were calculated via Beta/Sullivan. Total clin-ASD-FI score was created with a score from 0 to 1. Linear regression correlated clin-ASD-FI with ASD-FI scores and published cutoffs for the ASD-FI were used to create the new frailty cutoffs: not frail (NF: < 0.11), frail (F: 0.11-0.21) and severely frail (SF: > 0.21). Binary logistic regression assessed odds of complication or reop for frail patients. RESULTS: Five hundred thirty-one ASD patients (59.5 yrs, 79.5% F) were included. The final model had a R2 of 0.681, and significant factors were: < 18.5 or > 30 BMI (weight: 0.0625 out of 1), cardiac disease (0.125), disability employment status (0.3125), diabetes mellitus (0.0625), hypertension (0.0625), osteoporosis (0.125), blood clot (0.1875), and bowel incontinence (0.0625). These factors calculated the score from 0 to 1, with a mean cohort score of 0.13 ± 0.14. Breakdown by clin-ASD-FI score: 51.8% NF, 28.1% F, 20.2% SF. Increasing frailty severity was associated with longer LOS (NF: 7.0, F: 8.3, SF: 9.2 days; P < 0.001). Frailty independently predicted occurrence of any complication (OR: 9.357 [2.20-39.76], P = 0.002) and reop (OR: 2.79 [0.662-11.72], P = 0.162). CONCLUSIONS: Utilizing an existing ASD frailty index, we proposed a modified version eliminating the patient-reported components. This index is a true assessment of physiologic status, and represents a superior risk factor assessment compared to other tools for both primary and revision spinal deformity surgery as a result of its immutability with surgery, lack of subjectivity, and ease of use.

An Integrated 3-Dimentional Navigation System Increases the Accuracy, Efficiency, and Safety of Percutaneous Thoracolumbar Pedicle Screw Placement in Minimally Invasive Approaches: A Randomized Cadaveric Study.

STUDY DESIGN: Cadaveric study. OBJECTIVES: The purpose of this study was to compare a novel, integrated 3D navigational system (NAV) and conventional fluoroscopy in the accuracy, efficiency, and radiation exposure of thoracolumbar percutaneous pedicle screw (PPS) placement. METHODS: Twelve skeletally mature cadaveric specimens were obtained for twelve individual surgeons. Each participant placed bilateral PS at 11 segments, from T8 to S1. Prior to insertion, surgeons were randomized to the sequence of techniques and the side (left or right). Following placement, a CT scan of the spine was obtained for each cadaver, and an independent reviewer assessed the accuracy of screw placement using the Gertzbein grading system. Outcome metrics of interest included a comparison of breach incidence/severity, screw placement time, total procedure time, and radiation exposure between the techniques. Bivariate statistics were employed to compare outcomes at each level. RESULTS: A total of 262 screws (131 using each technique) were placed. The incidence of cortical breaches was significantly lower with NAV compared to FG (9% vs 18%; P = .048). Of breaches with NAV, 25% were graded as moderate or severe compared to 39% in the FG subgroup (P = .034). Median time for screw placement was significantly lower with NAV (2.7 vs 4.1 min/screw; P = .012), exclusive of registration time. Cumulative radiation exposure to the surgeon was significantly lower for NAV-guided placement (9.4 vs 134 µGy, P = .02). CONCLUSIONS: The use of NAV significantly decreased the incidence of cortical breaches, the severity of screw breeches, screw placement time, and radiation exposure to the surgeon when compared to traditional FG.

Reliability of a Novel Classification System for Thoracic Disc Herniations.

STUDY DESIGN: This is a cross-sectional survey. OBJECTIVE: The aim was to assess the reliability of a proposed novel classification system for thoracic disc herniations (TDHs). SUMMARY OF BACKGROUND DATA: TDHs are complex entities varying substantially in many factors, including size, location, and calcification. To date, no comprehensive system exists to categorize these lesions. METHODS: Our proposed system classifies 5 types of TDHs using anatomic and clinical characteristics, with subtypes for calcification. Type 0 herniations are small (≤40% of spinal canal) TDHs without significant spinal cord or nerve root effacement; type 1 are small and paracentral; type 2 are small and central; type 3 are giant (>40% of spinal canal) and paracentral; and type 4 are giant and central. Patients with types 1 to 4 TDHs have correlative clinical and radiographic evidence of spinal cord compression. Twenty-one US spine surgeons with substantial TDH experience rated 10 illustrative cases to determine the system's reliability. Interobserver and intraobserver reliability were determined using the Fleiss kappa coefficient. Surgeons were also surveyed to obtain consensus on surgical approaches for the various TDH types. RESULTS: High agreement was found for the classification system, with 80% (range 62% to 95%) overall agreement and high interrater and intrarater reliability (kappa 0.604 [moderate to substantial agreement] and kappa 0.630 [substantial agreement], respectively). All surgeons reported nonoperative management of type 0 TDHs. For type 1 TDHs, most respondents (71%) preferred posterior approaches. For type 2 TDHs, responses were roughly equivalent for anterolateral and posterior options. For types 3 and 4 TDHs, most respondents (72% and 68%, respectively) preferred anterolateral approaches. CONCLUSIONS: This novel classification system can be used to reliably categorize TDHs, standardize description, and potentially guide the selection of surgical approach. Validation of this system with regard to treatment and clinical outcomes represents a line of future study.

Optimizing Surgical Efficiency in Complex Spine Surgery Using Virtual Reality as a Communication Technology to Promote a Shared Mental Model: A Case Series and Review.

BACKGROUND AND OBJECTIVES: Virtual reality (VR) is an emerging technology that can be used to promote a shared mental model among a surgical team. We present a case series demonstrating the use of 3-dimensional (3D) VR models to visually communicate procedural steps to a surgical team to promote a common operating objective. We also review the literature on existing uses of VR for preoperative communication and planning in spine surgery. METHODS: Narrations of 3 to 4-minute walkthroughs were created in a VR visualization platform, converted, and distributed to team members through text and email the night before surgical intervention. A VR huddle was held immediately before the intervention to refine surgical goals. After the intervention, the participating team members' perceptions on the value of the tool were assessed using a survey that used a 5-point Likert scale. MEDLINE, Google Scholar, and Dimensions AI databases were queried from July 2010 to October 2022 to examine existing literature on preoperative VR use to plan spine surgery. RESULTS: Three illustrative cases are presented with accompanying video. Postoperative survey results demonstrate a positive experience among surgical team members after reviewing preoperative plans created with patient-specific 3D VR models. Respondents felt that preoperative VR video review was "moderately useful" or more useful in improving their understanding of the operational sequence (71%, 5/7), in enhancing their ability to understand their role (86%, 6/7), and in improving the safety or efficiency of the case (86%, 6/7). CONCLUSION: We present a proof of concept of a novel preoperative communication tool used to create a shared mental model of a common operating objective for surgical team members using narrated 3D VR models. Initial survey results demonstrate positive feedback among respondents. There is a paucity of literature investigating VR technology as a means for preoperative surgical communication in spine surgery. ETHICS: Institutional review board approval (IRB-300009785) was obtained before this study.

Metastasis of Intracranial Meningioma to the Osseous Spine: Systematic Literature Review and Case Report.

BACKGROUND: Osseous spinal metastases from intracranial meningiomas are rare but represent a serious disease progression. A literature review was performed on this topic to understand the clinical course of patients with this disease entity. We also present a case of spinal metastasis in a patient with a World Health Organization grade III meningioma. METHODS: The PubMed/MEDLINE database was queried on August 15, 2021, using the keywords (meningioma) AND (metastasis) AND (vertebra∗ OR spin∗). All publications reporting outcomes of patients with meningioma metastatic to the spine were included. Disease characteristics, treatment modality, and outcomes were extracted from each study. Because data availability varied widely between studies, no meta-analysis was performed. RESULTS: A total of 30 articles with 33 cases were included. Outcome data varied greatly in terms of quality and length of follow-up. Of 28 cases with reported outcomes data, 20 resulted in patient mortality ranging from a few weeks to 5 years after spinal metastasis. Mean (standard deviation) survival time was 5.8 (6.4) years following initial diagnosis, but only 1.4 (3.2) years from spinal metastasis. The longest survivor was noted to have no recurrence of disease 4 years after spinal metastasis. CONCLUSIONS: Bony spinal metastasis from intracranial meningioma is an extremely rare occurrence. Within the limits of the available literature, outcomes of patients with this disease appear to be poor. However, data reporting is inconsistent, and several articles did not report any outcome data. Further study is needed to better clarify the course and prognosis of this disease.

Virtual Reality-Enabled Resident Education of Lateral-Access Spine Surgery.

OBJECTIVE: Lateral-access spine surgery has many benefits, but adoption has been limited by a steep learning curve. Virtual reality (VR) is gaining popularity and lends itself as a useful tool in enhancing neurosurgical resident education. We thus sought to assess whether VR-based simulation could enhance the training of neurosurgery residents in lateral spine surgery. METHODS: Neurosurgery residents completed a VR-based lateral spine module on lateral patient positioning and performing lateral lumbar interbody fusion using the PrecisionOS VR system on the Meta Quest 2 headset. Simulation occurred 1×/week every other week for a total of 3 simulations over 6 weeks. Pre- and postintervention surveys as well as intrasimulation performance metrics were assessed over time. RESULTS: The majority of resident participants showed improvement in performance scores, including an automated PrecisionOS precision score, number of radiographs used within the simulation, and time to completion. All participants showed improvement in comfort with anatomic landmarks for lateral access surgery, confidence performing lateral surgery without direct supervision, and assessing fluoroscopy in spine surgery for hardware placement and image interpretation. Participant perception on the utility of VR as an educational tool also improved. CONCLUSIONS: VR-based simulation enhanced neurosurgical residents' ability to understand lateral access surgery. Immersive surgical simulation resulted in improved resident confidence with surgical technique and workflow, perceived improvement in anatomical knowledge, and simulation performance scores. Trainee perceptions on virtual simulation and training as a curriculum supplement also improved following completion of VR training.

Radiographic and Clinical Outcomes After Stand-Alone Anterior Lumbar Interbody Fusion for Symptomatic L5-S1 Retrolisthesis.

BACKGROUND AND OBJECTIVES: Degenerative lumbar spondylolisthesis is associated with significant pain and disability. The literature on the treatment options and clinical outcomes for lumbar anterolisthesis is robust, but very few reports specifically evaluate lumbar retrolisthesis. This study investigated surgical outcomes for symptomatic L5-S1 retrolisthesis treated with stand-alone L5-S1 anterior lumbar interbody fusion (ALIF). METHODS: All patients with symptomatic L5-S1 retrolisthesis treated with stand-alone L5-S1 ALIF at a single institution over a 7-year period were identified. Exhaustive nonoperative management had failed for all patients. Patients with previous lumbar fusion were excluded. Preoperative and postoperative radiographic images and patient-reported outcome measures for 20 patients (14 males and 6 females; mean [SD] age, 50.3 [13.7] years) were analyzed. RESULTS: The mean (SD) follow-up was 43.0 (23.7) months (range, 12.1-102.5 months). Patients experienced postoperative improvements in L5-S1 retrolisthesis (P = .048), L5-S1 disk height and angle (P < .001), L5 foraminal height (P < .001), L5-S1 lordosis (P < .001), and lumbar lordosis (P = .01). There were no significant changes in spinopelvic parameters. At the most recent follow-up, minimal clinically important differences in Oswestry Disability Index score, 36-Item Short-Form Survey (SF-36), and numerical rating scale score for leg pain were achieved in 11 of 20 (55%), 7 of 14 (50%), and 7 of 13 (54%) patients, respectively. All patients demonstrated fusion with no graft subsidence at up to 32 months. No patient experienced intraoperative complications, was readmitted, or required a subsequent posterior decompression or fusion because of refractory symptoms. CONCLUSION: In our cohort, stand-alone L5-S1 ALIF was associated with radiographic and clinical improvement in patients with symptomatic L5-S1 retrolisthesis.

Stable Regional and Global Alignment in Patients Treated With Minimally Invasive Lateral Retropleural Thoracic Diskectomy Without Fixation.

BACKGROUND AND OBJECTIVES: Thoracic disk herniations are challenging to treat, and open transthoracic or minimally invasive thoracoscopic approaches are associated with significant morbidity, substantial costs, and steep learning curves. The minimally invasive lateral retropleural thoracic diskectomy (MIS-LRP-TD) approach is straightforward and is associated with lower perioperative morbidity. With MIS-LRP-TD, the overlying rib, ipsilateral pedicle, ligamentum flavum, posterior longitudinal ligament, and posterior third of the adjacent vertebral bodies are resected. Adjunct fixation is typically not performed, eliminating hardware-related complications and costs. This radiographic study investigates long-term global and thoracic spine alignment after MIS-LRP-TD without fixation. METHODS: This study was a single-institution, retrospective evaluation of all patients who underwent MIS-LRP-TD without fixation between November 7, 2017 and July 19, 2022. Preoperative and the most recent postoperative radiographs were used to determine the C7 plumb line to central sacral vertical line, thoracic Cobb angle (TCA), segmental Cobb angle, C7 to sagittal vertical axis, thoracic kyphosis, and segmental kyphosis. RESULTS: In total, 22 patients with 24 disk herniations underwent MIS-LRP-TD without fixation. The mean (SD) radiographic follow-up was 12.9 (11.2) months. Overall, no significant differences were seen in C7 plumb line to central sacral vertical line (P = .65), C7 to sagittal vertical axis (P = .99), thoracic kyphosis (P = .30), TCA (P = .28), segmental kyphosis (P = .27), or segmental Cobb angle (P = .56) at follow-up. One patient demonstrated a >5° change in TCA but remained asymptomatic. CONCLUSION: Despite requiring extensive resection of the middle column and ipsilateral costovertebral joint at the index level, MIS-LRP-TD without adjunct fixation does not lead to significant global, regional, or segmental deformity. Thus, MIS-LRP-TD appears to be a safe, effective treatment approach for challenging thoracic disk herniations.

Transpsoas Approaches to the Lumbar Spine: Lateral and Prone.

The lateral transpsoas approach has become fundamental to minimally invasive spine surgery. The large interbody grafts that can be placed through this approach allow for robust arthrodesis of the anterior column, indirect decompression, and restoration of lordosis without disrupting the posterior musculature or ligamentous structures. The lateral decubitus position has traditionally been used for this approach but the prone position has gained popularity because it can reduce operating times for patients who also require posterior pedicle screw fixation. The transpsoas approach can be effectively performed in either position but surgeons should know the nuances that distinguish them.

Pseudarthrosis after four-level anterior cervical discectomy and fusion without posterior fixation.

OBJECTIVE: Fusion rates and long-term outcomes are well established for anterior cervical discectomy and fusion (ACDF) of 3 levels or fewer, but there is a paucity of similar data on 4-level fusions. The authors evaluated long-term fusion rates and clinical outcomes after 4-level ACDF without supplemental posterior instrumentation. METHODS: The authors retrospectively reviewed patients who underwent 4-level ACDF at a single institution with at least 1-year of radiological follow-up. Fusion was determined by measuring change in interspinous distance at each segment on dynamic radiographs or by the presence of bridging bone on CT scans at minimum 1-year follow-up. Clinical outcomes were assessed using Neck Disability Index and Short Form-36. RESULTS: A total of 63 patients (252 levels) met the inclusion criteria for the study, with a mean follow-up of 2.6 years. Complete radiographic fusion at all 4 levels was observed in 26 patients (41.3%). Of the 37 patients (58.7%) with radiographic pseudarthrosis, there was a mean of 1.35 nonfused levels. The fusion rate per level, however, was 80.2% (202/252 levels). The most common level demonstrating nonunion was the distal segment (C6-7), showing pseudarthrosis in 29 patients (46.8%), followed by the most proximal segment (C3-4) demonstrating nonunion in 9 patients (14.5%). The mean improvement in Neck Disability Index and Short Form-36 was 15.7 (p < 0.01) and 5.8 (p = 0.14), respectively, with improvement in both scores surpassing the minimum clinically important difference. One patient (1.6%) required revision surgery for symptomatic pseudarthrosis, and 5 patients (7.9%) underwent revision for symptomatic adjacent-segment disease. Patient-reported outcomes results are limited by the low rate of 1-year follow-up (50.8%), whereas reoperation data were available for all 63 patients. CONCLUSIONS: More than half of patients undergoing 4-level ACDF without posterior fixation demonstrated pseudarthrosis of at least 1 level-most commonly the distal C6-7 level. One patient required revision for symptomatic pseudarthrosis. Patient-reported outcomes showed significant improvements at 1-year follow-up, but clinical follow-up was limited. This is the largest series to date to evaluate fusion outcomes in 4-level ACDF.

A comparison of modern-era anterior lumbar interbody fusion and minimally invasive transforaminal lumbar interbody fusion at the lumbosacral junction.

OBJECTIVE: Interbody fusion is the primary method for achieving arthrodesis across the lumbosacral junction in the setting of degenerative pathologies, such as spondylosis and spondylolisthesis. Two common techniques are anterior lumbar interbody fusion (ALIF) and posterior transforaminal lumbar interbody fusion (TLIF). In recent years, interbody design and technology have advanced, and most earlier studies comparing ALIF and TLIF did not specifically assess the lumbosacral junction. This study compared changes in radiographic and clinical parameters between patients undergoing modern-era single-level ALIF and minimally invasive surgery (MIS) TLIF at L5-S1. METHODS: Consecutive patients who underwent single-segment L5-S1 ALIF or MIS TLIF performed by the senior authors over a 6-year interval (January 1, 2016-November 30, 2021) were retrospectively reviewed. Upright radiographs were used to determine pre- and postoperative lumbar lordosis, segmental lordosis, disc angle, and neuroforaminal height. Improvements in patient-reported outcome scores (Oswestry Disability Index and SF-36) were also compared. RESULTS: Overall, 108 patients (58 [54%] men, 50 [46%] women; mean [SD] age 57.6 [13.5] years) were included in the study. ALIF was performed in 49 patients, and TLIF was performed in 59 patients. The most common treatment indications were spondylolisthesis (50%, 54/108) and spondylosis (46%, 50/108). The cohorts did not differ in terms of intraoperative (p > 0.99) or postoperative (p = 0.73) complication rates. The mean (SD) hospital length of stay was significantly shorter for patients undergoing TLIF than ALIF (1.3 [0.6] days vs 2.0 [1.4] days, p < 0.001). Both techniques significantly improved L5-S1 segmental lordosis, disc angle, and neuroforaminal height (p ≤ 0.008). ALIF versus TLIF significantly increased mean [SD] segmental lordosis (12.5° [7.3°] vs 2.0° [5.7°], p < 0.001), disc angle (14.8° [5.5°] vs 3.0° [6.1°], p < 0.001), and neuroforaminal height (4.5 [4.6] mm vs 2.4 [3.0] mm, p = 0.008). Improvements in patient-reported outcome parameters and reoperation rates were similar between cohorts. CONCLUSIONS: When treating patients at a single segment across the lumbosacral junction, ALIF resulted in significantly greater increases in segmental lordosis, L5-S1 disc angle, and neuroforaminal height compared with MIS TLIF. Improvements in clinical parameters and reoperation rates were similar between the 2 techniques.

Bilateral sacroiliac joint fusion in long constructs using self-harvesting porous S2-alar iliac screws with an integrated tulip: technical considerations and early clinical and radiographic experience.

OBJECTIVE: The incidence of sacroiliac joint (SIJ) dysfunction after lumbosacral fusion is high. Upfront bilateral SIJ fusion using novel fenestrated self-harvesting porous S2-alar iliac (S2AI) screws could reduce the incidence of SIJ dysfunction and need for subsequent SIJ fusion. In this study, the authors report their early clinical and radiographic results of SIJ fusion using this novel screw. METHODS: The authors began using self-harvesting porous screws in July 2022. This is a retrospective review of consecutive patients at a single institution who underwent long thoracolumbar surgery with extension to the pelvis using this porous screw. Radiographic parameters of regional and global alignment were collected preoperatively and at the time of last follow-up. The incidence of intraoperative complications and need for revision were collected. The incidences of mechanical complications, including screw breakage, implant loosening/pullout, and screw cap dislocation at the time of last follow-up were also collected. RESULTS: Ten patients with a mean age of 67 years were included, 6 of whom were male. Seven patients had a thoracolumbar construct with extension to the pelvis. Three patients had upper instrumented vertebrae at the proximal lumbar spine. Intraoperative breach was not encountered in any of the patients (0%). Postoperatively, 1 patient (10%) had screw breakage at the neck of the tulip of the modified iliac screw discovered at routine follow-up without clinical sequalae. CONCLUSIONS: Use of self-harvesting porous S2AI screws incorporated into long thoracolumbar constructs was safe and feasible, demanding unique technical considerations. Long-term clinical and radiographic follow-up with a large patient cohort is necessary to determine their durability and efficacy to achieve SIJ arthrodesis and prevent SIJ dysfunction.

Minimally Invasive Surgery Strategies to Prevent Proximal Junctional Kyphosis.

Proximal junctional kyphosis (PJK) is a common complication following long-segment thoracolumbar fusions for patients with adult spinal deformities. PJK is described as a progressive kyphosis at the upper instrumented vertebra or 1 or 2 segments adjacent to the instrumented vertebra. This condition can lead to proximal junction failure, which results in vertebral body fractures, screw pullouts, and neurological deficits. Revision surgery is necessary to address symptomatic PJK. Research efforts have been dedicated to elucidating risk factors and prevention strategies. It has been postulated that minimally invasive surgery (MIS) techniques may help prevent PJK because these techniques aim to preserve the soft tissue integrity at the top of the construct and maintain posterior element support. In this article, the authors define PJK, describe MIS strategies to prevent PJK, and compare PJK rates after MIS with PJK rates after open approaches for long-segment thoracolumbar fusion.