Trends in lumbar spinal fusion-a literature review

Effect of pedicle screw misplacement on the pull-out strength using personalized finite element modeling

Intraoperative misplacement of vertebral pedicle screws is prevalent. While a pedicle screw misplacement of up to 4 mm is often considered safe by clinical standards, this may reduce the pull-out strength thereby increasing the risk of postoperative screw loosening. This study aimed to compare the pull-out strength of ideally-placed and misplaced pedicle screws via personalized finite element (FE) modeling simulations. Three-dimensional FE models to simulate pull-out tests of pedicle screws were constructed. Vertebral geometries and material properties were both determined based on computed tomography images from lumbar spine (L1-L5) of a 29-year-old healthy male individual. Pedicle screws were bilaterally placed under four conditions: ideal placement (no cortex perforation) as well as minor medial, minor lateral, and severe lateral misplacements causing cortex perforations. Minor and severe misplacements corresponded to, respectively, grades C and D of the Gertzbein classification. After meshing and voxel-based vertebral material assignments based on two distinct mappings from literature, pull-out strengths were estimated by considering a strain-based damage model to accurately simulate bone fractures. Results indicated that the mean of FE-predicted pull-out forces for ideally-placed screws (1583 and 2412 N for material mappings 1 and 2, respectively) was within the range of previous experimental data (ranging from 1016 to 2443 N) thus confirming the model validation. The mean of all pull-out forces for each misplaced screw group was significantly smaller (p < 0.05) than that of the ideally-placed screws, e.g., 20 % for minor medial, 22 % for minor lateral, and 37 % for severe lateral misplacements. These findings indicated that even clinically-acceptable screw misplacements (up to 4 mm) could significantly reduce the pull-out strengths of pedicle screws thus imposing higher risk of postoperative screw loosening. To avoid these common screw misplacements, the use of advanced approaches for pedicle screw placements appears to be imperative.

The Impact of Previous Lumbar Spine Surgery on Primary Total Hip Arthroplasty: Minimum 2-Year Outcomes Controlling for Approach and Technology

BACKGROUND

Prior lumbar spine surgery (LSS) can limit spine mobility, potentially increasing hip motion requirements. This study aimed to assess the influence of LSS on primary total hip arthroplasty (THA).

METHODS

Retrospective analysis was conducted on patients who underwent THA with prior LSS. Included patients had completed patient reported outcomes (PRO) and visual analog scale (VAS) for pain questionnaires or had a documented revision surgery with a minimum 2-year follow-up. Patients were propensity matched to a benchmark control group of patients who did not have previous spine pathology in a 1:3 ratio, controlling for age at surgery, surgical approach, use of advanced technology, sex, and body mass index (BMI). The analysis included comparisons of hip arthroplasty thresholds and complications. Sub-analyses based on the type of lumbar surgery and type of approach were also conducted.

RESULTS

There were 244 hips included in the study. The LSS group reported comparatively lower postoperative PRO scores. However, the LSS group experienced a similar magnitude of improvement. The LSS group met patient acceptable symptom state (PASS) threshold for Forgotten Joint Score (FJS) at a significantly lower rate. The LSS had a higher frequency of complications leading to revision THA with a relative risk of 24 and a relative risk of 20.8 for revision THA due to instability. Comparing patients by type of LSS, PROs, the percentage of patients reaching hip arthroplasty thresholds, and the revision THA rates were similar. There was no significant difference in complications considering the type of approach.

CONCLUSION

Patients who had prior LSS who underwent primary THA demonstrated equivalent improvements in PROs, but achieved lower overall postoperative scores and met hip arthroplasty thresholds at lower rates. Furthermore, patients undergoing primary THA with prior LSS had a higher risk of complications leading to revision surgery, including a 24-fold relative risk for complications leading to revision and a 20.8-fold relative risk of revision due to instability.

Diabetes and heart disease do not affect short-term lumbar fusion outcomes accounting for other risk factors in a matched cohort analysis

Objectives

Comprehensive preoperative management involves the identification and optimization of medical comorbidities while avoiding excessive healthcare utilization. While diabetes and heart disease are major causes of morbidity that can worsen surgical outcomes, further study is needed to evaluate how well current perioperative strategies mitigate their risks. This study employs an exact matching protocol to isolate the effects of both diabetes and cardiovascular disease on spine surgery outcomes.

Methods

4680 consecutive patients undergoing single-level, posterior-only lumbar fusion were retrospectively enrolled. Univariate logistic regression was performed on comorbidity subgroups, then coarsened exact matching (CEM) was employed for patients with diabetes or cardiovascular disease. Patients were matched 1:1 on ten patient and procedural characteristics known to affect neurosurgical outcomes. Separate pairs of exact-matched cohorts were generated to isolate both cardiovascular disease (matched n = 192), and diabetes (matched n = 380). Primary outcomes were surgical complications; length of stay; discharge disposition (home vs. non-home); and 30- and 90-day Emergency Department (ED) visits, readmissions, reoperations, and mortality.

Results

Cardiovascular disease and diabetes subgroups were not associated with short term outcomes after matching to control for confounders. Compared to univariate statistics, this method demonstrates that confounding control variables may drive outcomes more than these comorbidities themselves.

Conclusion

Between otherwise exactly matched patients undergoing lumbar fusion, diabetes and cardiovascular disease posed no greater risk of short-term adverse outcomes. This suggests proper selection criteria for surgical candidates and effective current perioperative strategies to mitigate these common comorbidities. Further studies are warranted to assess and optimize the cost-effectiveness of preoperative management for patients with common comorbidities.

Advances in implants and bone graft types for lumbar spinal fusion surgery

The increasing prevalence of spinal disorders worldwide necessitates advanced treatments, particularly interbody fusion for severe cases that are unresponsive to non-surgical interventions. This procedure, especially 360° lumbar interbody fusion, employs an interbody cage, pedicle screw-and-rod instrumentation, and autologous bone graft (ABG) to enhance spinal stability and promote fusion. Despite significant advancements, a persistent 10% incidence of non-union continues to result in compromised patient outcomes and escalated healthcare costs. Innovations in lumbar stabilisation seek to mimic the properties of natural bone, with evolving implant materials like titanium (Ti) and polyetheretherketone (PEEK) and their composites offering new prospects. Additionally, biomimetic cages featuring precisely engineered porosities and interconnectivity have gained traction, as they enhance osteogenic differentiation, support osteogenesis, and alleviate stress-shielding. However, the limitations of ABG, such as harvesting morbidities and limited fusion capacity, have spurred the exploration of sophisticated solutions involving advanced bone graft substitutes. Currently, demineralised bone matrix and ceramics are in clinical use, forming the basis for future investigations into novel bone graft substitutes. Bioglass, a promising newcomer, is under investigation despite its observed rapid absorption and the potential for foreign body reactions in preclinical studies. Its clinical applicability remains under scrutiny, with ongoing research addressing challenges related to burst release and appropriate dosing. Conversely, the well-documented favourable osteogenic potential of growth factors remains encouraging, with current efforts focused on modulating their release dynamics to minimise complications. In this evidence-based narrative review, we provide a comprehensive overview of the evolving landscape of non-degradable spinal implants and bone graft substitutes, emphasising their applications in lumbar spinal fusion surgery. We highlight the necessity for continued research to improve clinical outcomes and enhance patient well-being.

Total joint replacement of the lumbar spine: report of the first two cases with 16 years of follow-up

Background

Total joint replacement (TJR) of the lumbar spine is a revolutionary procedure that couples the clinical benefits of neural decompression with preservation of natural motion and sagittal balance at the operative level. The TJR procedure involves reconstruction of the entire motion segment using a posterior bilateral transforaminal approach to access the disc space. The TJR implant (MOTUS, 3Spine, Chattanooga, TN, USA) replaces the function of the intervertebral disc and facet joints, performing biomechanically as a new articulation for the resected, degenerated disc and facets. The implant has been optimized to simulate the kinematic characteristics of the three-joint complex.

Case Description

Two male patients, ages 32 and 38 years, underwent the first TJR procedures in 2007 in South Africa. Both patients had imaging evidence of advanced spinal degeneration with unremitting back and leg pain refractory to conservative management. Symptom amelioration was achieved postoperatively with markedly reduced pains scores and improved function at clinical follow-up. Both cases were recently re-examined after 16 years and the patients reported that the procedure significantly changed their lives. Neither believes they have a lingering back condition and they have been able to fully participate in all functions related to work, family and recreation. There was little to no imaging evidence of adjacent segment disease or arthritic changes at this long-term follow-up interval.

Conclusions

After 16 years of clinical follow-up, the implant continues to function normally, without evidence of adjacent segment degeneration and both patients continue to enjoy activities of daily living without back or leg pain or other functional impairments.

Prone Single Position Approach to Lateral Lumbar Interbody Fusion: Systematic Review and Meta-Analysis

BACKGROUND

Lateral lumbar interbody fusion (LLIF) with posterior screw fusion is a safe and effective treatment for patients suffering from degenerative spine disorders. While LLIF has been shown to restore disc height, decompress neural components, correct sagittal imbalances, and improve pain scores, the approach requires repositioning patients for posterior pedicle fixation, which requires 2 separate surgeries. The evolution of surgical techniques, navigation, and robotics has allowed for a single position approach to LLIF with the patient in the prone position. The purpose of this study was to perform a systematic review and meta-analysis comparing the prone single position (PSP) LLIF approach to the dual position LLIF approach. We hypothesized that PSP LLIF will have a reduced operative time, complication rate, and blood loss compared with the dual position LLIF procedure.

METHODS

A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. PubMed and Embase databases were searched with key terms: (lateral AND [interbody OR "inter body"] AND lumbar AND fusion) AND (prone OR single). Results were extracted and reviewed by 2 authors (MR and RB) per selection criteria. Patient demographics were extracted from the selected studies, along with surgical, patient-reported, and radiographic outcomes. A meta-analysis was performed using an unstandardized mean difference or log odds ratio with a confidence level of 95%.

RESULTS

Fifteen studies were included in the systematic review and 5 studies compared PSP LLIF to dual position LLIF for meta-analysis. PSP LLIF had a reduced operative time and length of stay compared with the dual position approach, although there was no significant reduction in estimated blood loss. Additionally, PSP LLIF improved lumbar lordosis more effectively than dual position LLIF. There was no difference in segmental lordosis or pelvic tilt. There was no difference in intraoperative complications, postoperative complications, or reoperations.

CONCLUSIONS

PSP LLIF reduces operative time and length of stay, with no relative increase in complications or reoperations compared with the dual position approach. Additionally, PSP LLIF improves lumbar lordosis relative to dual position LLIF, which may improve functional outcomes and reduce the risk of developing adjacent segment disease.

CLINICAL RELEVANCE

The associated operative and postoperative benefits of PSP LLIF may improve long-term outcomes of patients undergoing spinal fusion.

LEVEL OF EVIDENCE: 1

Prevalence of total joint arthroplasty in the adult spine deformity population

PURPOSE

The spine, hip, and knee are anatomically and biomechanically connected. Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are commonly employed to treat degenerative changes in the hip and knee, while fusion is used for spine degeneration. Spine deformity correction results in changes in sagittal alignment and pelvic parameters, and patients with stiff spines have higher rates of THA dislocation and revision due to instability. The goal of this study was to determine the prevalence of total joint arthroplasty (TJA) in adult spinal deformity (ASD) patients at our institution.

METHODS

Following Institutional Review Board approval, we retrospectively reviewed a list of cases performed by the senior author from 4/2017 to 5/2021. Patients > 18 years old undergoing preoperative evaluation for symptomatic lumbar degeneration or ASD were included. Patients < 18 years old, those diagnosed with adolescent idiopathic scoliosis, and non-fusion cases were excluded. Perioperative full-length standing EOS images were examined for the presence or absence of THA, TKA, or both. Demographic data was collected from patient electronic medical records, and statistical analyses were completed.

RESULTS

572 consecutive cases were reviewed, and 322 were excluded. 250 cases (97M:153F) were included in the final analysis, with a mean age of 61.8 ± 11.2 years. A total of 74 patients had a TJA (29.4%). THA was present in 41 patients (16.4%), and TKA was present in 49 patients (19.6%). Males had a higher prevalence of TJA, THA, and TKA (29.9%, 16.5%, and 21.6%) than females (29.4%, 16.3%, and 18.3%).

CONCLUSIONS

This study revealed a high prevalence TJA rate of 29.4% in ASD at our institution. This rate surpasses the prevalence rate reported among the general population in previous studies. High prevalence of patients with ASD and TJA may merit special surgical consideration.

Tomographic Assessment of Fusion Rate, Implant-Endplate Contact Area, Subsidence, and Alignment With Lumbar Personalized Interbody Implants at 1-Year Follow-Up

BACKGROUND

Incongruity between irregularly shaped vertebral endplates and the uniform surfaces of stock interbody fusion cages has been identified as contributing to cage subsidence, pseudarthrosis, and unpredictable alignment. Advances in manufacturing techniques have driven the development of personalized interbody cages (PICs) that can match individual endplate morphology and provide the exact shape and size needed to fill the disc space and achieve the planned correction. This study used computed tomography (CT) imaging to evaluate the implant-endplate contact area, fusion, subsidence, and achievement of planned alignment correction in patients receiving PIC devices.

METHODS

This retrospective study included patients treated for adult spinal deformity at a single site and implanted with PIC devices at L4 to L5 or L5 to S1 for segmental stabilization and alignment correction, who received 1-year postoperative CT images as part of their standard of care. An evaluation using 3-dimensional thin-section scans was conducted. Implant-endplate contact and signs of fusion were assessed in each CT slice across both endplates. The degree of subsidence as well as measures of segmental and global lumbar alignment were also assessed.

RESULTS

Fifteen patients were included in the study, with a mean age of 68.2 years. Follow-up ranged between 9 and 14 months. Twenty-six total lumbar levels were implanted; 20 with PIC devices via the anterior lumbar interbody fusion approach, 2 with stock cages via the anterior lumbar interbody fusion approach, and 4 with PIC devices via the transforaminal lumbar interbody fusion approach. CT analysis of PIC-implanted levels found an overall implant-endplate contact area ratio of 93.9%, a subsidence rate of 4.5%, a fusion rate of 100%, and satisfactory segmental and global lumbar correction compared with the preoperative plan.

CONCLUSIONS

PIC implants can provide nearly complete contact with endplate surfaces regardless of the individual endplate morphology. Subsidence, fusion, and alignment assessments in this tomographic study illustrated results consistent with the benefits of a personalized interbody implant.

LEVEL OF EVIDENCE: 4

Changes in Alignment at Untreated Vertebral Levels Following Short-Segment Fusion Using Personalized Interbody Cages: Leveraging Personalized Medicine to Reduce the Risk of Reoperation

BACKGROUND

An abnormal postoperative lordosis distribution index (LDI), which quantifies the ratio between the lordosis at L4 to S1 and the lordosis at L1 to S1, contributes to the development of adjacent segment disease and increased revision rates in patients undergoing short-segment lumbar intervertebral fusions. Incorporating preoperative spinopelvic parameters and LDI into the surgical plan for short-segment fusion is important for guiding alignment restoration and preserving normal preoperative alignment in unfused segments. This study examined changes in LDI, segmental lordosis, and lordosis of the unfused levels in patients treated with personalized interbody cage (PIC) implants.

METHODS

This retrospective study evaluated radiographic measurements from 111 consecutively treated patients diagnosed with degenerative spinal conditions and treated with a short-segment fusion of L4 to L5, L5 to S1, or L4 to S1 using PIC implant(s) within 6 months of the fusion procedure. Comparisons of intervertebral lordosis for treated and untreated levels as well as LDI pre- and postoperatively were performed.

RESULTS

In patients with a preoperative hypolordotic distribution (LDI < 50%), statistically significant increases were found in LDI postoperatively, approaching the normal LDI range (LDI 50%-80%). Likewise, patients with hyperlordotic distribution preoperatively (LDI > 80%) experienced a decrease in LDI postoperatively, trending toward the normal range, although the changes were not statistically significant. Intervertebral lordosis for the L5 to S1 level increased significantly following the placement of a PIC in the normal and hypolordotic LDI groups. Changes in intervertebral lordosis for L5 to S1 were not significant for patients with preoperative hyperlordotic LDI. Reciprocal changes in intervertebral lordosis at L1 to L4 were not observed in any groups.

CONCLUSIONS

PIC implants may provide a benefit for patients, particularly those with hypolordotic distributions preoperatively. They have the potential to further improve patient outcomes by helping surgeons to achieve patient-specific lordosis goals, which may help to reduce the risk of adjacent segment disease and revisions in patients undergoing short-segment lumbar intervertebral fusions.

CLINICAL RELEVANCE

Personalized implants can help surgeons achieve patient-specific alignment goals, potentially prevent adjacent segment disease, and reduce long-term reinterventions.

LEVEL OF EVIDENCE: 4

The projected increase of vertebral osteomyelitis in Germany implies a demanding challenge for future healthcare management of aging populations

PURPOSE

Since an increase in the occurrence of native vertebral osteomyelitis (VO) is expected and reliable projections are missing, it is urgent to provide a reliable forecast model and make it a part of future health care considerations.

METHODS

Comprehensive nationwide data provided by the Federal Statistical Office of Germany were used to forecast total numbers and incidence rates (IR) of VO as a function of age and gender until 2040. Projections were done using autoregressive integrated moving average model on historical data from 2005 to 2019 in relation to official population projections from 2020 to 2040.

RESULTS

The IR of VO is expected to increase from 12.4 in 2019 to 21.5 per 100,000 inhabitants [95% CI 20.9-22.1] in 2040. The highest increase is predicted in patients over 75 years of age for both men and women leading to a steep increase in absolute numbers, which is fourfold higher compared to patients younger than 75 years. While the IR per age group will not increase any further after 2035, the subsequent increase is due to a higher number of individuals aged 75 years or older.

CONCLUSIONS

Our data suggest that increasing IR of VO will seriously challenge healthcare systems, particularly due to demographic change and increasing proportions of populations turning 75 years and older. With respect to globally fast aging populations, future health care policies need to address this burden by anticipating limitations in financial and human resources and developing high-level evidence-based guidelines for prevention and interdisciplinary treatment.

Endovascular stenting of external iliac vein injury during anterior spine exposure

Anterior lumbar interbody fusion (ALIF) is a standard approach for the surgical management of patients with severe degenerative disease at the L4-L5 and lumbosacral (L5-S1) levels. ALIF is performed through retroperitoneal exposure but harbors a small risk of major vascular injury. In this case, we describe an emergent endovascular repair of an external iliac vein injury that occurred during ALIF with long-term follow-up. We discuss specific strategies in the decision making and technique that led to a successful outcome in this case. Endovascular stent grafting is a potential bailout option for serious iliac vein injury.

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

BACKGROUND AND OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Patient Comorbidities, Their Influence on Lumbar Spinal Fusion Surgery, and Recommendations to Reduce Unfavorable Outcomes

Improvements in healthcare management have led to a decrease in perioperative and postoperative complications. However, perioperative medical complications and mortality rates continue to increase in patients undergoing elective spinal surgeries. This trend is driven by the increase in the older population and the rise in the number of patients with more than two comorbidities. Managing patients with multiple comorbidities requires additional resources, augmenting the financial and societal burden. Despite the high risk of complications and mortality, patients with multiple comorbidities undergo spinal surgery for degenerative spinal conditions daily. These findings highlight the need for heightened awareness, patient education, and management of comorbidities before elective spinal surgeries. This article comprehensively reviews literature on the effects of medical comorbidities on spinal fusion surgery outcomes to increase awareness of the surgical complications associated with comorbidities. In addition, suggested preoperative and postoperative comorbidity management strategies are outlined.

Social determinants of health and disparities in spine surgery: a 10-year analysis of 8,565 cases using ensemble machine learning and multilayer perceptron

BACKGROUND CONTEXT

The influence of SDOH on spine surgery is poorly understood. Historically, researchers commonly focused on the isolated influences of race, insurance status, or income on healthcare outcomes. However, analysis of SDOH is becoming increasingly more nuanced as viewing social factors in aggregate rather than individually may offer more precise estimates of the impact of SDOH on healthcare delivery.

PURPOSE

The aim of this study was to evaluate the effects of patient social history on length of stay (LOS) and readmission within 90 days following spine surgery using ensemble machine learning and multilayer perceptron.

STUDY DESIGN

Retrospective chart review.

PATIENT SAMPLE

8,565 elective and emergency spine surgery cases performed from 2013 to 2023 using our institution's database of longitudinally collected electronic medical record information.

OUTCOMES MEASURES

Patient LOS, discharge disposition, and rate of 90-day readmission.

METHODS

Ensemble machine learning and multilayer perceptron were employed to predict LOS and readmission within 90 days following spine surgery. All other subsequent statistical analysis was performed using SPSS version 28. To further assess correlations among variables, Pearson's correlation tests and multivariate linear regression models were constructed. Independent sample t-tests, paired sample t-tests, one-way analysis of variance (ANOVA) with post-hoc Bonferroni and Tukey corrections, and Pearson's chi-squared test were applied where appropriate for analysis of continuous and categorical variables.

RESULTS

Black patients demonstrated a greater LOS compared to white patients, but race and ethnicity were not significantly associated with 90-day readmission rates. Insured patients had a shorter LOS and lower readmission rates compared to non-insured patients, as did privately insured patients compared to publicly insured patients. Patients discharged home had lower LOS and lower readmission rates, compared to patients discharged to other facilities. Marriage decreased both LOS and readmission rates, underweight patients showcased increased LOS and readmission rates, and religion was shown to impact LOS and readmission rates. When utilizing patient social history, lab values, and medical history, machine learning determined the top 5 most-important variables for prediction of LOS -along with their respective feature importances-to be insurance status (0.166), religion (0.100), ICU status (0.093), antibiotic use (0.061), and case status: elective or urgent (0.055). The top 5 most-important variables for prediction of 90-day readmission-along with their respective feature importances-were insurance status (0.177), religion (0.123), discharge location (0.096), emergency case status (0.064), and history of diabetes (0.041).

CONCLUSIONS

This study highlights that SDOH is influential in determining patient length of stay, discharge disposition, and likelihood of readmission following spine surgery. Machine learning was utilized to accurately predict LOS and 90-day readmission with patient medical history, lab values, and social history, as well as social history alone.

Spinal fusion surgery use among adults with low back pain enrolled in a digital musculoskeletal program: an observational study

OBJECTIVES

To compare 12-month spinal fusion surgery rates in the setting of low back pain among digital musculoskeletal (MSK) program participants versus a comparison cohort who only received usual care.

STUDY DESIGN

Retrospective cohort study with propensity score matched comparison cohort using commercial medical claims data representing over 100 million commercially insured lives.

METHODS

All study subjects experienced low back pain between January 2020 and December 2021. Digital MSK participants enrolled in the digital MSK low back program between January 2020 and December 2021. Non-participants had low back pain related physical therapy (PT) between January 2020 and December 2021. Digital MSK participants were matched to non-participants with similar demographics, comorbidities and baseline MSK-related medical care use. Spinal fusion surgery rates at 12 months post participation were compared.

RESULTS

Compared to non-participants, digital MSK participants had lower rates of spinal fusion surgery in the post-period (0.7% versus 1.6%; p < 0.001). Additionally, in the augmented inverse probability weighting (AIPW) model, digital MSK participants were found to have decreased odds of undergoing spinal fusion surgery (adjusted odds ratio: 0.64, 95% CI: 0.51-0.81).

CONCLUSIONS

This study provides evidence that participation in a digital MSK program is associated with a lower rate of spinal fusion surgery.

A comparative cohort study of surgical approaches for adult spinal deformity at a minimum 2-year follow-up

STUDY DESIGN

This study was a retrospective multi-center comparative cohort study.

MATERIALS AND METHODS

A retrospective institutional database of operative adult spinal deformity patients was utilized. All fusions > 5 vertebral levels and including the sacrum/pelvis were eligible for inclusion. Revisions, 3 column osteotomies, and patients with < 2-year clinical follow-up were excluded. Patients were separated into 3 groups based on surgical approach: 1) posterior spinal fusion without interbody (PSF), 2) PSF with interbody (PSF-IB), and 3) anteroposterior (AP) fusion (anterior lumbar interbody fusion or lateral lumbar interbody fusion with posterior screw fixation). Intraoperative, radiographic, and clinical outcomes, as well as complications, were compared between groups with ANOVA and χ2 tests.

RESULTS

One-hundred and thirty-eight patients were included for study (PSF, n = 37; PSF-IB, n = 44; AP, n = 57). Intraoperatively, estimated blood loss was similar between groups (p = 0.171). However, the AP group had longer operative times (547.5 min) compared to PSF (385.1) and PSF-IB (370.7) (p < 0.001). Additionally, fusion length was shorter in PSF-IB (11.4) compared to AP (13.6) and PSF (12.9) (p = 0.004). There were no differences between the groups in terms of change in alignment from preoperative to 2 years postoperative. There were no differences in clinical outcomes. While postoperative complications were largely similar between groups, operative complications were higher in the AP group (31.6%) compared to the PSF (5.4%) and PSF-IB (9.1) groups (p < 0.001).

CONCLUSION

While there were differences in intraoperative outcomes (operative time and fusion length), there were no differences in postoperative clinical or radiographic outcomes. AP fusion was associated with a higher rate of operative complications.

Management of Massive Flank Hernia After Lateral Lumbar Fusion: Preoperative Botulinum Toxin Injections and Open Repair - A Case Report

BACKGROUND Incisional flank hernias represent a complication after lateral lumbar spine surgery. Given the increasing rate of lateral lumbar interbody fusions, the rate of incisional flank hernias will increase. Since there are no reports of open massive flank hernia repair utilizing preoperative botulinum injections, we sought to publish this technique to provide surgeons with an innovative method for preoperatively treating patients with massive flank hernias. CASE REPORT A 75-year-old man with a history of coronary artery disease, chronic kidney disease, and abdominal hernia repair presented for evaluation of left lateral abdominal and left lower back bulging for 5 months. The symptoms began after an L2-L4 lateral lumbar spinal fusion. Physical examination revealed a left posterior lateral flank bulge. Computed tomography (CT) showed a fat-containing left posterolateral abdominal hernia. The patient was scheduled for CT-guided lateral abdominal wall botulinum injections, followed by open flank hernia repair. He tolerated the surgery well, was admitted for pain control, and discharged on day 2. Repeat imaging with CT at 3 months showed no evidence of patient's prior hernia defect. CONCLUSIONS Open flank hernia repair, in conjunction with preoperative botulinum toxin injections, allows for optimal visualization and re-approximation of the myofascial components of flank hernia defects. Failure to achieve adequate myofascial and skin closure, along with mesh reinforcement, in open flank hernia repair can result in various surgical site complications, including incisional flank hernia recurrence. We recommend further investigation on the benefits of botulinum injections as an adjunct in management of massive flank hernias.

Endplate weakening during cage bed preparation significantly reduces endplate load capacity

PURPOSE

To analyze the effect of endplate weakness prior to PLIF or TLIF cage implantation and compare it to the opposite intact endplate of the same vertebral body. In addition, the influence of bone quality on endplate resistance was investigated.

METHODS

Twenty-two human lumbar vertebrae were tested in a ramp-to-failure test. One endplate of each vertebral body was tested intact and the other after weakening with a rasp (over an area of 200 mm2). Either a TLIF or PLIF cage was then placed and the compression load was applied across the cage until failure of the endplate. Failure was defined as the first local maximum of the force measurement. Bone quality was assessed by determining the Hounsfield units (HU) on CT images.

RESULTS

With an intact endplate and a TLIF cage, the median force to failure was 1276.3N (693.1-1980.6N). Endplate weakening reduced axial endplate resistance to failure by 15% (0-23%). With an intact endplate and a PLIF cage, the median force to failure was 1057.2N (701.2-1735.5N). Endplate weakening reduced axial endplate resistance to failure by 36.6% (7-47.9%). Bone quality correlated linearly with the force at which endplate failure occurred. Intact and weakened endplates showed a strong positive correlation: intact-TLIF: r = 0.964, slope of the regression line (slope) = 11.8, p < 0.001; intact-PLIF: r = 0.909, slope = 11.2, p = 5.5E-05; weakened-TLIF: r = 0.973, slope = 12.5, p < 0.001; weakened-PLIF: r = 0.836, slope = 6, p = 0.003.

CONCLUSION

Weakening of the endplate during cage bed preparation significantly reduces the resistance of the endplate to subsidence to failure: endplate load capacity is reduced by 15% with TLIF and 37% with PLIF. Bone quality correlates with the force at which endplate failure occurs.

Provider's exposure to diversity contributes to socioeconomic disparities in lumbar and cervical fusion outcomes

Background

Studies report patient race, income, and education influence spinal fusion outcomes; fewer studies, however, examine the influence of provider factors such as exposure to diversity or cultural sensitivity.

Objective

To examine how providers' experience with diverse patient populations affects spinal fusion outcomes.

Methods

Retrospective review of 39,680 patients undergoing lumbar and cervical fusions, 2003-2021, in Clinformatics® Data Mart national database. We used the provider patient racial diversity index (pRDI)-a published metric of physician exposure to diverse patients-to divide patients into groups based their provider's category (I, II, III) where patients treated by category III providers had surgeons with the most diverse patient populations. Multivariate regression models on propensity score-matched cohorts examined the association between patient SES and provider category on post-operative outcomes.

Results

Black patients had decreased discharge home (OR 0.67; 95% CI 0.54-0.83) compared to white patients. Patients treated by category III providers had increased length of stay (Coeff. 0.62; 95% CI 0.43-0.81), charge (Coeff. 36800; 95% CI 29,200-44,400), and decreased discharge home (OR 0.90; 95% CI 0.83-0.97) compared to patients treated by category I providers. Asian patients treated by category II providers had decreased readmission (OR 0.38; 95% CI 0.14-0.96), and Black patients treated by category III providers had increased discharge home (OR 1.41; 95% CI 1.1-1.9) compared to those treated by category I providers.

Conclusion

While our study found two specific instances of improved spine surgery outcomes for minority patients treated by providers serving diverse patient populations, we present mixed findings overall. This study serves as the foundation for future research to better understand how provider pRDI affects outcomes in patients undergoing lumbar and cervical spine surgery.

Radiological Evaluation of Lumbar Endplate Dimensions in the Indian Population and Their Correlation With Cage Placement/Length in Diverse Lumbar Fusion Techniques

Background Lumbar fusion techniques are vital for treating various spinal conditions by promoting vertebral fusion to alleviate pain and restore stability. Given the anatomical uniqueness of the Indian skeletal structure, this study evaluates the radiological dimensions of lumbar endplates in the Indian population and their correlation with the placement and length of interbody cages used in various lumbar fusion techniques such as oblique lateral lumbar interbody fusion (OLIF), transforaminal lumbar interbody fusion (TLIF), and anterior lumbar interbody fusion (ALIF). This study aimed to conduct radiological measurements of lumbar endplates in the Indian population and correlate them with cage placement and length in lumbar fusion techniques. Methods This prospective study was conducted at the orthopaedic ward of a tertiary care center in Western Maharashtra, India. Healthy individuals (aged >18 years, either gender) selected with a 95% confidence level using Philip Core Integrity software (Amsterdam, Netherlands) were included in the study. We excluded those with a history of low back pain, previous lumbar spine surgeries, fractures, tuberculosis, tumors, deformities, degenerative diseases, or lesions affecting the lumbar spine. Quantitative measurements such as oblique and sagittal diameters, apophyseal ring widths, and interbody cage lengths were calculated using multiplanar reformatting with specific imaging parameters. Results A total of 150 individuals with an average age of 39.83 ± 14.17 years, ranging from 20 to 65 years. Among the study population, 68 were males and 82 were females. Among the male study population, oblique parameters such as Angle AOB and Mid-OD (oblique diameter) show considerable variability, with Angle AOB ranging from 51.43 ± 2.40 mm (L2 inferior) to 31.59 ± 4.25 mm (L5 inferior) and Mid-OD ranging from 41.59 ± 2.59 mm (L3 superior) to 34.38 ± 2.26 mm (S1 superior). Side-sagittal dimensions vary from 32.11 ± 2.50 mm (S1 superior) to 36.48 ±3.26 mm (L3 superior), emphasizing the need for tailored surgical planning. In contrast, females in the study population exhibit distinct anatomical profiles, with Angle AOB ranging from 52.15 ± 2.43 mm (L2 inferior) to 20.45 ± 5.45 mm (S1 superior) and Mid-OD from 33.48 ± 2.15 mm (L3 inferior) to 42.45 ± 2.59 mm (L3 superior). These findings underscore gender-specific anatomical differences crucial for individualized clinical evaluation and treatment strategies. Conclusion This study comprehensively analyzes oblique, side-sagittal, transverse, and midsagittal anatomic parameters across various vertebral levels in men and women, highlighting significant anatomical variations crucial for clinical assessments and surgical interventions.

Can local application of vancomycin reduce surgical site infection rate after open lumbar fusion surgery?: A multicenter retrospective cohort study

Surgical site infection (SSI) after posterior open lumbar fusion (POLF) is a major concern for both surgeons and patients. We sought to explore whether local application of vancomycin could decrease the rate of SSI. We reviewed the clinical data of patients who underwent POLF between June 2015 and June 2022 at 3 spinal centers. Patients were divided into those who received local vancomycin (vancomycin group) and those who did not (non-vancomycin group). The SSI rates at 12 months postoperatively were compared between the 2 groups. Although a trend toward a lower infection rate was observed in the vancomycin group than in the non-vancomycin group; the difference was not statistically significant (3.6% vs 5.5%, P = .121). However, we found that the postoperative SSI rate was significantly lower in the vancomycin group than in the non-vancomycin group (4.9% vs 11.4%, P = .041) in patients ≥ 2 fused segments, while there was no significant difference in postoperative SSI rate in patients with single fusion segment (3.1% vs 3.6%, P = .706). The logistic regression analysis indicated that the SSI rate in the non-vancomycin group was approximately 2.498 times higher than that in the vancomycin group (P = .048, odds ratio: 2.498, 95% confidence interval: 1.011-6.617) in patients with ≥2 fused segments. In SSI patients with confirmed pathogens, the SSI rate of Gram-negative bacteria in the vancomycin group was significantly higher than that in the non-vancomycin group (10/14 [71.4%] vs 5/22 [31.8%]), whereas the SSI rate of Gram-positive bacteria in the vancomycin group was significantly lower than that in the non-vancomycin group (4/14 [28.6%] vs 15/22 [68.2%]). Local administration of vancomycin is recommended in patients with ≥2 fused segments as it may facilitate to reduce the postoperative rate of SSI after POLF. Additionally, the local use of vancomycin can decrease the Gram-positive bacterial infections but is not effective against Gram-negative infections, which indirectly leads to an increase in the proportion of Gram-negative infections in SSI patients with confirmed pathogens.

Lumbar Decompression With and Without Fusion for Lumbar Stenosis With Spondylolisthesis: A Cost Utility Analysis

STUDY DESIGN

Markov model.

OBJECTIVE

To compare the cost-effectiveness of lumbar decompression alone (DA) with lumbar decompression with fusion (DF) for the management of adults undergoing surgery for lumbar stenosis with associated degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Rates of lumbar fusion have increased for all indications in the United States over the last 20 years. Recent randomized controlled trial data, however, have suggested comparable functional outcomes and lower reoperation rates for lumbar decompression and fusion as compared with DA in the treatment of lumbar stenosis with degenerative spondylolisthesis.

MATERIALS AND METHODS

A multistate Markov model was constructed from the US payer perspective of a hypothetical cohort of patients with lumbar stenosis with associated spondylolisthesis requiring surgery. Data regarding clinical improvement, costs, and reoperation were generated from contemporary randomized trial evidence, meta-analyses of recent prospective studies, and large retrospective cohorts. Base case, one-way sensitivity analysis, and probabilistic sensitivity analyses were conducted, and the results were compared with a WTP threshold of $100,000 (in 2022 USD) over a two-year time horizon. A discount rate of 3% was utilized.

RESULTS

The incremental cost and utility of DF relative to DA were $12,778 and 0.00529 aggregated quality adjusted life years. The corresponding incremental cost-effectiveness ratio of $2,416,281 far exceeded the willingness to pay threshold of $100,000. In sensitivity analysis, the results varied the most with respect to rate of improvement after DA, rate of improvement after lumbar decompression and fusion, and odds ratio of reoperation between the two groups. Zero percent of one-way and probabilistic sensitivity analyses achieved cost-effectiveness at the willingness-to-pay threshold.

CONCLUSIONS

Within the context of contemporary surgical data, DF is not cost-effective compared with DA in the surgical management of lumbar stenosis with associated spondylolisthesis over a two-year time horizon.

Socioeconomic disparities in lumbar fusion rates were exacerbated during the COVID-19 pandemic

Background

The COVID-19 pandemic disrupted healthcare access and utilization throughout the US, with variable impact on patients of different socioeconomic status (SES) and race. We characterize pre-pandemic and pandemic demographic and SES trends of lumbar fusion patients in the US.

Methods

Adults undergoing first-time lumbar fusion 1/1/2004-3/31/2021 were assessed in Clinformatics® Data Mart for patient age, geographical location, gender, race, education level, net worth, and Charlson Comorbidity Index (CCI). Multivariable regression models were used to evaluate the significance of trends over time, with a focus on pandemic trends 2020-2021 versus previous trends 2004-2019.

Results

The total 217,204 patients underwent lumbar fusions, 1/1/2004-3/31/2021. The numbers and per capita rates of lumbar fusions increased 2004-2019 and decreased in 2020 (first year of COVID-19 pandemic), with large variation in geographic distribution. There was overall a significant decrease in proportion of White patients undergoing lumbar fusion over time (OR=0.997, p<.001), though they were more likely to undergo surgery during the pandemic (OR=1.016, p<.001). From 2004-2021, patients were more likely to be educated beyond high school. Additionally, patients in the highest (>$500k) and lowest (<$25k) net worth categories had significantly more fusions over time (p<.001). During the pandemic (2020-2021), patients in higher net worth groups were more likely to undergo lumbar fusions ($150k-249k & $250k-499k: p<.001) whereas patients in the lowest net worth group had decreased rate of surgeries (p<.001). Lastly, patients' CCI increased significantly from 2004 to 2021 (coefficient=0.124, p<.001), and this trend held true during the pandemic (coefficient=0.179, p<.001).

Conclusions

To the best of our knowledge, our work represents the most comprehensive and recent characterization of SES variables in lumbar fusion rates. Unsurprisingly, lumbar fusions decreased overall with the onset of the COVID-19 pandemic. Importantly, disparities in fusion patients across patient race and wealth widened during the pandemic, reversing years of progress, a lesson we can learn for future public health emergencies.

Association Between Preoperative Cannabis Use and Increased Rate of Revision Surgery Following Spinal Fusion: A Systematic Review and Meta-Analysis

The use of cannabis as a method of chronic pain relief has skyrocketed since its legalization in states across the United States. Clinicians currently have a limited scope regarding the effectiveness of marijuana on surgical procedures. This systematic review aims to determine the effect of current cannabis use on the rate of failure of spinal fusions and overall surgical outcomes. A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement. PubMed, Embase, and Scopus were searched, identifying studies assessing spinal fusion with reported preoperative cannabis use. Outcomes of interest included reoperation due to fusion failure or pseudoarthrosis with a follow-up time of at least six months. Subgroups of cervical fusions alone and lumbar fusions alone were also analyzed. Certainty in evidence and bias was assessed using the GRADE criteria and ROBINS-I tool (PROSPERO #CRD42023463548). Four studies met the inclusion criteria, with a total of 788 patients (188 in the cannabis user group and 600 in the non-user group). The rate of revision surgery among cannabis users was higher than that in non-users for all spinal fusions (RR: 3.58, 95% CI: 1.67 to 7.66, p = 0.001). For cervical fusions alone, there remained a higher rate of revision surgery for cannabis users compared to non-users (RR: 4.47, 95% CI: 1.93 to 10.36, p = 0.0005). For lumbar fusions alone, there was no difference in the rates of revision surgery between cannabis users and non-users (RR: 1.21, 95% CI: 0.28 to 7.73, p = 0.79). Cannabis use was shown to be associated with a higher rate of pseudoarthrosis revisions in spinal fusions on meta-analysis. On subgroup stratification by spine region, cannabis use remained associated with pseudoarthrosis revisions on cervical fusions alone but not lumbar fusions alone. Further research with larger, randomized studies is required to fully elucidate the relationship between cannabis use and fusion, both in general and by spinal region.

Co-delivery of rhBMP-2 and zoledronic acid using calcium sulfate/hydroxyapatite carrier as a bioactive bone substitute to enhance and accelerate spinal fusion

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been FDA-approved for lumbar fusion, but supraphysiologic initial burst release due to suboptimal carrier and late excess bone resorption caused by osteoclast activation have limited its clinical usage. One strategy to mitigate the pro-osteoclast side effect of rhBMP-2 is to give systemic bisphosphonates, but it presents challenges with systemic side effects and low local bioavailability. The aim of this in vivo study was to analyze if posterolateral spinal fusion (PLF) could be improved by utilizing a calcium sulfate/hydroxyapatite (CaS/HA) carrier co-delivering rhBMP-2 and zoledronic acid (ZA). Six groups were allocated (CaS/HA, CaS/HA + BMP-2, CaS/HA + systemic ZA, CaS/HA + local ZA, CaS/HA + BMP-2 + systemic ZA, and CaS/HA + BMP-2 + local ZA). 10-week-old male Wistar rats, were randomly assigned to undergo L4-L5 PLF with implantation of group-dependent scaffolds. At 3 and 6 weeks, the animals were euthanized for radiography, μCT, histological staining, or biomechanical testing to evaluate spinal fusion. The results demonstrated that the CaS/HA biomaterial alone or in combination with local or systemic ZA didn't support PLF. However, the delivery of rhBMP-2 significantly promoted PLF. Combining systemic ZA with BMP-2 didn't enhance spinal fusion. Notably, the co-delivery of rhBMP-2 and ZA using the CaS/HA carrier significantly enhanced and accelerated PLF, without inhibiting systemic bone turnover, and potentially reduced the dose of rhBMP-2. Together, the treatment regimen of CaS/HA biomaterial co-delivering rhBMP-2 and ZA could potentially be a safe and cost-effective off-the-shelf bioactive bone substitute to enhance spinal fusion.

Qualitative study exploring the views of patients and healthcare providers on current rehabilitation practices after lumbar fusion surgery

OBJECTIVES

To explore the views of patients and healthcare providers on current rehabilitation after lumbar fusion surgery (LFS) to fuel the development of a novel rehabilitation care pathway.

DESIGN

A cross-sectional, qualitative study with an interpretive descriptive design.

SETTING

Academic and non-academic hospital setting in Belgium.

PARTICIPANTS

31 caregivers from (non)-academic settings and 5 patients with LFS were purposefully sampled and in-depth interviewed.

RESULTS

Out of the data of all interviews, participants reported opinions on 23 thematic clusters that were expressed in a time-contingent manner from the preoperative, perioperative to postoperative phase. Afterwards, themes were mapped to the Consolidated Framework for Implementation Research, with a larger role for concepts related to the innovation, inner and individual domain. As an overarching theme, the importance of an 'individualised, patient-centred rehabilitation built on a strong therapeutic alliance with an accessible interprofessional team' was stressed for patients undergoing LFS. Specifically, participants stated that a biopsychosocial approach to rehabilitation should start in the preoperative phase and immediately be continued postoperatively. No consensus was observed for movement restrictions postoperatively. Uniform communication between the involved caregivers was considered essential for optimal therapeutic alliance and clinical outcome. The precise role and competence of each member of the interprofessional team needs, therefore, to be clearly defined, respected and discussed. An accessible case manager to guide the patient trajectory and tackle problems could further support this. Interestingly, only patients, psychologists and physiotherapists addressed return to work as an important outcome after LFS.

CONCLUSIONS

This qualitative study identified key experiences and points to consider in the current and future rehabilitation pathway for LFS. Future research should incorporate these findings to build a novel rehabilitation pathway for LFS and evaluate its feasibility and cost-effectiveness.

TRIAL REGISTRATION NUMBER

This study was registered at clinicaltrials.gov (NCT03427294).

Biomechanical comparison of polyetheretherketone rods and titanium alloy rods in transforaminal lumbar interbody fusion: a finite element analysis

BACKGROUND

Whether polyetheretherketone (PEEK) rods have potential as an alternative to titanium alloy (Ti) rods in transforaminal lumbar interbody fusion (TLIF) remains unclear, especially in cases with insufficient anterior support due to the absence of a cage. The purpose of this study was to investigate biomechanical differences between PEEK rods and Ti rods in TLIF with and without a cage.

METHODS

An intact L1-L5 lumbar finite element model was constructed and validated. Accordingly, four TLIF models were developed: (1) Ti rods with a cage; (2) PEEK rods with a cage; (3) Ti rods without a cage; and (4) PEEK rods without a cage. The biomechanical properties were then compared among the four TLIF constructs.

RESULTS

With or without a cage, no obvious differences were found in the effect of PEEK rods and Ti rods on the range of motion, adjacent disc stress, and adjacent facet joint force. Compared to Ti rods, PEEK rods increase the average bone graft strain (270.8-6055.2 µE vs. 319.0-8751.6 µE). Moreover, PEEK rods reduced the stresses on the screw-rod system (23.1-96.0 MPa vs. 7.2-48.4 MPa) but increased the stresses on the cage (4.6-35.2 MPa vs. 5.6-40.9 MPa) and endplates (5.7-32.5 MPa vs. 6.6-37.6 MPa).

CONCLUSIONS

Regardless of whether a cage was used for TLIF, PEEK rods theoretically have the potential to serve as an alternative to Ti rods because they may provide certain stability, increase the bone graft strain, and reduce the posterior instrumentation stress, which might promote bony fusion and decrease instrumentation failure.

Development and validation of a nomogram to predict the risk of constipation after lumbar interbody fusion surgery

INTRODUCTION

To understand the incidence of postoperative constipation and the risk factors of constipation in patients with lumbar interbody fusion, we constructed and verified the constipation risk prediction model, so as to provide reference for the prevention and treatment of postoperative constipation.

METHODS

The data of patients undergoing lumbar interbody fusion in our hospital were retrospectively analyzed from December 2021 to December 2022. According to postoperative constipation, the patients were divided into constipation group and non-constipation group. Univariate logistic regression analysis and multivariate logistic regression analysis were used to determine independent risk factors for postoperative constipation. Based on independent risk factors, a nomogram was developed to predict the risk of constipation after lumbar interbody fusion. The prediction performance was assessed using receiver operating characteristic curve (ROC), calibration curve and decision curve analysis (DCA). Finally, bootstrapping method for internal validation was further evaluated the nomogram.

RESULTS

A total of 282 patients participated in the study. 176 patients (62.41%) after lumbar interbody occurred constipation, and 106 patients were asymptomatic. Multivariate regression analysis showed independent risk factors, including the use of calcium channel blockers, polypharmacy, postoperative bed time, and constipation history. Multivariate regression analysis was used to establish the model. The C-index of the nomogram was 0.827 (95% CI 0.779-0.875), and the C-index of interval bootstrapping validation was 0.813 (95% CI 0.765-0.861), and the area under the AUC was 0.800. The nomogram showed good discrimination ability.

CONCLUSIONS

The use of calcium channel blockers, polypharmacy, postoperative bed time, and history of constipation are independent risk factors for postoperative constipation in patients undergoing lumbar interbody fusion. The constructed risk prediction model has good discriminative ability.

Projections of Single-level and Multilevel Spinal Instrumentation Procedure Volume and Associated Costs for Medicare Patients to 2050

BACKGROUND

Instrumented spinal fusions can be used in the treatment of vertebral fractures, spinal instability, and scoliosis or kyphosis. Construct-level selection has notable implications on postoperative recovery, alignment, and mobility. This study sought to project future trends in the implementation rates and associated costs of single-level versus multilevel instrumentation procedures in US Medicare patients aged older than 65 years in the United States.

METHODS

Data were acquired from the Centers for Medicare & Medicaid Services from January 1, 2000, to December 31, 2019. Procedure costs and counts were abstracted using Current Procedural Terminology codes to identify spinal level involvement. The Prophet machine learning algorithm was used, using a Bayesian Inference framework, to generate point forecasts for 2020 to 2050 and 95% forecast intervals (FIs). Sensitivity analyses were done by comparing projections from linear, log-linear, Poisson and negative-binomial, and autoregressive integrated moving average models. Costs were adjusted for inflation using the 2019 US Bureau of Labor Statistics' Consumer Price Index.

RESULTS

Between 2000 and 2019, the annual spinal instrumentation volume increased by 776% (from 7,342 to 64,350 cases) for single level, by 329% (from 20,319 to 87,253 cases) for two-four levels, by 1049% (from 1,218 to 14,000 cases) for five-seven levels, and by 739% (from 193 to 1,620 cases) for eight-twelve levels (P < 0.0001). The inflation-adjusted reimbursement for single-level instrumentation procedures decreased 45.6% from $1,148.15 to $788.62 between 2000 and 2019, which is markedly lower than for other prevalent orthopaedic procedures: total shoulder arthroplasty (-23.1%), total hip arthroplasty (-39.2%), and total knee arthroplasty (-42.4%). By 2050, the number of single-level spinal instrumentation procedures performed yearly is projected to be 124,061 (95% FI, 87,027 to 142,907), with associated costs of $93,900,672 (95% FI, $80,281,788 to $108,220,932).

CONCLUSIONS

The number of single-level instrumentation procedures is projected to double by 2050, while the number of two-four level procedures will double by 2040. These projections offer a measurable basis for resource allocation and procedural distribution.

Bioactive Moldable Click Chemistry Polymer Cement with Nano-Hydroxyapatite and Growth Factor-Enhanced Posterolateral Spinal Fusion in a Rabbit Model

Spinal injuries or diseases necessitate effective fusion solutions, and common clinical approaches involve autografts, allografts, and various bone matrix products, each with limitations. To address these challenges, we developed an innovative moldable click chemistry polymer cement that can be shaped by hand and self-cross-linked in situ for spinal fusion. This self-cross-linking cement, enabled by the bioorthogonal click reaction, excludes the need for toxic initiators or external energy sources. The bioactivity of the cement was promoted by incorporating nanohydroxyapatite and microspheres loaded with recombinant human bone morphogenetic protein-2 and vascular endothelial growth factor, fostering vascular induction and osteointegration. The release kinetics of growth factors, mechanical properties of the cement, and the ability of the scaffold to support in vitro cell proliferation and differentiation were evaluated. In a rabbit posterolateral spinal fusion model, the moldable cement exhibited remarkable induction of bone regeneration and effective bridging of spine vertebral bodies. This bioactive moldable click polymer cement therefore presents a promising biomaterial for spinal fusion augmentation, offering advantages in safety, ease of application, and enhanced bone regrowth.

A Novel Intraoperative CT Navigation System for Spinal Fusion Surgery in Lumbar Degenerative Disease: Accuracy and Safety of Pedicle Screw Placement

Background: In recent years, intraoperative computed tomography (CT) navigation has become widely used for the insertion of pedicle screws in spinal fusion surgery. However, conventional intraoperative CT navigation may be impaired by infrared interference between the infrared camera and surgical instruments, which can lead to the misplacement of pedicle screws. Recently, a novel intraoperative CT navigation system, NextAR, has been developed. It uses a small infrared camera mounted on surgical instruments within the surgical field. NextAR navigation can minimize the problem of infrared interference and be expected to improve the accuracy of pedicle screw placement. Methods: This study investigated the accuracy of pedicle screw insertion under NextAR navigation in spinal fusion surgery for lumbar degenerative diseases. The accuracy of pedicle screw placement was evaluated in 15 consecutive patients using a CT grading scale. Results: Screw perforation occurred in only 1 of the total 70 screws (1.4%). Specifically, there was one grade 1 perforation within 2 mm, but no perforations larger than 2 mm. There were no reoperations or neurological complications due to screw misplacement. Conclusions: NextAR navigation can provide high accuracy for pedicle screw insertion and help ensure safe spinal fusion surgery for lumbar degenerative diseases.

Addressing the Impact of Race and Ethnicity on Musculoskeletal Spine Care in the United States

➤ Despite being a social construct, race has an impact on outcomes in musculoskeletal spine care.➤ Race is associated with other social determinants of health that may predispose patients to worse outcomes.➤ The musculoskeletal spine literature is limited in its understanding of the causes of race-related outcome trends.➤ Efforts to mitigate race-related disparities in spine care require individual, institutional, and national initiatives.

Impact of unplanned readmissions on lumbar surgery outcomes: a national study of 33,447 patients

BACKGROUND CONTEXT

Unplanned readmissions following lumbar spine surgery have immense clinical and financial implications. However, little is known regarding the impact of unplanned readmissions on patient-reported outcomes (PROs) following lumbar spine surgery.

PURPOSE

To evaluate the impact of unplanned readmissions, including specific readmission reasons, on patient reported outcomes 12 months after lumbar spine surgery.

STUDY DESIGN/SETTING

A retrospective cohort study of prospectively collected data was conducted using patients included in the lumbar module of the Quality and Outcomes Database (QOD), a national, multicenter spine registry.

PATIENT SAMPLE

A total of 33,447 patients who underwent elective lumbar spine surgery for degenerative diseases were included. Mean age was 59.8 (SD=14.04), 53.6% were male, 89.5% were white, 45.9% were employed, and 47.5% had private insurance.

OUTCOME MEASURES

Unplanned 90-day readmissions and 12-month patient-reported outcomes (PROs) including numeric rating scale (NRS) scores for back and leg pain, Oswestry Disability Index (ODI) scores, EuroQol-5 Dimension (EQ-5D) scores, and North American Spine Society (NASS) patient-satisfaction scores.

METHODS

The lumbar module of the QOD was queried for adults undergoing elective lumbar spine surgery for degenerative disease. Unplanned 90-day readmissions were classified into 4 groups: medical, surgical, pain-only, and no readmissions. Medical and surgical readmissions were further categorized into primary reason for readmission. 12-month PROs assessing patient back and leg pain (NRS), disability (ODI), quality of life (EQ-5D), and patient satisfaction were collected. Multivariable models predicting 12-month PROs were built controlling for covariates.

RESULTS

A total of 31,430 patients (94%) had no unplanned readmission while 2,017 patients (6%) had an unplanned readmission within 90 days following lumbar surgery. Patients with readmissions had significantly worse 12-month PROs compared with those with no unplanned readmissions in covariate-adjusted models. Using Wald-df as a measure of predictor importance, surgical readmissions were associated with the worst 12-month outcomes, followed by pain-only, then medical readmissions. In separate covariate adjusted models, we found that readmissions for pain, SSI/wound dehiscence, and revisions were among the most important predictors of worse outcomes at 12-months.

CONCLUSIONS

Unplanned 90-day readmissions were associated with worse pain, disability, quality of life, and greater dissatisfaction at 12-months, with surgical readmissions having the greatest impact, followed by pain-only readmissions, then medical readmissions. Readmissions for pain, SSI/wound dehiscence, and revisions were the most important predictors of worse outcomes. These results may help providers better understand the factors that impact outcomes following lumbar spine surgery and promote improved patient counseling and perioperative management.

Low Household Income Increases Hospital Length of Stay and Decreases Home Discharge Rates in Lumbar Fusion

STUDY DESIGN

Retrospective Matched Cohort Study.

OBJECTIVES

Low median household income (MHI) has been correlated with worsened surgical outcomes, but few studies have rigorously controlled for demographic and medical factors at the patient level. This study isolates the relationship between MHI and surgical outcomes in a lumbar fusion cohort using coarsened exact matching.

METHODS

Patients undergoing single-level, posterior lumbar fusion at a single institution were consecutively enrolled and retrospectively analyzed (n = 4263). Zip code was cross-referenced to census data to derive MHI. Univariate regression correlated MHI to outcomes. Patients with low MHI were matched to those with high MHI based on demographic and medical factors. Outcomes evaluated included complications, length of stay, discharge disposition, 30- and 90 day readmissions, emergency department (ED) visits, reoperations, and mortality.

RESULTS

By univariate analysis, MHI was significantly associated with 30- and 90 day readmission, ED visits, reoperation, and non-home discharge, but not mortality. After exact matching (n = 270), low-income patients had higher odds of non-home discharge (OR = 2.5, P = .016) and higher length of stay (mean 100.2 vs 92.6, P = .02). There were no differences in surgical complications, ED visits, readmissions, or reoperations between matched groups.

CONCLUSIONS

Low MHI was significantly associated with adverse short-term outcomes from lumbar fusion. A matched analysis controlling for confounding variables uncovered longer lengths of stay and higher rates of discharge to post-acute care (vs home) in lower MHI patients. Socioeconomic disparities affect health beyond access to care, worsen surgical outcomes, and impose costs on healthcare systems. Targeted interventions must be implemented to mitigate these disparities.

Cannabis Use is Associated With Higher Rates of Pseudarthrosis Following TLIF: A Multi-Institutional Matched-Cohort Study

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

To compare the rates of pseudarthrosis in patients undergoing 1 to 3 level transforaminal lumbar interbody fusion (TLIF) procedures between cannabis users and noncannabis users.

SUMMARY OF BACKGROUND DATA

Recreational use of cannabis is common, though it remains poorly studied and legally ambiguous in the United States. Patients with back pain may turn to adjunctive use of cannabis to manage their pain. However, the implications of cannabis use on the achievement of bony fusion are not well-characterized.

METHODS

Patients who underwent 1 to 3 level TLIF for degenerative disc disease or degenerative spondylolisthesis between 2010 and 2022 were identified using the PearlDiver Mariner all-claims insurance database. Cannabis users were identified with ICD 10 code F12.90. Patients undergoing surgery for nondegenerative pathologies such as tumors, trauma, or infection were excluded. 1:1 exact matching was performed using demographic factors, medical comorbidities, and surgical factors which were significantly associated with pseudarthrosis in a linear regression model. The primary outcome measure was development of pseudarthrosis within 24 months after 1 to 3 level TLIF. The secondary outcomes were the development of all-cause surgical complications as well as all-cause medical complications.

RESULTS

A 1:1 exact matching resulted in two equal groups of 1593 patients who did or did not use cannabis and underwent 1 to 3 level TLIF. Patients who used cannabis were 80% more likely to experience pseudarthrosis compared with patients who do not [relative risk (RR): 1.816, 95% CI: 1.291-2.556, P <0.001]. Similarly, cannabis use was associated with significantly higher rates of all-cause surgical complications (RR: 2.350, 95% CI: 1.399-3.947, P =0.001) and all-cause medical complications (RR: 1.934, 95% CI: 1.516-2.467, P <0.001).

CONCLUSION

After 1:1 exact matching to control for confounding variables, the findings of this study suggest that cannabis use is associated with higher rates of pseudarthrosis, as well as higher rates of all-cause surgical and all-cause medical complications. Further studies are needed to corroborate our findings.

Are We Finally Ready for Total Joint Replacement of the Spine? An Extension of Charnley's Vision

Professor Sir John Charnley has been rightfully hailed as a visionary innovator for conceiving, designing, and validating the Operation of the Century-the total hip arthroplasty. His groundbreaking achievement forever changed the orthopedic management of chronically painful and dysfunctional arthritic joints. However, the well-accepted surgical approach of completely removing the diseased joint and replacing it with a durable and anatomically based implant never translated to the treatment of the degenerated spine. Instead, decompression coupled with fusion evolved into the workhorse intervention. In this commentary, the authors explore the reasons why arthrodesis has remained the mainstay over arthroplasty in the field of spine surgery as well as discuss the potential shift in the paradigm when it comes to treating degenerative lumbar disease.

Predictive factors of symptomatic lumbar pseudoarthrosis following multilevel primary lumbar fusion

Background

Lumbar spinal fusion surgery is a well-established treatment for various spinal disorders. However, one of its complications, pseudoarthrosis, poses a significant concern. This study aims to explore the incidence, time and predictive factors contributing to pseudoarthrosis in patients who have undergone lumbar fusion surgery over a 10-year period.

Methods

Data for this research was sourced from the PearlDiver database where insurance claims of patients who underwent multilevel lumbar spinal fusion between 01/01/2010 and 10/31/2022 were examined for claims of pseudoarthrosis within the 10 years of their index procedure. A variety of demographic, comorbid, and surgical factors were assessed, including age, gender, Elixhauser Comorbidity Index (ECI), surgical approach, substance use disorders and history of spinal disorders. Statistical analyses, including chi-squared tests, multivariate analysis, and cox survival analysis were employed to determine significant associations.

Results

Among the 76,337 patients included in this retrospective study, 2.70% were diagnosed with symptomatic lumbar pseudoarthrosis at an average of 7.38 years in a 10-year follow-up. Multivariate and Cox hazard analyses revealed that significant predictors of symptomatic pseudoarthrosis development following multilevel primary lumbar fusion include vitamin D deficiency, osteoarthritis, opioid and NSAID use, tobacco use, and a prior history of congenital spine disorders.

Conclusions

In summary, this study revealed a 2.70% incidence of symptomatic lumbar pseudoarthrosis within 10 years of the index procedure. It highlighted several potential predictive factors, including comorbidities, surgical approaches, and substance use disorders, associated with the development of symptomatic pseudoarthrosis. Future research should focus on refining our understanding of these factors to improve patient outcomes and optimize healthcare resource allocation.

Effects of Preoperative Glucocorticoid Use on Patients Undergoing Single-Level Lumbar Fusions: A Retrospective Propensity Score-Matched Registry Study

Objective Spinal fusions are gaining popularity as a means of treating spinal deformity and instability from a range of pathologies. The prevalence of glucocorticoid use has also increased in recent decades, and their systemic effects are well-documented. Although commonly used in the preoperative period, the effects of steroids on outcomes among patients undergoing spinal fusions are inadequately described. This study compares the odds of developing complications among patients who underwent single-level lumbar fusions with and without preoperative glucocorticoid use in hopes of establishing more evidence-based parameters for guiding preoperative steroid use. Methods The TriNetX multi-institutional electronic health record database was used to perform a retrospective, propensity score-matched analysis of clinical outcomes of two cohorts of patients who underwent posterior or posterolateral single-level lumbar fusions with and without interbody fusion, those who used glucocorticoids for at least one week within a year of fusion and those who did not. The outcomes of interest were examined within 30 days of the operation and included death, reoperation, deep or superficial surgical site infection (SSI), pneumonia, reintubation, ventilator dependence, tracheostomy, acute kidney injury (AKI), renal insufficiency, pulmonary embolism (PE) or deep venous thrombosis (DVT), urinary tract infection (UTI), emergency department (ED) visit, sepsis, and myocardial infarction (MI). Results The odds of developing pneumonia within 30 days of spinal fusion in the cohort that used glucocorticoids within one year of operation compared to the cohort without glucocorticoid use was 0.67 (p≤0.001, 95% CI: 0.59-0.69). The odds of requiring a tracheostomy within 30 days of spinal fusion in the cohort that used glucocorticoids within one year of operation compared to the cohort without glucocorticoid use was 0.39 (p≤0.001, 95% CI: 0.26-0.60). The odds of reoperation, deep and superficial SSI, and ED visits within 30 days of operation were significantly higher for the same glucocorticoid-receiving cohort, with odds ratios of 1.4 (p=0.003, 95% CI: 1.11-1.65), 1.86 (p≤0.001, 95% CI: 1.31-2.63), 2.28 (p≤0.001, 95% CI: 1.57-3.31), and 1.25 (p≤0.001, 95% CI: 1.17-1.33), respectively. After propensity score-matching, there was no significant difference between the odds of death, DVT, PE, MI, UTI, AKI, sepsis, reintubation, and ventilator dependence between the two cohorts. Conclusion In support of much of the current literature regarding preoperative glucocorticoid use and rates of complications, patients who underwent a single-level lumbar fusion and have used glucocorticoids for at least a week within a year of operation experienced significantly higher odds of reoperation, deep and superficial SSI, and ED visits. However, these patients using glucocorticoids were also found to have lower odds of developing pneumonia, renal insufficiency, and tracheostomy requirement than those who did not use steroids within a year of surgery.

The Effect of Preoperative Marijuana Use on Surgical Outcomes, Patient-Reported Outcomes, and Opioid Consumption Following Lumbar Fusion

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVES

To (1) investigate the effect of marijuana use on surgical outcomes following lumbar fusion, (2) determine how marijuana use affects patient-reported outcomes measures (PROMs), and (3) determine if marijuana use impacts the quantity of opioids prescribed.

METHODS

Patients > 18 years of age who underwent primary one- or two-level lumbar fusion with preoperative marijuana use at our institution were identified. A 3:1 propensity match incorporating patient demographics and procedure type was conducted to compare preoperative marijuana users to non-marijuana users. Patient demographics, surgical characteristics, surgical outcomes (90-day all-cause and 90-day surgical readmissions, reoperations, and revision surgeries), pre- and postoperative narcotic usage, and PROMs were compared between groups. Multivariate regression models were created to determine the effect of marijuana on surgical reoperations patient-reported outcomes (PROMs) 1-year postoperatively.

RESULTS

Of the 259 included patients, 65 used marijuana preoperatively. Multivariate logistic regression analysis demonstrated that marijuana use (OR = 2.28, P = .041) significantly increased the likelihood of having a spine reoperation. No other surgical outcome was found to be significantly different between groups. Multivariate linear regression analysis showed that marijuana use was not significantly associated with changes in 1-year postoperative PROMs (all, P > .05). The quantity of pre- and postoperative opioids prescriptions was not significantly different between groups (all, P > .05).

CONCLUSIONS

Preoperative marijuana use increased the likelihood of a spine reoperation for any indication following lumbar fusion, but it was not associated with 90-day all cause readmission, surgical readmission, the magnitude of improvement in PROMs, or differences in opioid consumption.

LEVEL OF EVIDENCE

III.

Comparing Patient-Reported Outcomes, Complications, Readmissions, and Revisions in Posterior Lumbar Fusion With, Versus Without, an Interbody Device

STUDY DESIGN

Retrospective analysis on prospectively collected data.

OBJECTIVES

To compare posterior lumbar fusions with versus without an interbody in: (1) Patient-reported outcomes (PROs) at 1 year and (2) postoperative complications, readmission, and reoperations.

SUMMARY OF BACKGROUND DATA

Elective lumbar fusion is commonly used to treat various lumbar pathologies. Two common approaches for open posterior lumbar fusion include posterolateral fusion (PLF) alone without an interbody and with an interbody through techniques, like transforaminal lumbar interbody fusion. Whether fusion with or without an interbody leads to better outcomes remains an area of active research.

PATIENTS AND METHODS

The Lumbar Module of the Quality Outcomes Database was queried for adults undergoing elective primary posterior lumbar fusion with or without an interbody. Covariates included demographic variables, comorbidities, primary spine diagnosis, operative variables, and baseline PROs, including Oswestry Disability Index, North American Spine Society satisfaction index, numeric rating scale-back/leg pain, and Euroqol 5-dimension. Outcomes included complications, reoperations, readmissions, return to work/activities, and PROs. Propensity score matching and linear regression modeling were used to estimate the average treatment effect on the treated to assess the impact of interbody use on patient outcomes.

RESULTS

After propensity matching, there were 1044 patients with interbody and 215 patients undergoing PLF. The average treatment effect on the treated analysis showed that having an interbody or not had no significant impact on any outcome of interest, including 30-day complications and reoperations, 3-month readmissions, 12-month return to work, and 12-month PROs.

CONCLUSION

There were no discernible differences in outcomes between patients undergoing PLF alone versus with an interbody in elective posterior lumbar fusion. These results add to the growing body of evidence that posterior lumbar fusions with and without an interbody seem to have similar outcomes up to 1 year postoperatively when treating degenerative lumbar spine conditions.

A matched-control study on the impact of depressive disorders following lumbar fusion for adult spinal deformity: an analysis of a nationwide administrative database

PURPOSE

In recent years, depression rates have been on the rise, resulting in soaring mental health issues globally. There is paucity of literature about the impact of depression on lumbar fusion for adult spine deformity. The purpose of this study is to investigate whether patients with depressive disorders undergoing lumbar deformity fusion have higher rates of (1) in-hospital length of stay; (2) ninety-day medical and surgical complications; and (3) medical reimbursement.

METHODS

A retrospective study was performed using a nationwide administrative claims database from January 2007 to December 2015 for patients undergoing lumbar fusion for spine deformity. Study participants with depressive disorders were selected and matched to controls by adjusting for sex, age, and comorbidities. In total, the query yielded 3706 patients, with 1286 who were experiencing symptoms of depressive disorders, and 2420 who served as the control cohort.

RESULTS

The study revealed that patients with depressive disorders had significantly higher in-hospital length of stay (6.0 days vs. 5.0 days, p < 0.0001) compared to controls. Study group patients also had higher incidence and odds of ninety-day medical and surgical complications (10.2% vs. 5.0%; OR, 2.50; 95% CI, 2.16-2.89; p < .0001). Moreover, patients with depressive disorders had significantly higher episode of care reimbursement ($54,539.2 vs. $51,645.2, p < 0.0001).

CONCLUSION

This study illustrated that even after controlling for factors such as sex, age, and comorbidities, patients with depressive disorders had higher rates of in-hospital length of stay, medical and surgical complications, and total reimbursement.

Understanding Geospatial Trends in Lumbar Fusion Incidence and Technique in Medicare Populations

STUDY DESIGN

Retrospective study with epidemiologic analysis of public Medicare data.

OBJECTIVE

This study seeks to utilize geospatial analysis to identify distinct trends in lumbar fusion incidence and techniques in Medicare populations.

SUMMARY OF BACKGROUND DATA

With an aging population and new technologies, lumbar fusion is an increasingly common procedure. There is controversy, however, regarding which indications and techniques achieve optimal outcomes, leading to significant intersurgeon variation and potential national disparities in care.

MATERIALS AND METHODS

Medicare billing datasets were supplemented with Census Bureau socioeconomic data from 2013 to 2020. These databases listed lumbar fusions billed to Medicare by location, specialty, and technique. Hotspots and coldspots of lumbar fusion incidence and technique choice were identified with county-level analysis and compared with Mann-Whitney U . A linear regression of fusion incidence and a logistic regression of lumbar fusion hotspots/coldspots were also calculated.

RESULTS

Between 2013 and 2020, 624,850 lumbar fusions were billed to Medicare. Lumbar fusion hotspots performed fusions at nearly five times the incidence of coldspots (101.6-21.1 fusions per 100,000 Medicare members) and were located in the Midwest, Colorado, and Virginia while coldspots were in California, Florida, Wisconsin, and the Northeast. Posterior and posterolateral fusion were the most favored techniques, with hotspots in the Northeast. Combined posterior and posterolateral fusion and posterior interbody fusion was the second most favored technique, predominantly in Illinois, Missouri, Arkansas, and Colorado.

CONCLUSIONS

The geographic distribution of lumbar fusions correlates with variations in residency training, fellowship, and specialty. The geospatial patterning in both utilization and technique reflects a lack of consensus in the application of lumbar fusion. The strong variance in utilization is a potentially worrying finding that could suggest that the nonstandardization of lumbar fusion indication has led to both overtreatment and undertreatment across the nation.

LEVEL OF EVIDENCE

Level 3-retrospective.

Does the interfacing angle between pedicle screws and support rods affect clinical outcomes after posterior thoracolumbar fusion? A retrospective clinical study

BACKGROUND CONTEXT

Proper alignment and tightening of the pedicle screw/rod assembly after instrumented posterior fusion of the lower spine is known to be crucial in order to achieve satisfactory clinical results. Such interfacing angle mismatches indicate stress overloading of the implant system.

PURPOSE

The objective of this study is to investigate the incidence of postoperative screw/rod interfacing angle mismatch and to analyze the impact of mismatches on clinical outcome in terms of (1) revision surgery, (2) adjacent segment degeneration (ASD), and (3) pain.

STUDY DESIGN

This is a monocentric retrospective observational study.

PATIENT SAMPLE

Patients underwent fusion surgery with pedicle screw/rod systems for predominantly degenerative pathologies.

OUTCOME MEASURES

Pedicle screw/rod interfacing angle mismatch (mismatch is the angular deviation from 90° formed by the rod axis and the pedicle screw head axis as an indicator for missing form-fit) revision rate, ASD at the immediately adjacent cranial segment and VAS pain.

METHODS

Revision refers to subsequent procedures in which all or part of the original implant configuration is changed or removed. Radiographic parameters are evaluated using a/p and lateral radiographs at final follow-up. The interfacing angle mismatch between pedicle screw and rod is measured as the angle between two parallel lines on either side of each pedicle screw head and a line laterally along the associated rod. Multiple comparisons are counteracted by Bonferroni correction, adjusted significance level is at *p<.01.

RESULTS

Pedicle screw and rod interfacing angle mismatch was found in 171/406 (42.1%) of patients undergoing fusion surgery, affecting 613/3016 (20.3%) screws. The overall revision incidence was 11.8% (48/406), and a new ASD occurred in 12.1% of all patients (49/406) with an average follow-up of 5 years. Mean VAS pain score at final follow-up was 2.0. Comparison of the two groups with and without mismatches revealed statistically significantly higher (1) numbers of revision procedures performed (26.9% vs 0.9%), (2) numbers of new ASD developed (27.5% vs 3.8%), and (3) higher VAS pain scores (2.8/10 vs 1.4/10) for cases with mismatch. When comparing patients who underwent intraoperative correction and/or reduction with those who did not, statistically significant more screw mismatches (63.4% vs 39.7%) and revision surgeries (29.3% vs 9.9%) were noted in patients who had these forceful maneuvers.

CONCLUSIONS

Pedicle screw/rod interfacing angle mismatch is a frequent occurrence after fusion surgery. Mismatches indicate that the construct was assembled under mechanical stress. All preventable mechanical stresses, for example, unintentional uncontrolled forces on the instrumentation, should be avoided as much as possible, as they can negatively influence the clinical outcome.

Effects of open and minimally invasive Transforaminal Lumbar Interbody Fusion (TLIF) surgical techniques on mechanical behaviour of fused L3-L4 FSU: A comparative finite element study

For predicting the biomechanical effects of the fusion procedure, finite element (FE) analysis is widely used as a preclinical tool. Although several FE studies examined the efficacies of various fusion surgical techniques, comparative studies on Open and minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF) procedures incorporating a follower coordinate system have not been investigated yet. The current FE study evaluates the ranges of motion (ROM) and load distributions of Open-TLIF and MIS-TLIF implanted models, under physiological loading such as compression, flexion, extension and lateral bending. The most noteworthy finding from the investigation is that both the fusion procedures significantly reduced the ROMs of the implanted segment (L3-L4) and full model (L1-L5) by at least 89 % and 44 %, respectively, compared to the intact model. For all loading situations, over 95 % of the implanted models' cancellous bone volume was subjected to von Mises strains ranging from 0.0003 to 0.005. The maximum von Mises strain was observed to be localized on a small amount of cancellous bone volume (<5 %). The likelihood of adjacent segment degeneration is higher in the case of MIS-TLIF due to the higher stress (22-53 MPa) and strain (0.018-0.087) noticed on the upper facet of the L3 vertebra.

Robot-navigated pedicle screw insertion can reduce intraoperative blood loss and length of hospital stay: analysis of 1,633 patients utilizing propensity score matching

BACKGROUND CONTEXT

Navigation and robotic technologies have emerged as an alternative option to conventional freehand techniques for pedicle screw insertion. However, the effectiveness of these technologies in reducing the perioperative complications of spinal fusion surgery remains limited due to the small cohort size in the existing literature.

PURPOSE

To investigate whether utilization of robotically navigated pedicle screw insertion can reduce the perioperative complications of spinal fusion surgery-including reoperations-with a sizeable cohort.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Patients who underwent primary lumbar fusion surgery between 2019 and 2022.

OUTCOME MEASURES

Perioperative complications including readmission, reoperation, its reasons, estimated blood loss, operative time, and length of hospital stay.

METHODS

Patients' data were collected including age, sex, race, body mass index, upper-instrumented vertebra, lower-instrumented vertebra, number of screws inserted, and primary procedure name. Patients were classified into the following two groups: freehand group and robot group. The variable-ratio greedy matching was utilized to create the matched cohorts by propensity score and compared the outcomes between the two group.

RESULTS

A total of 1,633 patients who underwent primary instrumented spinal lumbar fusion surgery were initially identified (freehand 1,286; robot 347). After variable ratio matching was performed with age, sex, body mass index, fused levels, and upper instrumented vertebrae level, 694 patients in the freehand group and 347 patients in robot groups were selected. The robot group showed less estimated blood loss (418.9±398.9 vs 199.2±239.6 ml; p<.001), shorter LOS (4.1±3.1 vs 3.2±3.0 days; p<.001) and similar operative time (212.5 vs 222.0 minutes; p=.151). Otherwise, there was no significant difference in readmission rate (3.6% vs 2.6%; p=.498), reoperation rate (3.2% vs 2.6%; p=.498), and screw malposition requiring reoperation (five cases, 0.7% vs one case, 0.3%; p=1.000).

CONCLUSIONS

Perioperative complications requiring readmission and reoperation were similar between fluoroscopy guided freehand and robotic surgery. Robot-guided pedicle screw insertion can enhance surgical efficiency by reducing intraoperative blood loss and length of hospital stay without extending operative time.

Using Novel Segmentation Technology to Define Safe Corridors for Minimally Invasive Posterior Lumbar Interbody Fusion

BACKGROUND AND OBJECTIVES

There has been a rise in minimally invasive methods to access the intervertebral disk space posteriorly given their decreased tissue destruction, lower blood loss, and earlier return to work. Two such options include the percutaneous lumbar interbody fusion through the Kambin triangle and the endoscopic transfacet approach. However, without accurate preoperative visualization, these approaches carry risks of damaging surrounding structures, especially the nerve roots. Using novel segmentation technology, our goal was to analyze the anatomic borders and relative sizes of the safe triangle, trans-Kambin, and the transfacet corridors to assist surgeons in planning a safe approach and determining cannula diameters.

METHODS

The areas of the safe triangle, Kambin, and transfacet corridors were measured using commercially available software (BrainLab, Munich, Germany). For each approach, the exiting nerve root, traversing nerve roots, theca, disk, and vertebrae were manually segmented on 3-dimensional T2-SPACE magnetic resonance imaging using a region-growing algorithm. The triangles' borders were delineated ensuring no overlap between the area and the nerves.

RESULTS

A total of 11 patients (65.4 ± 12.5 years, 33.3% female) were retrospectively reviewed. The Kambin, safe, and transfacet corridors were measured bilaterally at the operative level. The mean area (124.1 ± 19.7 mm2 vs 83.0 ± 11.7 mm2 vs 49.5 ± 11.4 mm2) and maximum permissible cannula diameter (9.9 ± 0.7 mm vs 6.8 ± 0.5 mm vs 6.05 ± 0.7 mm) for the transfacet triangles were significantly larger than Kambin and the traditional safe triangles, respectively (P < .001).

CONCLUSION

We identified, in 3-dimensional, the borders for the transfacet corridor: the traversing nerve root extending inferiorly until the caudal pedicle, the theca medially, and the exiting nerve root superiorly. These results illustrate the utility of preoperatively segmenting anatomic landmarks, specifically the nerve roots, to help guide decision-making when selecting the optimal operative approach.

Spinal Deformity, Surgery at the Cervicothoracic Junction, and American Society of Anesthesiologists Class Increase the Risk of Post-surgical Intensive Care Unit Treatment after Dorsal Spine Surgery: A Single-Center Multivariate Analysis of 962 Patients

STUDY DESIGN

This was a retrospective multivariate analysis of preoperative risk factors leading to intensive care unit (ICU) admissions in patients undergoing elective or acute dorsal spine surgery.

PURPOSE

Numerous studies have predicted a substantial increase in spine surgeries within the next decades, potentially overwhelming hospitals' resources, including ICU occupancy. Accurate estimates of whether patients need postsurgical ICU treatment are pivotal for both resource allocation and patient safety.

OVERVIEW OF LITERATURE

Risk factors leading to ICU admissions after dorsal spine surgery have been extensively examined for lumbar elective surgery. Studies including other anatomical segments of the spine and nonelective surgery regarding postsurgical ICU treatment probability are lacking.

METHODS

This study was designed to be a single-center multivariate analysis of data retrospectively collected from a tertiary care university hospital. Patients undergoing dorsal spine surgery from 2009 to 2019 were included in this study. The patients' demographic data were analyzed to determine potential preoperative risk factors for ICU admission after surgery using multiple logistic regression.

RESULTS

In our cohort, 962 patients with a mean age of 71.1±0.55 years were included. Surgeries involved 3.24±0.08 spinal levels on average. The incidence of ICU treatment after surgery was 30.4% (n=292). Multivariate logistic regression showed a markedly increased odds ratio (OR) for patients undergoing surgery of the cervicothoracic junction (OR, 8.86) and those undergoing surgery for spinal deformity treatment (OR, 7.7). Additionally, cervical procedures (OR, 3.29), American Society of Anesthesiologists (ASA) class 3-4 (OR, 2.74), spondylodiscitis (OR, 2.47), fusion of ≥3 levels (OR, 1.94), and age >75 years (OR, 1.33) were associated with an increased risk of postsurgical ICU admission.

CONCLUSIONS

The findings highlight the relevance of anatomical location, preoperative diagnosis, ASA class, and length of surgery regarding the predictability of postoperative ICU admission. Our data allowed for more sophisticated estimates regarding the need for ICU treatment after dorsal spine surgery, guiding the surgeon through patient selection, communication, and ICU admission predictability.

A Predictive Model of Failure to Rescue After Thoracolumbar Fusion

OBJECTIVE

Although failure to rescue (FTR) has been utilized as a quality-improvement metric in several surgical specialties, its current utilization in spine surgery is limited. Our study aims to identify the patient characteristics that are independent predictors of FTR among thoracolumbar fusion (TLF) patients.

METHODS

Patients who underwent TLF were identified using relevant diagnostic and procedural codes from the National Surgical Quality Improvement Program (NSQIP) database from 2011-2020. Frailty was assessed using the risk analysis index (RAI). FTR was defined as death, within 30 days, following a major complication. Univariate and multivariable analyses were used to compare baseline characteristics and early postoperative sequelae across FTR and non-FTR cohorts. Receiver operating characteristic (ROC) curve analysis was used to assess the discriminatory accuracy of the frailty-driven predictive model for FTR.

RESULTS

The study cohort (N = 15,749) had a median age of 66 years (interquartile range, 15 years). Increasing frailty, as measured by the RAI, was associated with an increased likelihood of FTR: odds ratio (95% confidence interval [CI]) is RAI 21-25, 1.3 [0.8-2.2]; RAI 26-30, 4.0 [2.4-6.6]; RAI 31-35, 7.0 [3.8-12.7]; RAI 36-40, 10.0 [4.9-20.2]; RAI 41- 45, 21.5 [9.1-50.6]; RAI ≥ 46, 45.8 [14.8-141.5]. The frailty-driven predictive model for FTR demonstrated outstanding discriminatory accuracy (C-statistic = 0.92; CI, 0.89-0.95).

CONCLUSION

Baseline frailty, as stratified by type of postoperative complication, predicts FTR with outstanding discriminatory accuracy in TLF patients. This frailty-driven model may inform patients and clinicians of FTR risk following TLF and help guide postoperative care after a major complication.

Stand-alone ALIF versus TLIF in patients with low back pain - A propensity-matched cohort study with two-year follow-up

Introduction

Instrumented lumbar fusion by either the anterior or transforaminal approach has different advantages and disadvantages. Few studies have compared PatientReported Outcomes Measures (PROMs) between stand-alone anterior lumbar interbody fusion (SA-ALIF) and transforaminal lumbar interbody fusion (TLIF).

Research question

This is a register-based dual-center study on patients with severe disc degeneration (DD) and low back pain (LBP) undergoing single-level SA-ALIF or TLIF. Comparing PROMs, including disability, quality of life, back- and leg-pain and patient satisfaction two years after SA-ALIF or TLIF, respectively.

Material and methods

Data were collected preoperatively and at one and two-year follow-up. The primary outcome was Oswestry Disability Index (ODI). The secondary outcomes were patient satisfaction, walking ability, visual analog scale (VAS) scores for back and leg pain, and quality of life (QoL) measured by the European Quality of Life-5 Dimensions (EQ-5D) index score. To reduce baseline differences between groups, propensity-score matching was employed in a 1:1 fashion.

Results

92 patients were matched, 46 S A-ALIF and 46 TLIF. They were comparable preoperatively, with no significant difference in demographic data or PROMs (P > 0.10). Both groups obtained statistically significant improvement in the ODI, QoL and VAS-score (P < 0.01), but no significant difference was observed (P = 0.14). No statistically significant differences in EQ-5D index scores (P = 0.25), VAS score for leg pain (P = 0.88) and back pain (P = 0.37) at two years follow-up.

Conclusion

Significant improvements in ODI, VAS-scores for back and leg pain, and EQ-5D index score were registered after two-year follow-up with both SA-ALIF and TLIF. No significant differences in improvement.

Anesthesia practice among joint arthroplasty patients with a previous lumbar spine surgery

STUDY OBJECTIVE

To analyze the use of neuraxial techniques in total hip or knee arthroplasty patients who previously underwent lumbar spine surgeries.

DESIGN

Retrospective analysis of a national database.

SETTING

U.S. hospitals.

PATIENTS

Patients undergoing a total hip or knee arthroplasty, stratified by those with a previous lumbar fusion or decompression procedure.

MEASUREMENTS

Our primary outcome was the use of neuraxial anesthesia; secondary outcomes included combined complications, cardio-pulmonary complications, and prolonged length of stay. Patients with and without a history of a lumbar procedure were compared using mixed-effects regression.

MAIN RESULTS

Among 758,857 THAs 8961 had a history of lumbar fusion and 8599 of decompression. Among 1,387,335 TKAs 15,827 had a history of lumbar fusion and 13,652 of decompression. History of a lumbar fusion was associated with lower odds of neuraxial anesthesia use in THA (OR: 0.74 CI: 0.70-0.79, p ≤0.0001) and TKA (OR: 0.80 CI: 0.77-0.84, p ≤0.0001).

CONCLUSIONS

Previous lumbar fusion -but not decompression- surgery is associated with lower neuraxial anesthesia in THA/TKA patients, despite its use being universally associated with decreased length of stay. More research is needed to address the importance of neuraxial techniques in patients with prior spine surgery.