The prevalence of complications associated with lumbar and thoracic spinal deformity surgery in the elderly population: a meta-analysis

Evaluating Computer Vision, Large Language, and Genome-Wide Association Models in a Limited Sized Patient Cohort for Pre-Operative Risk Stratification in Adult Spinal Deformity Surgery

Background: Adult spinal deformities (ASD) are varied spinal abnormalities, often necessitating surgical intervention when associated with pain, worsening deformity, or worsening function. Predicting post-operative complications and revision surgery is critical for surgical planning and patient counseling. Due to the relatively small number of cases of ASD surgery, machine learning applications have been limited to traditional models (e.g., logistic regression or standard neural networks) and coarse clinical variables. We present the novel application of advanced models (CNN, LLM, GWAS) using complex data types (radiographs, clinical notes, genomics) for ASD outcome prediction. Methods: We developed a CNN trained on 209 ASD patients (1549 radiographs) from the Stanford Research Repository, a CNN pre-trained on VinDr-SpineXR (10,468 spine radiographs), and an LLM using free-text clinical notes from the same 209 patients, trained via Gatortron. Additionally, we conducted a GWAS using the UK Biobank, contrasting 540 surgical ASD patients with 7355 non-surgical ASD patients. Results: The LLM notably outperformed the CNN in predicting pulmonary complications (F1: 0.545 vs. 0.2881), neurological complications (F1: 0.250 vs. 0.224), and sepsis (F1: 0.382 vs. 0.132). The pre-trained CNN showed improved sepsis prediction (AUC: 0.638 vs. 0.534) but reduced performance for neurological complication prediction (AUC: 0.545 vs. 0.619). The LLM demonstrated high specificity (0.946) and positive predictive value (0.467) for neurological complications. The GWAS identified 21 significant (p < 10-5) SNPs associated with ASD surgery risk (OR: mean: 3.17, SD: 1.92, median: 2.78), with the highest odds ratio (8.06) for the LDB2 gene, which is implicated in ectoderm differentiation. Conclusions: This study exemplifies the innovative application of cutting-edge models to forecast outcomes in ASD, underscoring the utility of complex data in outcome prediction for neurosurgical conditions. It demonstrates the promise of genetic models when identifying surgical risks and supports the integration of complex machine learning tools for informed surgical decision-making in ASD.

Inter-Specimen Analysis of Diverse Finite Element Models of the Lumbar Spine

Over the past few decades, there has been a growing popularity in utilizing finite element analysis to study the spine. However, most current studies tend to use one specimen for their models. This research aimed to validate multiple finite element models by comparing them with data from in vivo experiments and other existing finite element studies. Additionally, this study sought to analyze the data based on the gender and age of the specimens. For this study, eight lumbar spine (L2-L5) finite element models were developed. These models were then subjected to finite element analysis to simulate the six fundamental motions. CT scans were obtained from a total of eight individuals, four males and four females, ranging in age from forty-four (44) to seventy-three (73) years old. The CT scans were preprocessed and used to construct finite element models that accurately emulated the motions of flexion, extension, lateral bending, and axial rotation. Preloads and moments were applied to the models to replicate physiological loading conditions. This study focused on analyzing various parameters such as vertebral rotation, facet forces, and intradiscal pressure in all loading directions. The obtained data were then compared with the results of other finite element analyses and in vivo experimental measurements found in the existing literature to ensure their validity. This study successfully validated the intervertebral rotation, intradiscal pressure, and facet force results by comparing them with previous research findings. Notably, this study concluded that gender did not have a significant impact on the results. However, the results did highlight the importance of age as a critical variable when modeling the lumbar spine.

The 5-item modified frailty index predicts spinal osteotomy outcomes better than age in adult spinal deformity patients: an ACS - NSQIP analysis

PURPOSE

To evaluate the utility of 5-Item Modified Frailty Index (mFI-5) as compared to chronological age in predicting outcomes of spinal osteotomy in Adult Spinal Deformity (ASD) patients.

METHODS

Using Current Procedural and Terminology (CPT) codes, the American College of Surgeons National Surgery Quality Improvement Program (ACS-NSQIP) database was queried for adult patients undergoing spinal osteotomy from 2015 to 2019. Multivariate regression analysis was performed to evaluate the effect of baseline frailty status, measured by mFI-5 score, and chronological age on postoperative outcomes. Receiver-operating characteristic (ROC) curve analysis was performed to analyze the discriminative performance of age versus mFI-5.

RESULTS

A total of 1,789 spinal osteotomy patients (median age 62 years) were included in the analysis. Among the patients assessed, 38.5% (n = 689) were pre-frail, 14.6% frail (n = 262), and 2.2% (n = 39) severely frail using the mFI-5. Based on the multivariate analysis, increasing frailty tier was associated with worsening outcomes, and higher odds ratios (OR) for poor outcomes were found for increasing frailty tiers as compared to age. Severe frailty was associated with the worst outcomes, e.g., unplanned readmission (OR 9.618, [95% CI 4.054-22.818], p < 0.001) and major complications (OR 5.172, [95% CI 2.271-11.783], p < 0.001). In the ROC curve analysis, mFI-5 score (AUC 0.838) demonstrated superior discriminative performance than age (AUC 0.601) for mortality.

CONCLUSIONS

The mFI5 frailty score was found to be a better predictor than age of worse postoperative outcomes in ASD patients. Incorporating frailty in preoperative risk stratification is recommended in ASD surgery.

Surgery for Metastatic Spinal Disease in Octogenarians and Above: Analysis of 78 Patients

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVE

Octogenarians living with spinal metastases are a challenging population to treat. Our objective was to identify the rate, types, management, and predictors of complications and survival in octogenarians following surgery for spinal metastases.

METHODS

A retrospective review of a prospectively collected cohort of patients aged 80 years or older who underwent surgery for metastatic spinal tumor treatment between 2008 and 2019 were included. Demographic, intraoperative, complications, and postoperative follow-up data was collected. Cox proportional hazards regression and logistic regression were used to associate variables with overall survival and postoperative complications, respectively.

RESULTS

78 patients (mean 83.6 years) met inclusion criteria. Average operative time and blood loss were 157 minutes and 615 mL, respectively. The median length of stay was 7 days. The overall complication rate was 31% (N = 24), with 21% considered major and 7% considered life-threatening or fatal. Blood loss was significantly associated with postoperative complications (OR = 1.002; P = 0.02) and mortality (HR = 1.0007; P = 0.04). Significant associations of increased risk of death were also noted with surgeries with decompression, and cervical/cervicothoracic index level of disease. For deceased patients, median time to death was 4.5 months. For living patients, median follow-up was 14.5 months. The Kaplan-Meier based median overall survival for the cohort was 11.6 months (95% CI: 6.2-19.1).

CONCLUSIONS

In octogenarians undergoing surgery with instrumentation for spinal metastases, the median overall survival is 11.6 months. There is an increased complication rate, but only 7% are life-threatening or fatal. Patients are at increased risk for complications and mortality particularly when performing decompression with stabilization, with increasing intraoperative blood loss, and with cervical/cervicothoracic tumors.

A standardized postoperative bowel regimen protocol after spine surgery

Objectives

Spine surgery is associated with early impairment of gastrointestinal motility, with postoperative ileus rates of 5–12%. A standardized postoperative medication regimen aimed at early restoration of bowel function can reduce morbidity and cost, and its study should be prioritized.

Methods

A standardized postoperative bowel medication protocol was implemented for all elective spine surgeries performed by a single neurosurgeon from March 1, 2022 to June 30, 2022 at a metropolitan Veterans Affairs medical center. Daily bowel function was tracked and medications were advanced using the protocol. Clinical, surgical, and length of stay data are reported.

Results

Across 20 consecutive surgeries in 19 patients, mean age was 68.9 years [standard deviation (SD) = 10; range 40–84]. Seventy-four percent reported preoperative constipation. Surgeries consisted of 45% fusion and 55% decompression; lumbar retroperitoneal approaches constituted 30% (10% anterior, 20% lateral). Two patients were discharged in good condition prior to bowel movement after meeting institutional discharge criteria; the other 18 cases all had return of bowel function by postoperative day (POD) 3 (mean = 1.8-days, SD = 0.7). There were no inpatient or 30-day complications. Mean discharge occurred 3.3-days post-surgery (SD = 1.5; range 1–6; home 95%, skilled nursing facility 5%). Estimated cumulative cost of the bowel regimen was $17 on POD 3.

Conclusions

Careful monitoring of return of bowel function after elective spine surgery is important for preventing ileus, reducing healthcare cost, and ensuring quality. Our standardized postoperative bowel regimen was associated with return of bowel function within 3 days and low costs. These findings can be utilized in quality-of-care pathways.

Risk factors of early complications after thoracic and lumbar spinal deformity surgery: a systematic review and meta-analysis

PURPOSE

To determine risk factors increasing susceptibility to early complications (intraoperative and postoperative within 6 weeks) associated with surgery to correct thoracic and lumbar spinal deformity.

METHODS

We systematically searched the PubMed and EMBASE databases for studies published between January 1990 and September 2021. Observational studies evaluating predictors of early complications of thoracic and lumbar spinal deformity surgery were included. Pooled odds ratio (OR) or standardized mean difference (SMD) with 95% confidence intervals (CI) was calculated via the random effects model.

RESULTS

Fifty-two studies representing 102,432 patients met the inclusion criteria. Statistically significant patient-related risk factors for early complications included neurological comorbidity (OR = 3.45, 95% CI 1.83-6.50), non-ambulatory status (OR = 3.37, 95% CI 1.96-5.77), kidney disease (OR = 2.80, 95% CI 1.80-4.36), American Society of Anesthesiologists score > 2 (OR = 2.23, 95% CI 1.76-2.84), previous spine surgery (OR = 1.98, 95% CI 1.41-2.77), pulmonary comorbidity (OR = 1.94, 95% CI 1.21-3.09), osteoporosis (OR = 1.60, 95% CI 1.17-2.20), cardiovascular diseases (OR = 1.46, 95% CI 1.20-1.78), hypertension (OR = 1.37, 95% CI 1.23-1.52), diabetes mellitus (OR = 1.84, 95% CI 1.30-2.60), preoperative Cobb angle (SMD = 0.43, 95% CI 0.29, 0.57), number of comorbidities (SMD = 0.41, 95% CI 0.12, 0.70), and preoperative lumbar lordotic angle (SMD = - 0.20, 95% CI - 0.35, - 0.06). Statistically significant procedure-related factors were fusion extending to the sacrum or pelvis (OR = 2.53, 95% CI 1.53-4.16), use of osteotomy (OR = 1.60, 95% CI 1.12-2.29), longer operation duration (SMD = 0.72, 95% CI 0.05, 1.40), estimated blood loss (SMD = 0.46, 95% CI 0.07, 0.85), and number of levels fused (SMD = 0.37, 95% CI 0.03, 0.70).

CONCLUSION

These data may contribute to development of a systematic approach aimed at improving quality-of-life and reducing complications in high-risk patients.

Clinical Importance, Incidence and Risk Factors for the Development of Postoperative Ileus Following Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective observational study of a cohort of consecutive patients.

OBJECTIVES

Postoperative ileus (POI) is associated with a variety of adverse effects. Although the incidence of and risk factors for POI following spinal surgery have been reported, the frequency and pathology of POI after spinal corrective surgery for adult spinal deformity (ASD) are still largely unknown. The study objectives were to: (1) clarify the prevalence and clinical significance of POI, (2) elucidate the risk factors for POI, (3) determine radiographically which preoperative and/or postoperative spinal parameters predominantly influence the risk of POI after spinal corrective surgery for ASD.

METHODS

We included data from 144 consecutive patients who underwent spinal corrective surgery. Perioperative medical complications and clinical information were extracted from patient electronic medical records. Preoperative radiographic parameters and changes in radiographic parameters after surgery were compared between patients with and without POI. Multivariate logistic regression analyses were performed to clarify potential risk factors for POI.

RESULTS

POI developed in 25/144 (17.4%) patients and was the most common complication in the present study. The frequencies of smoking, gastroesophageal reflux disease, and lateral lumbar interbody fusion (LLIF), as well as the duration of surgery were significantly greater in the group with POI versus the group without POI. Among radiographic parameters, only the change in thoracolumbar kyphosis (TLK) from before to after surgery was significantly larger in the group with POI. Multivariate logistic regression analysis showed that male sex, LLIF and large changes in TLK from before to after surgery were significantly associated with the development of POI.

CONCLUSIONS

These results suggested that LLIF and large corrections in TLK were independent risk factors for POI after ASD surgery. When patients with ASD have large TLK preoperatively, and it is determined that a large correction is needed, physicians must be aware of the potential for occurrence of POI.

Artificial Intelligence in Adult Spinal Deformity

Artificial Intelligence is gaining traction in medicine for its ease of use and advancements in technology. This study evaluates the current literature on the use of artificial intelligence in adult spinal deformity.

Osteoporosis is associated with increased minor complications following single level ALIF and PSIF: an analysis of 7,004 patients

Background

Osteoporosis is a prevalent disease that predisposes patients to fracture and additional post-operative complications, potentially contributing to decreased quality of life. The objective of the current study is to (I) characterize the demographic trends of individuals with osteoporosis undergoing single level posterior spine instrumentation and fusion (PSIF) and anterior lumbar interbody fusion (ALIF); (II) determine the association between osteoporosis and postoperative complications; (III) identify whether the use of bone strengthening medications is associated with improved outcomes.

Methods

A retrospective review of the Mariner Claims Database was conducted on patients undergoing single level ALIF (CPT 22558) and PSIF (CPT 22840) between 2011 and 2017. Diagnosis of osteoporosis (CPT 77080, CPT 77801, CPT 77082) included a bone density scan within two years of surgery. Patients with osteoporosis were 1:1 matched to controls. Patients taking bone enhancing medications prior to surgery were compared to those that did not take medications. Multivariable logistic regression analyses were performed to evaluate post-operative complication risk factors.

Results

3,502 patients with diagnosed osteoporosis underwent ALIF and PSIF, of which 788 (22.5%) were treated with supplemental medication. Diagnosis of osteoporosis was associated with an increased risk of pulmonary embolism [1.1% vs. 0.4%, odds ratio (OR) 2.48, 95% confidence interval (CI): 1.36-4.53, P=0.003] and minor complications (16.7% vs. 12.9%, OR 1.15, 95% CI: 1.01-1.30, P=0.039). Revision rates two-years post-operatively were not significantly different between patients with osteoporosis and matched controls (P>0.05). There were no differences in outcomes between osteoporotic patients who received medications and those who did not receive medication (P>0.05).

Conclusions

Osteoporosis is common in a nationally-representative Medicare database cohort. Pre-operative diagnosis of osteoporosis is associated with increased minor complications following ALIF and PSIF. Pre-operative osteoporosis treatment is not associated with a significant difference in post-operative outcomes. The current study can guide pre-operative counseling in this cohort.

The minimally invasive interbody selection algorithm for spinal deformity

OBJECTIVE

Minimally invasive surgery (MIS) for spinal deformity uses interbody techniques for correction, indirect decompression, and arthrodesis. Selection criteria for choosing a particular interbody approach are lacking. The authors created the minimally invasive interbody selection algorithm (MIISA) to provide a framework for rational decision-making in MIS for deformity.

METHODS

A retrospective data set of circumferential MIS (cMIS) for adult spinal deformity (ASD) collected over a 5-year period was analyzed by level in the lumbar spine to identify surgeon preferences and evaluate segmental lordosis outcomes. These data were used to inform a Delphi session of minimally invasive deformity surgeons from which the algorithm was created. The algorithm leads to 1 of 4 interbody approaches: anterior lumbar interbody fusion (ALIF), anterior column release (ACR), lateral lumbar interbody fusion (LLIF), and transforaminal lumbar interbody fusion (TLIF). Preoperative and 2-year postoperative radiographic parameters and clinical outcomes were compared.

RESULTS

Eleven surgeons completed 100 cMISs for ASD with 338 interbody devices, with a minimum 2-year follow-up. The type of interbody approach used at each level from L1 to S1 was recorded. The MIISA was then created with substantial agreement. The surgeons generally preferred LLIF for L1-2 (91.7%), L2-3 (85.2%), and L3-4 (80.7%). ACR was most commonly performed at L3-4 (8.4%) and L2-3 (6.2%). At L4-5, LLIF (69.5%), TLIF (15.9%), and ALIF (9.8%) were most commonly utilized. TLIF and ALIF were the most selected approaches at L5-S1 (61.4% and 38.6%, respectively). Segmental lordosis at each level varied based on the approach, with greater increases reported using ALIF, especially at L4-5 (9.2°) and L5-S1 (5.3°). A substantial increase in lordosis was achieved with ACR at L2-3 (10.9°) and L3-4 (10.4°). Lateral interbody arthrodesis without the use of an ACR did not generally result in significant lordosis restoration. There were statistically significant improvements in lumbar lordosis (LL), pelvic incidence-LL mismatch, coronal Cobb angle, and Oswestry Disability Index at the 2-year follow-up.

CONCLUSIONS

The use of the MIISA provides consistent guidance for surgeons who plan to perform MIS for deformity. For L1-4, the surgeons preferred lateral approaches to TLIF and reserved ACR for patients who needed the greatest increase in segmental lordosis. For L4-5, the surgeons' order of preference was LLIF, TLIF, and ALIF, but TLIF failed to demonstrate any significant lordosis restoration. At L5-S1, the surgical team typically preferred an ALIF when segmental lordosis was desired and preferred a TLIF if preoperative segmental lordosis was adequate.

INDIRECT DECOMPRESSION BY LATERAL FUSION: ANALYSIS OF SAGITAL ALIGNMENT

ABSTRACT Objective: To verify the effectiveness of indirect decompression after lateral access fusion in patients with high pelvic incidence. Methods: A retrospective, non-comparative, non-randomized analysis of 22 patients with high pelvic incidence who underwent lateral access fusion, 11 of whom were male and 11 female, with a mean age of 63 years (52-74), was conducted. Magnetic resonance exams were performed within one year after surgery. The cross-sectional area of the thecal sac, anterior and posterior disc heights, and bilateral foramen heights, measured pre- and postoperatively in axial and sagittal magnetic resonance images, were analyzed. The sagittal alignment parameters were measured using simple radiographs. The clinical results were evaluated using the ODI and VAS (back and lower limbs) questionnaires. Results: In all cases, the technique was performed successfully without neural complications. The mean cross-sectional area increased from 126.5 mm preoperatively to 174.3 mm postoperatively. The mean anterior disc height increased from 9.4 mm preoperatively to 12.8 mm postoperatively, while the posterior disc height increased from 6.3 mm preoperatively to 8.1 mm postoperatively. The mean height of the right foramen increased from 157.3 mm in the preoperative period to 171.2 mm in the postoperative period and that of the left foramen increased from 139.3 mm in the preoperative to 158.9 mm in the postoperative. Conclusions: This technique is capable of correcting misalignment in spinal deformity, achieving fusion and promoting the decompression of neural elements. Level of evidence III; Retrospective study.

Long-length tomosynthesis and 3D-2D registration for intraoperative assessment of spine instrumentation

PURPOSE

A system for long-length intraoperative imaging is reported based on longitudinal motion of an O-arm gantry featuring a multi-slot collimator. We assess the utility of long-length tomosynthesis and the geometric accuracy of 3D image registration for surgical guidance and evaluation of long spinal constructs.

METHODS

A multi-slot collimator with tilted apertures was integrated into an O-arm system for long-length imaging. The multi-slot projective geometry leads to slight view disparity in both long-length projection images (referred to as 'line scans') and tomosynthesis 'slot reconstructions' produced using a weighted-backprojection method. The radiation dose for long-length imaging was measured, and the utility of long-length, intraoperative tomosynthesis was evaluated in phantom and cadaver studies. Leveraging the depth resolution provided by parallax views, an algorithm for 3D-2D registration of the patient and surgical devices was adapted for registration with line scans and slot reconstructions. Registration performance using single-plane or dual-plane long-length images was evaluated and compared to registration accuracy achieved using standard dual-plane radiographs.

RESULTS

Longitudinal coverage of ∼50-64 cm was achieved with a single long-length slot scan, providing a field-of-view (FOV) up to (40 × 64) cm², depending on patient positioning. The dose-area product (reference point air kerma × x-ray field area) for a slot scan ranged from ∼702-1757 mGy·cm², equivalent to ∼2.5 s of fluoroscopy and comparable to other long-length imaging systems. Long-length scanning produced high-resolution tomosynthesis reconstructions, covering ∼12-16 vertebral levels. 3D image registration using dual-plane slot reconstructions achieved median target registration error (TRE) of 1.2 mm and 0.6° in cadaver studies, outperforming registration to dual-plane line scans (TRE = 2.8 mm and 2.2°) and radiographs (TRE = 2.5 mm and 1.1°). 3D registration using single-plane slot reconstructions leveraged the ∼7-14° angular separation between slots to achieve median TRE ∼2 mm and <2° from a single scan.

CONCLUSION

The multi-slot configuration provided intraoperative visualization of long spine segments, facilitating target localization, assessment of global spinal alignment, and evaluation of long surgical constructs. 3D-2D registration to long-length tomosynthesis reconstructions yielded a promising means of guidance and verification with accuracy exceeding that of 3D-2D registration to conventional radiographs.

Comparison of Effectiveness between Cobalt Chromium Rods versus Titanium Rods for Treatment of Patients with Spinal Deformity: A Systematic Review and Meta-Analysis

Background

Biomechanical properties of rods determine their ability to correct spinal deformity and prevention of postoperative sagittal and coronal changes. The selection of a proper rod material is crucial due to their specific mechanical properties that influence the surgical outcome. The purpose of this study is to compare the effectiveness of cobalt chromium rods versus titanium rods for the treatment of spinal deformity by a systematic review and meta-analysis.

Methods

PubMed, EMBASE, and the Cochrane library were searched for observational and biomechanical studies comparing cobalt chromium and titanium rods in terms of correction rate, thoracic kyphosis, lumbar lordosis, incidence of rod fracture, fatigue life of contoured rod, bending stiffness of rods, and occurrence of proximal junctional kyphosis. The demographic data and mean values of outcomes of interest were extracted from each group and compared by their mean difference as an overall outcome measure. The Review Manager software (RevMan 5.3) was utilized at a 95% significance level.

Results

Eleven eligible studies with 641 participants for 7 observational studies and 35 samples for 4 biomechanical studies were identified. There were no significant differences between cobalt chromium and titanium rods in the correction rate of spinal deformity. Postoperative thoracic kyphosis was well restored in the cobalt chromium group with statistical significance (p value = 0.009). The incidence of rod fracture was high in titanium rods compared to cobalt chromium rods with significant difference (p value = 0.0001). Proximal junctional kyphosis occurs more in the cobalt chromium group with a significant difference (p value = 0.0009). No statistical significance between two materials in terms of lumbar lordosis, fatigue of life, and bending stiffness of rods.

Conclusion

The cobalt chromium rod is better than titanium rod for effective correction of spinal deformity and postoperative stability of the spine. However, the use of cobalt chromium rods is associated with increased risk of proximal junctional kyphosis.