Rapid Tumor DNA Analysis of Cerebrospinal Fluid Accelerates Treatment of Central Nervous System Lymphoma.

Delays and risks associated with neurosurgical biopsies preclude timely diagnosis and treatment of central nervous system (CNS) lymphoma and other CNS neoplasms. We prospectively integrated targeted rapid genotyping of cerebrospinal fluid (CSF) into the evaluation of 70 patients with CNS lesions of unknown etiology. Participants underwent genotyping of CSF-derived DNA using a qPCR-based approach for parallel detection of single-nucleotide variants in the MYD88, TERT promoter, IDH1, IDH2, BRAF and H3F3A genes within 80 minutes of sample acquisition. Canonical mutations were detected in 42% of patients with neoplasms, including cases of primary and secondary CNS lymphoma, glioblastoma, IDH-mutant brainstem glioma and H3K27M-mutant diffuse midline glioma. Genotyping results eliminated the need for surgical biopsies in 7/33 (21.2%) cases of newly diagnosed neoplasms, resulting in significantly accelerated initiation of disease-directed treatment (median 3 vs 12 days; p = 0.027). This assay was then implemented in a Clinical Laboratory Improvement Amendments (CLIA) environment, with 2-day median turnaround for diagnosis of central nervous system lymphoma from 66 patients across 4 clinical sites. Our study prospectively demonstrates that targeted rapid CSF genotyping influences oncologic management for suspected CNS tumors.

Pedicled omental flaps for complex wound reconstruction following surgery for primary spine tumors of the mobile spine and sacrum.

OBJECTIVE: Surgery for primary tumors of the mobile spine and sacrum often requires complex reconstruction techniques to cover soft-tissue defects and to treat wound and CSF-related complications. The anatomical, vascular, and immunoregulatory characteristics of the omentum make it an excellent local substrate for the management of radiation soft-tissue injury, infection, and extensive wound defects. This study describes the authors' experience in complex wound reconstruction using pedicled omental flaps to cover defects in surgery for mobile spine and sacral primary tumors. METHODS: A retrospective cohort analysis was conducted on 34 patients who underwent pedicled omental flap reconstruction after en bloc resection of primary sacral and mobile spine tumors between 2010 and 2020. The study focused on assessing the indications for omental flap usage, including soft-tissue coverage, protection against postoperative radiation therapy, infection management, vascular supply for bone grafts, and dural defect and CSF leak repair. Patient demographic characteristics, tumor characteristics, surgical outcomes, and follow-up data were analyzed to determine the procedure's efficacy and complication rates. RESULTS: From 2010 to 2020, 34 patients underwent pedicled omental flap reconstruction after en bloc resection of sacral (24 of 34 [71%]) and mobile spine (10 of 34 [29%]) primary tumors, mostly chordomas. The patient cohort included 21 men and 13 women with a median (range) age of 60 (32-89) years. The most common indication for omental flap was soft-tissue coverage (20 of 34 [59%]). Other indications included protecting abdominopelvic organs for postoperative radiation therapy (6 of 34 [18%]), treating infections (5 of 34 [15%]), providing vascular supply for free fibular bone graft (1 of 34 [3%]), and repairing large dural defects and CSF leak (2 of 34 [6%]). The median (range) follow-up was 24 (0-132) months, during which 71% (24 of 34) of patients did not require additional surgery for wound-related complications. At last follow-up, 59% (20 of 34) had stable disease and 32% (11 of 34) had recurrence, had progression of disease, or had been discharged to hospice after treatment. CONCLUSIONS: The pedicled omentum is an effective local tissue graft that can be used for complex wound reconstruction and management of high-risk closures in primary spine tumors. This technique may have a lower rate of complications than other approaches and may influence surgical planning and flap selection in challenging cases.

Radical surgical resection with molecular margins is associated with improved survival in IDH wildtype GBM.

BACKGROUND: Survival is variable in patients with glioblastoma IDH wild-type (GBM), even after comparable surgical resection of radiographically-detectable disease, highlighting the limitations of radiographic assessment of infiltrative tumor anatomy. The majority of post-surgical progressive events are failures within 2cm of the resection margin, motivating supramaximal resection strategies to improve local control. However, which patients benefit from such radical resections remains unknown. METHODS: We developed a predictive model to identify which IDH wild-type GBM are amenable to radiographic gross total resection (GTR). We then investigated whether GBM survival heterogeneity following GTR is correlated with microscopic tumor burden a by analyzing tumor cell content at the surgical margin with a rapid qPCR-based method for detection of TERT promoter mutation. RESULTS: Our predictive model for achievable GTR, developed on retrospective radiographic and molecular data of GBM patients undergoing resection, had an AUC of 0.83, sensitivity of 62%, and specificity of 90%. Prospective analysis of this model in 44 patients found 89% of patients were correctly predicted to achieve a RV<4.9cc. Of the 44 prospective patients undergoing rapid qPCR TERT promoter mutation analysis at the surgical margin, 7 had undetectable TERT mutation, of which 5 also had a gross total resection (RV<1cc). In these 5 patients at 30 months follow up, 75% showed no progression, compared to 0% in the group with TERT mutations detected at the surgical margin (p=0.02). CONCLUSIONS: These findings identify a subset of patients with GBM that may derive local control benefit from radical resection to undetectable molecular margins.

Imaging of Adult Malignant Soft Tissue Tumors of the Spinal Canal: A Guide for Spine Surgeons.

BACKGROUND: Malignant soft tissue spinal canal tumors compromise 20% of all spinal neoplasms. They may be primary or metastatic lesions, originating from a diverse range of tissues within and surrounding the spinal canal. These masses can present as diverse emergencies such as secondary cauda equina syndrome, vascular compromise, or syringomyelia. Interpretation of malignant soft tissue spinal canal tumors imaging is an essential for non-radiologists in the setting of emergencies. This task is intricate due to a great radiologic pattern overlap among entities. METHODS: We present a step-by-step strategy that can guide nonradiologists identify a likely malignant soft tissue lesion in the spinal canal based on imaging features, as well as a review of the radiologic features of malignant soft tissue spinal canal tumors. RESULTS: Diagnosis of soft tissue spinal canal malignancies starts with the identification of the lesion's spinal level and its relationship to the dura and medulla. The second step consists of characterizing it as likely-malignant based on radiological signs like a larger size, ill-defined margins, central necrosis, and/or increased vascularity. The third step is to identify additional imaging features such as intratumoral hemorrhage or cyst formation that can suggest specific malignancies. The physician can then formulate a differential diagnosis. The most encountered malignant soft tissue tumors of the spinal canal are anaplastic ependymomas, anaplastic astrocytomas, metastatic tumors, lymphoma, peripheral nerve sheath tumors, and central nervous system melanomas. A review of the imaging features of every type/subtype of lesion is presented in this work. Although magnetic resonance imaging remains the modality of choice for spinal tumor assessment, other techniques such as dynamic contrast agent-enhanced perfusion magnetic resonance imaging or diffusion-weighted imaging could guide diagnosis in specific situations. CONCLUSIONS: In this review, diagnostic strategies for several spinal cord tumors were presented, including anaplastic ependymoma, metastatic spinal cord tumors, anaplastic and malignant astrocytoma, lymphoma, malignant peripheral nerve sheath tumors , and primary central nervous system melanoma. Although the characterization of spinal cord tumors can be challenging, comprehensive knowledge of imaging features can help overcome these challenges and ensure optimal management of spinal canal lesions.

The Impact of Preoperative Spinal Injection Timing on Postoperative Complications of Lumbar Decompression Surgery.

BACKGROUND AND OBJECTIVES: Epidural steroid injections (ESIs) are commonly used for lower back pain management. The effect of these injections on lumbar decompression surgery outcomes is hitherto underexplored. The study objective was to determine the impact of ESIs on postoperative rates of medical and surgical complications and to define the appropriate interval before lumbar decompression surgery. METHODS: This retrospective all-payer database analysis identified 587 651 adult patients undergoing one- to three-level laminectomies from January 2010 to October 2021. A 2:1 propensity score match accounting for comorbidities, levels of surgery, and demographics was performed to create two cohorts: (1) 43 674 patients who had received an ESI in the 90 days before laminectomy and (2) 87 348 patients who had not received an ESI. The primary outcome was the rates of medical and surgical complications between groups at 30 days postoperatively. Patients were divided into five cohorts based on injection time before surgery: 1 to 30 days, 31 to 45 days, 46 to 60 days, 61 to 75 days, and 76 to 90 days. Logistic regression was performed between groups to identify temporal associations of complication rates. Confidence intervals of 95% are provided when appropriate. P values < .01 were considered significant. RESULTS: Rates of medical complications within 30 days of surgery were significantly higher in those with ESI compared with control (4.83% vs 3.9%, P < .001). Cerebrospinal fluid (CSF) leak rates were increased in the ESI group at 0.28% vs 0.1% (P < .001), but surgical site infection rates were not significantly different between groups (1.31% vs 1.42% P = .11). ESI performed within 30 days was associated with increased odds of CSF leak (OR: 5.32, 95% CI: 3.96-7.15). CONCLUSION: Preoperative ESI increases the risk of CSF leak and medical complications after lumbar decompression. Because these complications were significantly associated with ESIs given 1 to 30 days before surgery, avoiding ESIs at least 30 days before surgery may be advisable.

A guide to finite element analysis models of the spine for clinicians.

Finite element analysis (FEA) is a computer-based mathematical method commonly used in spine and orthopedic biomechanical research. Advances in computational power and engineering modeling and analysis software have enabled many recent technical applications of FEA. Through the use of FEA, a wide range of scenarios can be simulated, such as physiological processes, mechanisms of disease and injury, and the efficacy of surgical procedures. Such models have the potential to enhance clinical studies by allowing comparisons of surgical treatments that would be impractical to perform in human or animal studies, and by linking model results to treatment outcomes. While traditional ex vivo experiments are limited by variabilities in tissue, the complexity of test setup, cost, measurable biomechanical parameters, and the repeatability of experiments, FEA models can be used to measure a wide range of clinically relevant biomechanical parameters. Generic or patient-specific anatomical models can be modified to simulate different clinical and surgical conditions under simulated physiological conditions. Despite these capabilities, there is limited understanding of the clinical applicability and translational potential of FEA models. For spine surgeons, a comprehensive understanding of the key features, strengths, and limitations of FEA models of the spine and their ability to personalize treatment options and assist in clinical decision-making would significantly enhance the impact of FEA research. Furthermore, fostering collaborations between surgeons and engineers could augment the clinical use of these models. The purpose of this review was to highlight key features of FEA model building for clinicians. To illustrate these features, the authors present an example of the use of FEA models in comparing FDA-approved disc arthroplasty implants.

Machine learning-based detection of sarcopenic obesity and association with adverse outcomes in patients undergoing surgical treatment for spinal metastases.

OBJECTIVE: The distributions and proportions of lean and fat tissues may help better assess the prognosis and outcomes of patients with spinal metastases. Specifically, in obese patients, sarcopenia may be easily overlooked as a poor prognostic indicator. The role of this body phenotype, sarcopenic obesity (SO), has not been adequately studied among patients undergoing surgical treatment for spinal metastases. To this end, here the authors investigated the role of SO as a potential prognostic factor in patients undergoing surgical treatment for spinal metastases. METHODS: The authors identified patients who underwent surgical treatment for spinal metastases between 2010 and 2020. A validated deep learning approach evaluated sarcopenia and adiposity on routine preoperative CT images. Based on composition analyses, patients were classified with SO or nonsarcopenic obesity. After nearest-neighbor propensity matching that accounted for confounders, the authors compared the rates and odds of postoperative complications, length of stay, 30-day readmission, and all-cause mortality at 90 days and 1 year between the SO and nonsarcopenic obesity groups. RESULTS: A total of 62 patients with obesity underwent surgical treatment for spinal metastases during the study period. Of these, 37 patients had nonsarcopenic obesity and 25 had SO. After propensity matching, 50 records were evaluated that were equally composed of patients with nonsarcopenic obesity and SO (25 patients each). Patients with SO were noted to have increased odds of nonhome discharge (OR 6.0, 95% CI 1.69-21.26), 30-day readmission (OR 3.27, 95% CI 1.01-10.62), and 90-day (OR 4.85, 95% CI 1.29-18.26) and 1-year (OR 3.78, 95% CI 1.17-12.19) mortality, as well as increased time to mortality after surgery (12.60 ± 19.84 months vs 37.16 ± 35.19 months, p = 0.002; standardized mean difference 0.86). No significant differences were noted in terms of length of stay or postoperative complications when comparing the two groups (p > 0.05). CONCLUSIONS: The SO phenotype was associated with increased odds of nonhome discharge, readmission, and postoperative mortality. This study suggests that SO may be an important prognostic factor to consider when developing care plans for patients with spinal metastases.

Outcomes Following 2-Level Cervical Interventions with Cage-and-Plate, Zero-Profile, or Arthroplasty Constructs.

BACKGROUND: Though cage-and-plate constructs are widely used for disk height restoration in surgery for cervical disc disease, concerns over range of motion limitations and adjacent disc space violations have fueled the development of artificial disc and zero-profile constructs. This study investigated the outcomes of patients undergoing two-level cervical interventions via arthroplasty, cage-and-plate, or zero-profile constructs. METHODS: Patients undergoing two-level anterior cervical procedures between 2010 and 2020 were identified using an all-payer claims database. Logistic regression models were utilized to develop criteria for a 1:1:1-exact match procedure. The primary outcome was the need for additional surgery within 30 months, and the secondary outcomes included medical and surgical complications observed within 30 days of index intervention. P values < 0.05 were considered statistically significant. RESULTS: 133,831 patients were identified as undergoing two-level anterior cervical interventions. Seven thousand three hundred seventy-one records were analyzed through a 1:1:1 match. Patients who received zero-profile versus cage-and-plate constructs had significantly decreased odds of requiring additional surgery within 30 months (Odds Ratio [OR] 0.64; 95% Confidence Interval [CI] 0.51-0.81). However, postoperative medical complications were increased among patients who received zero-profile constructs compared to cage-and-plate (OR 1.59; 95%CI 1.07-2.37). Patients who underwent arthroplasty also had decreased odds for additional surgery versus cage-and-plate (OR 0.75; 95%CI 0.60-0.93). There was no significant difference between arthroplasty and cage-and-plate constructs in developing postoperative surgical or medical complications. CONCLUSIONS: Among patients undergoing two-level interventions, cage-and-plate constructs were associated with increased odds of additional surgery within 30 months following index procedures when compared to zero-profile constructs or arthroplasty.

Implication of nutritional status for adverse outcomes after surgery for metastatic spine tumors.

OBJECTIVE: Surgery for metastatic spinal tumors can have a substantial impact on patients' quality of life by alleviating pain, improving function, and correcting spinal instability when indicated. The decision to operate is difficult because many patients with cancer are frail. Studies have highlighted the importance of preoperative nutritional status assessments; however, little is known about which aspects of nutrition accurately inform clinical outcomes. This study investigates the interaction and prognostic importance of various nutritional and frailty measures in patients with spinal metastases. METHODS: A retrospective analysis of consecutive patients who underwent surgery for spinal metastases between 2014 and 2020 at the Massachusetts General Hospital was performed. Patients were stratified according to the New England Spinal Metastasis Score (NESMS). Frailty was assessed using the metastatic spinal tumor frailty index. Nutrition was assessed using the prognostic nutritional index (PNI), preoperative body mass index, albumin, albumin-to-globulin ratio, and platelet-to-lymphocyte ratio. Outcomes included postoperative survival and complication rates, with focus on wound-related complications. RESULTS: This study included 154 individuals (39% female; mean [SD] age 63.23 [13.14] years). NESMS 0 and NESMS 3 demonstrated the highest proportions of severely frail patients (56.2%) and nonfrail patients (16.1%), respectively. Patients with normal nutritional status (albumin-to-globulin ratio and PNI) had a better prognosis than those with poor nutritional status when stratified by NESMS. Multivariable regression adjusted for NESMS and frailty showed that a PNI > 40.4 was significantly associated with decreased odds of 90-day complications (OR 0.93, 95% CI 0.85-0.98). After accounting for age, sex, primary tumor pathology, physical function, nutritional status, and frailty, a preoperative nutrition consultation was associated with a decrease in postoperative wound-related complications (average marginal effect -5.00%; 95% CI -1.50% to -8.9%). CONCLUSIONS: The PNI was most predictive of complications and may be a key biomarker for risk stratification in the 90 days following surgery. Nutrition consultation was associated with a reduced risk of wound-related complications, attesting to the importance of this preoperative intervention. These findings suggest that nutrition plays an important role in the postsurgical course and should be considered when developing a treatment plan for spinal metastases.

Anorectal Manifestations of Treatment-Refractory Monkeypox Requiring Surgical Intervention.

Anorectal manifestations of monkeypox are increasingly being recognized as a potentially serious complication. We present the case of an HIV-positive, tecovirimat-treated male presenting with monkeypox virus-associated severe proctitis with associated perianal pathology. Despite the use of antiviral agents and intravenous vaccinia immune globulin, the monkeypox-associated perianal lesions evolved into abscesses, requiring incision and drainage. This report highlights a multidisciplinary approach involving surgery for anorectal complications of monkeypox virus-associated proctitis and perianal lesions. Surgery may offer immediate relief and reduce the potential long-term morbidity associated with severe monkeypox virus-associated rectal and perianal manifestations refractory to available medical countermeasures.

Resisting subsidence with a truss Implant: Application of the "Snowshoe" principle for interbody fusion devices.

The primary objective was to compare the subsidence resistance properties of a novel 3D-printed spinal interbody titanium implant versus a predicate polymeric annular cage. We evaluated a 3D-printed spinal interbody fusion device that employs truss-based bio-architectural features to apply the snowshoe principle of line length contact to provide efficient load distribution across the implant/endplate interface as means of resisting implant subsidence. Devices were tested mechanically using synthetic bone blocks of differing densities (osteoporotic to normal) to determine the corresponding resistance to subsidence under compressive load. Statistical analyses were performed to compare the subsidence loads and evaluate the effect of cage length on subsidence resistance. The truss implant demonstrated a marked rectilinear increase in resistance to subsidence associated with increase in the line length contact interface that corresponds with implant length irrespective of subsidence rate or bone density. In blocks simulating osteoporotic bone, comparing the shortest with the longest length truss cage (40 vs. 60 mm), the average compressive load necessary to induce subsidence of the implant increased by 46.4% (383.2 to 561.0 N) and 49.3% (567.4 to 847.2 N) for 1 and 2 mm of subsidence, respectively. In contrast, for annular cages, there was only a modest increase in compressive load when comparing the shortest with the longest length cage at a 1 mm subsidence rate. The Snowshoe truss cages demonstrated substantially more resistance to subsidence than corresponding annular cages. Clinical studies are required to support the biomechanical findings in this work.

Can We Use Artificial Intelligence Cluster Analysis to Identify Patients with Metastatic Breast Cancer to the Spine at Highest Risk of Postoperative Adverse Events?

OBJECTIVE: Group patients who required open surgery for metastatic breast cancer to the spine by functional level and metastatic disease characteristics to identify factors that predispose to poor outcomes. METHODS: A retrospective analysis included patients managed at 2 tertiary referral centers from 2008 to 2020. The primary outcome was a 90-day adverse event. A 2-step unsupervised cluster analysis stratified patients into cohorts using function at presentation, preoperative spine radiation, structural instability, epidural spinal cord compression (ESCC), neural deficits, and tumor location/hormone status. Comparisons were performed using χ2 test and one-way analysis of variance. RESULTS: Five patient "clusters" were identified. High function (HIGH) had thoracic metastases and an Eastern Cooperative Oncology Group (ECOG) score of 1.0 ± 0.8. Low function/irradiated (LOW + RADS) had preoperative radiation and the lowest Karnofsky scores (56.0 ± 10.6). Estrogen receptor or progesterone receptor (ER/PR) positive patients had >90% estrogen/progesterone positivity and moderate Karnofsky scores (74.0 ± 11.5). Lumbar/noncompressive (NON-COMP) had the fewest patients with ESCC grade 2 or 3 epidural disease (42.1%, P < 0.001). Low function/neurologic deficits (LOW + NEURO) had ESCC grade 2 or 3 disease and neurologic deficits. Adverse event rates were 25.0% in the HIGH group, 73.3% in LOW + RADS, 24.0% in ER/PR, 31.6% in NON-COMP, and 60.0% in LOW + NEURO (P = 0.003). CONCLUSIONS: Function at presentation, tumor hormone signature, radiation history, and epidural compression delineated postoperative trajectory. We believe our results can aid in expectation management and the identification of at-risk patients who may merit closer surveillance following surgical intervention.

Assessment of Spinal Metastases Surgery Risk Stratification Tools in Breast Cancer by Molecular Subtype.

BACKGROUND: Breast cancer molecular features and modern therapies are not included in spine metastasis prediction algorithms. OBJECTIVE: To examine molecular differences and the impact of postoperative systemic therapy to improve prognosis prediction for spinal metastases surgery and aid surgical decision making. METHODS: This is a retrospective multi-institutional study of patients who underwent spine surgery for symptomatic breast cancer spine metastases from 2008 to 2021 at the Massachusetts General Hospital and Brigham and Women's Hospital. We studied overall survival, stratified by breast cancer molecular subtype, and calculated hazard ratios (HRs) adjusting for demographics, tumor characteristics, treatments, and laboratory values. We tested the performance of established models (Tokuhashi, Bauer, Skeletal Oncology Research Group, New England Spinal Metastases Score) to predict and compare all-cause. RESULTS: A total of 98 patients surgically treated for breast cancer spine metastases were identified (100% female sex; median age, 56 years [IQR, 36-84 years]). The 1-year probabilities of survival for hormone receptor positive, hormone receptor positive/human epidermal growth factor receptor 2+, human epidermal growth factor receptor 2+, and triple-negative breast cancer were 63% (45 of 71), 83% (10 of 12), 0% (0 of 3), and 12% (1 of 8), respectively ( P < .001). Patients with triple-negative breast cancer had a higher proportion of visceral metastases, brain metastases, and poor physical activity at baseline. Postoperative chemotherapy and endocrine therapy were associated with prolonged survival. The Skeletal Oncology Research Group prognostic model had the highest discrimination (area under the receiver operating characteristic, 0.77 [95% CI, 0.73-0.81]). The performance of all prognostic scores improved when preoperative molecular data and postoperative systemic treatment plans was considered. CONCLUSION: Spine metastases risk tools were able to predict prognosis at a significantly higher degree after accounting for molecular features which guide treatment response.

Effects of rod diameter on kinematics of posterior cervical spine instrumented constructs: an ex vivo study.

OBJECTIVE: Posterior cervical spine fixation is a robust strategy for stabilizing the spine for a wide range of spinal disorders. With the evolution of spinal implant technology, posterior fixation with lateral mass screws in the subaxial spine is now common. Despite interest in variable rod diameters to meet a wide range of clinical needs such as trauma, revision, and deformity surgery, indications for use of posterior cervical spine fixation are not clear. This laboratory investigation evaluates the mechanical stability and kinematic properties of lateral mass fixation with various commercially available rod diameters. METHODS: The authors conducted an ex vivo experiment using 13 fresh-frozen human cervical spine specimens, instrumented from C3 to C6 with lateral mass screws, to evaluate the effects of titanium rod diameter on kinematic stability. Each intact spine was tested using a kinematic profiling machine with an optoelectrical camera and infrared sensors applying 1.5-Nm bending moments to the cranial vertebra (C2) simulating flexion-extension, lateral bending, and axial rotation anatomical motions. A compressive follower preload of 150 N was applied in flexion-extension prior to application of a bending moment. Instrumented spines were then tested with rod diameters of 3.5, 4.0, and 4.5 mm. The kinematic data between intact and surgical cases were studied using a nonparametric Wilcoxon signed-rank test. A multivariable, multilevel linear regression model was built to identify the relationship between segmental motion and rod diameter. RESULTS: Instrumentation resulted in significant reduction in range of motion in all three rod constructs versus intact specimens in flexion-extension, lateral bending, and axial rotation (p < 0.05). The maximum reductions in segmental ROM versus intact spines in 3.5-, 4.0-, and 4.5-mm rod constructs were 61%, 71%, and 81% in flexion-extension; 70%, 76%, and 81% in lateral bending; and 50%, 60%, and 75% in axial rotation, respectively. Segmental motion at the adjacent segments (C2-3 and C6-7) increased significantly (p < 0.05) with increasing rod diameter. The 4.5-mm rod construct had the greatest increase in motion compared to the intact spine. CONCLUSIONS: With increasing rod diameters from 3.5 to 4.0 mm, flexion-extension, lateral bending, and axial rotation across C3-6 were significantly reduced (p < 0.05). Similar trends were observed with a statistically significant reduction in motion in all anatomical planes when the rod diameter was increased to 4.5 mm. Although the increase in rod diameter resulted in a more rigid construct, it also created an increase (p < 0.05) in the kinematics of the adjacent segments (C2-3 and C6-7). Whether this increase translates into adverse long-term clinical effects in vivo requires further investigation and clinical assessment.

Machine Learning Applications of Surgical Imaging for the Diagnosis and Treatment of Spine Disorders: Current State of the Art.

Recent developments in machine learning (ML) methods demonstrate unparalleled potential for application in the spine. The ability for ML to provide diagnostic faculty, produce novel insights from existing capabilities, and augment or accelerate elements of surgical planning and decision making at levels equivalent or superior to humans will tremendously benefit spine surgeons and patients alike. In this review, we aim to provide a clinically relevant outline of ML-based technology in the contexts of spinal deformity, degeneration, and trauma, as well as an overview of commercial-level and precommercial-level surgical assist systems and decisional support tools. Furthermore, we briefly discuss potential applications of generative networks before highlighting some of the limitations of ML applications. We conclude that ML in spine imaging represents a significant addition to the neurosurgeon's armamentarium-it has the capacity to directly address and manifest clinical needs and improve diagnostic and procedural quality and safety-but is yet subject to challenges that must be addressed before widespread implementation.

Evaluating frailty, mortality, and complications associated with metastatic spine tumor surgery using machine learning-derived body composition analysis.

OBJECTIVE: Cancer patients with spinal metastases may undergo surgery without clear assessments of prognosis, thereby impacting the optimal palliative strategy. Because the morbidity of surgery may adversely impact recovery and initiation of adjuvant therapies, evaluation of risk factors associated with mortality risk and complications is critical. Evaluation of body composition of cancer patients as a surrogate for frailty is an emerging area of study for improving preoperative risk stratification. METHODS: To examine the associations of muscle characteristics and adiposity with postoperative complications, length of stay, and mortality in patients with spinal metastases, the authors designed an observational study of 484 cancer patients who received surgical treatment for spinal metastases between 2010 and 2019. Sarcopenia, muscle radiodensity, visceral adiposity, and subcutaneous adiposity were assessed on routinely available 3-month preoperative CT images by using a validated deep learning methodology. The authors used k-means clustering analysis to identify patients with similar body composition characteristics. Regression models were used to examine the associations of sarcopenia, frailty, and clusters with the outcomes of interest. RESULTS: Of 484 patients enrolled, 303 had evaluable CT data on muscle and adiposity (mean age 62.00 ± 11.91 years; 57.8% male). The authors identified 2 clusters with significantly different body composition characteristics and mortality risks after spine metastases surgery. Patients in cluster 2 (high-risk cluster) had lower muscle mass index (mean ± SD 41.16 ± 7.99 vs 50.13 ± 10.45 cm2/m2), lower subcutaneous fat area (147.62 ± 57.80 vs 289.83 ± 109.31 cm2), lower visceral fat area (82.28 ± 48.96 vs 239.26 ± 98.40 cm2), higher muscle radiodensity (35.67 ± 9.94 vs 31.13 ± 9.07 Hounsfield units [HU]), and significantly higher risk of 1-year mortality (adjusted HR 1.45, 95% CI 1.05-2.01, p = 0.02) than individuals in cluster 1 (low-risk cluster). Decreased muscle mass, muscle radiodensity, and adiposity were not associated with a higher rate of complications after surgery. Prolonged length of stay (> 7 days) was associated with low muscle radiodensity (mean 30.87 vs 35.23 HU, 95% CI 1.98-6.73, p < 0.001). CONCLUSIONS: Body composition analysis shows promise for better risk stratification of patients with spinal metastases under consideration for surgery. Those with lower muscle mass and subcutaneous and visceral adiposity are at greater risk for inferior outcomes.