Katsos, Konstantinos

BACKGROUND AND OBJECTIVES: Minimum clinically important differences (MCIDs) for patient-reported outcome metrics (PROMs) in patients with cervical spondylotic myelopathy (CSM) lack consensus on the most appropriate calculation method. This retrospective study aimed to identify the optimal MCIDs for commonly used PROMs in CSM. METHODS: The CSM database from the Quality Outcomes Database SpineCORe Study Group was analyzed. Baseline, 3-month, and 24-month PROM values for Neck Disability Index (NDI), 5-dimension Euro-quality of life (EQ-5D) in quality-adjusted life years, modified Japanese Orthopaedic Association (mJOA) score, and neck/arm pain numeric rating scale (NRS) were collected. MCIDs were calculated for each PROM using previously validated techniques. MCID values were compared using the area under the curve (AUC) with the North American Spine Society satisfaction scale as an anchor. RESULTS: A total of 1141 patients with CSM undergoing surgery were included in this analysis. Improvement of ≥30% from baseline was the optimal MCID for NDI and neck/arm NRS. At 24 months, the optimal percentage cutoff MCID for these instruments resulted in AUCs of 0.76, 0.72, and 0.67, similar to the 30% improvement method, with AUCs of 0.73, 0.71, and 0.67, respectively. Numeric cutoffs (0.065 at 3 months; 0.149 at 24 months) were the superior MCIDs for EQ-5D. For mJOA score, a severity-adjusted MCID outperformed other methods, yielding an AUC of 0.67 at 24 months. MCIDs were achieved in 63% of patients for NDI, 59% for neck pain NRS, 61% for arm pain NRS, 52% for EQ-5D, and 59% for mJOA score at 24 months. CONCLUSION: Using the Quality Outcomes Database SpineCORe data set, we defined optimal MCIDs for key PROMs in CSM. A ≥30% improvement from baseline was optimal in NDI and arm/neck NRS. An absolute numeric cutoff was superior for EQ-5D (0.149 at the 24-month follow-up). A severity-adjusted MCID performed best for mJOA score. These redefined benchmarks better capture the treatment impact and guide care decisions for patients with CSM.

OBJECTIVE Isthmic spondylolisthesis impacts up to 11.5% of the general population. For patients who have failed conservative therapy, decompression and fusion or decompression alone are options for surgical management. However, there remains debate as to whether reduction of mobile spondylolisthesis is integral to good patient outcomes. The present systematic review and meta-analysis aimed to address this by comparing clinical and radiological outcomes between patients treated with fusion in situ and those undergoing fusion with reduction of isthmic spondylolisthesis. METHODS The Scopus, EMBASE, Medline, and Cochrane databases were systematically queried on the basis of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify studies comparing treatment outcomes in patients with isthmic spondylolisthesis after in situ fusion or fusion with spondylolisthesis reduction. Endpoints of interest included Oswestry Disability Index (ODI) score, hospitalization duration, operative morbidity, and rates of surgical revision. Data from individual studies were aggregated using random-effects models to assess combined effects. RESULTS Of 277 identified studies, 7 studies were included with an aggregate 308 patients (143 underwent fusion in situ and 165 underwent reduction). Patients who underwent reduction for isthmic lumbar spondylolisthesis had significantly lower rates of pseudarthrosis at last follow-up (OR 0.22, p = 0.03). Estimated blood loss, operative time, hospitalization duration, change in ODI score, change in back pain (visual analog scale [VAS]), and reoperation rate did not differ significantly between groups. CONCLUSIONS For patients with isthmic spondylolisthesis, the present data suggest that fusion with reduction of spondylolisthesis may lower rates of pseudarthrosis as compared to in situ fusion. However, operative morbidity and improvement in patient-reported outcomes were similar between strategies.

BACKGROUND AND OBJECTIVES: Cervical spinal cord injury (SCI) can occur in the absence of easily identifiable osseoligamentous abnormalities, such as fractures and dislocations. The role of surgery in the management of this condition remains to be elucidated. METHODS: A comprehensive literature search was conducted to identify studies investigating outcomes after surgical management of cervical SCI without fracture and dislocation. Random-effects model meta-analysis was performed, with neurological improvement and time to surgery as primary end points. Subgroup analysis by time to surgery was performed to assess neurological improvement between patients undergoing surgery within 72 hours of injury vs later than 72 hours after injury. RESULTS: A total of 16 studies yielding 398 surgically treated patients with this condition were analyzed. The mean age at the time of injury was 52 ± 33.8 years, and male patients comprised 86.4% (95% CI: 76.6%-94.4%). The mean number of spinal cord segments affected was 2.5 ± 4. Injury was most commonly inflicted by falls (58.4%, 95% CI: 46.6%-69.9%), followed by motor vehicle accidents (30.5%, 95% CI: 23.4%-38%). Preoperatively, abnormal magnetic resonance imaging findings were observed in 125 patients (31.4%), and included: Intervertebral disk injury in 33 patients (26.4%); Cord edema in 23 patients (18.4%); Cord contusion in 22 patients (17.6%); Ligamentous injury in 6 patients (4.8%); and MRI abnormalities not specified in 41 patients (32.8%). Postoperatively, neurological improvement was noted in 62% (95% CI: 21.4%-95.2%) of patients who underwent surgery within 72 hours after injury, and in 71.1% (95% CI: 33%-98.1%) of the patients who underwent surgery later than 72 hours after injury ( P = .8). CONCLUSION: This meta-analysis demonstrated high rates of neurological improvement in patients treated surgically for cervical SCI without fracture and dislocation. No significant differences were noted between patients undergoing surgery acutely, within 72 hours after injury, and patients being treated surgically later in the course of cervical SCI without fracture and dislocation.

OBJECTIVE The aim of this study was to evaluate mortality and progression outcomes in patients undergoing stereotactic radiosurgery (SRS) for breast cancer brain metastases and to identify associated risk factors using a national quality registry. METHODS The NeuroPoint Alliance (NPA) SRS Registry was employed for this study, which conducted prospective enrollment of patients undergoing SRS at 16 participating centers from 2017 to 2024. Outcomes of interest included the post-SRS EQ-5D score change, overall survival, local progression, out-of-field progression, and overall intracranial progression. For all time-to-event analyses, Kaplan-Meier curves and multivariable Cox regressions with hazard ratios were used. RESULTS A total of 138 patients (127 female, mean age 59.8 years) were identified; 46.4% had a single lesion, 42.0% had 2–4 lesions, and 11.6% had ≥ 5 lesions, while 87.0% had a Karnofsky Performance Status (KPS) score between 80 and 100. The median overall survival was 17.9 months, and independent predictors of all-cause mortality included a KPS score ≤ 90 (HR 6.73) and diabetes mellitus (HR 3.35). The median time to local progression was 19.8 months. More than 5 lesions at baseline (HR 9.03) and a marginal dose ≤ 17.6 Gy (HR 8.00) were predictive of local recurrence. The median was not reached for out-of-field progression, and predictors included ≥ 2 lesions at the time of SRS (HR 3.20) and a marginal dose ≤ 17.6 Gy (HR 4.61). At the final follow-up assessment, 17.1% of patients experienced no change according to the EQ-5D, while 34.3% had improvement, 11.4% had mixed results, and 37.1% had worsened health. In the multivariable linear regression model, pre-SRS resection (r = 1.92) and baseline EQ-5D score (r = 1.29) were statistically significant predictors of quality of life at the final follow-up assessment. CONCLUSIONS Using real-world data from the NPA SRS Registry, this study demonstrated comparable outcomes in patients who underwent SRS for breast cancer brain metastases compared with those of previous literature. The number of lesions at the time of SRS and the marginal dose were independent risk factors for local recurrence, out-of-field progression, and overall intracranial progression. Pre-SRS resection and baseline EQ-5D score were independent predictors of quality of life following SRS.

OBJECTIVE This study aimed to develop an artificial intelligence (AI) model for automatically detecting Hounsfield unit (HU) values at the L1 vertebra in preoperative thoracolumbar CT scans. This model serves as a screening tool for osteoporosis in patients undergoing spine surgery, offering an alternative to traditional bone mineral density measurement methods like dual-energy x-ray absorptiometry. METHODS The authors utilized two CT scan datasets, comprising 501 images, which were split into training, validation, and test subsets. The nnU-Net framework was used for segmentation, followed by an algorithm to calculate HU values from the L1 vertebra. The model’s performance was validated against manual HU calculations by expert raters on 56 CT scans. Statistical measures included the Dice coefficient, Pearson correlation coefficient, intraclass correlation coefficient (ICC), and Bland-Altman plots to assess the agreement between AI and human-derived HU measurements. RESULTS The AI model achieved a high Dice coefficient of 0.91 for vertebral segmentation. The Pearson correlation coefficient between AI-derived HU and human-derived HU values was 0.96, indicating strong agreement. ICC values for interrater reliability were 0.95 and 0.94 for raters 1 and 2, respectively. The mean difference between AI and human HU values was 7.0 HU, with limits of agreement ranging from −21.1 to 35.2 HU. A paired t-test showed no significant difference between AI and human measurements (p = 0.21). CONCLUSIONS The AI model demonstrated strong agreement with human experts in measuring HU values, validating its potential as a reliable tool for automated osteoporosis screening in spine surgery patients. This approach can enhance preoperative risk assessment and perioperative bone health optimization. Future research should focus on external validation and inclusion of diverse patient demographics to ensure broader applicability.

OBJECTIVE The aims of this study were to 1) define the incidence of transforaminal lumbar interbody fusion (TLIF) interbody subsidence; 2) determine the relative importance of preoperative and intraoperative patient- and instrumentation-specific risk factors predictive of postoperative subsidence using CT-based assessment; and 3) determine the impact of TLIF subsidence on postoperative complications and fusion rates. METHODS All adult patients who underwent one- or two-level TLIF for lumbar degenerative conditions at a multi-institutional academic center between 2017 and 2019 were retrospectively identified. Patients with traumatic injury, infection, malignancy, previous fusion at the index level, combined anterior-posterior procedures, surgery with greater than two TLIF levels, or incomplete follow-up were excluded. Interbody subsidence at the superior and inferior endplates of each TLIF level was directly measured on the endplate-facing surface of both coronal and sagittal CT scans obtained greater than 6 months postoperatively. Patients were grouped based on the maximum subsidence at each operative level classified as mild, moderate, or severe based on previously documented < 2-mm, 2- to 4-mm, and ≥ 4-mm thresholds, respectively. Univariate and regression analyses compared patient demographics, medical comorbidities, preoperative bone quality, surgical factors including interbody cage parameters, and fusion and complication rates across subsidence groups. RESULTS A total of 67 patients with 85 unique fusion levels met the inclusion and exclusion criteria. Overall, 28% of levels exhibited moderate subsidence and 35% showed severe subsidence after TLIF with no significant difference in the superior and inferior endplate subsidence. Moderate (≥ 2-mm) and severe (≥ 4-mm) subsidence were significantly associated with decreases in cage surface area and Taillard index as well as interbody cages with polyetheretherketone (PEEK) material and sawtooth surface geometry. Severe subsidence was also significantly associated with taller preoperative disc spaces, decreased vertebral Hounsfield units (HU), the absence of bone morphogenetic protein (BMP) use, and smooth cage surfaces. Regression analysis revealed decreases in Taillard index, cage surface area, and HU, and the absence of BMP use predicted subsidence. Severe subsidence was found to be a predictor of pseudarthrosis but was not significantly associated with revision surgery. CONCLUSIONS Patient-level risk factors for TLIF subsidence included decreased HU and increased preoperative disc height. Intraoperative risk factors for TLIF subsidence were decreased cage surface area, PEEK cage material, bullet cages, posterior cage positioning, smooth cage surfaces, and sawtooth surface designs. Severe subsidence predicted TLIF pseudarthrosis; however, the causality of this relationship remains unclear.

OBJECTIVE The role of interbodies in lumbar arthrodesis has been insufficiently supported by evidence, impacting clinical decision-making and occasionally insurance coverage. This study aimed to compare clinical and radiological outcomes between lumbar arthrodesis with a synthetic interbody spacer (cage) versus structural bone graft alone (autograft or allograft) in patients with degenerative spine disease. METHODS A systematic review of the literature was performed to identify studies directly comparing outcomes of lumbar interbody arthrodesis with and without interbody cage use. The outcomes of individual studies were synthesized in meta-analyses using random-effects models. RESULTS Twenty studies with 1508 patients (769 with an interbody cage and 739 without an interbody cage) were included. Interbody cage placement was associated with a significantly greater increase in disc height after surgery (4.0 mm vs 3.4 mm, p < 0.01). There was a significantly greater reduction of back pain (visual analog scale [VAS] score) in cases in which an interbody cage was used (5.4 vs 4.7, p = 0.03). Fusion rates were 5.5% higher in the cage group (96.3% vs 90.8%) and reached statistical significance (p = 0.03). No statistically significant differences were identified between the two groups regarding all-cause reoperation rates, complication rates, or improvement in Oswestry Disability Index score or leg pain (VAS score). CONCLUSIONS These results suggest that implantation of an interbody cage is associated with higher rates of fusion, more effective maintenance of disc height, and greater improvement of back pain. This study underlines the clinical value of interbody cages in lumbar arthrodesis for patients with degenerative spine disease.

OBJECTIVE Use of bone morphogenetic protein (BMP)—an osteoinductive agent commonly used in lumbar arthrodesis—is off-label for cervical arthrodesis. This study aimed to identify the effect of BMP use on clinical and radiological outcomes in instrumented cervical arthrodesis. METHODS A comprehensive systematic review of the literature was performed to identify studies directly comparing outcomes between cervical arthrodeses with and without using BMP. Outcomes were analyzed separately for cases of anterior cervical discectomy and fusion (ACDF) and posterior cervical fusion (PCF). RESULTS A total of 20 studies with 5828 patients (1948 with BMP and 3880 without BMP) were included. In the ACDF cases, BMP use was associated with higher fusion rates (98.9% vs 93.6%, risk difference [RD] 8%; risk ratio [RR] 1.12, p = 0.02), lower reoperation rates (2.2% vs 3.1%, RD 3%; RR 0.48, p = 0.04), and higher risk of dysphagia (24.7% vs 8.1%, RD 11%; RR 1.93, p = 0.02). No significant differences in the Neck Disability Index, neck pain, or arm pain scores were associated with the use of BMP. On subgroup meta-analysis of ACDF cases, older age (≥ 50 years) and higher BMP dose (≥ 0.9 mg/level) were associated with significantly higher fusion rates and relatively lower risk for dysphagia, whereas arthrodesis of fewer segments (< 2 levels) showed significantly higher dysphagia rates without a significant increase in fusion rates. In the PCF cases, the use of BMP was not associated with significant differences in fusion (p = 0.38) or reoperation (p = 0.61) rates but was associated with significantly higher blood loss during surgery (mean difference 146.7 ml, p ≤ 0.01). CONCLUSIONS Use of BMP in ACDF offers higher rates of augmented fusion and lower rates of all-cause reoperation but with an increased risk of dysphagia. The benefit of fusion outweighs the risk of dysphagia with a higher BMP dose in older patients being operated on for < 2 levels. The use of BMP in PCF seems to have a less important effect on clinical and radiological outcomes.

Study Design: Retrospective cohort analysis. Objective: To determine whether the C2 exposure technique was a predictor of change in cervical alignment and patient-reported outcomes measures (PROMs) after posterior cervical decompression and fusion (PCDF) for degenerative indications. Background: In PCDF handling of the C2 posterior paraspinal musculature during the operative approach varies by surgeon technique. To date, no studies have investigated whether maintenance of the upper cervical semispinalis cervicis attachments as compared with complete reflection of upper cervical paraspinal musculature from the posterior bony elements is associated with superior radiographic and clinical outcomes after PCDF. Patients and Methods: All adult patients who underwent C2–T2 PCDF for myelopathy or myeloradiculopathy at multi-institutional academic centers between 2013 and 2020 were retrospectively identified. Patients were dichotomized by the C2 exposure technique into semispinalis preservation or midline muscular reflection groups. Preoperative and short and long-term postoperative radiographic outcomes (upper cervical alignment, global alignment, and fusion status) and PROMs (Visual Analog Scale–Neck, Neck Disability Index, and Short Form-12) were collected. Univariate analysis compared patient factors, radiographic measures, and PROMs across C2 exposure groups. Results: A total of 129 patients met the inclusion/exclusion criteria (73 muscle preservation and 56 muscle reflection). Patients in the muscular preservation group were on average younger (P = 0.005) and more likely to have bone morphogenic protein (P < 0.001) and C2 pars screws (P = 0.006) used during surgery. Preoperative to postoperative changes in C2 slope, C2 tilt, C2–C3 segmental lordosis, C2–C3 listhesis, C0–C2 Cobb angle, proximal junctional kyphosis, ADI, C1 lamina-occiput distance, C2 sagittal vertical axis, C2–C7 lordosis, and PROMs at all follow-up intervals did not vary significantly by C2 exposure technique. Likewise, there were no significant differences in fusion status, C2–C3 pseudoarthrosis, C2 screw loosening, and complication and revision rates between C2 exposure groups. Conclusions: Preservation of C2 semispinalis attachments versus muscular reflection did not significantly impact cervical alignment, clinical outcomes, or proximal junction complications in long-segment PCDF. Level of Evidence: Level III.

BACKGROUND AND OBJECTIVES: Cervical disk arthroplasty (CDA) offers the advantage of motion preservation in the treatment of focal cervical pathology. At present, implant sizing is performed using subjective tactile feedback and imaging of trial cages. This study aims to construct interpretable machine learning (IML) models to accurately predict postoperative range of motion (ROM) and identify the optimal implant sizes that maximize ROM in patients undergoing CDA. METHODS: Adult patients who underwent CDA for single-level disease from 2012 to 2020 were identified. Patient demographics, comorbidities, and outcomes were collected, including symptoms, examination findings, subsidence, and reoperation. Affected disk height, healthy rostral disk height, and implant height were collected at sequential time points. Linear regression and IML models, including bagged regression tree, bagged multivariate adaptive regression spline, and k-nearest neighbors, were used to predict ROM change. Model performance was assessed by calculating the root mean square error (RMSE) between predicted and actual changes in ROM in the validation cohort. Variable importance was assessed using RMSE loss. Area under the curve analyses were performed to identify the ideal implant size cutoffs in predicting improved ROM. RESULTS: Forty-seven patients were included. The average RMSE between predicted and actual ROM was 7.6° (range: 5.8-10.1) in the k-nearest neighbors model, 7.8° (range: 6.5-10.0) in the bagged regression tree model, 7.8° (range: 6.2-10.0) in the bagged multivariate adaptive regression spline model, and 15.8° (range: 14.3-17.5°) in a linear regression model. In the highest-performing IML model, graft size was the most important predictor with RMSE loss of 6.2, followed by age (RMSE loss = 5.9) and preoperative caudal disk height (RMSE loss = 5.8). Implant size at 110% of the normal adjacent disk height was the optimal cutoff associated with improved ROM. CONCLUSION: IML models can reliably predict change in ROM after CDA within an average of 7.6 degrees of error. Implants sized comparably with the healthy adjacent disk may maximize ROM.