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OBJECTIVE: To develop a deep learning algorithm for diagnosing lumbar central canal stenosis (LCCS) using abdominal CT (ACT) and lumbar spine CT (LCT). MATERIALS AND METHODS: This retrospective study involved 109 patients undergoing LCTs and ACTs between January 2014 and July 2021. The dural sac on CT images was manually segmented and classified as normal or stenosed (dural sac cross-sectional area ≥ 100 mm2 or < 100 mm2, respectively). A deep learning model based on U-Net architecture was developed to automatically segment the dural sac and classify the central canal stenosis. The classification performance of the model was compared on a testing set (990 images from 9 patients). The accuracy, sensitivity, and specificity of automatic segmentation were quantitatively evaluated by comparing its Dice similarity coefficient (DSC) and intraclass correlation coefficient (ICC) with those of manual segmentation. RESULTS: In total, 990 CT images from nine patients (mean age ± standard deviation, 77 ± 7 years; six men) were evaluated. The algorithm achieved high segmentation performance with a DSC of 0.85 ± 0.10 and ICC of 0.82 (95% confidence interval [CI]: 0.80,0.85). The ICC between ACTs and LCTs on the deep learning algorithm was 0.89 (95%CI: 0.87,0.91). The accuracy of the algorithm in diagnosing LCCS with dichotomous classification was 84%(95%CI: 0.82,0.86). In dataset analysis, the accuracy of ACTs and LCTs was 85%(95%CI: 0.82,0.88) and 83%(95%CI: 0.79,0.86), respectively. The model showed better accuracy for ACT than LCT. CONCLUSION: The deep learning algorithm automatically diagnosed LCCS on LCTs and ACTs. ACT had a diagnostic performance for LCCS comparable to that of LCT.

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OBJECTIVE: The study aimed to investigate the correlation between fat fraction (FF), R2* value of vertebrae based on IDEAL-IQ sequence and bone mineral density (BMD) based on QCT, and their diagnostic value for low BMD and osteoporosis. MATERIALS AND METHODS: Subgroups were divided according to different gender, age, BMI and bone mass to compare the differences in parametric variables. One-way ANOVA, independent samples t-test, correlation coefficient analysis, linear regression analysis and ROC curve analysis were performed. RESULTS: Significant differences were found in FF among different bone mass groups, and between different gender and age groups. While R2* only had significant difference between different gender groups and males with different age. BMD was significantly negatively correlated with FF, especially in women, and FF significantly negatively affected BMD after controlling for gender, age and BMI. There was mildly positive correlation between BMD and R2* in men, and R2* significantly positively influenced BMD controlling for the confounders. In addition, FF was positively correlated with age, whereas R2* was negatively correlated with age in men. FF had high diagnostic efficacy for low bone mass and osteoporosis, while R2* alone was weakly diagnostic. CONCLUSION: Vertebral FF can be served as a potential important imaging biomarker for assessing low BMD and osteoporosis, and R2* of males can be utilized as an complementary parameter for evaluating osteoporosis. ADVANCES IN KNOWLEDGE: The IDEAL-IQ sequence has the potential to be used as an accessory examination in the diagnosis of osteoporosis, assessment of treatment efficacy and prediction of fracture risk.

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BACKGROUND: Pediatric lumbar spondylolysis, a stress fracture of the lumbar spine, frequently affects young athletes, and nonoperative treatment is often the first choice of management. Because the union rate in lumbar spondylolysis is lower than that in general fatigue fractures, identifying risk factors for nonunion is essential for optimizing treatment. PURPOSE: To determine the risk factors for nonunion after nonoperative treatment of acute pediatric lumbar spondylolysis through multivariate analysis. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: We analyzed 574 pediatric patients (mean age, 14.3 ± 1.9 years) with lumbar spondylolysis who underwent nonoperative treatment between 2015 and 2022. Nonoperative treatment included the elimination of sports activities, bracing, and weekly athletic rehabilitation, with follow-up computed tomography. Patient data, lesion characteristics, sports history, presence of spina bifida occulta at the lamina with a lesion or at the lumbosacral spine excluding the lesion level, and lumbosacral parameters were examined. Differences between the union and nonunion groups were investigated using multivariate analysis to determine the risk factors for nonunion. RESULTS: Of the 574 patients, 81.7% achieved bone union. Multivariate analysis revealed that an L5 lesion and the progression of the main and contralateral lesion stages were significant independent risk factors for nonunion. An L5 lesion had a lower union rate than non-L5 lesions. As the main lesion progressed, the likelihood of nonunion increased significantly, and the progression of the contralateral lesion also showed a similar trend. Spina bifida occulta and lumbosacral parameters were not significant predictors of nonunion in this study. CONCLUSION: We identified the L5 lesion level and the progression of the main and contralateral lesion stages as independent risk factors for nonunion in pediatric lumbar spondylolysis after nonoperative treatment. These findings aid in treatment decision-making. When bone union cannot be expected with nonoperative treatment, symptomatic treatment is required without prolonged external fixation and rest, and without aiming for bone union. Individualized treatment plans are crucial based on identified risk factors.

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This work focuses on the growth patterns of the human fourth lumbar vertebra (L4) in a paediatric population, with specific attention to sexual dimorphism. The study aims to understand morphological and density changes in the vertebrae through age-dependent statistical shape and statistical appearance models, which can describe full three-dimensional anatomy. Results show that the main growth patterns are associated with isotropic volumetric vertebral growth, a decrease in the relative size of the vertebral foramen, and an increase in the length of the transverse processes. Moreover, significant sexual dimorphism was demonstrated during puberty. We observe significant age and sex interaction in the anterior vertebral body height (P = 0.005), where females exhibited an earlier increase in rates of vertebral height evolution. Moreover, we also observe an increase in cross-sectional area (CSA) with age (P = 0.020), where the CSA is smaller in females than in males (significant sex effect P = 0.042). Finally, although no significant increase in trabecular bone density with age is observed (P = 0.363), a trend in the statistical appearance model suggests an increase in density with age.

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INTRODUCTION: The disco-vertebral junction (DVJ) of the lumbar spine contains thin structures with short T2 values, including the cartilaginous endplate (CEP) sandwiched between the bony vertebral endplate (VEP) and the nucleus pulposus (NP). We previously demonstrated that ultrashort-echo-time (UTE) MRI, compared to conventional MRI, is able to depict the tissues at the DVJ with improved contrast. In this study, we sought to further optimize UTE MRI by characterizing the contrast-to-noise ratio (CNR) of these tissues when either single echo or echo subtraction images are used and with varying echo times (TEs). METHODS: In four cadaveric lumbar spines, we acquired 3D Cones (a UTE sequence) images at varying TEs from 0.032 ms to 16 ms. Additionally, spin echo T1- and T2-weighted images were acquired. The CNRs of CEP-NP and CEP-VEP were measured in all source images and 3D Cones echo subtraction images. RESULTS: In the spin echo images, it was challenging to distinguish the CEP from the VEP, as both had low signal intensity. However, the 3D Cones source images at the shortest TE of 0.032 ms provided an excellent contrast between the CEP and the VEP. As the TE increased, the contrast decreased in the source images. In contrast, the 3D Cones echo subtraction images showed increasing CNR values as the second TE increased, reaching statistical significance when the second TE was above 10 ms (p < 0.05). CONCLUSIONS: Our study highlights the feasibility of incorporating UTE MRI for the evaluation of the DVJ and its advantages over conventional spin echo sequences for improving the contrast between the CEP and adjacent tissues. Additionally, modulation of the contrast for the target tissues can be achieved using either source images or subtraction images, as well as by varying the echo times.

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Background: Postoperative sagittal alignment has been shown to be associated with patient-reported outcome measures (PROMs) following open lumbar decompression procedures, although it is unknown whether preoperative sagittal imbalance affects clinical outcomes of minimally invasive surgical (MIS) decompression only surgery. Purpose: We sought to evaluate the impact of preoperative pelvic incidence-lumbar lordosis (PI-LL) imbalance on PROMs after MIS laminectomy for the treatment of neurogenic claudication symptoms. Methods: We conducted a retrospective cohort study of adult patients undergoing MIS laminectomy for degenerative lumbar spinal stenosis between April 2017 and April 2021 at a single institution. Of the 52 patients included (mean follow-up, 17 months) radiographs were taken prior to surgery and assessed for sagittal alignment parameters. Patients were grouped based on the preoperative PI-LL (balanced vs unbalanced). Changes in PROMs were compared between unbalanced PI-LL and balanced PI-LL groups. Minimal clinically important difference (MCID) for Oswestry Disability Index (ODI) was also assessed. Results: Of the 52 patients, 17 (32.7%) had unbalanced age-adjusted preoperative PI-LL. There was no significant difference found in PROMs between unbalanced and balanced PI-LL groups preoperatively or at final follow-up. Compared with those with unbalanced PI-LL, patients with balanced PI-LL were shown to have no added benefit in achieving MCID for ODI at long-term follow-up and no added benefit in the time to achieving MCID. Conclusion: These retrospective findings suggest that patients with unbalanced preoperative PI-LL may experience significant benefit in long-term clinical outcomes following MIS laminectomy, similarly to those with balanced PI-LL at baseline. The findings also suggest that the presence of sagittal imbalance preoperatively may not appreciably influence the long-term clinical outcomes following MIS laminectomy. Prospective study involving a larger population is warranted.

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Background: Grit, defined as perseverance and passion for long-term goals, and self-control, defined as the capacity to regulate impulses in the presence of momentarily gratifying temptations or diversion, have shown to be predictors of professional achievement. Their role in health care outcomes is less well understood. Purpose: We sought to determine whether grit and self-control are associated with patient-reported outcome measures (PROMs) following spine surgery. Methods: We conducted a retrospective review of adult patients who underwent cervical or lumbar procedures by a single fellowship-trained spine surgeon between March 2017 and October 2020. We included patients who underwent anterior cervical discectomy and fusion, cervical disk replacement, minimally invasive laminectomy/laminoplasty (MI-D), or minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) with minimum 1-year follow-up. Grit and self-control scores were collected 1 year after the surgery. PROMs were collected preoperatively and at 6 postoperative timepoints. Grit and self-control were compared between patients who achieved substantial clinical benefit (SCB) in either physical or mental health versus those who did not. The association between grit/self-control and change in PROMs was also assessed. Results: In the 129 patients included in the analysis, we found that patients who achieved SCB in mental health had significantly higher grit scores than those who did not. In bivariate analysis, self-control was associated with greater improvement in leg pain scores at 1-year and 2-year follow-up following an MI-D. For the MI-TLIF cohort, grit was associated with a smaller change in Short Form 12 mental component score at 6 weeks, and self-control was associated with a smaller change in Patient-Reported Outcome Measurement Information System Physical Function at the 6-month timepoint. Grit and self-control were not associated with PROMs at other timepoints. Conclusion: This retrospective review found that grit and self-control were not significantly associated with PROMs at most postoperative timepoints in patients who underwent spine surgery.

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Objective: To investigate the potential association between anxiety and depression and surgical outcomes in patients undergoing LSS. By analyzing data from the Nationwide Inpatient Sample (NIS) database, we aim to identify whether anxiety and depression serve as predictors for postoperative complications and pain-related symptoms. Methods: A retrospective analysis was conducted via the NIS database. Those undergoing LSS from 2010 to 2019 were divided into four groups: those with a diagnosis of anxiety, depression, both depression and anxiety, and neither depression nor anxiety. The chi-squared test, rank sum test, the Student-Newman-Keuls, least significant difference, and Bonferroni tests were used to identify differences between these groups. Logistic regression analysis was utilized to determine if anxiety and depression were predictors for postoperative complications and pain-related symptoms. Results: From 2010 to 2019, 832,099 patients undergoing LSS were identified. Patients with either anxiety or depression were associated with heavier economic burdens ($85,375, $76,840, $88,542 in the anxiety, depression, and comorbid group, respectively, p < 0.001) and prolonged hospital stay (p < 0.001). They were identified to experience higher risks of various complications especially thrombophilia (OR = 1.82, and 1.55 in the anxiety and the depression group, respectively, p < 0.01). Multiple pain-related symptoms, but face reduced risks of inpatient mortality (OR = 0.71, 0.75, and 0.63 in the anxiety, depression, and comorbid group, respectively, p < 0.01). Conclusions: The overall morbidities of depression and anxiety were relatively high. Psychiatric comorbidities were closely correlated with the negative outcomes after LSS. The psychological health of patients receiving LSS requires necessary attention to ensure pain control and prevent complications postoperatively.

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BACKGROUND CONTEXT: Lumbar spinal fusion is an increasingly common operation to treat symptoms related to degenerative disorders of the spine including radiculopathy and pain. As the volume of spine surgeries grows, it is becoming increasingly common for procedures to take place in non-tertiary care centers, including orthopaedic specialty hospitals (OSH). While previous research demonstrates that surgical outcomes at an OSH are non-inferior to those at a tertiary referral center (TRC), the implications of this difference on patient-reported outcome measures (PROMs) have not been sufficiently assessed. PURPOSE: The objectives of this study were (1) to determine if changes in patient reported outcome measures (PROMs) after elective lumbar spinal fusion surgery differ between patients who undergo surgery at an orthopedic specialty hospital (OSH) and those who undergo surgery at a tertiary referral center (TRC) and (2) to characterize differences in short-term outcomes between hospitals. STUDY DESIGN: Retrospective cohort study. PATIENT SAMPLE: Adult patients (≥ 18 years old) who underwent primary, elective single-level posterior lumbar decompression and fusion between January 2014 and December 2021 at a tertiary referral center or an orthopaedic specialty hospital. OUTCOME MEASURES: PROMs: Oswestry Disability Index (ODI), Short-form 12 (SF12) Mental Component Summary (MCS); SF12 Physical Component Summary (PCS); Visual Analogue Back and Leg (VAS Back/Leg) METHODS: PROMs were collected preoperatively, 6 months after surgery, and 1 year after surgery. Six-month and 1-year delta PROM values were calculated by subtracting the preoperative PROM score from the 6-month or 1-year score, respectively. Multivariable linear regression analyses were conducted to assess the independent effect of hospital location on postoperative PROM scores. RESULTS: A total of 288 patients were identified as part of the study cohort including 205 patients who underwent surgery at the tertiary hospital and 83 patients who underwent surgery at the OSH. OSH patients had shorter length of stay (1.57 ± 0.72 vs. 3.28 ± 1.32, p<0.001), however there was no difference in discharge disposition or 90-day readmission rates between hospitals (p>0.05). At 6 months, having surgery at the specialty hospital was associated with higher PCS (estimate = 2.96, confidence interval: 0.21 - 5.71, p=0.035). At 1-year postoperatively, the location of surgery no longer demonstrated significant associations with PROM scores. Preoperative PROM scores demonstrated significant associations with 6-month and 1-year scores for each PROM (p<0.05) except VAS leg at 6 months postoperatively. CONCLUSION: To our knowledge, this is one of the largest studies investigating PROMs at OSH versus TRCs for single-level lumbar fusions. We demonstrated that at one-year follow-up, there is not a significant difference in PROM improvement between patients who undergo surgery at a TRC and patients who do so at an OSH.

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STUDY DESIGN: Retrospective study. OBJECTIVE: The objective of this study is to investigate the association of waterpipe smoking with lumbar intervertebral disc degeneration (IVDD). METHODS: This is a retrospective chart review study. A total of 286 adults who underwent a lumbar magnetic resonance imaging (MRI) at a tertiary medical center were included and divided into three groups. Group 1 (n = 125) included non-smokers, group 2 (n = 80) smoked cigarettes only, and group 3 (n = 81) smoked waterpipe only. The intervertebral discs were graded using the Pfirmann disc degeneration grading system. RESULTS: The study showed higher lumbar disc degeneration scores for waterpipe and cigarette smokers compared to non-smokers at all spinal levels. Specifically, post hoc analysis showed that there was a significant difference at L1-L2 between cigarette smokers and non-smokers (P = 0.007) and between waterpipe smokers and non-smokers (P = 0.013), and a significant difference at L3-L4 and L4-L5 between non-smokers and cigarettes smokers (P < .001 and P = .029 respectively). CONCLUSION: Waterpipe smoking is associated with lumbar intervertebral disc degeneration.

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BACKGROUND: Adult spinal deformity (ASD) is a common problem in today's aging adult population, particularly in the thoracolumbar spine. This can lead to severe pain and disability, leading to poorer quality of life. Traditionally, open deformity correction has been the mainstay of treatment for these patients as it provides an excellent operative corridor; however, this comes with severe risk and high complication rates. There has been a trend towards more minimally invasive approaches to correct the deformity while persevering the muscle and soft tissue surrounding the bony spine across the fusion. METHODS: We describe a minimally invasive surgical technique through a Wiltse approach without invading the paraspinal musculature to gain access to the bony spine to perform lumbar interbody fusions and osteotomies. RESULTS: A total of 3 patients were identified for this technical note who underwent the TROPIC procedure for ASD. The patients had severe coronal and rotational imbalance. We were able to achieve adequate correction through an approach without disturbing the spinal musculature and soft tissues. CONCLUSIONS: This technique provides benefits of spinal rotational and coronal plane correction and restores lordosis with current advancements of today's technologies without the downsides of an open surgical approach.

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Background: Several assessment tools have been developed to estimate a patient's likelihood risk of falling. None of these measures estimate the contributions of the visual, vestibular, and somatosensory systems to fall risk, especially in patients with degenerative lumbar spine disease. Methods: Degenerative lumbar spine patients with radiculopathy (LD) and healthy subjects who were 35-70 years old without spine complaints were recruited. Patient reported outcome measures (PROMs) were collected prior to testing. Fall risk assessment was completed using Computer Dynamic Posturography (CDP), a computer-controlled balance machine that allows cone of economy (CoE) and cone of pressure (CoP) measurements. All patients completed Sensory Organization Tests (SOT) which include normal and perturbed stability, both with and without visual cues. Results: In total, 43 spine patients and 12 healthy controls were included, with mean age 57.8 years, 39.5% females, and mean BMI of 29.3 kg/m2. Nearly all CoE and most CoP dimensions were found to be larger in LD patients compared to controls across nearly all subtests (p<.05), with the largest dimensions generally observed in the surrounding and support sway testing condition. In LD patients, ODI and PROMIS Pain Interference were negatively correlated with CoE and CoP measurements (p<.05). Conclusions: In this prospective study, body sway was assessed as a function of CoE and CoP using the CDP system and was found to be elevated in spine patients, especially when they experienced increasing levels of visual and vestibular stimulation. The ability to identify the primary drivers of balance disorders is essential in spine patients and may be helpful in the development of a patient-specific treatment plan, which may in the future aid with fall-prevention initiatives.

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OBJECTIVE: To investigate in vivo 6-degree-of-freedom (DOF) vertebral motion in patients with isthmic spondylolisthesis (IS) during various functional weight-bearing activities. METHODS: Fifteen asymptomatic volunteers (mean age 54.8 years) and fourteen patients with IS at L4-5 (mean age 53.4 years) were recruited. The positions of the vertebrae (L4-L5) in the supine, standing, flexion-extension, left-right twisting and left-right bending positions were determined using previously described CT-based models and dual fluoroscopic imaging techniques. Local coordinate systems were established at the center of the anterior vertebra of L4 isthmic spondylolisthesis (AIS), the posterior lamina of L4 isthmic spondylolisthesis (PIS) and the center of the L5 vertebra to obtain the 6DOF range of motion (ROM) at L4-L5 and the range of motion (ROM) between the AIS and the PIS. RESULTS: The translation along the anteroposterior axis at L4-L5 during flexion-extension, left-right bending and left-right twisting was significantly greater than that of the healthy participants. However, the translation along the mediolateral axis at L4-L5 presented paradoxical motion under different positions: the ROM increased in the supine-standing and flexion-extension positions but decreased in the left-right bending and left-right twisting positions. The separation along the anteroposterior axis during flexion was significantly greater than that during standing, on average, reaching more than 1 mm. The separation along the mediolateral axis during standing, flexion and extension was significantly greater than that in the supine position. CONCLUSIONS: This study revealed the occurrence of displacement between the AIS and PIS, primarily in the form of separation during flexion. Symptomatic patients with isthmic spondylolisthesis exhibit intervertebral instability, which might be underestimated by flexion-extension radiographs.

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INTRODUCTION/AIMS: Nusinersen intrathecal administration can be challenging in spinal muscular atrophy (SMA) adults. We aimed to determine if the ultrasound (US)-assistance reduces the number of needle attempts and needle redirections needed for intrathecal drug administration and its impact on the procedure time, the incidence of adverse events (AEs), and patient satisfaction in these patients. METHODS: Fifty-eight patients aged 18 years and older scheduled for intrathecal nusinersen injection were enrolled and randomized (1:1 ratio) into Group 1 (nusinersen infusion with US-assisted technique) or Group 2 (nusinersen infusion with landmark-based technique). The number of attempts, number of redirections, periprocedural time, AEs and patient satisfaction were reported. Continuous variables were compared with the Student t-test or Wilcoxon rank sum test. Categorical variables were evaluated with the Chi-square test or Fisher's exact test in case of expected frequencies <5. The p-values <.05 were considered statistically significant. RESULTS: There were no statistical differences in the number of attempts, AEs, or patient satisfaction between the two groups. The number of needle redirections was significantly lower in the ultrasound group versus landmark-based group (p < .05) in both the overall group of patients and in the subgroup with difficult spines. The periprocedural time was about 40 seconds longer in US-group versus landmark-based group (p < .05). DISCUSSION: In SMA adults, US assistance reduces the number of needle redirections needed for intrathecal drug administration. These results suggest that the US assistance may be advantageous for nusinersen therapy to reduce the therapeutic burden of intrathecal infusion.

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INTRODUCTION: Patients with symptomatic lumbar spinal stenosis (sLSS) are often limited in their walking range because of worsening symptoms, which is thought to induce changes in the gait pattern. The aim of this study was to determine whether changes in gait pattern and muscle activity in these patients are elicited by a walking stress and differ from asymptomatic controls. METHODS: Twenty patients with sLSS and 19 asymptomatic controls performed a 30-minute walking stress. Gait was assessed using seven inertial sensors and sagittal joint range of motion (ROM) was calculated during different phases of gait. Muscle activation of the gluteus medius, erector spinae and multifidus muscles was measured by surface electromyography (EMG) and integrated EMGs (normalized to the maximum during gait) were calculated. Differences between groups and time points (beginning and end) were assessed using mixed factorial analysis of variance. RESULTS: Patients had less knee extension ROM in terminal stance, less knee flexion ROM in swing and less overall hip flexion/extension ROM than controls (p ≤ 0.03). There were no functionally relevant changes in these parameters during the walking stress. The integrated EMG was greater in all muscles in patients than in controls and increased in both groups during the walking stress in the paraspinal but not in the gluteus medius muscle. There was no interaction between group and time for any of the parameters. CONCLUSION: Differences in gait pattern and muscle activity between patients with sLSS and controls are generally present, but are not amplified by a walking stress.

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Contemporary injury tolerance of the lumbar spine for under-body blast references axial compression and bending moments in a limited range. Since injuries often occur in a wider range of flexion and extension with increased moment contribution, this study expands a previously proposed combined loading injury criterion for the lumbar spine. Fifteen cadaveric lumbar spine failure tests with greater magnitudes of eccentric loading were incorporated into an existing injury criterion to augment its applicability and a combined loading injury risk model was proposed by means of survival analysis. A loglogistic distribution was the most representative of injury risk, resulting in optimized critical values of Fr,crit = 6011 N, and My,crit = 904 Nm for the proposed combined loading metric. The 50% probability of injury resulted in a combined loading metric value of 1, with 0.59 and 1.7 corresponding to 5 and 95% injury risk, respectively. The inclusion of eccentric loaded specimens resulted in an increased contribution of the bending moment relative to the previously investigated flexion/extension range (previous My,crit = 1155 Nm), with the contribution of the resultant sagittal force reduced by nearly 200 N (previous Fr,crit = 5824 N). The new critical values reflect an expanded flexion/extension range of applicability of the previously proposed combined loading injury criterion for the human lumbar spine during dynamic compression.

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OBJECTIVE: Patients with serum albumin levels < 3.5 g/dL are considered malnourished, but there is a paucity of data regarding the outcomes of patients with albumin levels > 3.5 g/dL. The objective of this study was to evaluate the effect of albumin on postoperative outcome in patients undergoing elective cervical and lumbar spine procedures. METHODS: The Michigan Spine Surgery Improvement Collaborative database was queried for lumbar and cervical fusion surgeries between January 2020 and December 2022. Patients were grouped by preoperative serum albumin levels: < 3.5 g/dL, 3.5-3.7 g/dL, 3.8-4.0 g/dL, and > 4.0 g/dL. Primary outcomes included urinary retention, ileus, dysphagia, surgical site infection (SSI), readmission within 30 and 90 days, return to the operating room, and length of stay (LOS) ≥ 4 days. Multivariate analysis was conducted to adjust for potential confounders. RESULTS: This study included 15,629 lumbar cases and 6889 cervical cases. Within the lumbar cohort, an albumin level of 3.5-3.7 g/dL was associated with an increased risk of readmission at 30 days (p = 0.048) and 90 days (p = 0.005) and an LOS ≥ 4 days (p < 0.001). An albumin level of 3.8-4.0 g/dL was associated with an increased risk of an LOS ≥ 4 days (p < 0.001). Within the cervical cohort, an albumin level of 3.5-3.7 g/dL was associated with an increased risk of SSI (p = 0.023), readmission at 30 days (p < 0.002) and 90 days (p < 0.001), return to the operating room (p = 0.002), and an LOS ≥ 4 days (p < 0.001). An albumin level of 3.8-4.0 g/dL was associated with an increased risk of readmission at 30 days (p = 0.012) and 90 days (p = 0.001) and an LOS ≥ 4 days (p < 0.001). CONCLUSIONS: This study maintains that patients with hypoalbunemia undergoing spine surgery are at risk for postoperative adverse events. However, there also exist significant associations between borderline serum albumin levels of 3.5-4.0 g/dL and increased risk of postoperative adverse events.

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Background: In this study, we examined the impact and degree of lumbar stenosis on cerebrospinal fluid (CSF) protein concentration. Methods: In this retrospective study, we analyzed protein concentrations in CSF samples of 61 patients with lumbar spinal stenosis (LSS) obtained during pre-operative myelography. Patients were divided into two groups: those showing no block to contrast (Group A) versus those showing medium block to contrast below the lumbar puncture level (Group B). Results: The CSF protein concentration in Group B (104.3 ± 59 g/dL) patients with medium block was significantly greater than that in Group A (65.1 ± 33 g/dL) patients without medium block. Conclusion: A higher average CSF protein concentration was seen in Group B patients with significant lumbar stenosis versus Group A patients without significant lumbar stenosis. Theoretically, damage to the cauda equina in patients with LSS may cause these elevated CSF protein levels.

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Purpose: This study aimed to evaluate the biomechanical response or load transfer on the osteoporotic L1 vertebra under torsional loading. Methods: To achieve this goal, a numerical model of osteoporotic vertebra in various trabecular bone degenerations was developed and tested. The mechanical behavior of the model was represented taking into account the anisotropic properties of the cancellous bone, which provided a more realistic mechanical picture of the biological subsystem. To ensure the reliability of osteoporotic degradation, the thinning of cortical bone and the appearance of gaps between trabecular bone and cortical bone were also taken into account when creating the models. Results: Finite element (FE) analysis showed that the deformations of cortical bone thinning and detachment of the cortical bone from the trabecular tissue lead to local instability of the vertebra. As a result, the cortical bone of a vertebra loses its load-bearing capacity, even if the strength limit is not reached. Conclusions: The results obtained allow us to state that taking into account the thinning of the trabeculae, which creates voids, is extremely important for load-bearing capacity of osteoporotic vertebrae. However, a limitation of this study is the lack of experimental data to ensure consistency with the computer simulation results.

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