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Background: Oblique lumbar intervertebral fusion aims to decompress spinal nerves via an interbody fusion cage, but the optimal surgical strategy, including implant selection for specific patient characteristics, remains unclear. A biomechanical model was developed to assess how pathophysiological characteristics and instrumentation impact spinal realignment, indirect decompression, and cage subsidence risk., Methods: A finite element model of the L4-L5 segment was derived from a validated asymptomatic T1-S1 spine model. Five cases of grade I spondylolisthesis with normal or osteoporotic bone densities and initial disc heights of 4.3 to 8.3 mm were simulated. Oblique lumbar intervertebral fusion with cage heights of 10, 12, and 14 mm (12° lordosis) was examined. Postoperative changes in disc height, foraminal and spinal canal dimensions, segmental lordosis, and vertebral slip were assessed. Vertebral stresses and displacements under 10 Nm flexion and 400 N gravitational load were compared between stand-alone constructs and bilateral pedicle screw fixation using rods of 4.75, 5.5, and 6 mm diameters., Findings: Oblique lumbar intervertebral fusion significantly improved postoperative disc height, foraminal and spinal canal dimensions, with the greatest enhancements observed with 14 mm cages. Bilateral pedicle screw fixation markedly reduced cortical endplate stresses and displacements compared to stand-alone constructs, with added benefits from larger rod diameters. Low bone density increased displacements by 63 %., Interpretation: Thicker cages achieve better decompression but increase subsidence risk. Bilateral pedicle screw fixation with 6 mm rods minimizes endplate stresses and displacements, especially in osteoporotic cases. Future research will validate these findings and explore the model's potential for surgical planning., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. Carl-Eric Aubin reports academic R&D support from the Natural Sciences and Engineering Research Council of Canada (NSERC) (industrial research chair program with Medtronic of Canada). Mathieu Chayer reports financial support was provided by Quebec Research Fund Nature and Technology. Mathieu Chayer reports financial support was provided by TransMedTech Institute. Mathieu Chayer reports financial support was provided by Natural Sciences and Engineering Research Council of Canada. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Lumbar stiffness leads to greater hip dependence to achieve sagittal motion and increases instability after total hip arthroplasty (THA). We aimed to determine parameters that influence lumbar stiffness among patients with hip pathology. We hypothesized that modifiable (degenerative changes, spinal canal stenosis, facet orientation) and nonmodifiable factors (muscle condition) would be associated with lumbar spine stiffness. In this retrospective case-cohort study from a tertiary referral center, consecutive patients presenting at a hip specialist clinic underwent standing and deep-seated radiographic assessment to measure lumbar lordosis (∆LL) (stiffness: ∆LL < 20°), hip flexion (∆PFA: pelvic femoral angle), and degree of degenerative-disc-disease (DDD) (facet osteoarthritis, disc height, endplate proliferative changes). Of these, 65 patients were selected with previous lumbar spine magnetic resonance imaging, allowing to determine lumbar facet orientation, spinal canal stenosis (Schizas classification), and flexor- and extensor-muscle atrophy (Goutallier classification). Mean ∆LL was 45° (range: 11°-72°) and four patients (6%) exhibited spine stiffness. Patients with multilevel DDD (n = 22) had less ∆LL than those with no/single level (n = 43) DDD (34° [range: 11°-53°] vs. 51° [21°-72°]; p < 0.001). Number of DDD levels correlated strongly with ∆LL (ρ = -0.642; p < 0.001). Spinal stiffness was only seen in patients with ≥4 DDD levels. There was no correlation between ∆LL and facet orientation (p > 0.05). ∆LL correlated strongly with extensor atrophy at L3-L4 (ρ = -0.473), L4-L5 (ρ = -0.520), and L5-S1 (ρ = -0.473) and poorly with flexors at L4-L5 (ρ = -0.134) and L5-S1 (ρ = -0.227). Lumbar stiffness is dependent on modifiable (muscle atrophy) and nonmodifiable (extend of DDD) factors. This can guide nonoperative management of hip pathology, emphasizing the relevance of core muscle rehabilitation to improve posture and stiffness. Identification ≥4 DDD levels should alert surgeons of increased THA instability risk. Level of evidence: level IV, cohort series., (© 2023 Orthopaedic Research Society.)

Objective: Length of stay (LOS) is a contributor to costs and resource utilization. The primary goal of this study was to identify patient, clinical, surgical, and institutional variables that influence LOS after elective surgery for thoracolumbar degenerative pathology. The secondary objective was to examine variability in LOS and institutional strategies used to decrease LOS., Methods: This is a retrospective study of prospectively collected data from a multicentric cohort enrolled in the Canadian Spine Outcomes and Research Network (CSORN) between January 2015 and October 2020 who underwent elective thoracolumbar surgery (discectomy [1 or 2 levels], laminectomy [1 or 2 levels], and posterior instrumented fusion [up to 5 levels]). Prolonged LOS was defined as LOS greater than the median. Logistic regression models were used to determine factors associated with prolonged LOS for each procedure. A survey was sent to the principal investigators of the participating healthcare institutions to understand institutional practices that are used to decrease LOS., Results: A total of 3700 patients were included (967 discectomies, 1094 laminectomies, and 1639 fusions). The median LOSs for discectomy, laminectomy, and fusion were 0.0 (IQR 1.0), 1.0 (IQR 2.0), and 4.0 (IQR 2.0) days, respectively. On multivariable analysis, predictors of prolonged LOS for discectomy were having more leg pain, higher Oswestry Disability Index (ODI) scores, symptom duration more than 2 years, having undergone an open procedure, occurrence of an adverse event (AE), and treatment at an institution without protocols to reduce LOS (p < 0.05). Predictors of prolonged LOS for laminectomy were increased age, living alone, higher ODI scores, higher BMI, open procedures, longer operative time, AEs, and treatment at an institution without protocols to reduce LOS (p < 0.05). For posterior instrumented fusion, predictors of prolonged LOS were older age, living alone, more comorbidities, higher ODI scores, longer operative time, AEs, and treatment at an institution without protocols to reduce LOS (p < 0.05). The laminectomy group had the largest variability in LOS (SD 4.4 days, range 0-133 days). Three hundred fifty-four patients (22%) had an LOS above the 75th percentile. Ten institutions (53%) had either Enhanced Recovery After Surgery or standardized protocols in place., Conclusions: Among the factors identified in this study, worse baseline ODI scores, experiencing AEs, and treatment at an institution without protocols aimed at reducing LOS were predictive of prolonged LOS in all surgical groups. The laminectomy group had the largest variability in LOS.

Background: Opioid use in North America has increased rapidly in recent years. Preoperative opioid use is associated with several negative outcomes. Our objectives were to assess patterns of opioid use over time in Canadian patients who undergo spine surgery and to determine the effect of spine surgery on 1-year postoperative opioid use., Methods: A retrospective analysis was performed on prospectively collected data from the Canadian Spine Outcomes and Research Network for patients undergoing elective thoracic and lumbar surgery. Self-reported opioid use at baseline, before surgery and at 1 year after surgery was compared. Baseline opioid use was compared by age, sex, radiologic diagnosis and presenting complaint. All patients meeting eligibility criteria from 2008 to 2017 were included., Results: A total of 3134 patients provided baseline opioid use data. No significant change in the proportion of patients taking daily (range 32.3%-38.2%) or intermittent (range 13.7%-22.5%) opioids was found from pre-2014 to 2017. Among patients who waited more than 6 weeks for surgery, the frequency of opioid use did not differ significantly between the baseline and preoperative time points. Significantly more patients using opioids had a chief complaint of back pain or radiculopathy than neurogenic claudication (p < 0.001), and significantly more were under 65 years of age than aged 65 years or older (p < 0.001). Approximately 41% of patients on daily opioids at baseline remained so at 1 year after surgery., Conclusion: These data suggest that additional opioid reduction strategies are needed in the population of patients undergoing elective thoracic and lumbar spine surgery. Spine surgeons can be involved in identifying patients taking opioids preoperatively, emphasizing the risks of continued opioid use and referring patients to appropriate evidence-based treatment programs., Competing Interests: S. Christie, E. Abraham, R. Rampersaud, N. Manson and C. Fisher report receiving consulting fees from Medtronic, outside the submitted work. J. Paquet reports receiving an institutional grant from Medtronic, outside the submitted work. E. Abraham and N. Manson report receiving unrestricted research grants from Medtronic, outside the submitted work. R. Rampersaud and C. Fisher report receiving royalties from Medtronic, outside the submitted work. C. Fisher reports receiving consulting fees from NuVasive and fellowship support and an institutional research grant from AO Spine, outside the submitted work. No other competing interests were declared., (© 2020 Joule Inc. or its licensors.)

Background: In a public health-care system, patients often experience lengthy wait times to see a spine surgeon for consultation, and most patients are found not to be surgical candidates, thereby prolonging the wait time for those who are. The aim of this study was to evaluate whether a self-administered 3-item questionnaire (3IQ) could reprioritize consultation appointments and reduce wait times for lumbar spinal surgical candidates., Methods: This prospective, pragmatic, blinded, randomized controlled quality improvement study was conducted at a single Canadian academic health-care center. This study enrolled 227 consecutive eligible participants with an elective lumbar condition who were referred for consultation with a spine surgeon. All participants were mailed the 3IQ after their referral was received. Patients were randomized into the intervention group, in which leg-dominant pain reported on the 3IQ resulted in an upgrade in priority to be seen, or into the control group, in which no change to wait-list priority occurred. The main outcome measured was time to consultation for participants who were deemed surgical candidates following consultation., Results: There were no significant differences between groups with regard to demographics, overall group wait times, proportion of surgical candidates, or disability. A total of 33 patients were deemed surgical candidates after consultation. The median wait from referral to consultation was shorter for the 16 surgical candidates in the intervention group (2.5 months; interquartile range [IQR]: 2.0 to 4.8 months) compared with the 17 surgical candidates in the control group (4.5 months; IQR: 3.4 to 6.9 months; p = 0.090). The odds of seeing a surgical candidate within the acceptable time frame of 3 months were 5.4 times greater (95% confidence interval: 1.2 to 24.5 times; p = 0.024) in the intervention group., Conclusions: The use of a simple, self-administered questionnaire to reprioritize referrals resulted in shorter consultation wait times for patients who required a surgical procedure and significantly increased the number of surgical candidates seen within the acceptable time frame. It may be valuable to consider adding the 3IQ to clinical care practices to better triage these patients on waiting lists.

Purpose: The authors have developed a "para-midline" approach to the posterior lumbar spine using a virtually avascular surgical plane not previously described in the literature. It was their purpose to document consistent MRI presence of this plane and to prospectively evaluate its clinical use in terms of blood loss., Methods: Fifty consecutive patients undergoing primary lumbar surgery on 1-3 levels were prospectively enrolled from September 2014 to May 2015. The para-midline approach was used in all cases. The deep lumbar fascia is longitudinally incised on either side of the spinous processes instead of directly in the midline, which reveals the para-midline fatty plane. Blood loss during the approach and overall blood loss were recorded for all patients. MRIs from each patient were reviewed by an experienced neuroradiologist to determine the presence of the para-midline fatty plane., Results: There was no recorded blood loss during the approach for all procedures. The average overall blood loss was 60 cc (20-200 cc). No patient required a transfusion intraoperatively or postoperatively. The fatty para-midline plane was noted on preoperative MRI at all operated levels in all patients. The average width of this plane was 6.5 mm (2-17 mm)., Conclusions: The para-midline approach for lumbar surgery is associated with less blood loss than traditional, subperiosteal exposure techniques. The fatty interval through which this approach is made is universally present and identifiable on MRI. The authors offer this approach as a means of decreasing the risks associated with blood loss and transfusion with posterior lumbar surgery.

Study Design: Retrospective medical record review., Objective: The purpose of this study was to determine whether a history of abdominal/pelvic surgery confers an increased risk of retroperitoneal anterior approach-related complications when undergoing anterior lumbar interbody fusion., Summary of Background Data: As anterior lumbar interbody fusion gains popularity, both anterior retroperitoneal approach have become increasingly used., Methods: The records of 263 patients, who underwent infraumbilical retroperitoneal approach to the anterior aspect of the lower lumbar spine for a degenerative spine condition between 2007 and 2011 were retrospectively reviewed. Patient's demographics, risk factors, preoperative diagnosis, surgical history, level of the anterior fusion, and perioperative complications were collected. Anterior retroperitoneal approach to the spine was carried out by a single general surgeon., Results: Ninety-seven patients (37%) developed at least 1 complication. Forty-nine percent of patients with a history of abdominal surgery developed a postoperative complication compared with 28% of patients without such history (RR = 1.747, P≤ 0.001). After controlling for other factors such as age, sex, body mass index, diagnostic groups, and preoperative comorbidities (hypertension, diabetes, and smoking status), these differences remained statistically significant. When each type of complication was considered separately, there was a statistically significant difference in the incidence of general complications (RR = 2.384, P = 0.007), instrumentation-related complications (RR = 2.954, P = 0.010), and complications related to the anterior approach (RR = 1.797, P = 0.021)., Conclusion: Anterior lumbar interbody fusion via a midline incision and a retroperitoneal approach was associated with 37% overall rate of complication. Patients with a history of abdominal or pelvic surgery are at a higher risk of developing general, instrumentation, and anterior approach-related complications.

Study Design: Retrospective analysis was performed of a multi-center Canadian Spine Outcomes and Research Network (CSORN) surgical database. Objective: To determine the rate and time to return to work (RTW) based on workload intensity after elective degenerative lumbar spine surgery. Methods: Patients working pre-operatively, aged greater than 18, who underwent a primary one- or two-level elective lumbar spine surgery for degenerative conditions between January 2015 and October 2020 were evaluated. The percentage of patients who returned to work at 1 year and the time to RTW post-operatively were analyzed based on workload intensity. Results: Of the 1290 patients included in the analysis, the overall rate of RTW was 82% at 1 year. Based on workload there was no significant difference in time to RTW after a fusion procedure, with median time to RTW being 10 weeks. For non-fusion procedure, the sedentary group had a statistically significantly quicker time to RTW than the light-moderate (P <.005) and heavy-very heavy (<.027) groups. Conclusions: The rate of RTW ranged between 84% for patients with sedentary work to 77% for patient with a heavy-very heavy workload. Median time to resumption of work was about 10 weeks following a fusion regardless of work intensity. There was more variability following non-fusion surgeries such as laminectomy and discectomy reflecting the patient's job demands. [ABSTRACT FROM AUTHOR]

Background Context: Resident involvement in the operating room is a vital component of their medical education. Conflicting and limited research exists regarding the effects of surgical resident participation on spine surgery patient outcomes.Purpose: To determine the effect of resident involvement on surgery duration, length of hospital stay and 30-day postoperative complication rates in common spinal surgery using the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP) database.Study Design: Multicenter retrospective cohort study.Patient Sample: A total of 1,441 patients met the inclusion criteria: 1,142 patients had surgeries with an attending physician alone and 299 patients had surgeries with trainee involvement. All anterior cervical or posterior lumbar surgery patients were identified. Patients who had missing trainee involvement information, surgery for cancer, preoperative infection or dirty wound classification, spine fractures, traumatic spinal cord injury, intradural surgery, thoracic surgery, and emergency surgery were excluded.Outcome Measures: The main outcomes of interest analyzed from the ACS-NSQIP database included surgical complications, medical complications, length of hospital stay, and surgery duration.Methods: Propensity score for risk of any complication was calculated to account for baseline characteristic differences between the attending alone and trainee present group. Multivariate logistic regression was used to investigate the impact of resident involvement on surgery duration, length of hospital stay, and 30-day postoperative complication rates.Results: After adjusting using the calculated propensity score, the multivariate analysis demonstrated that there was no significant difference in any complication rates between surgeries involving trainees compared to surgeries with attending surgeons alone. Surgery times were found to be significantly longer for surgeries involving trainees. To further explore this relationship, separate analyses were performed for tertiles of predicted surgery duration, cervical or lumbar surgery, fusion or nonfusion, and inpatient or outpatient surgery. The effect of trainee involvement on increasing surgery time remained significant for medium predicted surgery duration, longer predicted surgery duration, cervical surgery, lumbar surgery, fusion surgery, and inpatient surgery. There were no significant differences reported for any other factors.Conclusions: After adjusting for confounding, we demonstrated in a national database that resident involvement in surgeries did not increase complication rates. We demonstrated that surgeries with more complex features may lead to an increase in operative time when trainees are involved. Further study is required to determine how to efficiently integrate resident involvement in surgeries without affecting their medical education. [ABSTRACT FROM AUTHOR]

Spinal metastases occur primarily in the thoracic spine (50%–60%), less commonly in the lumbar (30%–35%), and, infrequently, in the cervical spine (10%–15%). There has been only 1 study with a limited population comparing the postoperative outcome among cervical, thoracic, and lumbar spine metastasis. The aim of this study is to identify whether the region of surgically treated spinal metastasis affects postoperative outcomes. A retrospective study of patients with spinal metastasis was performed. The collected data were as follows: age, gender, smoking history, tumor histology, revised Tokuhashi score, preoperative and postoperative American Spinal Injury Association score, region of spinal metastasis, ambulatory status, surgical approach, surgery time, blood loss, complications, length of hospital stay, postoperative pain relief, postoperative adjuvant therapy, and survival. Data were analyzed to identify the factors affecting the survival and postoperative functional outcome. We studied 191 patients with spinal metastasis including 47 cervical spine metastases, 96 thoracic spine metastases, and 48 lumbar spine metastases, with a mean age of 60.91 ± 9.72 years. The overall median survival was 7 months (95% confidence interval, 2.9–20.63 months). Univariate analysis showed that region of the spine involved with metastasis did not significantly affect the survival and postoperative motor function improvement. Multivariate analysis showed that revised Tokuhashi score, postoperative radiotherapy, and postoperative chemotherapy were independent factors affecting survival. The rate of 30-day complications among patients with different regions of spine metastasis did not reach significance. The postoperative outcomes of patients undergoing surgery for metastases are not affected by the region of the spine. [ABSTRACT FROM AUTHOR]

Lumbar interbody fusion (LIF) is a surgical treatment for degenerative diseases of the lumbar spine. Decompression of neural elements can be achieved directly via posterior approaches, or indirectly through anterior approaches. Though direct decompression through posterior approaches are traditionally used, indirect decompression through anterior approaches and restoration of anatomical disc height with large implants is also well described. To date, there is limited comparative evidence supporting the superiority of one surgical approach over another in terms of long-term clinical outcomes. Our objective is to compare long-term (>1 year) outcomes between anterior (indirect decompression) and posterior (direct decompression) approaches to lumber interbody fusion (LIF) surgery by means of a matched cohort using a nationwide, multicenter observational registry. This is a one-to-one propensity score matched analysis using data from the Canadian Spine Outcomes and Research Network national registry, a nationwide multicentre database compiling prospectively collected data from 18 tertiary care academic and nonacademic hospitals across Canada. Data were collected for adult patients with a degenerative diagnosis who underwent anterior or posterior LIF between January 1, 2015, and February 15, 2022. Patient-reported outcome measures (PROMs) were compared and included Oswestry Disability Index (ODI), the 12-item Short-Form Health Survey (SF)-12 survey, and numerical rating scales (NRS) for leg and back pain at 12 months and 24 months after surgery. Adverse events were also reported according to a standardized protocol. Baseline variables were used in a logistic regression model for calculating the propensity score for being in the anterior or posterior cohort. There were 1,339 patients who met inclusion criteria. Sixty-seven patients were in the anterior cohort and 1,272 were in the posterior cohort. Before matching, patients in the anterior cohort were significantly younger and had a lower BMI. Following matching, 55 patient pairs were identified, and the mean (SD) ages were 60 (10.5) and 62 (10.7) years (p=0.25), the mean (SD) BMI 27.8 (5.46) and 27.3 (4.88) kg/m2 (p=0.61), and the proportion of females 56.4% and 54.6% (p=0.84) for anterior and posterior cohorts, respectively. At 1-year follow up, patients in the anterior cohort had significantly less back pain (2 vs 4 NRS, p=0.0086), however this difference did not persist at 2-years of follow-up. Using prospectively collected data from a large nationwide registry in Canada, we demonstrated that anterior LIF through indirect decompression is associated with less back pain at 1-year follow-up compared to the standard posterior (direct decompression) approaches, but at 2-years follow-up both approaches yielded similar pain relief. Taken together, posterior direct decompression and anterior indirect decompression are reliable methods for interbody fusion of the lumbar spine with comparable long term results. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Background: With spinal surgery rates increasing in North America, models that are able to accurately predict which patients are at greater risk of developing complications are highly warranted. However, the previously published methods which have used large, multi-centre databases to develop their prediction models have relied on the receiver operator characteristics curve with the associated area under the curve (AUC) to assess their model's performance. Recently, it has been found that a precision-recall curve with the associated F1-score could provide a more realistic analysis for these models.Purpose: To develop a logistic regression (LR) model for the prediction of complications following posterior lumbar spine surgery and to then assess for any difference in performance of the model when using the AUC versus the F1-score.Study Design: Retrospective review of a prospective cohort.Patient Sample: The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) registry was used. All patients that underwent posterior lumbar spine surgery between 2005 to 2016 with appropriate data were included.Outcome Measures: Both the AUC and F1-score were utilized to assess the prognostic performance of the prediction model.Methods: In order to develop the LR model used to predict a complication during or following spine surgery, 19 variables were selected by three orthopedic spine surgeons from the NSQIP registry. Two datasets were developed for this analysis: (1) an imbalanced dataset, which was taken directly from the NSQIP registry, and (2) a down-sampled set. The purpose of the down-sampled set was to balance the data in order to evaluate whether balancing the data had an effect on model performance. The AUC and F1-score were applied to both of these datasets.Results: Within the NSQIP database, 52,787 spine surgery cases were identified of which only 10% of these cases had complications during surgery. Applying the LR model showed a large difference between the AUC (0.69) and the F1 score (0.075) on the imbalanced dataset. However, no major differences existed between the AUC and F1-score when the data was balanced and the LR model was reapplied (0.69 and 0.62, AUC and F1-score, respectively).Conclusions: The F1-score detected a drastically lower performance for the prediction of complications when using the imbalanced data, but detected a performance similar to the AUC level when balancing techniques were utilized for the dataset. This difference is due to a low precision score when many false positive classifications are present, which is not identified when using the AUC value. This lowers the utility of the AUC score, as many of the datasets used in medicine are imbalanced. Therefore, we recommend using the F1-score on large, prospective databases when the data is imbalanced with a large amount of true negative classifications. [ABSTRACT FROM AUTHOR]