γδ T Cells Support Pancreatic Oncogenesis by Restraining αß T Cell Activation.

Inflammation is paramount in pancreatic oncogenesis. We identified a uniquely activated γδT cell population, which constituted ∼40% of tumor-infiltrating T cells in human pancreatic ductal adenocarcinoma (PDA). Recruitment and activation of γδT cells was contingent on diverse chemokine signals. Deletion, depletion, or blockade of γδT cell recruitment was protective against PDA and resulted in increased infiltration, activation, and Th1 polarization of αßT cells. Although αßT cells were dispensable to outcome in PDA, they became indispensable mediators of tumor protection upon γδT cell ablation. PDA-infiltrating γδT cells expressed high levels of exhaustion ligands and thereby negated adaptive anti-tumor immunity. Blockade of PD-L1 in γδT cells enhanced CD4(+) and CD8(+) T cell infiltration and immunogenicity and induced tumor protection suggesting that γδT cells are critical sources of immune-suppressive checkpoint ligands in PDA. We describe γδT cells as central regulators of effector T cell activation in cancer via novel cross-talk.

The attainment of a patient acceptable symptom state in patients undergoing revision spine fusion.

INTRODUCTION: Revision lumbar fusion is most commonly due to nonunion, adjacent segment disease (ASD), or recurrent stenosis, but it is unclear if diagnosis affects patient outcomes. The primary aim of this study was to assess whether patients achieved the patient acceptable symptom state (PASS) or minimal clinically important difference (MCID) after revision lumbar fusion and assess whether this was influenced by the indication for revision. METHODS: We retrospectively identified all 1-3 level revision lumbar fusions at a single institution. Oswestry Disability Index (ODI) was collected at preoperative, three-month postoperative, and one-year postoperative time points. The MCID was calculated using a distribution-based method at each postoperative time point. PASS was set at the threshold of ≤ 22. RESULTS: We identified 197 patients: 56% with ASD, 28% with recurrent stenosis, and 15% with pseudarthrosis. The MCID for ODI was 10.05 and 10.23 at three months and one year, respectively. In total, 61% of patients with ASD, 52% of patients with nonunion, and 65% of patients with recurrent stenosis achieved our cohort-specific MCID at one year postoperatively with ASD (p = 0.78). At one year postoperatively, 33.8% of ASD patients, 47.8% of nonunion patients, and 37% of patients with recurrent stenosis achieved PASS without any difference between indication (p = 0.47). CONCLUSIONS: The majority of patients undergoing revision spine fusion experience significant postoperative improvements regardless of the indication for revision. However, a large proportion of these patients do not achieve the patient acceptable symptom state. While revision spine surgery may offer substantial benefits, these results underscore the need to manage patient expectations.

Relating preoperative MCS-12 to microdiscectomy outcomes.

PURPOSE: To determine the impact of poor mental health on patient-reported and surgical outcomes after microdiscectomy. METHODS: Patients ≥ 18 years who underwent a single-level lumbar microdiscectomy from 2014 to 2021 at a single academic institution were retrospectively identified. Patient-reported outcomes (PROMs) were collected at preoperative, three-month, and one-year postoperative time points. PROMs included the Oswestry Disability Index (ODI), Visual Analog Scale Back and Leg (VAS Back and VAS Leg, respectively), and the mental and physical component of the short form-12 survey (MCS and PCS). The minimum clinically important differences (MCID) were employed to compare scores for each PROM. Patients were categorized as having worse mental health or better mental health based on a MCS threshold of 50. RESULTS: Of 210 patients identified, 128 (61%) patients had a preoperative MCS score ≤ 50. There was no difference in 90-day surgical readmissions or spine reoperations within one year. At 3- and 12-month time points, both groups demonstrated improvements in all PROMs (p < 0.05). At three months postoperatively, patients with worse mental health had significantly lower PCS (42.1 vs. 46.4, p = 0.004) and higher ODI (20.5 vs. 13.3, p = 0.006) scores. Lower mental health scores were associated with lower 12-month PCS scores (43.3 vs. 48.8, p < 0.001), but greater improvements in 12-month ODI (- 28.36 vs. - 18.55, p = 0.040). CONCLUSION: While worse preoperative mental health was associated with lower baseline and postoperative PROMs, patients in both groups experienced similar improvements in PROMs. Rates of surgical readmissions and reoperations were similar among patients with varying preoperative mental health status.

Irrigation and Debridement for Early Periprosthetic Knee Infection: Is It Effective?

BACKGROUND: Irrigation and debridement (I&D) is performed for early management of periprosthetic joint infection (PJI) following total knee arthroplasty (TKA). Symptom reporting is a subjective measure and may miss direct management of PJI. Utilizing an objective time interval from index procedure to I&D may better inform treatment decisions. METHODS: From 2009 to 2017, retrospective review was performed of 55 knee PJI cases at our institution. All patients underwent polyethylene liner exchange and I&D for PJI. Patients were stratified by time from index procedure to I&D (≤2 weeks, >2 weeks). Success was defined as eradication of infection and resolution of presenting symptoms. Failed cases required subsequent procedures due to infection. RESULTS: Average follow-up time after index TKA was 2.5 years. Among patients with I&D within 2 weeks of index TXA, 14 patients (82%) were successfully treated while 3 (18%) had infection recurrence. These outcomes were significantly improved compared to patients with I&D after 2 weeks: 19 (50%) successes and 19 (50%) failures (P = .024). Staphylococcal species were the most frequent pathogen in patients treated before and after 2 weeks of index TKA (39% and 50%, respectively). Outcomes were pathogen-independent in PJIs treated before or after 2 weeks of index TKA (P = .206 and .594, respectively). CONCLUSION: Our results demonstrate that patients with early PJI managed with I&D and liner exchange within 2 weeks of index TKA had higher rates of treatment success when compared to those with I&D beyond 2 weeks. These findings suggest that time from index TKA to I&D is an objective and reliable indicator of treatment success when considering I&D in acute onset knee PJI.

Biomechanical Comparison of Corticopedicular Spine Fixation versus Pedicle Screw Fixation in a Lumbar Degenerative Spondylolisthesis Finite Element Analysis Model.

OBJECTIVE: To compare the stability of a corticopedicular posterior fixation (CPPF) device with traditional pedicle screws for decompression and fusion in adult degenerative lumbar spondylolisthesis. METHODS: Finite element analysis (FEA) was used in a validated model of grade 1 L4-L5 spondylolisthesis to compare segmental stability after laminectomy alone, laminectomy with pedicle screw fixation, or laminectomy with CPPF device fixation. A 500-N follower load was applied to the model and different functional movements were simulated by applying a 7.5-Nm force in different directions. Outcomes included degrees of motion, tensile forces experienced in the CPPF device, and stresses in surrounding cortical bone. RESULTS: At maximum loading, laminectomy alone demonstrated a 1° increase in flexion range of motion, from 6.35° to 7.39°. Laminectomy with pedicle screw fixation and CPPF device fixation both reduced spinal segmental motion to ≤1° at maximum loading in all ranges of motion, including flexion (0.94° and 1.09°), extension (-0.85° and -1.08°), lateral bending (-0.56° and -0.96°), and torsion (0.63° and 0.91°), respectively. There was no significant difference in segmental stability between pedicle screw fixation and CPPF device fixation during maximum loading, with a difference of ≤0.4° in any range of motion. Tensile forces in the CPPF device remained ≤51% the ultimate load to failure (487 N) and stress in surrounding cortical bone remained ≤84% the ultimate stress of cortical bone (125.4 MPa) during maximum loading. CONCLUSIONS: CPFF fixation demonstrated similar segmental stability to traditional pedicle screw fixation whereas tensile forces and stress in surrounding cortical bone remained below the load to failure.

A new perspective on intervertebral disc calcification-from bench to bedside.

Disc degeneration primarily contributes to chronic low back and neck pain. Consequently, there is an urgent need to understand the spectrum of disc degeneration phenotypes such as fibrosis, ectopic calcification, herniation, or mixed phenotypes. Amongst these phenotypes, disc calcification is the least studied. Ectopic calcification, by definition, is the pathological mineralization of soft tissues, widely studied in the context of conditions that afflict vasculature, skin, and cartilage. Clinically, disc calcification is associated with poor surgical outcomes and back pain refractory to conservative treatment. It is frequently seen as a consequence of disc aging and progressive degeneration but exhibits unique molecular and morphological characteristics: hypertrophic chondrocyte-like cell differentiation; TNAP, ENPP1, and ANK upregulation; cell death; altered Pi and PPi homeostasis; and local inflammation. Recent studies in mouse models have provided a better understanding of the mechanisms underlying this phenotype. It is essential to recognize that the presentation and nature of mineralization differ between AF, NP, and EP compartments. Moreover, the combination of anatomic location, genetics, and environmental stressors, such as aging or trauma, govern the predisposition to calcification. Lastly, the systemic regulation of calcium and Pi metabolism is less important than the local activity of PPi modulated by the ANK-ENPP1 axis, along with disc cell death and differentiation status. While there is limited understanding of this phenotype, understanding the molecular pathways governing local intervertebral disc calcification may lead to developing disease-modifying drugs and better clinical management of degeneration-related pathologies.

Are tourniquets indicated in total knee arthroplasty in the era of tranexamic acid: A meta-analysis and systematic review.

Introduction: There is conflicting evidence in the literature regarding the clinical utility of tourniquets in total knee arthroplasty (TKA), specifically in regards to perioperative blood loss. In this meta-analysis and systematic review, we aim to evaluate the clinical advantages and disadvantages associated with tourniquet use in the setting of TKA. Methods: A systematic review was conducted through April 2017 using keywords: "tourniquet" and "total knee arthroplasty" or "total knee replacement". Perioperative variables including TXA use, blood loss, incidence of venous thromboembolism (VTE), and wound complications were either extracted from the studies or corresponding authors were contacted. A sub-analysis was conducted to evaluate the effects of TXA on intraoperative and total blood loss (TBL), and VTE incidence. Results: After review of 558 articles, 19 studies reporting outcomes in 1094 patients were analyzed. Intraoperative blood loss was significantly lower in the tourniquet cohorts compared to non-tourniquet (p < 0.01). TBL was reduced in tourniquet groups but not significantly (p = 0.08). In contrast, calculated blood loss was greater in tourniquet groups, but this difference was not significant (p = 0.43). There was a greater likelihood for wound complications and VTE among tourniquet assisted TKA, albeit only significant for the former (p = 0.01). TXA sub-analysis demonstrated intraoperative blood loss was significantly reduced with tourniquet use regardless of TXA implementation (p < 0.01). In studies without TXA, tourniquet patients were at greater risk of developing VTE (p = 0.08). These risks decreased with TXA administration. Conclusion: This meta-analysis demonstrates that tourniquets prevent intraoperative blood loss, yet within the postoperative period, there is no significant difference in TBL between tourniquet and non-tourniquet assisted TKA. Level of evidence: Level II; Systematic Review and Meta-Analysis.

The Surgical Algorithm for the AO Spine Sacral Injury Classification System.

STUDY DESIGN: Global cross-sectional survey. OBJECTIVE: To establish a surgical algorithm for sacral fractures based on the Arbeitsgemeinschaft für Osteosynthesefragen (AO) Spine Sacral Injury Classification System. SUMMARY OF BACKGROUND DATA: Although the AO Spine Sacral Injury Classification has been validated across an international audience of surgeons, a consensus on a surgical algorithm for sacral fractures using the Sacral AO Spine Injury Score (Sacral AOSIS) has yet to be developed. METHODS: A survey was sent to general orthopedic surgeons, orthopedic spine surgeons, and neurosurgeons across the five AO spine regions of the world. Descriptions of controversial sacral injuries based on different fracture subtypes were given, and surgeons were asked whether the patient should undergo operative or nonoperative management. The results of the survey were used to create a surgical algorithm based on each subtype's sacral AOSIS. RESULTS: An international agreement of 70% was decided on by the AO Spine Knowledge Forum Trauma experts to indicate a recommendation of initial operative intervention. Using this, sacral fracture subtypes of AOSIS 5 or greater were considered operative, while those with AOSIS 4 or less were generally nonoperative. For subtypes with an AOSIS of 3 or 4, if the sacral fracture was associated with an anterior pelvic ring injury (M3 case-specific modifier), intervention should be left to the surgeons' discretion. CONCLUSION: The AO Spine Sacral Injury Classification System offers a validated hierarchical system to approach sacral injuries. Through multispecialty and global surgeon input, a surgical algorithm was developed to determine appropriate operative indications for sacral trauma. Further validation is required, but this algorithm provides surgeons across the world with the basis for discussion and the development of standards of care and treatment.

In-hospital mortality trends after surgery for traumatic thoracolumbar injury: A national inpatient sample database study.

Introduction: Given the increasing incidence of traumatic thoracolumbar injuries in recent years, studies have sought to investigate potential risk factors for outcomes in these patients. Research question: The aim of this study was to investigate trends and risk factors for in-hospital mortality after fusion for traumatic thoracolumbar injury. Materials and methods: Patients undergoing thoracolumbar fusion after traumatic injury were queried from the National Inpatient Sample (NIS) from 2012 to 2017. Analysis was performed to identify risk factors for inpatient mortality after surgery. Results: Patients in 2017 were on average older (51.0 vs. 48.5, P = 0.004), had more admitting diagnoses (15.5 vs. 10.7, p < 0.001), were less likely to be White (75.8% vs. 81.2%, p = 0.006), were from a ZIP code with a higher median income quartile (Quartile 1: 31.4% vs. 28.6%, p = 0.011), and were more likely to have Medicare as a primary payer (22.9% vs. 30.1%, p < 0.001). Bivariate analysis of demographics and surgical characteristics demonstrated that patients in the in-hospital mortality group (n = 90) were older (70.2 vs. 49.6, p < 0.001), more likely to be male (74.4% vs. 62.8%, p = 0.031), had a great number of admitted diagnoses (21.3 vs. 12.7, p < 0.001), and were more likely to be insured by Medicare (70.0% vs. 27.0%, p < 0.001). Multivariate regression analysis found age (OR 1.06, p < 0.001) and Black race (OR 3.71, p = 0.007) were independently associated with in-hospital mortality. Conclusion: Our study of nationwide, traumatic thoracolumbar fusion procedures from 2012 to 2017 in the NIS database found older, black patients were at increased risk for in-hospital mortality after surgery.

Evaluation of perioperative care and drivers of cost in geriatric thoracolumbar trauma.

Introduction: As the population of elderly patients continues to rise, the number of these individuals presenting with thoracolumbar trauma is expected to increase. Research question: To investigate thoracolumbar fusion outcomes for patients with vertebral fractures as stratified by decade. Secondarily, we examined the variability of cost across age groups by identifying drivers of cost of care. Materials and methods: We queried the United States Nationwide Inpatient Sample(NIS) for adult patients undergoing spinal fusion for thoracolumbar fractures between 2012 and 2017. Patients were stratified by decade 60-69(sexagenarians), 70-79(septuagenarians) and 80-89(octogenarians). Bivariable analysis followed by multivariable regression was performed to assess independent predictors of length of stay(LOS), hospital cost, and discharge disposition. Results: A total of 2767 patients were included, of which 46%(N = 1268) were sexagenarians, 36% septuagenarians and 18%(N = 502) octogenarians. Septuagenarians and octogenarians had shorter LOS compared to sexagenarians(ß = -0.88 days; p = 0.012) and(ß = -1.78; p < 0.001), respectively. LOS was reduced with posterior approach(-2.46 days[95% CI: 3.73-1.19]; p < 0.001), while Hispanic patients had longer LOS(+1.97 [95% CI: 0.81-3.13]; p < 0.001). Septuagenarians had lower total charges $12,185.70(p = 0.040), while the decrease in charges in octogenarians was more significant, with a decrease of $26,016.30(p < 0.001) as compared to sexagenarians. Posterior approach was associated with a decrease of $24,337.90 in total charges(p = 0.026). Septuagenarians and octogenarians had 1.72 higher odds(p < 0.001) and 4.16 higher odds(p < 0.001), respectively, of discharge to a skilled nursing facility. Discussion and conclusions: Healthcare utilization in geriatric thoracolumbar trauma is complex. Cost reductions in the acute hospital setting may be offset by unaccounted costs after discharge. Further research into this phenomenon and observed racial/ethnic disparities must be pursued.

Does Paraspinal Muscle Mass Predict Lumbar Lordosis before and after Decompression for Degenerative Spinal Stenosis?

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVE: The purpose of this study was to determine if muscle mass and quality of the lumbar paraspinal muscles was associated with improvements in lumbar lordosis and other sagittal parameters after isolated posterior lumbar decompression surgery for lumbar spinal stenosis. SUMMARY OF BACKGROUND DATA: Over time, either due to degenerative changes or other spinal conditions, individuals may develop sagittal imbalance. In patients with lumbar spinal stenosis, sagittal imbalance can further exacerbate symptoms of pain and radiculopathy. Sarcopenia of paraspinal muscles has been implicated in previous spine research as a variable with influence on surgical outcomes. METHODS: Sagittal parameters were measured on preoperative and postoperative lateral lumbar radiographs and included lumbar lordosis (LL), sacral slope (SS), and pelvic tilt (PT). Preoperative MRI images were evaluated at the base of the L4 vertebral body to assess muscles mass of the psoas muscle and paravertebral muscles (PVM) and Goutallier grade of the PVM. Patients were divided into 3 muscle size groups based on PVM normalized for body size (PVM/BMI): Group A (smallest), Group B, and Group C (largest). RESULTS: Patients in Group C had greater LL preoperatively (51.5° vs. 47.9° vs. 43.2, P=0.005) and postoperatively (52.2° vs. 48.9° vs. 45.7°, P=0.043). There was no significant difference in the ∆LL values between groups (P>0.05). Patients in Group C had larger SS preoperatively (35.2° vs. 32.1° vs. 30.0°, P=0.010) and postoperatively (36.1° vs. 33.0° vs. 31.7°, P=0.030). Regression analysis showed that PVM/BMI was a significant predictor of LL preoperatively (P=0.039) and postoperatively (P=0.031), as well as SS preoperatively (P=0.001) and postoperatively (P<0.001). CONCLUSION: Muscle mass of the paravertebral muscles significantly impacts lumbar lordosis and sacral slope in patients with lumbar spinal stenosis before and after posterior lumbar decompression. These findings highlight a need to address risk factors for poor muscle quality in patients with sagittal imbalance.

Immediate vs. delayed venous thromboembolism prophylaxis following spine surgery: increased rate of unplanned reoperation for postoperative hematoma with immediate prophylaxis.

BACKGROUND CONTEXT: There is significant variability in postoperative chemoprophylaxis protocols amongst spine providers due to perceived risks and benefits, but limited data on the topic. At our institution, both orthopaedic spine and neurosurgery departments utilize unfractionated subcutaneous heparin in identical dosages and frequency, with the only difference being time to initiation postoperatively. PURPOSE: To evaluate the rate of symptomatic venous thromboembolism (VTEs) and unplanned reoperation for hematoma based on timing of chemoprophylaxis initiation. STUDY DESIGN/SETTING: Single institution retrospective cohort study. PATIENT SAMPLE: Patients undergoing elective spine surgery, excluding patients undergoing surgery in the setting of trauma, malignancy, or infection OUTCOME MEASURES: Outcome measures included the diagnosis of a venous thromboembolism within 90 days of surgery and unplanned reoperation for a hematoma METHODS: Patients undergoing elective spine surgery from 2017 to 2021 were grouped based on chemoprophylaxis protocol. In the "immediate" group, patients received subcutaneous heparin 5000 units every 8 hours starting immediately after surgery, and in the "delayed" group, patients received chemoprophylaxis starting postoperative day (POD)-2 for any decompressions and/or fusions involving a spinal cord level (i.e., L2 and above) and POD-1 for those involving only levels below the spinal cord (i.e., L3 to pelvis). A cox proportional hazards model was created to assess independent predictors of venous thromboembolic events, while a logistic regression was utilized for unplanned reoperations for hematoma. RESULTS: Of 8,704 patients, a total of 98 (1.13%) VTE events occurred, of which 43 (0.49%) were pulmonary embolism. Fifty-four patients (0.62%) had unplanned reoperations for postoperative hematomas. On cox proportional hazards model analysis, immediate chemoprophylaxis was not protective of a venous thromboembolism (Hazard Ratio: 1.18, p=.436), but, it was a significant independent predictor for unplanned reoperation for hematoma on multivariable logistic regression modeling (Odds Ratio: 3.29, p<.001). CONCLUSIONS: Both chemoprophylaxis protocols in our study resulted in low rates of VTE and postoperative hematoma. However, our findings suggest that the delayed chemoprophylaxis protocol may mitigate postoperative hematoma formation without increasing the risk for a thrombotic event.

The Effect of Muscle Quality on Outcomes after Microdiscectomy.

OBJECTIVES: To investigate the relationship between muscle quality and 1) patient-reported outcomes and 2) surgical outcomes after lumbar microdiscectomy surgery. METHODS: Adult patients (≥18 years) who underwent lumbar microdiscectomy from 2014 to 2021 at a single academic institution were identified. Outcomes were collected during the preoperative, 3-month, 6-month, and 1-year postoperative periods. Those included were the Oswestry Disability Index (ODI), Visual Analog Scale Back and Leg (VAS-Back and VAS-Leg, respectively), and the mental and physical component of the short-form 12 survey (MCS and PCS). Muscle quality was determined by 2 systems: the normalized total psoas area (NTPA) and a paralumbar-based grading system. Surgical outcomes including 90-day surgical readmissions and 1-year reoperations were also collected. RESULTS: Of the 218 patients identified, 150 had good paralumbar muscle quality and 165 had good psoas muscle quality. Bivariant analysis demonstrated no difference between groups regarding surgical outcomes (P > 0.05). Multivariable analysis demonstrated that better paralumbar muscle quality was not associated with any consistent changes in patient reported outcomes. Higher NTPA was associated with improved PCS at 6 months (est. = 6.703, [95% CI: 0.759-12.646], P = 0.030) and 12 months (est. = 6.625, [95% CI: 0.845-12.405], P = 0.027). There was no association between muscle quality and surgical readmissions or reoperations. CONCLUSIONS: Our analysis demonstrated that higher psoas muscle quality was associated with greater physical improvement postoperatively. Muscle quality did not affect surgical readmissions or reoperations. Additional studies are needed for further assessment of the implications of muscle quality on postoperative outcomes.

Which North American spine society disc herniation morphology descriptors are most associated with improvements in clinical outcomes after microdiscectomy?

Background: The North American Spine Society (NASS) assembled the first ever comprehensive naming system for describing lumbar disc disease, including lumbar disc herniation. The objectives of this study were (1) to determine which NASS descriptors are most predictive of independent patient-reported outcomes after microdiscectomy and (2) to identify the inter-rater reliability of each NASS descriptor. Methods: Adult patients (≥18 years) who underwent a lumbar microdiscectomy from 2014-2021 were retrospectively identified. Patient-reported outcome measures (PROMs) were collected at preoperative, 3-month, and 1-year postoperative time points. Lumbar disc herniations were evaluated and classified on preoperative MRI using the NASS lumbar disc nomenclature specific to disc herniation. Results: About 213 microdiscectomy patients were included in the final analysis. Herniation descriptors exhibiting the greatest reliability included sequestration status (κ=0.83), axial disc herniation area (κ=0.83), and laterality (κ=0.83). The descriptor with the lowest inter-rater reliability was direction of migration (κ=0.53). At 3 months, a sequestered herniation was associated with lower odds of achieving the minimal clinically important difference (MCID) for ODI (p=.004) and MCS (p=.032). At 12 months, a similar trend was observed for Oswestry Disability Index (ODI) MCID achievement (p=.001). At 3 months, a herniation with larger axial area was a predictor of MCID achievement in ODI (p=.004) and the mental component summary (MCS) (p=.009). Neither association persisted at 12 months; however, larger axial disc herniation area was able to predict MCID achievement in the Visual Analogue Scale (VAS) leg (p=.031) at 12 months. Conclusions: The utility of the NASS nomenclature system in predicting postoperative outcomes after microdiscectomy has yet to be studied. We showed that sequestration status and disc area are both reliable and able to predict the odds of achieving MCID in certain clinical outcomes at 3 months and 12 months after surgery. Hence, preoperative imaging analysis of lumbar disc herniations may be useful in accurately setting patient expectations.

The Role of L1PA in Patient-reported Outcomes in Patients Undergoing Single-level Lumbar Fusion for Degenerative Spondylolisthesis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine whether the L1 pelvic angle (L1PA) can be used to predict quality of life outcomes for adults one year after L4-L5 fusion to treat degenerative spondylolisthesis. SUMMARY OF BACKGROUND DATA: L1PA is beneficial in the evaluation of preoperative and postoperative quality of life outcomes in patients undergoing surgery for spinal deformity. No studies have examined its utility in surgical patients with degenerative spinal disease. METHODS: Patients undergoing L4-L5 posterolateral decompression and fusion or transforaminal lumbar interbody fusion for degenerative lumbar spondylolisthesis were grouped by preoperative and postoperative L1PA, and further stratified by cut offs of >7.2° and <7.2° based on previous literature. We also stratified patients by presence of an ideal calculated L1PA, defined as (0.5×Pelvic incidence) -21 +/-5°, as proposed by prior literature. Preoperative, one-year postoperative and Δ (postoperative minus preoperative) patient-reported outcome measures (PROMs) and radiographic measurements were collected. RESULTS: Twenty-four patients were identified with preoperative L1PAs <7.2° and 132 with L1PAs >7.2°. Eighteen patients were identified with postoperative L1PAs <7.2° and 138 with L1PAs>7.2°. Sixty-five and fifty-seven patients were identified as having ideal calculated preoperative and postoperative L1PAs, respectively. When using absolute cutoffs, L1PA correlated with pelvic tilt, pelvic incidence, and pelvic incidence-lumbar lordosis mismatch (PI-LL). When using calculated L1PAs, L1PA correlated with lumbar lordosis, PI-LL, pelvic tilt and sacral slope. With respect to PROMs, no statistically significant differences existed between cohorts both preoperatively and at one-year postoperatively on either univariate and multivariate analyses. CONCLUSION: L1PA may be a helpful radiographic consideration that translates to clinically relevant outcomes in spinal deformity. However, it does not appear as predictive of patient outcomes after single-level fusion for patients with L4-L5 degenerative spondylolisthesis. Further studies are warranted to investigate the role of L1PA in degenerative spine patients.

The Impact of Outpatient Physical Therapy on Patient-Reported Outcomes After Lumbar Fusion: Perspective from A Bundled Care Dataset.

OBJECTIVE/BACKGROUND: As value-based care grows in popularity across the United States, more payers have turned toward bundled payment models for surgical procedures. Though episode costs in spine are highly variable, physical therapy (PT) has been identified as a driver of 90-day cost. The goal of this study is to assess the impact of postoperative PT on patient-reported outcomes and cost after lumbar fusion surgery using bundled insurance data. METHODS: Bundled payment information of lumbar fusion episodes-of-care (EOC) from 2019 to 2021 was reviewed at a single, urban, tertiary care center. EOC comprised a 210-day period surrounding the date of the procedure, beginning 30 days preoperatively and ending 180 days postoperatively. Patients were grouped into physical therapy (PT) and no physical therapy (no PT) groups based on the presence of PT claims. RESULTS: Bivariate analysis of surgical outcomes revealed similar overall complication rates (P = 0.413), 30-day readmissions (P = 0.366), and 90-day readmissions (P = 0.774). Patients who did not participate in postoperative PT had significantly better preoperative physical component score (PCS) (P = 0.003), 6-month postoperative PCS (P = 0.001), and 6-month ΔPCS (P = 0.026) compared with patients who participated in postoperative PT. At 1-year follow-up, patients who did not participate in PT had less leg pain (P = 0.041) than those who did participate in PT. CONCLUSIONS: Our study finds that PT after lumbar fusion is not associated with significant improvement in Oswestry Disability Index, PCS, mental component score, or visual analog scale pain scores. Additionally, the number of PT sessions a patient attends has no correlation with improvement in these outcomes.

Impact of the Prognostic Nutritional Index on Outcomes in Native Spine Infection.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The objective of this study was to determine if baseline prognostic nutritional index (PNI) score could be used to predict outcomes in patients with native spine infections, including the need for operative intervention. SUMMARY OF BACKGROUND DATA: Nutritional status is an important, potentially modifiable risk factor, to consider in the native spine population. The prognostic nutritional index (PNI) score is a tool that has demonstrated utility as a marker of preoperative nutritional status in patients undergoing surgery, however it has not yet been studied in the context of native spine infection. METHODS: Adult patients (≥18 y) with a diagnosis of spine infection from 2017-2022 were retrospectively identified. Native spine infection was defined as a diagnosis of spinal infection in the absence of prior spine surgery within 3 months of diagnosis. PNI was calculated using the equation: PNI = 10 * serum albumin (g/dL) + 0.005 Total Lymphocyte Count (/µL. Patients were stratified into high or low PNI groups based on their PNI being above or below the average, respectively. RESULTS: There were 45 patients in the low PNI group and 56 patients in the high PNI group. Patients in the low PNI group were more likely to require surgery (P=0.046), had more levels decompressed (P=0.012), and were more likely to undergo two or more irrigation & debridement procedures (P=0.016). Patients in the low PNI group were also less likely to be discharged home (P=0.016). There was no difference in length of stay, inpatient complications, 90-day readmissions, 90-day ED visits, or 1-year reoperations between groups. CONCLUSION: While post-admission outcomes and inpatient complications were similar across PNI groups, PNI on admission provides useful insight into the severity of infection and predicts the need for operative intervention in patients presenting with native spine infection.

An Update in Complication Rates Associated With Anterior Lumbar Surgery: A Systematic Review and Meta-Analysis.

STUDY DESIGN: Systematic Review and meta-analysis. OBJECTIVE: To conduct an updated systematic review and meta-analysis of complications associated with different anterior fusion techniques/approaches and adjuvant resources (i.e., computed tomography angiography (CTA), rhBMP-2, and access surgeons). METHODS: A systematic review was conducted from 1/1/2014-4/1/2024 for studies evaluating the incidence of complications associated with anterior lumbar procedures. Comparisons of complications were made between surgical approach, use of CTA, rhBMP-2, and access surgeons. Meta-analyses were conducted using a generalized linear mixed model. RESULTS: 54 studies were included in the final analysis with 8066 patients and an average follow-up of 31.2 months. The overall complication rate associated with anterior lumbar surgery was 13.1%, including an intraoperative complication rate of 3.8%, postoperative complication rate of 7.4%, infection rate of 1.5%, and reoperation rate of 1.7%. Forest plot analysis showed no significant difference in overall complication rates between open and mini-open techniques, although mini-open techniques were associated with lower overall reoperation rates. The use of CTA was associated with an increase in intraoperative and overall complications, and the use of an access surgeon was associated with a decreased risk of reoperation. The use of rhBMP-2 was not associated with overall complication risk. CONCLUSIONS: While anterior lumbar surgery provides numerous benefits, surgeons and patients alike should be aware of the complication and safety profile prior to surgery. High quality studies are warranted to help elucidate the true benefit of certain techniques and adjuvant resources in reducing complications.

One Year Patient Reported Outcomes After Single-Level Lumbar Fusion at Orthopedic Specialty Hospital Compared to Tertiary Referral Center.

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.