Psoas muscle cross sectional area relates to bone density and microarchitecture in candidates for spine fusion surgery.

Prior studies demonstrate that muscle and bone health are integrally related, and both independently impact orthopedic surgery outcomes. However, relationships between bone density, in vivo microarchitecture, and muscle area have not been previously investigated in orthopedic surgery patients. This study assessed associations between psoas cross sectional area (CSA), bone mineral density (BMD), and microstructure in a cohort undergoing spine fusion. Pre-operatively, bilateral psoas CSA was measured on axial lumbar spine CT in the L3-L4 disc space. To adjust for body size, Psoas Muscle Index (PMI) was calculated (CSA divided by the square of patient height). High resolution peripheral quantitative CT (HR-pQCT, XtremeCT2) assessed volumetric BMD (vBMD), cortical (Ct) and trabecular (Tb) microarchitecture at the distal radius and tibia. Areal BMD (aBMD) was measured by DXA at the lumbar spine (LS), total hip (TH), femoral neck (FN), and the 1/3 radius (1/3R). Pearson correlations related psoas CSA and bone imaging parameters before and after correcting for height and weight. Among 88 patients included, mean age was 63 ± 12 years, BMI was 28 ± 7 kg/m2, 47 (53 %) were female. Larger psoas CSA was associated with higher vBMD, greater Ct thickness and better Tb microarchitecture (higher Tb number and lower Tb separation) at the tibia and radius. Larger psoas CSA was also associated with greater aBMD at TH and FN bilaterally and 1/3R (r 0.33 to 0.61; p < 0.002 for all comparisons). Psoas CSA was not associated with aBMD at the LS. Similar results were observed when relating PMI, and adjusting for age, height and weight to HR-pQCT and DXA measurements. Investigation of subgroups by sex demonstrated that relationships were similar magnitude among women but not the men. Patients who underwent primary compared to revision spine surgery had similar associations. Our results demonstrate a link between psoas muscle size and peripheral bone microarchitecture among patients undergoing posterior lumbar spinal fusion. Given the importance of both muscle and skeletal integrity to the success of spine surgery, further study regarding the associations between measurements of psoas muscle, bone microarchitecture, and surgical outcomes is warranted.

Robot-Assisted Spine Surgery: The Pearls and Pitfalls.

Robot-assisted spine surgery has gained notable popularity among surgeons because of recent advancements in technology. These innovations provide several key benefits, including high screw accuracy rates, reduced radiation exposure, customized preoperative and intraoperative planning options, and improved ergonomics for surgeons. Despite the promising outcomes reported in literature, potential technical challenges remain across various robotic platforms. It is crucial for surgeons to remember that robotic platforms are shared-control systems, requiring the surgeon to maintain primary control throughout the procedure. To ensure patient safety, surgeons should be well versed in common technical pitfalls and strategies to mitigate these limitations.

Analysis of 1027 Adverse Events Reports for Interspinous Process Devices From the US Food and Drug Administration Manufacturer and User Facility Device Experience Database.

BACKGROUND: Interspinous process devices (IPDs) introduce a new class of complications to surgical decompression without fusion: hardware-related complications. The purpose of this study was to describe the adverse events associated with IPDs. STUDY DESIGN: This was a retrospective review of the Food and Drug Administration Manufacturer and User Facility Device Experience database. METHODS: The database was queried from its inception to November 2022 for reports associated with "Prosthesis, Spinous Process Spacer/Plate." Entries were categorized by event type, patient impact, and interventions. RESULTS: A total of 943 surgery-related adverse events were identified. The most common intraoperative events were implant malfunctions (39.7%, n = 374) and fractures (2.2%, n = 21). The most common postoperative events were persistent pain (26.6%, n = 251), implant migration (19.1%, n = 180), and fracture (6.8%, n = 64). The most common resultant outcome of an adverse event was the need for revision surgery (48.8%, n = 460). The need for revision surgery was common in patients who experienced fracture (47.1%), implant migration (84.5%), infection (76.7%), and neurological complications (76.9%). Implant migration, fracture, and implant malfunction, 3 complications that are unique to decompression with an IPD as compared with traditional laminectomy, accounted for 45.9% of revisions (211/460), and revision was required in 33.0% of cases where 1 of these complications was reported (211/640). Implant malfunction made up 21.2% of Coflex complications, 47.3% of Superion complications, and 5.2% of X-Stop complications. CONCLUSIONS: The most common adverse events were implant malfunction, inadequate efficacy, implant migration, and fracture. Concerningly, these complications require revision surgery in one-third of cases when they occur. Implant-specific assessments demonstrate a high prevalence of implant malfunctions for the Coflex and Superion implants. CLINICAL RELEVANCE: Interspinous process devices introduce a new class of complications to isolated spinal decompression surgery: implant-related complications. These complications occur both intraoperatively and postoperatively, and they frequently necessitate revision surgery.

The Impact of Preoperative Sagittal Imbalance on Long-term Postoperative Outcomes Following Minimally Invasive Laminectomy.

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.

Are Grit and Self-Control Associated With Patient-Reported Outcomes Following Spine Surgery?

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.

Advanced Visualization in Minimally Invasive Spine Surgery: The Ergonomics, Economics, and Evolution of Camera-Based Tubes and Retractors.

BACKGROUND: Tubular spine surgery has emerged as a hallmark of minimally invasive spine (MIS) procedures. In recent years, thanks to technological advances, tubular dilators and retractors have been integrated with digital cameras to allow for ergonomic, high-definition visualization of the surgical field. OBJECTIVE: To detail the evolution, ergonomics, economics, and outcomes of camera-based tubular spine surgery, spanning the origins of MIS tubular techniques to the current use of operative microscopes and tube-mounted digital cameras (TMDCs). METHODS: This is a narrative review of studies examining the evolution of tubular spine surgery as well as its most recent advances, with a particular emphasis on advances in visualization of the surgical field. RESULTS: Despite early resistance to tubular techniques due to a steep learning curve, minimally invasive tubular approaches are being increasingly adopted by the mainstream spine surgical community, which has resulted in an expansion of both indications and procedural modalities. This can largely be attributed to the increased quality of visualization, as evidenced by improvements in microscopes as well as emerging technologies like exoscopes and TMDCs. Tubular MIS procedures have also achieved superior efficacy compared with open surgical approaches for the treatment of several spinal pathologies while allowing for improved ergonomics, which may have lasting consequences on surgeon longevity. CONCLUSIONS: Advances in visualization technologies have allowed tubular surgery to become an effective, ergonomic, and muscle-sparing alternative to open spine surgery. Further research is necessary to quantify the true costs and outcomes associated with nascent TMDC technology. CLINICAL RELEVANCE: This work elucidates developments in visualization for tubular spine surgery.

The Impact of Endplate Coverage on Heterotopic Ossification Following Cervical Disc Replacement: A Systematic Review and Meta Analysis.

STUDY DESIGN: Systematic review and meta-analysis. OBJECTIVE: Describe the impact of endplate coverage on HO in cervical disc replacement (CDR). SUMMARY OF BACKGROUND DATA: CDR is a motion-sparing alternative to anterior cervical discectomy and fusion. However, the high prevalence of heterotopic ossification threatens to diminish range of motion and limit this benefit associated with CDR. MATERIALS AND METHODS: A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. EMBASE and PubMed databases were queried. Results were deduplicated and screened. Relevant studies were included. All metrics that were reported in ≥3 studies were aggregated for analysis. SPSS was used to perform the meta-analysis. RESULTS: A total of 10 studies were included in the systematic review. Endplate coverage was assessed using a wide variety of measurements, including anteroposterior implant depth (ID), endplate depth (ED), exposed endplate depth (EED), implant depth to endplate depth ratio (ID:ED), EED to ED ratio (EED:ED), implant width (IW) to endplate width (EW) ratio (IW:EW), and the implant area (IA) to endplate area (EA) ratio (IA:EA). No evidence has linked ID (three studies) to HO. Mixed evidence has linked ID:ED (3/5) and IW:ED (1/2) to HO. All available evidence has linked ED (2), EED (4), EED:ED (2), and IA:EA (1) to HO. In our meta-analysis, ID was not found to be a significant risk factor for HO. However, EED and ID:ED were found to be significant risk factors for HO formation. CONCLUSIONS: Exposed endplate, especially as assessed by EED and ID:ED, is a significant risk factor for HO. Surgeons should focus on preoperative planning and intraoperative implant selection to maximize endplate coverage. While optimizing technique and implant selection is crucial, improved implant design may also be necessary to ensure that appropriate implant-endplate footprint matching is possible across the anatomic spectrum.

Impact of preoperative age-adjusted sagittal imbalance on radiographic and clinical outcomes following 1-level minimally invasive transforaminal lumbar interbody fusion for degenerative spondylolisthesis.

OBJECTIVE: Prior studies investigating the use of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) for treatment of degenerative lumbar conditions and concomitant sagittal deformity have not stratified patients by preoperative pelvic incidence (PI)-lumbar lordosis (LL) mismatch, which is the earliest parameter to deteriorate in mild sagittal deformity. Thus, the aim of the present study was to determine the impact of preoperative PI-LL mismatch on clinical outcomes and sagittal balance restoration among patients undergoing MI-TLIF for degenerative spondylolisthesis (DS). METHODS: Consecutive adult patients undergoing primary 1-level MI-TLIF between April 2017 and April 2022 for DS with ≥ 6 months radiographic follow-up were included. Patient-reported outcome measures (PROMs) included the Oswestry Disability Index, visual analog scale (VAS), 12-Item Short-Form Health Survey (SF-12), and Patient-Reported Outcomes Measurement Information System at preoperative, early postoperative (< 6 months), and late postoperative (≥ 6 months) time points. The minimal clinically important difference (MCID) for PROMs was also evaluated. Radiographic parameters included PI, LL, pelvic tilt (PT), and sagittal vertical axis (SVA). Patients were categorized into balanced and unbalanced groups based on preoperative PI-LL mismatch according to age-adjusted alignment goals. Changes in radiographic parameters and PROMs were evaluated. RESULTS: Eighty patients were included (L4-5 82.5%, grade I spondylolisthesis 82.5%, unbalanced 58.8%). Mean clinical and radiographic follow-up were 17.0 and 8.3 months, respectively. The average preoperative PI-LL was 18.8° in the unbalanced group and -3.3° in the balanced group. Patients with preoperative PI-LL mismatch had significantly worse preoperative PT (26.2° vs 16.4°, p < 0.001) and SVA (53.2 vs 9.0 mm, p = 0.001) compared with balanced patients. Patients with preoperative PI-LL mismatch also showed significantly worse PI-LL (16.0° vs 0.54°, p < 0.001), PT (25.9° vs 18.7°, p < 0.001), and SVA (49.4 vs 22.8 mm, p = 0.013) at long-term follow-up. No significant radiographic improvement was observed among unbalanced patients. All patients demonstrated significant improvements in all PROMs (p < 0.05) except for SF-12 mental component score. Achievement of MCID for VAS back score was significantly greater among patients with preoperative PI-LL mismatch (85.7% vs 65.5%, p = 0.045). CONCLUSIONS: Although 1-level MI-TLIF did not restore sagittal alignment in patients with preoperative PI-LL mismatch, patients presenting with DS can expect significant improvement in PROMs following 1-level MI-TLIF regardless of preoperative alignment or extent of correction. Thus, attaining good clinical outcomes in patients with mild sagittal imbalance may not require addressing imbalance directly.

Discrepancy between global- and disease-specific outcome measures following lumbar spine surgery.

OBJECTIVE: The aim of this study was to assess the correlation between patient-perceived changes in health and commonly utilized patient-reported outcome measures (PROMs) in lumbar spine surgery. METHODS: This was a retrospective review of prospectively collected data on consecutive patients who underwent lumbar microdiscectomy, lumbar decompression, or lumbar fusion at a single academic institution from 2017 to 2023. Correlation between the global rating of change (GRC) questionnaire, a 5-item Likert scale (much better, slightly better, about the same, slightly worse, and much worse), and PROMs (Oswestry Disability Index, visual analog scale for back and leg pain, 12-Item Short Form Health Survey Physical Component Summary and Mental Component Summary, and PROMIS physical function) was assessed using Spearman's rank correlation coefficients. RESULTS: A total of 1871 patients (397 microdiscectomies, 965 decompressions, and 509 fusions) were included. A majority of patients in each group rated their lumbar condition as much better at each postoperative time point compared with preoperatively and reported improved health status at each postoperative time point compared with the previous follow-up visit. Statistically significant but weak to moderate correlations were found between GRC and change in PROM scores from the preoperative time point. Correlation between GRC and change in PROM scores from the prior visit showed some statistically significant correlations, but the strengths ranged from very weak to weak. CONCLUSIONS: A majority of patients undergoing lumbar microdiscectomy, decompression, or fusion endorsed notable improvements in health status in the early postoperative period and continued to improve at late follow-up. However, commonly used PROMs demonstrated very weak to moderate correlations with patient-perceived changes in overall lumbar spine-related health status as determined by GRC. Therefore, currently used PROMs may not be as sensitive at detecting these changes or may not be adequately reflecting changes in health conditions that are meaningful to patients undergoing lumbar spine surgery.

What Is the Carbon Footprint of Adult Spinal Deformity Surgery?

Background/Objectives: While the economic cost of adult spinal deformity (ASD) surgery has been studied extensively, its environmental impact is unknown. The aim of this study is to determine the carbon footprint (CF) associated with ASD surgery. Methods: ASD patients who underwent > four levels of corrective surgery between 2017 and 2021 were included. The open group included a posterior-only, single-stage technique, while the minimally invasive surgery (MIS) group was defined as the use of lateral interbody fusion and percutaneous posterior screw fixation. The two groups were propensity-score matched to adjust for baseline demographic, surgical, and radiographic characteristics. Data on all disposables and reusable instruments, anesthetic gas, and non-gas medications used during surgery were collected from medical records. The CF of transporting, using, and disposing of each product and the footprint of energy use in operating rooms were calculated. The CF produced was evaluated using the carbon dioxide equivalent (CO2e), which is relative to the amount of CO2 with an equivalent global warming potential. Results: Of the 175 eligible patients, 15 pairs (65 ± 9 years, 47% female) were properly matched and analyzed for all variables. The average CF generated per case was 147.7 ± 37.3 kg-CO2e, of which 54% was attributable to energy used to sterilize reusable instruments, followed by anesthetic gas released into the environment (17%) and operating room air conditioning (15%). Conclusions: The CF generated during ASD surgery should be reduced using a multidisciplinary approach, taking into account that different surgical procedures have different impacts on carbon emission sources.

Predictors of Nonhome Discharge After Cervical Disc Replacement.

STUDY DESIGN: Retrospective review of a national database. OBJECTIVE: The aim of this study was to identify the factors that increase the risk of nonhome discharge after CDR. SUMMARY OF BACKGROUND DATA: As spine surgeons continue to balance increasing surgical volume, identifying variables associated with patient discharge destination can help expedite postoperative placement and reduce unnecessary length of stay. However, no prior study has identified the variables predictive of nonhome patient discharge after cervical disc replacement (CDR). METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried for patients who underwent primary 1-level or 2-level CDR between 2011 and 2020. Multivariable Poisson regression with robust error variance was employed to identify the predictors for nonhome discharge destination following surgery. RESULTS: A total of 7276 patients were included in this study, of which 94 (1.3%) patients were discharged to a nonhome destination. Multivariable regression revealed older age (OR: 1.076, P <0.001), Hispanic ethnicity (OR: 4.222, P =0.001), BMI (OR: 1.062, P =0.001), ASA class ≥3 (OR: 2.562, P =0.002), length of hospital stay (OR: 1.289, P <0.001), and prolonged operation time (OR: 1.007, P <0.001) as predictors of nonhome discharge after CDR. Outpatient surgery setting was found to be protective against nonhome discharge after CDR (OR: 0.243, P <0.001). CONCLUSIONS: Age, Hispanic ethnicity, BMI, ASA class, prolonged hospital stay, and prolonged operation time are independent predictors of nonhome discharge after CDR. Outpatient surgery setting is protective against nonhome discharge. These findings can be utilized to preoperatively risk stratify expected discharge destination, anticipate patient discharge needs postoperatively, and expedite discharge in these patients to reduce health care costs associated with prolonged length of hospital stay. LEVEL OF EVIDENCE: IV.

Level-specific comparison of 3D navigated and robotic arm-guided screw placement: an accuracy assessment of 1210 pedicle screws in lumbar surgery.

BACKGROUND CONTEXT: Robotic spine surgery, utilizing 3D imaging and robotic arms, has been shown to improve the accuracy of pedicle screw placement compared to conventional methods, although its superiority remains under debate. There are few studies evaluating the accuracy of 3D navigated versus robotic-guided screw placement across lumbar levels, addressing anatomical challenges to refine surgical strategies and patient safety. PURPOSE: This study aims to investigate the pedicle screw placement accuracy between 3D navigation and robotic arm-guided systems across distinct lumbar levels. STUDY DESIGN: A retrospective review of a prospectively collected registry. PATIENT SAMPLE: Patients undergoing fusion surgery with pedicle screw placement in the prone position, using either via 3D image navigation only or robotic arm guidance. OUTCOME MEASURE: Radiographical screw accuracy was assessed by the postoperative computed tomography (CT) according to the Gertzbein-Robbins classification, particularly focused on accuracy at different lumbar levels. METHODS: Accuracy of screw placement in the 3D navigation (Nav group) and robotic arm guidance (Robo group) was compared using Chi-squared test/Fisher's exact test with effect size measured by Cramer's V, both overall and at each specific lumbosacral spinal level. RESULTS: A total of 321 patients were included (Nav, 157; Robo, 189) and evaluated 1210 screws (Nav, 651; Robo 559). The Robo group demonstrated significantly higher overall accuracy (98.6 vs 93.9%; p<.001, V=0.25). This difference of no breach screw rate was signified the most at the L3 level (No breach screw: Robo 91.3 vs 57.8%, p<.001, V=0.35) followed by L4 (89.6 vs 64.7%, p<.001, V=0.28), and L5 (92.0 vs 74.5%, p<.001, V=0.22). However, screw accuracy at S1 was not significant between the groups (81.1 vs 72.0%, V=0.10). CONCLUSION: This study highlights the enhanced accuracy of robotic arm-guided systems compared to 3D navigation for pedicle screw placement in lumbar fusion surgeries, especially at the L3, L4, and L5 levels. However, at the S1 level, both systems exhibit similar effectiveness, underscoring the importance of understanding each system's specific advantages for optimization of surgical complications.

Impact of age on comparative outcomes of decompression alone versus fusion for L4 degenerative spondylolisthesis.

PURPOSE: To compare the outcomes of decompression alone and fusion for L4-5 DLS in different age cohorts (< 70 years, ≥ 70 years). METHODS: This retrospective cohort study included patients who underwent minimally invasive decompression or fusion for L4-5 DLS and had a minimum of 1-year follow-up. Outcome measures were: (1) patient-reported outcome measures (PROMs) (Oswestry Disability Index, ODI; Visual Analog Scale back and leg, VAS; 12-Item Short Form Survey Physical Component Score, SF-12 PCS), (2) minimal clinically important difference (MCID), (3) patient acceptable symptom state (PASS), (4) response on the global rating change (GRC) scale, and (5) complication rates. The decompression and fusion groups were compared for outcomes separately in the < 70-year and ≥ 70-year age cohorts. RESULTS: 233 patients were included, out of which 52% were < 70 years. Patients < 70 years showed non-significant improvement in SF-12 PCS and significantly lower MCID achievement rates for VAS back after decompression compared to fusion. Analysis of the ≥ 70-year age cohort showed no significant differences between the decompression and fusion groups in the improvement in PROMs, MCID/PASS achievement rates, and responses on GRC. Patients ≥ 70 years undergoing fusion had significantly higher in-hospital complication rates. When analyzed irrespective of the surgery type, both < 70-year and ≥ 70-year age cohorts showed significant improvement in PROMs with no significant difference. CONCLUSIONS: Patients < 70 years undergoing decompression alone did not show significant improvement in physical function and had significantly less MCID achievement rate for back pain compared to fusion. Patients ≥ 70 years showed no difference in outcomes between decompression alone and fusion.

Isolated decompression for degenerative spondylolisthesis is less costly than fusion even with high revision rates.

BACKGROUND CONTEXT: Isolated decompression and decompression with instrumented fusion are accepted surgical treatments for lumbar spondylolisthesis. Although isolated decompression is a less costly solution with similar patient-reported outcomes, it is associated with higher rates of reoperation than primary fusion. PURPOSE: To determine the costs associated with primary decompression, primary fusion, and decompression and fusion for degenerative spondylolisthesis. We further sought to establish at what revision rate is primary decompression still a less costly surgical treatment for degenerative lumbar spondylolisthesis. STUDY DESIGN/SETTING: A retrospective database study of the Medicare Provider Analysis and Review (MEDPAR) limited data set. PATIENT SAMPLE: Patients who underwent single-level fusion or decompression for degenerative spondylolisthesis. OUTCOME MEASURES: Cost of surgical care. METHODS: All inpatient stays that underwent surgery for single-level lumbar/lumbosacral degenerative spondylolisthesis in the 2019 calendar year (n=6,653) were queried from the MEDPAR limited data set. Patients were stratified into three cohorts: primary decompression (n=300), primary fusion (n=5,757), and revision fusion (n=566). Univariate analysis was conducted to determine cost differences between these groups and results were confirmed with multivariable regression. An economic analysis was then done to determine at what revision rate would primary decompression still be a less costly treatment choice. RESULTS: on univariate analysis, the cost of primary single-level decompression for spondylolisthesis was $14,690±9,484, the cost of primary single-level fusion was $26,376±11,967, and revision fusion was $26,686±11,309 (p<0.001). on multivariate analysis, primary fusion was associated with an increased cost of $3,751, and revision fusion was associated with increased cost of $7,502 (95%ci: 2,990-4,512, p<0.001). economic analysis found that a revision rate less than or equal to 43.8% would still result in primary decompression being less costly for a practice than primary fusion for all patients. CONCLUSIONS: Isolated decompression for degenerative lumbar spondylolisthesis is a less costly treatment choice even with rates of revision fusion as high as 43.8%. This was true even with an assumed revision rate of 0% after primary fusion. This study solely looks at cost data, however, and many patients may still benefit from primary fusion when appropriately indicated.

Practical Answers to Frequently Asked Questions in Anterior Cervical Spine Surgery for Degenerative Conditions.

INTRODUCTION: Surgical counseling enables shared decision making and optimal outcomes by improving patients' understanding about their pathologies, surgical options, and expected outcomes. Here, we aimed to provide practical answers to frequently asked questions (FAQs) from patients undergoing an anterior cervical diskectomy and fusion (ACDF) or cervical disk replacement (CDR) for the treatment of degenerative conditions. METHODS: Patients who underwent primary one-level or two-level ACDF or CDR for the treatment of degenerative conditions with a minimum of 1-year follow-up were included. Data were used to answer 10 FAQs that were generated from author's experience of commonly asked questions in clinic before ACDF or CDR. RESULTS: A total of 395 patients (181 ACDF, 214 CDR) were included. (1, 2, and 3) Will my neck/arm pain and physical function improve? Patients report notable improvement in all patient-reported outcome measures. (4) Is there a chance I will get worse? 13% (ACDF) and 5% (CDR) reported worsening. (5) Will I receive a significant amount of radiation? Patients on average received a 3.7 (ACDF) and 5.5 mGy (CDR) dose during. (6) How long will I stay in the hospital? Most patients get discharged on postoperative day one. (7) What is the likelihood that I will have a complication? 13% (8% minor and 5% major) experienced in-hospital complications (ACDF) and 5% (all minor) did (CDR). (8) Will I need another surgery? 2.2% (ACDF) and 2.3% (CDR) of patients required a revision surgery. (9 & 10) When will I be able to return to work/driving? Most patients return to working (median of 16 [ACDF] and 14 days [CDR]) and driving (median of 16 [ACDF] and 12 days [CDR]). CONCLUSIONS: The answers to the FAQs can assist surgeons in evidence-based patient counseling.

Morbidly Obese Patients Have Similar Clinical Outcomes and Recovery Kinetics After Minimally Invasive Decompression.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To study the impact of class 2/3 obesity (body mass index, BMI >35) on outcomes following minimally invasive decompression. SUMMARY OF BACKGROUND DATA: No previous study has analyzed the impact of class 2/3 obesity on outcomes following minimally invasive decompression. METHODS: Patients who underwent primary minimally invasive decompression were divided into 4 cohorts based on their BMI: normal (BMI 18.5 to <25), overweight (25 to <30), class 1 obesity (30 to <35), and class 2/3 obesity (BMI >35). Outcome measures were: 1) intraoperative variables: operative time, estimated blood loss (EBL); 2) patient reported outcome measures (PROMs) (Oswestry Disability Index, ODI; Visual Analog Scale, VAS back and leg; 12-Item Short Form Survey Physical Component Score, SF-12 PCS); 3) global rating change (GRC), minimal clinically important difference (MCID), and patient acceptable symptom state (PASS) achievement rates; 4) return to activities; and 5) complication and reoperation rates. RESULTS: 838 patients were included (226 normal, 357 overweight, 179 class 1 obesity, 76 class 2/3 obesity). Class 1 and 2/3 obesity groups had significantly greater operative times compared to the other groups. Class 2/3 obesity group had worse ODI, VAS back and SF-12 PCS preoperatively, worse ODI, VAS back, VAS leg and SF-12 PCS at <6 months, and worse ODI and SF-12 PCS at >6 months. However, they had significant improvement in all PROMs at both postoperative timepoints and the magnitude of improvement was similar to other groups. No significant differences were found in MCID and PASS achievement rates, likelihood of betterment on the GRC scale, return to activities, and complication/reoperation rates. CONCLUSIONS: Class 2/3 obese patients have worse PROMs pre- and post-operatively. However, they show similar improvement in PROMs, MCID and PASS achievement rates, likelihood of betterment, recovery kinetics, and complication/reoperation rates as other BMI groups following minimally invasive decompression.

Temporal Trends of Improvement After Minimally Invasive Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To analyze temporal trends in improvement after minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). SUMMARY OF BACKGROUND DATA: Although several studies have shown that patients improve significantly after MIS TLIF, evidence regarding the temporal trends in improvement is still largely lacking. METHODS: Patients who underwent primary single-level MIS TLIF for degenerative conditions of the lumbar spine and had a minimum of 2-year follow-up were included. Outcome measures were: 1) patient reported outcome measures (PROMs) (Oswestry Disability Index, ODI; Visual Analog Scale, VAS back and leg; 12-Item Short Form Survey Physical Component Score, SF-12 PCS); 2) global rating change (GRC); 3) minimal clinically important difference (MCID); and 4) return to activities. Timepoints analyzed were preoperative, 2 weeks, 6 weeks, 3 months, 6 months, 1 year, and 2 years. Trends across these timepoints were plotted on graphs. RESULTS: 236 patients were included. VAS back and VAS leg were found to have statistically significant improvement compared to the previous timepoint up to 3 months after surgery. ODI and SF-12 PCS were found to have statistically significant improvement compared to the previous timepoint up to 6 months after surgery. Beyond these timepoints, there was no significant improvement in PROMs. 80% of patients reported feeling better compared to preoperative by 3 months. >50% of patients achieved MCID in all PROMs by 3 months. Most patients returned to driving, returned to work, and discontinued narcotics at an average of 21, 20, and 10 days, respectively. CONCLUSIONS: Patients are expected to improve up to 6 months after MIS TLIF. Back pain and leg pain improve up to 3 months and disability and physical function improve up to 6 months. Beyond these timepoints, the trends in improvement tend to reach a plateau. 80% of patients feel better compared to preoperative by 3 months after surgery.

Psoas Muscle Health is Correlated With Time to Achieve MCID in Patients With Predominant Axial Back Pain Following Decompression Surgery: Early Results.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine the impact of psoas muscle health [cross-sectional area (CSA)] on achieving minimal clinically important differences (MCID) in patient-reported outcome measures (PROMs) following laminectomy for patients with predominant back pain (PBP) and leg pain (PLP). SUMMARY OF BACKGROUND DATA: Psoas muscle health is linked to postoperative outcomes in decompression patients, with MRI-based grading of psoas CSA correlating with these outcomes. However, evidence on its impact on symptomatic recovery, measured by PROMs, is lacking. METHODS: One hundred six patients with PBP (VAS back > VAS leg) and 139 patients with PLP (VAS leg > VAS back) who underwent laminectomy from 2017 to 2021 were included. Axial T2 MRI images were analyzed for psoas CSA using a validated method. Based on the lowest-quartile normalized total psoas area (NTPA) thresholds, patients were divided into "good" and "poor" muscle health groups. The correlation analyses were performed between the psoas CSA and changes in PROMs. Kaplan-Meier survival analysis was conducted to determine the probability of achieving MCID as a function of time. RESULTS: Of 106 patients with PBP, 83 (78.3%) had good muscle health, and 23 (21.6%) had poor muscle health. Of 139 patients with PLP, 54 (38.8%) had good muscle health, and 85 (61.1%) had poor muscle health. In the PBP group, older age was associated with poor muscle health (69.70±9.26 vs . 59.92±15.01, P =0.0002). For both cohorts, there were no differences in the rate of MCID achievement for any PROMs between the good and poor muscle health groups. In the PBP group, Kaplan-Meier analysis showed patients with good psoas health achieved MCID-VAS back and Oswestry Disability Index (ODI) in median times of 14 and 42 days ( P =0.045 and 0.015), respectively. CONCLUSION: Good psoas muscle health is linked to faster attainment of MCID, especially in patients with PBP compared with PLP after decompression surgery. LEVEL OF EVIDENCE: III.

Impact of Preoperative Symptom Duration on Patient-Reported Outcomes Following Cervical Disc Replacement for Cervical Radiculopathy.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To determine the impact of preoperative symptom duration on postoperative functional outcomes after cervical disc replacement (CDR) for radiculopathy. SUMMARY OF BACKGROUND DATA: CDR has emerged as a reliable and efficacious treatment option for degenerative cervical spine pathologies. The relationship between preoperative symptom duration and outcomes after CDR is not well established. METHODS: Patients with radiculopathy without myelopathy who underwent primary 1- or 2-level CDRs were included and divided into shorter (<6 mo) and prolonged (≥6 mo) cohorts based on preoperative symptom duration. Patient-reported outcome measures (PROMs) included neck disability index (NDI), visual analog scale (VAS) neck and arm. Changes in PROM scores and minimal clinically important difference (MCID) rates were calculated. Analyses were conducted on the early (within 3 mo) and late (6 mo-2 y) postoperative periods. RESULTS: A total of 201 patients (43.6±8.7 y, 33.3% female) were included. In both early and late postoperative periods, the shorter preoperative symptom duration cohort experienced significantly greater change from preoperative PROM scores compared with the prolonged symptom duration cohort for NDI, VAS-Neck, and VAS-Arm. The shorter symptom duration cohort achieved MCID in the early postoperative period at a significantly higher rate for NDI (78.9% vs. 54.9%, P =0.001), VAS-Neck (87.0% vs. 56.0%, P <0.001), and VAS-Arm (90.5% vs. 70.7%, P =0.002). Prolonged preoperative symptom duration (≥6 mo) was identified as an independent risk factor for failure to achieve MCID at the latest timepoint for NDI (OR: 2.9, 95% CI: 1.2-6.9, P =0.016), VAS-Neck (OR: 9.8, 95% CI: 3.7-26.0, P <0.001), and VAS-Arm (OR: 7.5, 95% CI: 2.5-22.5, P <0.001). CONCLUSIONS: Our study demonstrates improved patient-reported outcomes for those with shorter preoperative symptom duration undergoing CDR for radiculopathy, suggesting delayed surgical intervention may result in poorer outcomes and greater postoperative disability. LEVEL OF EVIDENCE: Level III.

Clinical and Radiological Predictors of Slower and Non-Improvement Following Surgical Treatment of L4-5 Degenerative Spondylolisthesis: Preliminary Results.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To identify the predictors of slower and non-improvement following surgical treatment of L4-5 degenerative lumbar spondylolisthesis (DLS). SUMMARY OF BACKGROUND DATA: There is limited evidence regarding clinical and radiological predictors of slower and non-improvement following surgery for L4-5 DLS. METHODS: Patients who underwent minimally invasive decompression or fusion for L4-5 DLS and had a minimum of 1-year follow-up were included. Outcome measures were: (1) minimal clinically important difference (MCID), (2) patient acceptable symptom state (PASS), and (3) global rating change (GRC). Clinical variables analyzed for predictors were age, gender, body mass index (BMI), surgery type, comorbidities, anxiety, depression, smoking, osteoporosis, and preoperative patient reported outcome measures (PROMs) (Oswestry Disability Index, ODI; Visual Analog Scale, VAS back and leg; 12-Item Short Form Survey Physical Component Score, SF-12 PCS). Radiological variables analyzed were slip percentage, translational and angular motion, facet diastasis/cyst/orientation, laterolisthesis, disc height, scoliosis, main and fractional curve Cobb angles, and spinopelvic parameters. RESULTS: 233 patients (37% decompression, 63% fusion) were included. At <3 months, high pelvic tilt (PT) (OR 0.92, P 0.02) and depression (OR 0.28, P 0.02) were predictors of MCID non-achievement and GRC non-betterment, respectively. Neither retained significance at >6 months and hence, were identified as predictors of slower improvement. At >6 months, low preoperative VAS leg (OR 1.26, P 0.01) and high facet orientation (OR 0.95, P 0.03) were predictors of MCID non-achievement, high L4-5 slip percentage (OR 0.86, P 0.03) and L5-S1 angular motion (OR 0.78, P 0.01) were predictors of GRC non-betterment, and high preoperative ODI (OR 0.96, P 0.04) was a predictor of PASS non-achievement. CONCLUSIONS: High PT and depression were predictors of slower improvement and low preoperative leg pain, high disability, high facet orientation, high slip percentage, and L5-S1 angular motion were predictors of non-improvement. However, these are preliminary findings and further studies with homogeneous cohorts are required to establish these findings.