Does robot-assisted navigation influence pedicle screw selection and accuracy in minimally invasive spine surgery?

OBJECTIVE: The accuracy of percutaneous pedicle screw placement has increased with the advent of robotic and surgical navigation technologies. However, the effect of robotic intraoperative screw size and trajectory templating remains unclear. The purpose of this study was to compare pedicle screw sizes and accuracy of placement using robotic navigation (RN) versus skin-based intraoperative navigation (ION) alone in minimally invasive lumbar fusion procedures. METHODS: A retrospective cohort study was conducted using a single-institution registry of spine procedures performed over a 4-year period. Patients who underwent 1- or 2-level primary or revision minimally invasive surgery (MIS)-transforaminal lumbar interbody fusion (TLIF) with pedicle screw placement, via either robotic assistance or surgical navigation alone, were included. Demographic, surgical, and radiographic data were collected. Pedicle screw type, quantity, length, diameter, and the presence of endplate breach or facet joint violation were assessed. Statistical analysis using the Student t-test and chi-square test was performed to evaluate the differences in pedicle screw sizes and the accuracy of placement between both groups. RESULTS: Overall, 222 patients were included, of whom 92 underwent RN and 130 underwent ION MIS-TLIF. A total of 403 and 534 pedicle screws were placed with RN and ION, respectively. The mean screw diameters were 7.25 ± 0.81 mm and 6.72 ± 0.49 mm (p < 0.001) for the RN and ION groups, respectively. The mean screw length was 48.4 ± 4.48 mm in the RN group and 45.6 ± 3.46 mm in the ION group (p < 0.001). The rates of "ideal" pedicle screws in the RN and ION groups were comparable at 88.5% and 88.4% (p = 0.969), respectively. The overall screw placement was also similar. The RN cohort had 63.7% screws rated as good and 31.4% as acceptable, while 66.1% of ION-placed screws had good placement and 28.7% had acceptable placement (p = 0.661 and p = 0.595, respectively). There was a significant reduction in high-grade breaches in the RN group (0%, n = 0) compared with the ION group (1.2%, n = 17, p = 0.05). CONCLUSIONS: The results of this study suggest that robotic assistance allows for placement of screws with greater screw diameter and length compared with surgical navigation alone, although with similarly high accuracy. These findings have implied that robotic platforms may allow for safe placement of the "optimal screw," maximizing construct stability and, thus, the ability to obtain a successful fusion.

Chitosan Coagulation Pretreatment to Enhance Ceramic Water Filtration for Household Water Treatment.

Viruses are major contributors to the annual 1.3 million deaths associated with the global burden of diarrheal disease morbidity and mortality. While household-level water treatment technologies reduce diarrheal illness, the majority of filtration technologies are ineffective in removing viruses due to their small size relative to filter pore size. In order to meet the WHO health-based tolerable risk target of 10-6 Disability Adjusted Life Years per person per year, a drinking water filter must achieve a 5 Log10 virus reduction. Ceramic pot water filters manufactured in developing countries typically achieve less than 1 Log10 virus reductions. In order to overcome the shortfall in virus removal efficiency in household water treatment filtration, we (1) evaluated the capacity of chitosan acetate and chitosan lactate, as a cationic coagulant pretreatment combined with ceramic water filtration to remove lab cultured and sewage derived viruses and bacteria in drinking waters, (2) optimized treatment conditions in waters of varying quality and (3) evaluated long-term continuous treatment over a 10-week experiment in surface waters. For each test condition, bacteria and virus concentrations were enumerated by culture methods for influent, controls, and treated effluent after chitosan pretreatment and ceramic water filtration. A > 5 Log10 reduction was achieved in treated effluent for E.coli, C. perfringens, sewage derived E. coli and total coliforms, MS2 coliphage, Qß coliphage, ΦX174 coliphage, and sewage derived F+ and somatic coliphages.

An Examination of Complication Rates and Surgery Durations in Elective Hand Surgery During the COVID-19 Pandemic.

Background: The COVID-19 pandemic presented unique challenges to hand surgeons as hospitals worked to adapt to unprecedented demands on resources and personnel. The purpose of this study is to evaluate the impact of COVID-19 on outcomes in elective hand surgery using a large national database. Methods: This is a retrospective review of the American College of Surgeons National Surgery Quality Improvement Program (ACS-NSQIP) dataset for patients undergoing elective hand procedures in 2019 and 2020. Demographics, comorbidities, procedural factors, and outcomes were compared between cases occurring in 2019 and 2020. Multivariable regressions were performed to evaluate the association between operative year and 30-day outcomes. Results: A total of 8971 patients were included with a mean age of 52.2 ± 16.7 and 52.8 ± 16.4 years for the 2019 and 2020 cohorts, respectively. Compared to the 2019 cohort, the 2020 cohort demonstrated higher prevalence of obesity (43.3% vs 40.8%, P = 0.019), hypertension requiring medication (32.9% vs 35.0%; P = 0.046), and American Association of Anesthesiologists (ASA) class ≥ 3 (30.4% vs 27.0%; P < 0.001). There were no significant differences in outcomes including 30-day readmissions, reoperation, or complications between cohorts on unadjusted or multivariable analysis. Conclusions: Elective hand cases performed during the pandemic were associated with longer operating times and more frequently involved patients with greater comorbidities. Despite these differences, patients undergoing surgery during the pandemic demonstrated similar outcomes including complications, readmissions, and reoperations compared to those undergoing surgery the year prior, suggesting that even in the setting of a pandemic, performing elective surgery is safe without an increased risk to the patient.

Feasibility of Saphenous Nerve Somatosensory-Evoked Potential Intraoperative Monitoring During Lumbar Spine Surgery: Early Results.

STUDY DESIGN: Retrospective review. OBJECTIVE: Assess the feasibility of saphenous nerve somatosensory evoked potentials (SN-SSEP) monitoring in lumbar spine surgeries. BACKGROUND CONTEXT: SN-SSEPs have been proposed for detecting lumbar plexus and femoral nerve injury during lateral lumbar surgery where tibial nerve (TN) SSEPs alone are insufficient. SN-SSEPs may also be useful in other types of lumbar surgery, as stimulation of SN below the knee derives solely from the L4 root and provides a means of L4 monitoring, whereas TN-SSEPs often do not detect single nerve root injury. The feasibility of routine SN-SSEP monitoring has not been established. METHODS: A total of 563 consecutive cases using both TN-SSEP and SN-SSEP monitoring were included. Anesthesia was at the discretion of the anesthesiologist, using an inhalant in 97.7% of procedures. SN stimulation was performed using 13 mm needle electrodes placed below the knee using 200-400 µsec pulses at 15 to 100 mA. Adjustments to stimulation parameters were made by the neurophysiology technician while obtaining baselines. Data were graded retrospectively for monitorability and cortical response amplitudes were measured by two independent reviewers. RESULTS: Ninety-eight percent of TN-SSEPs and 92.5% of SN-SSEPs were monitorable at baseline, with a mean response amplitude of 1.35 µV for TN-SSEPs and 0.71 µV for SN-SSEPs. A significant difference between the stimulation parameters used to obtain reproducible TN and SN-SSEPs at baseline was observed, with SN-SSEPs requiring greater stimulation intensities. Body mass index is not associated with baseline monitorability. Out of 20 signal changes observed, 11 involved SN, while TN-SSEPs were unaffected. CONCLUSION: With adjustments to stimulation parameters, SN-SSEP monitoring is feasible within a large clinical cohort without modifications to the anesthetic plan. Incorporating SN into standard intraoperative neurophysiological monitoring protocols for lumbar spine procedures may expand the role of SSEP monitoring to include detecting injury to the lumbar plexus. LEVEL OF EVIDENCE: 3.

Impact of Frailty and Cervical Radiographic Parameters on Postoperative Dysphagia Following Anterior Cervical Spine Surgery.

STUDY DESIGN: Retrospective review of a prospectively collected registry. OBJECTIVE: The purpose of the present study was to investigate the impact of frailty and radiographical parameters on postoperative dysphagia after anterior cervical spine surgery (ACSS). SUMMARY OF BACKGROUND DATA: There is a growing body of literature indicating an association between frailty and increased postoperative complications following various surgeries. However, few studies have investigated the relationship between frailty and postoperative dysphagia after anterior cervical spine surgery. MATERIALS AND METHODS: Patients who underwent anterior cervical spine surgery for the treatment of degenerative cervical pathology were included. Frailty and dysphagia were assessed by the modified Frailty Index-11 (mFI-11) and Eat Assessment Tool 10 (EAT-10), respectively. We also collected clinical demographics and cervical alignment parameters previously reported as risk factors for postoperative dysphagia. Multivariable logistic regression was performed to identify the odds ratio (OR) of postoperative dysphagia at early (2-6 weeks) and late postoperative time points (1-2 years). RESULTS: Ninety-five patients who underwent ACSS were included in the study. Postoperative dysphagia occurred in 31 patients (32.6%) at the early postoperative time point. Multivariable logistic regression identified higher mFI-11 score (OR, 4.03; 95% CI: 1.24-13.16; P =0.021), overcorrection of TS-CL after surgery (TS-CL, T1 slope minus C2-C7 lordosis; OR, 0.86; 95% CI: 0.79-0.95; P =0.003), and surgery at C3/C4 (OR, 12.38; 95% CI: 1.41-108.92; P =0.023) as factors associated with postoperative dysphagia. CONCLUSIONS: Frailty, as assessed by the mFI-11, was significantly associated with postoperative dysphagia after ACSS. Additional factors associated with postoperative dysphagia were overcorrection of TS-CL and surgery at C3/C4. These findings emphasize the importance of assessing frailty and cervical alignment in the decision-making process preceding ACSS.

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.

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.

Early NRS Leg and Back Thresholds Predict Clinical Recovery after MIS Transforaminal Lumbar Interbody Fusion for Degenerative Spine Disease.

STUDY DESIGN: This retrospective study included patients who underwent primary one-level minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF) for degenerative lumbar spine conditions. OBJECTIVE: To identify early predictors of failing to achieve the Oswestry Disability Index (ODI) minimum clinically important difference (MCID) one-year post-surgery. SUMMARY OF BACKGROUND DATA: Early identification of patients at risk of failing to achieve ODI-MCID is crucial for early intervention and improved postoperative counseling. Currently, no specific thresholds guide patient follow-up for optimal recovery. METHODS: The assessment included demographic information, surgical details, and patient-reported outcome measures (PROMs). PROMs were collected postoperatively at 2-, 6-, and 12-week time points, as well as at 6- and 12-months. RESULTS: The study included 166 patients, with 34% failing to achieve ODI-MCID at one year. Early VAS back and leg scores were found to be significant predictors of ODI-MCID achievement. The optimal thresholds identified were 2.25 for early VAS back and 4.25 for early VAS leg. A rerun regression identified the thresholds as independent predictors of ODI-MCID, with odds ratios of 0.31 for both measures. CONCLUSION: VAS back and leg score thresholds at 6-12 weeks can predict ODI-MCID achievement one year after MIS TLIF. Patients exceeding the identified thresholds may be at risk of failing ODI-MCID and should be monitored closely. LEVEL OF EVIDENCE: Level 3.

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.

Limited Improvement With Minimally Invasive Lumbar Decompression Alone for Degenerative Scoliosis With Cobb Angle Over 20°: The Impact of Decompression Location.

STUDY DESIGN: Retrospective review of a prospectively collected multisurgeon registry. OBJECTIVE: To evaluate the outcomes of minimally invasive (MI) decompression in patients with severe degenerative scoliosis (DS) and identify factors associated with poorer outcomes. SUMMARY OF BACKGROUND CONTEXT: MI decompression has gained widespread acceptance as a treatment option for patients with lumbar canal stenosis and DS. However, there is a lack of research regarding the clinical outcomes and the impact of MI decompression location in patients with severe DS exhibiting a Cobb angle exceeding 20°. MATERIALS AND METHODS: Patients who underwent MI decompression alone were included and categorized into the DS or control groups based on Cobb angle (>20°). Decompression location was labeled as "scoliosis-related" when the decompression levels were across or between end vertebrae and "outside" when the operative levels did not include the end vertebrae. The outcomes, including the Oswestry Disability Index (ODI), were compared between the propensity score-matched groups for improvement and minimal clinical importance difference (MCID) achievement at ≥1 year postoperatively. Multivariable regression analysis was conducted to identify factors contributing to the nonachievement of MCID in ODI of the DS group at the ≥1-year time point. RESULTS: A total of 253 patients (41 DS) were included in the study. Following matching for age, sex, osteoporosis status, psoas muscle area, and preoperative ODI, the DS groups exhibited a significantly lower rate of MCID achievement in ODI (DS: 45.5% vs. control 69.0%, P =0.047). The "scoliosis-related" decompression (odds ratio: 9.9, P =0.028) was an independent factor of nonachievement of MCID in ODI within the DS group. CONCLUSIONS: In patients with a Cobb angle >20°, lumbar decompression surgery, even in the MI approach, may result in limited improvement of disability and physical function. Caution should be exercised when determining a surgical plan, especially when decompression involves the level between or across the end vertebrae. LEVEL OF EVIDENCE: 3.

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.

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.

Predictors for Failure to Respond to Erector Spinae Plane Block Following Minimally Invasive Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To identify the risk factors associated with failure to respond to erector spinae plane (ESP) block following minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). SUMMARY OF BACKGROUND DATA: ESP block is an emerging opioid-sparing regional anesthetic that has been shown to reduce immediate postoperative pain and opioid demand following MI-TLIF-however, not all patients who receive ESP blocks perioperatively experience a reduction in immediate postoperative pain. METHODS: This was a retrospective review of consecutive patients undergoing 1-level MI-TLIF who received ESP blocks by a single anesthesiologist perioperatively at a single institution. ESP blocks were administered in the OR following induction. Failure to respond to ESP block was defined as patients with a first numerical rating scale (NRS) score post-surgery of >5.7 (mean immediate postoperative NRS score of control cohort undergoing MI TLIF without ESP block). Multivariable logistic regressions were performed to identify predictors for failure to respond to ESP block. RESULTS: A total of 134 patients were included (mean age 60.6 years, 43.3% females). The median and interquartile range (IQR) first pain score post-surgery was 2.5 (0.0-7.5). Forty-nine (36.6%) of patients failed to respond to ESP block. In the multivariable regression analysis, several independent predictors for failure to respond to ESP block following MI TLIF were identified: female sex (OR 2.33, 95% CI 1.04-5.98, P=0.040), preoperative opioid use (OR 2.75, 95% CI 1.03- 7.30, P=0.043), anxiety requiring medication (OR 3.83, 95% CI 1.27-11.49, P=0.017), and hyperlipidemia (OR 3.15, 95% CI 1.31-7.55, P=0.010). CONCLUSIONS: Our study identified several predictors for failure to respond to ESP block following MI TLIF including female sex, preoperative opioid pain medication use, anxiety, and hyperlipidemia. These findings may help inform the approach to counseling patients on perioperative outcomes and pain expectations following MI-TLIF with ESP block. LEVEL OF EVIDENCE: III.

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.

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.

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.

The Impact of Posterior Intervertebral Osteophytes on Patient-Reported Outcome Measures After L5-S1 Anterior Lumbar Interbody Fusion and Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: (1) To develop a reliable grading system to assess the severity of posterior intervertebral osteophytes and (2) to investigate the impact of posterior intervertebral osteophytes on clinical outcomes after L5-S1 decompression and fusion through anterior lumbar interbody fusion (ALIF) and minimally-invasive transforaminal lumbar interbody fusion (MIS-TLIF). BACKGROUND: There is limited evidence regarding the clinical implications of posterior lumbar vertebral body osteophytes for ALIF and MIS-TLIF surgeries and there are no established grading systems that define the severity of these posterior lumbar intervertebral osteophytes. PATIENTS AND METHODS: A retrospective analysis of patients undergoing L5-S1 ALIF or MIS-TLIF was performed. Preoperative and postoperative patient-reported outcome measures of the Oswestry Disability Index (ODI) and leg Visual Analog Scale (VAS) at 2-week, 6-week, 12-week, and 6-month follow-up time points were assessed. Minimal clinically important difference (MCID) for ODI of 14.9 and VAS leg of 2.8 were utilized. Osteophyte grade was based on the ratio of osteophyte length to foraminal width. "High-grade" osteophytes were defined as a maximal osteophyte length >50% of the total foraminal width. RESULTS: A total of 70 consecutive patients (32 ALIF and 38 MIS-TLIF) were included in the study. There were no significant differences between the two cohorts in patient-reported outcome measures or achievement of MCID for Leg VAS or ODI preoperatively or at any follow-ups. On multivariate analysis, neither the surgical approach nor the presence of high-grade foraminal osteophytes was associated with leg VAS or ODI scores at any follow-up time point. In addition, neither the surgical approach nor the presence of high-grade foraminal osteophytes was associated with the achievement of MCID for leg VAS or ODI at 6 months. CONCLUSION: ALIF and MIS-TLIF are both valid options for treating degenerative spine conditions and lumbar radiculopathy, even in the presence of high-grade osteophytes that significantly occupy the intervertebral foramen. LEVEL OF EVIDENCE: 3.

Unplanned readmissions following ambulatory spine surgery: assessing common reasons and risk factors.

BACKGROUND CONTEXT: Although outpatient spine surgery is becoming increasingly popular in the United States, unplanned readmission following outpatient surgery remains a significant postoperative concern. PURPOSE: This study aimed to (1) describe the incidence and timing of 30-day unplanned readmission after ambulatory lumbar and cervical spine surgery (2) evaluate the common reasons for readmission, and (3) identify factors associated with readmission in this population. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Patients who underwent ambulatory cervical or lumbar spine surgery between 2015 and 2020 were identified in the National Surgical Quality Improvement Program (NSQIP) database. OUTCOME MEASURES: Hospital readmission within 30 postoperative days. METHODS: Patients who underwent ambulatory cervical or lumbar spine surgery between 2015 and 2020 were identified using the National Surgical Quality Improvement Program (NSQIP) database. Reasons for and timing of unplanned readmissions were recorded. Multivariable poisson regressions were employed to determine any independent predictors of readmission. RESULTS: A total of 33,092 ambulatory cervical and 68,115 ambulatory lumbar spine surgery patients were identified. Incidences of 30-day readmission were 3.37% and 3.07% among cervical and lumbar patients, respectively. The most common surgical site-related reasons for readmission included uncontrolled pain, recurrence of disc herniation or major symptom, and postoperative hematoma/seroma. Common nonsurgical site-related reasons included gastrointestinal, neurological, and cardiovascular complications. Factors associated with readmission among cervical patients included age ≥55, BMI ≥35, functional dependence, diabetes, smoking, COPD, and steroid use, whereas factors associated with readmission following lumbar spine surgery included age ≥65, female sex, BMI ≥35, functional dependence, ASA ≥3, diabetes, smoking, COPD, and hypertension (p<.05 for all). CONCLUSION: This study highlights the common reasons and factors associated with unplanned readmission following ambulatory spine surgery. Consideration of these factors may be critical to ensuring appropriate patient selection for ambulatory spine surgery.

Practical answers to frequently asked questions in minimally invasive lumbar spine surgery.

BACKGROUND CONTEXT: Surgical counseling enables shared decision-making (SDM) by improving patients' understanding. PURPOSE: To provide answers to frequently asked questions (FAQs) in minimally invasive lumbar spine surgery. STUDY DESIGN: Retrospective review of prospectively collected data. PATIENT SAMPLE: Patients who underwent primary tubular minimally invasive lumbar spine surgery in form of transforaminal lumbar interbody fusion (MI-TLIF), decompression alone, or microdiscectomy and had a minimum of 1-year follow-up. OUTCOME MEASURES: (1) Surgical (radiation exposure and intraoperative complications) (2)Immediate postoperative (length of stay [LOS] and complications) (3) Clinical outcomes (Visual Analog Scale- back and leg, VAS; Oswestry Disability Index, ODI; 12-Item Short Form Survey Physical Component Score, SF-12 PCS; Patient-Reported Outcomes Measurement Information System Physical Function, PROMIS PF; Global Rating Change, GRC; return to activities; complications/reoperations) METHODS: The outcome measures were analyzed to provide answers to ten FAQs that were compiled based on the authors' experience and a review of literature. Changes in VAS back, VAS leg, ODI, and SF-12 PCS from preoperative values to the early (<6 months) and late (>6 months) postoperative time points were analyzed with Wilcoxon Signed Rank Tests. % of patients achieving minimal clinically important difference (MCID) for these patient-reported outcome measures (PROMs) at the two time points was evaluated. Changes in PROs from preoperative values too early (<6 months) and late (≥6 months) postoperative time points were analyzed within each of the three groups. Percentage of patients achieving MCID was also evaluated. RESULTS: Three hundred sixty-six patients (104 TLIF, 147 decompression, 115 microdiscectomy) were included. The following FAQs were answered: (1) Will my back pain improve? Most patients report improvement by >50%. About 60% of TLIF, decompression, and microdiscectomy patients achieved MCID at ≥6 months. (2) Will my leg pain improve? Most patients report improvement by >50%. 56% of TLIF, 67% of decompression, and 70% of microdiscectomy patients achieved MCID at ≥6 months. (3) Will my activity level improve? Most patients report significant improvement. Sixty-six percent of TLIF, 55% of decompression, and 75% of microdiscectomy patients achieved MCID for SF-12 PCS. (4) Is there a chance I will get worse? Six percent after TLIF, 14% after decompression, and 5% after microdiscectomy. (5) Will I receive a significant amount of radiation? The radiation exposure is likely to be acceptable and nearly insignificant in terms of radiation-related risks. (6) What is the likelihood that I will have a complication? 17.3% (15.4% minor, 1.9% major) for TLIF, 10% (9.3% minor and 0.7% major) for decompression, and 1.7% (all minor) for microdiscectomy (7) Will I need another surgery? Six percent after TLIF, 16.3% after decompression, 13% after microdiscectomy. (8) How long will I stay in the hospital? Most patients get discharged on postoperative day one after TLIF and on the same day after decompression and microdiscectomy. (9) When will I be able to return to work? >80% of patients return to work (average: 25 days after TLIF, 14 days after decompression, 11 days after microdiscectomy). (10) Will I be able to drive again? >90% of patients return to driving (average: 22 days after TLIF, 11 days after decompression, 14 days after microdiscectomy). CONCLUSIONS: These concise answers to the FAQs in minimally invasive lumbar spine surgery can be used by physicians as a reference to enable patient education.

Improvement in predominant back pain following minimally invasive decompression for spinal stenosis.

OBJECTIVE: The objective of this study was to assess the outcomes of patients with predominant back pain (pBP) undergoing minimally invasive decompression surgery compared with patients with nonpredominant back pain (npBP). METHODS: This was a retrospective cohort study. Patients were divided into two groups based on the presenting complaint: 1) pBP, defined as visual analog scale (VAS) back pain score > VAS leg pain score; and 2) npBP. Changes in patient-reported outcome measures (PROMs) were compared at the early (< 6 months) and late (≥ 6 months) postoperative time points. Outcomes measures were: 1) PROMs (Oswestry Disability Index [ODI], VAS back and leg pain scores, 12-Item Short-Form Health Survey Physical Component Score [SF-12 PCS], and Patient-Reported Outcomes Measurement Information System Physical Function [PROMIS PF]), and 2) minimal clinically important difference (MCID) achievement rate and time. For the late MCID achievement point, a second analysis was conducted restricting VAS back and leg pain scores only to patients with preoperative scores ≥ 5. RESULTS: Three hundred ninety patients were included (126 with pBP and 264 with npBP). There were no differences in patient demographics and operated levels. There were no differences in preoperative ODI, SF-12 PCS, and PROMIS PF scores. The pBP cohort had a significantly greater preoperative VAS back pain score than the npBP cohort, whereas the npBP cohort had a significantly greater preoperative VAS leg pain score than the pBP cohort. There were no differences in the absolute values or changes in ODI, VAS back pain, SF-12 PCS, and PROMIS PF scores at any time point. There was a significant difference in the early VAS leg pain scores (greater in npBP) that disappeared by the late postoperative time point. There was no difference in the MCID achievement rate in the ODI, SF-12 PCS, or PROMIS PF scores. By the late postoperative time point, 51.2% and 55.3% achieved an MCID on the ODI, 58.1% and 62.7% on the SF-12 PCS, 60% and 67.6% on the PROMIS PF, 81.1% and 73.2% on VAS back pain scores for those with preoperative scores ≥ 5, and 72% and 83.6% on VAS leg pain scores for those with preoperative scores ≥ 5 for the pBP and npBP cohorts, respectively. Additionally, there were no differences in time to MCID achievement for any PROMs. CONCLUSIONS: The pBP and npBP cohorts showed similar improvement in PROMs and MCID achievement rates. This result shows that minimally invasive laminectomy is equally effective for patients presenting with pBP or npBP.