Factors Causing Delay in Discharge in Patients Eligible for Ambulatory Lumbar Fusion Surgery

Class 2/3 obesity leads to worse outcomes following minimally invasive transforaminal lumbar interbody fusion

BACKGROUND CONTEXT

There is lack of evidence regarding the impact of class 2/3 obesity (body mass index [BMI] ≥35) on outcomes following minimally invasive transforaminal lumbar interbody fusion (MI-TLIF).

PURPOSE

To analyze clinical outcomes, return to activities, fusion rates, and complication/reoperation rates following MI-TLIF in class 2/3 obese patients and compare them with other BMI groups.

STUDY DESIGN

Retrospective cohort.

PATIENT SAMPLE

Patients who underwent primary single-level tubular MI-TLIF for degenerative conditions of lumbar spine and had a minimum of 1-year follow-up were included. Patients 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

(1) operative variables: operative time, estimated blood loss (EBL), postoperative length of stay (LOS); (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; (5) fusion rates; and (6) complication and reoperation rates. Two postoperative timepoints were defined: early (<6 months) and late (≥6 months).

METHODS

Differences between the 4 BMI cohorts in demographics and outcome measures were analyzed with appropriate statistical tests. Subgroup analyses were performed to compare outcomes between (1) class 2 and class 3 obesity groups and (2) patients with and without metabolic syndrome. Regression analyses were performed to analyze the relationship of BMI groups and metabolic syndrome with PASS achievement.

RESULTS

Three hundred and ninety patients were included (119 normal, 160 overweight, 67 class 1 obesity, 44 class 2/3 obesity). There was no significant difference in intraoperative variables. Although no significant difference was seen between the groups in PROMs at <6 months, class 2/3 obesity group had significantly worse PROMs, lower PASS achievement rates, and lower MCID achievement rates in VAS leg and SF-12 PCS at ≥6 months. There were no significant differences in the MCID achievement rates in ODI and VAS back and responses on the GRC scale. Although class 2/3 obesity group had a lower fusion rate (67% vs. >87% in other groups), this difference was not statistically significant. Class 2/3 obesity group had significantly higher postoperative LOS (62 hours vs. <50 hours in other groups) and took significantly greater number of days to return to driving (74 days vs. <40 days in other groups). No significant difference was found in return to work and discontinuation of narcotics. The groups had similar complication and reoperation rates. On subgroup analysis, postoperative PROMs did not show any difference between (1) class 2 and class 3 obesity groups and (2) patients with and without metabolic syndrome. On regression analysis, class 2 and class 3 obesity groups showed a significant negative relationship with PASS achievement. Class 2 obese patients were 3.7 times and class 3 obese groups were 5 times less likely to achieve PASS.

CONCLUSIONS

Class 2/3 obese patients undergoing MI-TLIF had significantly worse PROMs and lower MCID and PASS achievement rates at ≥6 months. They took longer to be discharged from the hospital and return to driving following surgery. Class 2 obese patients were 3.7 times and class 3 obese groups were 5 times less likely to achieve an acceptable symptom state after surgery.

Outcomes of Minimally Invasive Decompression Alone Versus Fusion for Predominant Back Pain

Background

Although a few recent studies showed good outcomes in back pain-predominant patients following decompression alone, none of the studies had a comparative fusion group.

Purpose

We sought to compare outcomes of minimally invasive decompression alone versus fusion in patients with predominant back pain.

Methods

This retrospective cohort study included patients who underwent minimally invasive decompression alone or fusion and had preoperative back pain > leg pain. Outcome measures were (1) patient-reported outcome measures (PROMs), (2) minimal clinically important difference (MCID) achievement, (3) patient acceptable symptom state (PASS) achievement, and (4) global rating change (GRC). As a subgroup analysis, MCID, PASS, and GRC rates were also compared between the decompression and fusion groups for patients with preoperative back pain < leg pain.

Results

Of 510 patients included, there were statistically significant improvements in all PROMs in both groups at <6 and >6 months with no significant difference in the magnitude of improvement. The fusion group showed significantly higher MCID achievement rates for Visual Analog Scale (VAS) back at <6 months (85% vs 70%) and Oswestry Disability Index (ODI) at >6 months (67% vs 51%). Proportion of patients achieving PASS and feeling better after surgery based on response to GRC showed no difference between the groups. The subgroup analysis for decompression versus fusion in patients with preoperative back pain < leg pain showed no differences in MCID, PASS, or GRC rates.

Conclusions

This retrospective cohort study found that in patients with predominant back pain, minimally invasive decompression alone had significantly less MCID achievement rates in VAS back at <6 months and ODI at >6 months. However, it did lead to an overall significant improvement in PROMs, similar PASS achievement rates, and similar responses on the GRC scale.

Clinical and Radiologic Predictors of Slower Improvement and Nonimprovement After Surgical Treatment of L4-L5 Degenerative Spondylolisthesis: Preliminary Results

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To identify the predictors of slower and nonimprovement after surgical treatment of L4-5 degenerative lumbar spondylolisthesis (DLS).

SUMMARY OF BACKGROUND DATA

There is limited evidence regarding clinical and radiologic predictors of slower and nonimprovement 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). Radiologic 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

Two hundred thirty-three patients (37% decompression and 63% fusion) were included. At less than three months, high pelvic tilt (PT) (OR: 0.92, P= 0.02) and depression (OR: 0.28, P= 0.02) were predictors of MCID nonachievement and GRC nonbetterment, respectively. Neither retained significance at above six months and hence, were identified as predictors of slower improvement. At above six 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 nonachievement, 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 nonbetterment, and high preoperative ODI (OR: 0.96, P= 0.04) was a predictor of PASS nonachievement.

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 nonimprovement. However, these are preliminary findings and further studies with homogeneous cohorts are required to establish these findings.

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.

The association between surgical start time and spine surgery outcomes

OBJECTIVE

Neurosurgical operations, including spine surgeries, often occur outside "normal business hours" due to the urgent or emergent nature of cases. This study investigates the association of surgical start time (SST) with spine surgery outcomes.

METHODS

A retrospective cross-sectional study was performed using electronic health record data from a multi-hospital academic health system from 2017 to 2024. Eligible patients included adults who underwent spine surgery with a recorded SST. Patients were separated into a regular hours group (7:00 A.M. to 5:00 P.M.) and an afterhours group (SST outside this time window). The association between SST and extended length of stay (greater than 3 days), readmission, and discharge disposition was examined.

RESULTS

The sample included 12,658 patients with 10,737 (84.8 %) patients in the regular hours group and 1921 (15.2 %) patients in the afterhours group. Afterhours SST had significantly increased rates of extended length of stay, non-home discharge disposition, and readmission compared to regular hours SST. Adjusting for age, comorbidities, case classification, the time from admission to SST, and surgery type, afterhours SST was significantly associated with non-home discharge disposition (OR 1.27, 95 % CI 1.12 - 1.45, p < 0.001).

CONCLUSION

This is the largest study to examine the association of SST with outcomes of spine surgery. Controlling for potential confounders, afterhours SST was significantly associated with non-home discharge disposition.

Venous Thromboembolism Rates Have Not Decreased in Elective Lumbar Fusion Surgery from 2011 to 2020

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

This study aimed to (1) evaluate for any temporal trends in the rates of VTE, deep venous thrombosis (DVT), pulmonary embolism (PE), and mortality from 2011 to 2020 and (2) identify the predictors of VTE following lumbar fusion surgery.

METHODS

Annual incidences of 30-day VTE, DVT, PE, and mortality were calculated for each of the operation year groups from 2011 to 2020. Multivariable Poisson regression was utilized to test the association between operation year and primary outcomes, as well as to identify significant predictors of VTE.

RESULTS

A total of 121,205 patients were included. There were no statistically significant differences in VTE, DVT, PE, or mortality rates among the operation year groups. Multivariable regression analysis revealed that compared to 2011, operation year 2019 was associated with significantly lower rates of DVT. Age, BMI, prolonged operation time, prolonged length of stay, non-home discharge, anterior fusion, smoking status, functional dependence, and chronic steroid use were identified as independent predictors of VTE following lumbar fusion. Female sex, Hispanic ethnicity, and outpatient surgery setting were identified as protective factors from VTE in this cohort.

CONCLUSIONS

Rates of VTE after lumbar fusion have remained mostly unchanged between 2011 and 2020. Older age, higher BMI, longer operation time, prolonged length of stay, non-home discharge, anterior fusion, smoking, functional dependence, and steroid use were independent predictors of VTE after lumbar fusion, while female sex, Hispanic ethnicity, and outpatient surgery were the protective factors.

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.

Clinical Application of Different Doses of Hydromorphone Slow-Release Analgesia in Lumbar Fusion in Elderly Patients

INTRODUCTION

The aim of this study is to examine the analgesic efficacy of varying doses of hydromorphone hydrochloride in conjunction with absorbable gelatin sponge for postoperative pain management in elderly individuals undergoing lumbar fusion surgery. Additionally, the study aims to assess the sustained release analgesic properties of this combination and to determine the optimal dosage of hydromorphone hydrochloride for effective pain relief.

METHODS

A total of 113 elderly patients (aged ≥ 65 years old) meeting the criteria for 1-2-level posterior lumbar fusion surgery at Ganzhou City People's Hospital between July 2022 and August 2023 were randomly assigned to four groups: group A (0.2 mg hydromorphone hydrochloride 1 ml), group B (0.3 mg hydromorphone hydrochloride 1.5 ml), group C (0.4 mg hydromorphone hydrochloride 2 ml), and group D (0.9% normal saline 2 ml) for standard anesthesia induction and maintenance. Prior to suturing the incision, gelfoam was utilized to administer epidural analgesia to each group. Following the surgical procedure, an intravenous analgesia pump was utilized for pain management. The baseline infusion rate was set at 0.5 ml/h. Patient-controlled analgesia (PCA) was administered at a dose of 2 ml, with a lockout interval of 20 min, allowing the patient to self-administer as needed. Pain relief was assessed using the visual analogue scale (VAS) prior to surgery, as well as at 1 day and 3 days post-operation. The frequency of PCA requests within the initial 48-h postoperative period, the remedial analgesia with dezocine, postoperative adverse reactions, and duration of hospitalization were documented for analysis.

RESULTS

The VAS scores of groups B and C were found to be significantly lower than those of group D 1 day after the operation. Additionally, VAS scores at 3 days post-operation, remedial rate of dezocine and PCA follow-up times at 48 h in groups A, B, and C were significantly lower compared to group D (P < 0.001). There was no statistically significant difference between group B and group C in VAS scores at 1 day and 3 days post-operation, as well as PCA follow-up times at 48 h post-operation (P < 0.001). Furthermore, the VAS scores of groups B and C were lower than those of group A at 1 day and 3 days post-operation (P < 0.05). The PCA frequency of group C was also lower than that of group A at 48 h post-operation (P < 0.05).

CONCLUSION

The combination of hydromorphone hydrochloride and absorbable gelatin sponge epidural analgesia has been shown to enhance postoperative pain management. A dosage of 0.4 mg of hydromorphone hydrochloride may be considered an appropriate analgesic dose, as it can provide effective pain relief without eliciting adverse reactions.

TRIAL REGISTRATION

ChiCTR.org.cn(ChiCTR2200064863). Registered on October 20, 2022.

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.

Predicting conversion of ambulatory ACDF patients to inpatient: a machine learning approach

BACKGROUND CONTEXT

Machine learning is a powerful tool that has become increasingly important in the orthopedic field. Recently, several studies have reported that predictive models could provide new insights into patient risk factors and outcomes. Anterior cervical discectomy and fusion (ACDF) is a common operation that is performed as an outpatient procedure. However, some patients are required to convert to inpatient status and prolonged hospitalization due to their condition. Appropriate patient selection and identification of risk factors for conversion could provide benefits to patients and the use of medical resources.

PURPOSE

This study aimed to develop a machine-learning algorithm to identify risk factors associated with unplanned conversion from outpatient to inpatient status for ACDF patients.

STUDY DESIGN/SETTING

This is a machine-learning-based analysis using retrospectively collected data.

PATIENT SAMPLE

Patients who underwent one- or two-level ACDF in an ambulatory setting at a single specialized orthopedic hospital between February 2016 to December 2021.

OUTCOME MEASURES

Length of stay, conversion rates from ambulatory setting to inpatient.

METHODS

Patients were divided into two groups based on length of stay: (1) Ambulatory (discharge within 24 hours) or Extended Stay (greater than 24 hours but fewer than 48 hours), and (2) Inpatient (greater than 48 hours). Factors included in the model were based on literature review and clinical expertise. Patient demographics, comorbidities, and intraoperative factors, such as surgery duration and time, were included. We compared the performance of different machine learning algorithms: Logistic Regression, Random Forest (RF), Support Vector Machine (SVM), and Extreme Gradient Boosting (XGBoost). We split the patient data into a training and validation dataset using a 70/30 split. The different models were trained in the training dataset using cross-validation. The performance was then tested in the unseen validation set. This step is important to detect overfitting. The performance was evaluated using the area under the curve (AUC) of the receiver operating characteristics analysis (ROC) as the primary outcome. An AUC of 0.7 was considered fair, 0.8 good, and 0.9 excellent, according to established cut-offs.

RESULTS

A total of 581 patients (59% female) were available for analysis. Of those, 140 (24.1%) were converted to inpatient status. The median age was 51 (IQR 44-59), and the median BMI was 28 kg/m2 (IQR 24-32). The XGBoost model showed the best performance with an AUC of 0.79. The most important features were the length of the operation, followed by sex (based on biological attributes), age, and operation start time. The logistic regression model and the SVM showed worse results, with an AUC of 0.71 each.

CONCLUSIONS

This study demonstrated a novel approach to predicting conversion to inpatient status in eligible patients for ambulatory surgery. The XGBoost model showed good predictive capabilities, superior to the older machine learning approaches. This model also revealed the importance of surgical duration time, BMI, and age as risk factors for patient conversion. A developing field of study is using machine learning in clinical decision-making. Our findings contribute to this field by demonstrating the feasibility and accuracy of such methods in predicting outcomes and identifying risk factors, although external and multi-center validation studies are needed.

Intravenous versus oral acetaminophen for pain and quality of recovery after ambulatory spine surgery: a randomized controlled trial

INTRODUCTION

As ambulatory spine surgery increases, efficient recovery and discharge become essential. Multimodal analgesia is superior to opioids alone. Acetaminophen is a central component of multimodal protocols and both intravenous and oral forms are used. While some advantages for intravenous acetaminophen have been touted, prospective studies with patient-centered outcomes are lacking in ambulatory spine surgery. A substantial cost difference exists. We hypothesized that intravenous acetaminophen would be associated with fewer opioids and better recovery.

METHODS

Patients undergoing ambulatory spine surgery were randomized to preoperative oral placebo and intraoperative intravenous acetaminophen or preoperative oral acetaminophen. All patients received general anesthesia and multimodal analgesia. The primary outcome was 24-hour opioid use in intravenous morphine milligram equivalents (MMEs), beginning with arrival to the postanesthesia care unit (PACU). Secondary outcomes included pain, Quality of Recovery (QoR)-15 scores, postoperative nausea and vomiting, recovery time, and correlations between pain catastrophizing, QoR-15, and pain.

RESULTS

A total of 82 patients were included in final analyses. Demographics were similar between groups. For the primary outcome, the median 24-hour MMEs did not differ between groups (12.6 (4.0, 27.1) vs 12.0 (4.0, 29.5) mg, p=0.893). Postoperative pain ratings, PACU MMEs, QoR-15 scores, and recovery time showed no differences. Spearman's correlation showed a moderate negative correlation between postoperative opioid use and QoR-15.

CONCLUSION

Intravenous acetaminophen was not superior to the oral form in ambulatory spine surgery patients. This does not support routine use of the more expensive intravenous form to improve recovery and accelerate discharge.

TRIAL REGISTRATION NUMBER

NCT04574778.

Development and external validation of a predictive model for prolonged length of hospital stay in elderly patients undergoing lumbar fusion surgery: comparison of three predictive models

PURPOSE

This study aimed to develop a predictive model for prolonged length of hospital stay (pLOS) in elderly patients undergoing lumbar fusion surgery, utilizing multivariate logistic regression, single classification and regression tree (hereafter, "classification tree") and random forest machine-learning algorithms.

METHODS

This study was a retrospective review of a prospective Geriatric Lumbar Disease Database. The primary outcome measure was pLOS, which was defined as the LOS greater than the 75th percentile. All patients were grouped as pLOS group and non-pLOS. Three models (including logistic regression, single-classification tree and random forest algorithms) for predicting pLOS were developed using training dataset and internal validation using testing dataset. Finally, online tool based on our model was developed to assess its validity in the clinical setting (external validation).

RESULTS

The development set included 1025 patients (mean [SD] age, 72.8 [5.6] years; 632 [61.7%] female), and the external validation set included 175 patients (73.2 [5.9] years; 97[55.4%] female). Multivariate logistic analyses revealed that older age (odds ratio [OR] 1.06, p < 0.001), higher BMI (OR 1.08, p = 0.002), number of fused segments (OR 1.41, p < 0.001), longer operative time (OR 1.02, p < 0.001), and diabetes (OR 1.05, p = 0.046) were independent risk factors for pLOS in elderly patients undergoing lumbar fusion surgery. The single-classification tree revealed that operative time ≥ 232 min, delayed ambulation, and BMI ≥ 30 kg/m2 as particularly influential predictors for pLOS. A random forest model was developed using the remaining 14 variables. Intraoperative EBL, operative time, delayed ambulation, age, number of fused segments, BMI, and RBC count were the most significant variables in the final model. The predictive ability of our three models was comparable, with no significant differences in AUC (0.73 vs. 0.71 vs. 0.70, respectively). The logistic regression model had a higher net benefit for clinical intervention than the other models. The nomogram was developed, and the C-index of external validation for PLOS was 0.69 (95% CI, 0.65-0.76).

CONCLUSION

This investigation produced three predictive models for pLOS in elderly patients undergoing lumbar fusion surgery. The predictive ability of our three models was comparable. Logistic regression model had a higher net benefit for clinical intervention than the other models. Our predictive model could inform physicians about elderly patients with a high risk of pLOS after surgery.

Erector Spinae Plane Block Reduces Immediate Postoperative Pain and Opioid Demand After Minimally Invasive Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

Matched cohort comparison.

OBJECTIVE

To determine perioperative outcomes of erector spinae plane (ESP) block for minimally invasive transforaminal lumbar interbody fusion (MI-TLIF).

SUMMARY OF BACKGROUND DATA

There is a paucity of data on the impact of lumbar ESP block on perioperative outcomes and its safety in MI-TLIF.

MATERIALS AND METHODS

Patients who underwent 1-level MI-TLIF and received the ESP block (group E ) were included. An age and sex-matched control group was selected from a historical cohort that received the standard-of-care (group NE). The primary outcome of this study was 24-hour opioid consumption in morphine milligram equivalents. Secondary outcomes were pain severity measured by a numeric rating scale, opioid-related side effects, and hospital length of stay. Outcomes were compared between the two groups.

RESULTS

Ninety-eight and 55 patients were included in the E and NE groups, respectively. There were no significant differences between the two cohorts in patient demographics. Group E had lower 24-hour postoperative opioid consumption ( P = 0.117, not significant), reduced opioid consumption on a postoperative day (POD) 0 ( P = 0.016), and lower first pain scores postsurgery ( P < 0.001). Group E had lower intraoperative opioid requirements ( P < 0.001), and significantly lower average numeric rating scale pain scores on POD 0 ( P = 0.034). Group E reported fewer opioid-related side effects as compared with group NE, although this was not statistically significant. The average highest postoperative pain score within 3 hours postprocedurally was 6.9 and 7.7 in the E and NE cohorts, respectively ( P = 0.029). The median length of stay was comparable between groups with the majority of patients in both groups being discharged on POD 1.

CONCLUSIONS

In our retrospective matched cohort, ESP blocks resulted in reduced opioid consumption and decreased pain scores on POD 0 in patients undergoing MI-TLIF.

LEVEL OF EVIDENCE

Level 3.

Preoperative Disability Influences Effectiveness of MCID and PASS in Predicting Patient Improvement Following Lumbar Spine Surgery

STUDY DESIGN

Retrospective cohort.

SUMMARY OF BACKGROUND DATA

Although minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) are utilized to interpret Oswestry Disability Index (ODI), it is unclear whether there is a clearly better metric between the two and if not, which metric should be utilized when.

OBJECTIVE

To compare the characteristics of MCID and PASS when interpreting ODI after lumbar spine surgery.

METHODS

Patients who underwent primary minimally invasive transforaminal lumbar interbody fusion or decompression were included. The ODI and global rating change data at 1 year were analyzed. The global rating change was collapsed to a dichotomous outcome variable-(a) improved, (b) not improved The sensitivity, specificity, positive predictive value and negative predictive value of MCID and PASS were calculated for the overall cohort and separately for patients with minimal, moderate, and severe preoperative disability. Two groups with patients who achieved PASS but not MCID and patients who achieved MCID but not PASS were analyzed.

RESULTS

Two hundred twenty patients (mean age 62 y, 57% males) were included. PASS (86% vs. 69%) and MCID (88% vs. 63%) had significantly greater sensitivity in patients with moderate and severe preoperative disability, respectively. Nineteen percent of patients achieved PASS but not MCID and 10% of patients achieved MCID but not PASS, with the preoperative ODI being significantly greater in the latter. Most of these patients still reported improvement with no significant difference between the 2 groups (93% vs. 86%).

CONCLUSION

Significant postoperative clinical improvement is most effectively assessed by PASS in patients with minimal or moderate preoperative disability and by MCID in patients with severe preoperative disability. Adequate interpretation of ODI using the PASS and MCID metrics warrants individualized application as their utility is highly dependent on the degree of preoperative disability.

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.

Risk Factors for Unexpected Conversion From Ambulatory to Inpatient Admission Among One-level or Two-level ACDF Patients

STUDY DESIGN/SETTING

A retrospective observational study.

OBJECTIVE

The aim of this study was to investigate the factors associated with the conversion of patient status from ambulatory anterior cervical discectomy and fusion (ACDF) to inpatient.

SUMMARY OF BACKGROUND DATA

Surgeries are increasingly performed in an ambulatory setting in an era of rising healthcare costs and pressure to improve patient satisfaction. ACDF is a common ambulatory cervical spine surgery, however, there are certain patients who are unexpectedly converted from an outpatient procedure to inpatient admission and little is known about the risk factors for conversion.

MATERIALS AND METHODS

Patients who underwent one-level or two-level ACDF in an ambulatory setting at a single specialized orthopedic hospital between February 2016 to December 2021 were included. Baseline demographics, surgical information, complications, and conversion reasons were compared between patients with ambulatory surgery or observational stay (stay <48 h) and inpatient (stay >48 h).

RESULTS

In total, 662 patients underwent one-level or two-level ACDF (median age, 52 yr; 59.5% were male), 494 (74.6%) patients were discharged within 48 hours and 168 (25.4%) patients converted to inpatient. Multivariable logistic regression analysis demonstrated that females, low body mass index <25, American Society of Anesthesiologists classification (ASA) ≥3, long operation, high estimated blood loss, upper-level surgery, two-level fusion, late operation start time, and high postoperative pain score were considered independent risk factors for conversion to inpatient. Pain management was the most common reason for the conversion (80.0%). Ten patients (1.5%) needed reintubation or remained intubated for airway management.

CONCLUSIONS

Several independent risk factors for prolonged hospital stay after ambulatory ACDF surgery were identified. Although some factors are unmodifiable, other factors, such as procedure duration, operation start time, and blood loss could be potential targets for intervention. Surgeons should be aware of the potential for life-threatening airway complications in ambulatory-scheduled ACDF.

Poor muscle health and low preoperative ODI are independent predictors for slower achievement of MCID after minimally invasive decompression

BACKGROUND CONTEXT

Although some previous studies have analyzed predictors of nonimprovement, most of these have focused on demographic and clinical variables and have not accounted for radiological predictors. In addition, while several studies have examined the degree of improvement after decompression, there is less data on the rate of improvement.

PURPOSE

To identify the risk factors and predictors (both radiological and nonradiological) for slower as well as nonachievement of minimal clinically important difference (MCID) after minimally invasive decompression.

DESIGN

Retrospective cohort.

PATIENT SAMPLE

Patients who underwent minimally invasive decompression for degenerative lumbar spine conditions and had a minimum of 1-year follow up were included. Patients with preoperative Oswestry Disability Index (ODI) <20 were excluded.

OUTCOME MEASURE

MCID achievement in ODI (cut off 12.8).

METHODS

Patients were stratified into two groups (achieved MCID, did not achieve MCID) at two timepoints (early ≤3 months, late ≥6 months). Nonradiological (age, gender, BMI, comorbidities, anxiety, depression, number of levels operated, preoperative ODI, preoperative back pain) and radiological (MRI - Schizas grading for stenosis, dural sac cross-sectional area, Pfirrmann grading for disc degeneration, psoas cross-sectional area and Goutallier grading, facet cyst/effusion; X-ray - spondylolisthesis, lumbar lordosis, spinopelvic parameters) variables were assessed with comparative analysis to identify risk factors and with multiple regression models to identify predictors for slower achievement of MCID (MCID not achieved by ≤3 months) and nonachievement of MCID (MCID not achieved at ≥6 months).

RESULTS

A total of 338 patients were included. At ≤3 months, patients who did not achieve MCID had significantly lower preoperative ODI (40.1 vs 48.1, p<0.001) and worse psoas Goutallier grading (p=.048). At ≥6 months, patients who did not achieve MCID had significantly lower preoperative ODI (38 vs 47.5, p<.001), higher age (68 vs 63 years, p=.007), worse average L1-S1 Pfirrmann grading (3.5 vs 3.2, p=.035), and higher rate of pre-existing spondylolisthesis at the operated level (p=.047). When these and other probable risk factors were put into a regression model, low preoperative ODI (p=.002) and poor Goutallier grading (p=.042) at the early timepoint and low preoperative ODI (p<.001) at the late timepoint came out as independent predictors for MCID nonachievement.

CONCLUSION

After minimally invasive decompression, low preoperative ODI and poor muscle health are risk factors and predictors for slower achievement of MCID. For nonachievement of MCID, low preoperative ODI, higher age, greater disc degeneration, and spondylolisthesis are risk factors and low preoperative ODI is the only independent predictor.

Floor-Mounted Robotic Pedicle Screw Placement in Lumbar Spine Surgery: An Analysis of 1,050 Screws

OBJECTIVE

To analyze the usage of floor-mounted robot in minimally invasive lumbar fusion.

METHODS

Patients who underwent minimally invasive lumbar fusion for degenerative pathology using floor-mounted robot (ExcelsiusGPS) were included. Pedicle screw accuracy, proximal level violation rate, pedicle screw size, screw-related complications, and robot abandonment rate were analyzed.

RESULTS

Two hundred twenty-nine patients were included. Most surgeries were primary single-level fusion. Sixty-five percent of surgeries had intraoperative computed tomography (CT) workflow, 35% had preoperative CT workflow. Sixty-six percent were transforaminal lumbar interbody fusion, 16% were lateral, 8% were anterior, and 10% were a combined approach. A total of 1,050 screws were placed with robotic assistance (85% in prone position, 15% in lateral position). Postoperative CT scan was available for 80 patients (419 screws). Overall pedicle screw accuracy rate was 96.4% (prone, 96.7%; lateral, 94.2%; primary, 96.7%; revision, 95.3%). Overall poor screw placement rate was 2.8% (prone, 2.7%; lateral, 3.8%; primary, 2.7%; revision, 3.5%). Overall proximal facet and endplate violation rates were 0.4% and 0.9%. Average diameter and length of pedicle screws were 7.1 mm and 47.7 mm. Screw revision had to be done for 1 screw (0.1%). Use of the robot had to be aborted in 2 cases (0.8%).

CONCLUSION

Usage of floor-mounted robotics for the placement of lumbar pedicle screws leads to excellent accuracy, large screw size, and negligible screw-related complications. It does so for screw placement in prone/lateral position and primary/revision surgery alike with negligible robot abandonment rates.

Prevalence and associated factors of postoperative orthostatic intolerance at University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia, 2022: cross sectional study

BACKGROUND

Postoperative orthostatic intolerance is an inability to maintain an upright position because of symptoms of cerebral hypoperfusion. It is a common problem in the early postoperative period and hinders early mobilization, however, there is limited information about factors associated with it. Thus, the main aim of this study was to determine the prevalence and identify factors associated with postoperative orthostatic intolerance.

METHOD

Hospital based cross-sectional study was conducted from April 08 to July 20, 2022, at University of Gondar comprehensive Specialized Hospital. A semi-structured questionnaire containing sociodemographic variables and perioperative factors related to anesthesia and surgery was used for data collection. The presence of postoperative orthostatic intolerance during the first ambulation was evaluated with a standardized symptom checklist which contains symptoms of orthostatic intolerance. Binary logistic regression analysis was performed to assess factors associated with postoperative orthostatic intolerance. In multivariable regression, variables with P-value < 0.05 were considered statistically significant.

RESULT

A total of 420 patients were included in this study with a response rate of 99.06%. Postoperative orthostatic intolerance was experienced in 254 (60.5%) participants. Being female (AOR = 2.27; 95% CI = 1.06-4.86), low BMI (AOR = 0.79; 95% CI = 0.71-0.95), ASA II and above (AOR = 3.34; 95% CI = 1.34-8.28), low diastolic blood pressure (AOR = 0.82; 95% CI = 0.88-0.99), general anesthesia (AOR = 3.26, 95% CI = 1.31-8.12), high intraoperative blood lose (AOR = 0.93, 95% CI = 0.88-0.99), high postoperative fluid intake (AOR = 2.09, 95% CI = 1.23-3.55), pain before ambulation (AOR = 1.99, 95% CI = 1.28-3.11) and pain during ambulation (AOR = 1.82, 95% CI = 1.23-2.69) were the significant factors associated with orthostatic intolerance.

CONCLUSION

Our study revealed that postoperative orthostatic intolerance was experienced in nearly two-thirds of participants. During the time of ambulation, assessing patients for the presence of orthostatic intolerance is necessary to reduce the adverse effects of postoperative OI. In addition, maintaining preoperative normotension, reducing intraoperative blood loss and optimizing postoperative pain control is recommended to reduce the risk of postoperative orthostatic intolerance.

Comparison of Transforaminal Lumbar Interbody Fusion in the Ambulatory Surgery Center and Traditional Hospital Settings, Part 2: Assessment of Surgical Safety in Medicare Beneficiaries

(1) Background: The clinical benefits and procedural efficiencies of performing minimally invasive fusion procedures, such as transforaminal lumbar interbody fusion (TLIF), in the ambulatory surgery center (ASC) are becoming increasingly well established. Currently, Medicare does not provide reimbursement for its beneficiaries eligible for TLIF in the ASC due to a lack of evidence regarding procedural safety. However, the initiation of the Hospital Without Walls program allowed for traditional hospital procedures to be relocated to other facilities such as ASCs, providing a unique opportunity to evaluate the utility of TLIF in the ASC in Medicare-age patients. (2) Methods: This single-center, retrospective study compared baseline characteristics, intraoperative variables, and 30-day postoperative safety outcomes between 48 Medicare-age patients undergoing TLIF in the ASC and 48 patients having the same procedure as hospital in-patients. All patients had a one-level TLIF using the VariLift®-LX expandable lumbar interbody fusion device. (3) Results: There were similar patient characteristics, procedural efficiency, and occurrence of clinical 30-day safety events between the two study groups. However, there was a marked and statistically significant difference in the median length of stay favoring TLIF patients treated in the ASC (23.9 h vs. 1.6 h, p = 0.001). All ASC-treated patients were discharged on the day of surgery. Postoperative visits to address adverse events were rare in either group. (4) Conclusions: These findings provide evidence that minimally invasive TLIF can be performed safely and efficiently in the ASC in Medicare-age patients. With same-day discharge, fusion procedures performed in the ASC offer a similar safety and more attractive cost-benefit profile for older patients than the same surgery undertaken in the traditional hospital setting. The Centers for Medicare and Medicaid Services should strongly consider extending the appropriate reimbursement codes (CPT ® 22630, 22633) for minimally invasive TLIF and PLIF to the ASC Covered Procedure List so that Medicare-age patients can realize the clinical benefits of surgeries performed in this setting.

Influence of Preoperative Disability on Clinical Outcomes in Patients Undergoing Anterior Lumbar Interbody Fusion

BACKGROUND

Few studies have examined the influence of preoperative disability through the Oswestry Disability Index (ODI) on clinical outcomes in patients undergoing anterior lumbar interbody fusion (ALIF).

METHODS

Patients undergoing ALIF were separated into 2 groups based on ODI<41 (lower disability) versus ODI≥41% (higher disability). Patient-reported outcomes (PROs) were collected at preoperative and postoperative 6-week/12-week/6-month/1-year/2-year time points. Physical function PROs were Patient-Reported Outcomes Measurement Information System Physical Function and 12-item Short Form Physical Component Score. Mental function PROs were 12-item Short Form Mental Component Score and Patient Health Questionnaire-9. Pain PROs were visual analog scale back and visual analog scale leg. ODI was the disability PRO.

RESULTS

A total of 148 patients were identified, with 52 patients with lower disability. Higher disability patients demonstrated significant improvement in mental function (P ≤ 0.010, all). Lower disability patients demonstrated superior postoperative PROs in physical function, mental function, back pain, and disability outcomes (P ≤ 0.034, all). Minimum clinically important difference achievement rates for lower disability patients were higher for back pain and lower for mental function and disability outcomes (P ≤ 0.041, all).

CONCLUSIONS

Independent of preoperative disability, patients undergoing ALIF reported significant postoperative improvement in physical function, pain, and disability outcomes. Patients with lower preoperative disability continued to report superior PROs in mental function, back pain, and disability postoperatively. Minimum clinically important difference achievement rates for lower disability patients were higher for back pain and lower in mental function and disability outcomes. Patients undergoing ALIF with higher preoperative disability may experience greater clinically meaningful improvement in mental function and disability.

Ambulatory Lumbar Fusion: A Systematic Review of Perioperative Protocols, Patient Selection Criteria, and Outcomes

STUDY DESIGN/SETTING

Systematic review.

OBJECTIVE

The primary purpose was to propose patient selection criteria and perioperative best practices that can serve as a starting point for an ambulatory lumbar fusion program. The secondary purpose was to review patient-reported outcomes (PROs) after ambulatory lumbar fusion.

SUMMARY OF BACKGROUND

As healthcare costs rise, there is an increasing emphasis on cost saving strategies (i.e. outpatient/ambulatory surgeries). Lumbar fusion procedures remain a largely inpatient surgery. Early studies have shown that fusion procedures can be safely preformed in an outpatient setting but no review has summarized these findings and best practices.

MATERIALS AND METHODS

This study was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed/MEDLINE, The Cochrane Library, and Embase were searched. The following data were collected: (1) study design; (2) number of participants; (3) patient population; (4) procedure types; (5) procedure setting; (6) inclusion criteria; (7) protocols; (8) adverse events; (9) PROs; and (10) associations between patient/surgical factors, setting, and outcomes.

RESULTS

The search yielded 20 publications. The following selection criteria for ambulatory lumbar fusion were identified: age below 70, minimal comorbidities, low/normal body mass index, no tobacco use, and no opioid use. The perioperative protocol can include a multimodal analgesic regimen. The patient should be observed for at least three hours after surgery. The patient should not be discharged without an alertness check and a neurological examination. Patients experienced significant improvements in PROs after ambulatory lumbar fusion; similarly, when compared to an inpatient group, ambulatory lumbar fusion patients experienced a comparable or superior improvement in PROs.

CONCLUSION

There are two critical issues surrounding ambulatory lumbar fusion: (1) Who is the ideal patient, and (2) What needs to be done to enable expedited discharge? We believe this review will provide a foundation to assist surgeons in making decisions regarding the performance of lumbar fusion on an ambulatory basis.

LEVEL OF EVIDENCE

Level III.

ODI <25 Denotes Patient Acceptable Symptom State After Minimally Invasive Lumbar Spine Surgery

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To determine the Oswestry Disability Index (ODI) cutoff for achieving Patient Acceptable Symptom State (PASS) at one year following minimally invasive lumbar spine surgery.

SUMMARY OF BACKGROUND DATA

An absolute score denoting PASS, rather than a change score denoting minimal clinically important difference (MCID), might be a better metric to assess clinical outcomes.

MATERIALS AND METHODS

Patients who underwent primary minimally invasive transforaminal lumbar interbody fusion or decompression were included. The outcome measure was ODI. The anchor question was the Global Rating Change: "Compared with preoperative, you feel (1) much better, (2) slightly better, (3) same, (4) slightly worse, or (5) much worse." For analysis, it was collapsed to a dichotomous outcome variable (acceptable=response of 1 or 2, unacceptable=response of 3, 4, or 5). Proportion of patients achieving PASS and the ODI cutoff using receiver operating characteristic curve analyses were assessed for the overall cohort as well as subgroups based on age, sex, type of surgery, and preoperative ODI. Differences between the PASS and MCID metrics were analyzed.

RESULTS

A total of 137 patients were included. In all, 87% of patients achieved PASS. Patients less than or equal to 65 years and those undergoing fusion were more likely to achieve PASS. The receiver operating characteristic curve analysis revealed an ODI cutoff of 25.2 to achieve PASS (area under the curve: 0.872, sensitivity: 82%, specificity: 83%). The subgroup analyses based on age, sex, and preoperative ODI revealed area under the curve >0.8 and ODI threshold values consistent between 25.2 and 25.5 (except 28.4 in patients with preoperative ODI >40). PASS was found to have significantly higher sensitivity compared with MCID (82% vs. 69%, P =0.01).

CONCLUSIONS

Patients with ODI <25 are expected to achieve PASS, irrespective of age, sex, and preoperative disability. PASS was found to have significantly higher sensitivity than MCID.

LEVEL OF EVIDENCE

3.

Improvement following minimally invasive transforaminal lumbar interbody fusion in patients aged 70 years or older compared with younger age groups

OBJECTIVE

The goal of this study was to assess the outcomes of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) in patients ≥ 70 years old and compare them to younger age groups.

METHODS

This was a retrospective study of data that were collected prospectively. Patients who underwent primary single-level MI-TLIF were included and divided into 3 groups: age < 60, 60-69, and ≥ 70 years. The outcome measures were as follows: 1) patient-reported outcome measures (PROMs) (i.e., visual analog scale [VAS] for back and leg pain, Oswestry Disability Index [ODI], 12-Item Short-Form Health Survey Physical Component Summary [SF-12 PCS]); 2) minimum clinically important difference (MCID) achievement; 3) return to activities; 4) opioid discontinuation; 5) fusion rates; and 6) complications/reoperations.

RESULTS

A total of 147 patients (age < 60 years, 62; 60-69 years, 47; ≥ 70 years, 38) were included. All the groups showed significant improvements in all PROMs at the early (< 6 months) and late (≥ 6 months) time points and there was no significant difference between the groups. Although MCID achievement rates for VAS leg and ODI were similar, they were lower in the ≥ 70-year-old patient group for VAS back and SF-12 PCS. Although the time to MCID achievement for ODI and SF-12 PCS was similar, it was greater in the ≥ 70-year-old patient group for VAS back and leg. There was no significant difference between the groups in terms of return to activities, opioid discontinuation, fusion rates, and complication/reoperation rates.

CONCLUSIONS

Although patients > 70 years of age may be less likely and/or take longer to achieve MCID compared to their younger counterparts, they show an overall significant improvement in PROMs, a similar likelihood of returning to activities and discontinuing opioids, and comparable fusion and complication/reoperation rates following MI-TLIF.