Impact of Metabolic Syndrome on Early Postoperative Outcomes After Cervical Disk Replacement: A Propensity-matched Analysis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To compare the demographics, perioperative variables, and complication rates following cervical disk replacement (CDR) among patients with and without metabolic syndrome (MetS). SUMMARY OF BACKGROUND DATA: The prevalence of MetS-involving concurrent obesity, insulin resistance, hypertension, and hyperlipidemia-has increased in the United States over the last 2 decades. Little is known about the impact of MetS on early postoperative outcomes and complications following CDR. METHODS: The 2005-2020 National Surgical Quality Improvement Program was queried for patients who underwent primary 1- or 2-level CDR. Patients with and without MetS were divided into 2 cohorts. MetS was defined, according to other National Surgical Quality Improvement Program studies, as concurrent diabetes mellitus, hypertension requiring medication, and body mass index ≥30 kg/m2. Rates of 30-day readmission, reoperation, complications, length of hospital stay, and discharge disposition were compared using χ2 and Fisher exact tests. One to 2 propensity-matching was performed, matching for demographics, comorbidities, and number of operative levels. RESULTS: A total of 5395 patients were included for unmatched analysis. Two hundred thirty-six had MetS, and 5159 did not. The MetS cohort had greater rates of 30-day readmission (2.5% vs. 0.9%; P=0.023), morbidity (2.5% vs. 0.9%; P=0.032), nonhome discharges (3% vs. 0.6%; P=0.002), and longer hospital stays (1.35±4.04 vs. 1±1.48 days; P=0.029). After propensity-matching, 699 patients were included. All differences reported above lost significance (P>0.05) except for 30-day morbidity (superficial wound infections), which remained higher for the MetS cohort (2.5% vs. 0.4%, P=0.02). CONCLUSIONS: We identified MetS as an independent predictor of 30-day morbidity in the form of superficial wound infections following single-level CDR. Although MetS patients experienced greater rates of 30-day readmission, nonhome discharge, and longer lengths of stay, MetS did not independently predict these outcomes after controlling for baseline differences in patient characteristics. LEVEL OF EVIDENCE: Level III.

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.

Severe Obesity Is an Independent Risk Factor of Early Readmission and Nonhome Discharge After Cervical Disc Replacement.

OBJECTIVE: Despite growing interest in cervical disc replacement (CDR) for conditions such as cervical radiculopathy, limited data exists describing the impact of obesity on early postoperative outcomes and complications. These data are especially important as nearly half of the adult population in the United States is expected to become obese (body mass index [BMI] ≥ 30 kg/m2) by 2030. The goal of this study was to compare the demographics, perioperative variables, and complication rates following CDR. METHODS: The 2005-2020 American College of Surgeons National Surgical Quality Improvement Program datasets were queried for patients who underwent primary 1- or 2-level CDR. Patients were divided into 3 cohorts: Nonobese (BMI: 18.5-29.9 kg/m2), Obese class-I (BMI: 30-34.9 kg/m2), Obese class-II/III (BMI ≥ 35 kg/m2). Morbidity was defined as the presence of any complication within 30 days postoperatively. Rates of 30-day readmission, reoperation, morbidity, individual complications, length of stay, frequency of nonhome discharge disposition were collected. RESULTS: A total of 5,397 patients were included for analysis: 3,130 were nonobese, 1,348 were obese class I, and 919 were obese class II/III. There were more 2-level CDRs performed in the class II/III cohort compared to the nonobese group (25.7% vs. 21.5%, respectively; p < 0.05). Class-II/III had more nonhome discharges than class I and nonobese (2.1% vs. 0.5% vs. 0.7%, respectively; p < 0.001). Readmission rates differed as well (nonobese: 0.5%, class I: 1.1%, class II/III: 2.1%; p < 0.001) with pairwise significance between class II/II and nonobese. Class II/III obesity was an independent risk factor for both readmission (odds ratio [OR], 3.32; p = 0.002) and nonhome discharge (OR, 2.51; p = 0.02). Neither 30-day reoperation nor morbidity rates demonstrated significance. No mortalities were reported. CONCLUSION: Although obese class-II/III were risk factors for 30-day readmission and nonhome discharge, there was no significant difference in reoperation rates or morbidity. CDR procedures can continue to be safely preformed independent of obesity status.

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.

NDI <21 Denotes Patient Acceptable Symptom State After Degenerative Cervical Spine Surgery.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To determine the Neck Disability Index (NDI) cut-off for achieving patient acceptable symptom state (PASS) at six months following degenerative cervical spine surgery. SUMMARY OF BACKGROUND DATA: An absolute score denoting PASS might be a better marker to assess clinical outcomes than a change score denoting minimal clinically important difference. MATERIALS AND METHODS: Patients who underwent primary anterior cervical decompression and fusion, cervical disk replacement, or laminectomy were included. The outcome measure was NDI. The anchor used to assess PASS achievement at six months was the response on the Global Rating Change: "Compared with preoperative, you feel (1) much better, (2) slightly better, (3) same, (4) slightly worse, or (5) much worse." It was converted to a dichotomous outcome variable (acceptable=response of 1 or 2, unacceptable=response of 3, 4, or 5) for analyses. The overall cohort and subgroups based on age (65 yr and below, above 65 yr), sex, myelopathy, and preoperative NDI (≤40, >40) were analyzed for the proportion of patients achieving PASS and the NDI cut-off using receiver operator curve. RESULTS: Seventy-five patients (42 anterior cervical decompression and fusion, 23 cervical disc replacement, 10 laminectomy) were included. 79% of patients achieved PASS. Males, patients with age 65 years and below, preoperative NDI ≤40, and absence of myelopathy were more likely to achieve PASS. The receiver operator curve analysis revealed an Oswestry Disability Index cut-off of 21 to achieve PASS (area under the curve, AUC: 0.829, sensitivity: 81%, specificity: 80%). The subgroup analyses based on age, sex, myelopathy, and preoperative NDI revealed AUCs >0.7 and NDI threshold values consistent between 17 and 23. CONCLUSIONS: With an AUC of 0.829, NDI showed an excellent discriminative ability. Patients with NDI ≤21 are expected to achieve PASS following degenerative cervical spine surgery.

Predictors of Subsidence and its Clinical Impact After Expandable Cage Insertion in Minimally Invasive Transforaminal Interbody Fusion.

STUDY DESIGN: Retrospective review of prospectively collected multisurgeon data. OBJECTIVE: Examine the rate, clinical impact, and predictors of subsidence after expandable minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) cage. SUMMARY OF BACKGROUND DATA: Expandable cage technology has been adopted in MI-TLIF to reduce the risks and optimize outcomes. Although subsidence is of particular concern when using expandable technology as the force required to expand the cage can weaken the endplates, its rates, predictors, and outcomes lack evidence. MATERIALS AND METHODS: Patients who underwent 1 or 2-level MI-TLIF using expandable cages for degenerative lumbar conditions and had a follow-up of >1 year were included. Preoperative and immediate, early, and late postoperative radiographs were reviewed. Subsidence was determined if the average anterior/posterior disc height decreased by >25% compared with the immediate postoperative value. Patient-reported outcomes were collected and analyzed for differences at the early (<6 mo) and late (>6 mo) time points. Fusion was assessed by 1-year postoperative computed tomography. RESULTS: One hundred forty-eight patients were included (mean age, 61 yr, 86% 1-level, 14% 2-level). Twenty-two (14.9%) demonstrated subsidence. Although statistically not significant, patients with subsidence were older, had lower bone mineral density, and had higher body mass index and comorbidity burden. Operative time was significantly higher ( P = 0.02) and implant width was lower ( P < 0.01) for subsided patients. Visual analog scale-leg was significantly lower for subsided patients compared with nonsubsided patients at a >6 months time point. Long-term (>6 mo) patient-acceptable symptom state achievement rate was lower for subsided patients (53% vs . 77%), although statistically not significant ( P = 0.065). No differences existed in complication, reoperation, or fusion rates. CONCLUSIONS: Of the patients, 14.9% experienced subsidence predicted by narrower implants. Although subsidence did not have a significant impact on most patient-reported outcome measures and complication, reoperation, or fusion rates, patients had lower visual analog scale-leg and patient-acceptable symptom state achievement rates at the >6-month time point. LEVEL OF EVIDENCE: Level 4.

Female Sex and Supine Proximal Lumbar Lordosis Are Associated With the Size of the LLIF "Safe Zone" at L4-L5.

STUDY DESIGN: Retrospective chart review. OBJECTIVE: Identify demographic and sagittal alignment parameters that are independently associated with femoral nerve position at the L4-L5 disk space. SUMMARY OF BACKGROUND DATA: Iatrogenic femoral nerve or lumbar plexus injury during lateral lumbar interbody fusion (LLIF) can result in neurological complications. The LLIF "safe zone" is the anterior half to two third of the disk space. However, femoral nerve position varies and is inconsistently identifiable on magnetic resonance imaging. The safe zone is also narrowest at L4-L5. METHODS: An analysis of patients with symptomatic lumbar spine pathology and magnetic resonance imaging with a visibly identifiable femoral nerve evaluated at a single large academic spine center from January 1, 2017, to January 8, 2020, was performed. Exclusion criteria were transitional anatomy, severe hip osteoarthritis, coronal deformity with cobb >10 degrees, > grade 1 spondylolisthesis at L4-L5 and anterior migration of the psoas.Standing and supine lumbar lordosis (LL) and its proximal (L1-L4) and distal (L4-S1) components were measured. Femoral nerve position on sagittal imaging was then measured as a percentage of the L4 inferior endplate. A stepwise multivariate linear regression of sagittal alignment and LL parameters was then performed. Data are written as estimate, 95% CI. RESULTS: Mean patient age was 58.2±14.7 years, 25 (34.2%) were female and 26 (35.6%) had a grade 1 spondylolisthesis. Mean femoral nerve position was 26.6±10.3% from the posterior border of L4. Female sex (-6.6, -11.1 to -2.1) and supine proximal lumbar lordosis (0.4, 0.1-0.7) were independently associated with femoral nerve position. CONCLUSIONS: Patient sex and proximal LL can serve as early indicators of the size of the femoral nerve safe zone during a transpsoas LLIF approach at L4-L5.

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.

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.

Comparison of Relative Value Units and 30-Day Outcomes Between Primary and Revision Pediatric Spinal Deformity Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The aim of this study was to compare the relative value units (RVUs) and 30-day outcomes between primary and revision pediatric spinal deformity (PSD) surgery. SUMMARY OF BACKGROUND DATA: PSD surgery is frequently complicated by the need for reoperation. However, there is limited literature on physician reimbursement rates and short-term outcomes following primary versus revision spinal deformity surgery in the pediatric population. MATERIALS AND METHODS: This study utilizes data obtained from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) Pediatric database. Patients between 10 and 18 years of age who underwent posterior spinal deformity surgery between 2012 and 2018 were included. Univariate and multivariate regression were used to assess the independent impact of revision surgery on RVUs and postoperative outcomes, including 30-day readmission, reoperation, morbidity, and complications. RESULTS: The study cohort included a total of 15,055 patients, with 358 patients who underwent revision surgery. Patients in the revision group were more likely to be younger and male sex. Revision surgery more commonly required osteotomy (13.7% vs. 8.3%, P =0.002).Univariate analysis revealed higher total RVUs (71.09 vs. 60.51, P <0.001), RVUs per minute (0.27 vs. 0.23, P <0.001), readmission rate (6.7% vs. 4.0%, P =0.012), and reoperation rate (7.5% vs. 3.3%, P <0.001) for the revision surgery group. Morbidity rates were found to be statistically similar. In addition, deep surgical site infection, pulmonary embolism, and urinary tract infection were more common in the revision group. After controlling for baseline differences in multivariate regression, the differences in total RVUs, RVUs per minute, reoperation rate, and rate of pulmonary embolism between primary and revision surgery remained statistically significant. CONCLUSIONS: Revision PSD surgery was found to be assigned appropriately higher mean total RVUs and RVUs per minute corresponding to the higher operative complexity compared with primary surgery. Revision surgery was also associated with poorer 30-day outcomes, including higher frequencies of reoperation and pulmonary embolism. 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.

Robotics Reduces Radiation Exposure in Minimally Invasive Lumbar Fusion Compared With Navigation.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To compare robotics and navigation for minimally invasive elective lumbar fusion in terms of radiation exposure and time demand. SUMMARY OF BACKGROUND DATA: Although various studies have been conducted to demonstrate the benefits of both navigation and robotics over fluoroscopy in terms of radiation exposure, literature is lacking in studies comparing robotics versus navigation. MATERIALS AND METHODS: Patients who underwent elective one-level or two-level minimally invasive transforaminal lumbar interbody fusion (TLIF) by a single surgeon using navigation (Stryker SpineMask) or robotics (ExcelsiusGPS) were included (navigation 2017-2019, robotics 2019-2021, resulting in prospective cohorts of consecutive patients for each modality). All surgeries had the intraoperative computed tomography workflow. The two cohorts were compared for radiation exposure [fluoroscopy time and radiation dose: image capture, surgical procedure, and overall) and time demand (time for setup and image capture, operative time, and total operating room (OR) time]. RESULTS: A total of 244 patients (robotics 111, navigation 133) were included. The two cohorts were similar in terms of baseline demographics, primary/revision surgeries, and fusion levels. For one-level TLIF, total fluoroscopy time, total radiation dose, and % of radiation for surgical procedure were significantly less with robotics compared with navigation (20 vs. 25 s, P <0.001; 38 vs. 42 mGy, P =0.05; 58% vs. 65%, P =0.021). Although time for setup and image capture was significantly less with robotics (22 vs. 25 min, P <0.001) and operative time was significantly greater with robotics (103 vs. 93 min, P <0.001), there was no significant difference in the total OR time (145 vs. 141 min, P =0.25). Similar findings were seen for two-level TLIF as well. CONCLUSION: Robotics for minimally invasive TLIF, compared with navigation, leads to a significant reduction in radiation exposure both to the surgeon and patient, with no significant difference in the total OR time.

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

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To analyze the postoperative factors that led delayed discharge in patients who would have been eligible for ambulatory lumbar fusion (ALF). SUMMARY OF BACKGROUND DATA: Assessing postoperative inefficiencies is vital to increase the feasibility of ALF. MATERIALS AND METHODS: Patients who underwent single-level minimally invasive transforaminal lumbar interbody fusion and would have met the eligibility criteria for ALF were included. Length of stay (LOS); time in postanesthesia recovery unit (PACU); alertness and neurological examination, and pain scores at three and six hours; type of analgesia; time to physical therapy (PT) visit; reasons for PT nonclearance; time to per-oral (PO) intake; time to voiding; time to readiness for discharge were assessed. Time taken to meet each discharge criterion was calculated. Multiple regression analyses were performed to study the effect of variables on postoperative parameters influencing discharge. RESULTS: Of 71 patients, 4% were discharged on the same day and 69% on postoperative day 1. PT clearance was the last-met discharge criterion in 93%. Sixty-six percent did not get PT evaluation on the day of surgery. Seventy-six percent required intravenous opioids and <60% had adequate pain control. Twenty-six percent had orthostatic intolerance. The median postoperative LOS was 26.9 hours, time in PACU was 4.2 hours, time to PO intake was 6.5 hours, time to first void was 6.3 hours, time to first PT visit was 17.7 hours, time to PT clearance was 21.8 hours, and time to discharge readiness was 21.9 hours. Regression analysis showed that time to PT clearance, time to PO intake, time to voiding, time in PACU, and pain score at three hours had a significant effect on LOS. CONCLUSIONS: Unavailability of PT, surgery after 1  pm , orthostatic intolerance, inadequate pain control, prolonged PACU stay, and long feeding and voiding times were identified as modifiable factors preventing same-day discharge. LEVEL OF EVIDENCE: 4.

Recovery Kinetics After Commonly Performed Minimally Invasive Spine Surgery Procedures.

STUDY DESIGN: Single-center, multisurgeon, retrospective review. OBJECTIVE: To evaluate the timing of return to commonly performed activities following minimally invasive spine surgery. Identify preoperative factors associated with these outcomes. SUMMARY OF BACKGROUND DATA: Studies have reported return to activities with open techniques, but the precise timing of when patients return to these activities after minimally invasive surgery remains uncertain. MATERIALS AND METHODS: Patients who underwent either minimally invasive lumbar laminectomy (MI-L) or minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) were included. Patient-reported outcome measures, return to drive, return to work, and discontinuation of opioids data were reviewed. Regression was conducted to identify factors associated with return to driving by 15 days, return to work by 30 days, and for discontinuing opioids by 15 days. A composite group analysis was also performed for patients who returned to all three activities by 30 days. RESULTS: In total, 123 MI-L patients and 107 MI-TLIF patients were included. Overall, 88.8% of MI-L patients and 96.4% of MI-TLIF patients returned to driving in 11 and 18.5 days, respectively. In all, 91.9% of MI-L patients and 85.7% of MI-TLIF patients returned to work in 14 and 25 days. In all, 88.7% of MI-L patients and 92.6% of MI-TLIF patients discontinued opioids in a median of seven and 11 days. Overall, 96.2% of MI-L patients and 100% of MI-TLIF patients returned to all three activities, with a median of 27 and 31 days, respectively. Male sex [odds ratio (OR)=3.57] and preoperative 12-Item Short Form Physical Component Score (OR=1.08) are associated with return to driving by 15 days. Male sex (OR=3.23) and preoperative 12-Item Short Form Physical Component Score (OR=1.07) are associated with return to work by 30 days. Preoperative Visual Analog Scale back was associated with decreased odds of discontinuing opioids by 15 days (OR=0.84). CONCLUSION: Most patients return to activity following MI-L and MI-TLIF. These findings serve as an important compass for preoperative counseling.

Improvement following minimally invasive lumbar decompression in patients 80 years or older compared with younger age groups.

OBJECTIVE: The objective of this study was to assess the outcomes of minimally invasive lumbar decompression in patients ≥ 80 years of age and compare them with those of younger age groups. METHODS: This was a retrospective cohort study. Patients who underwent primary unilateral laminotomy for bilateral decompression (ULBD) (any number of levels) and had a minimum of 1 year of follow-up were included and divided into three groups by age: < 60 years, 60-79 years, and ≥ 80 years. The outcome measures were 1) patient-reported outcome measures (PROMs) (visual analog scale [VAS] back and leg, Oswestry Disability Index [ODI], 12-Item Short-Form Health Survey [SF-12] Physical Component Summary [PCS] and Mental Component Summary [MCS] scores, and Patient-Reported Outcomes Measurement Information System Physical Function [PROMIS PF]); 2) percentage of patients achieving the minimal clinically important difference (MCID) and the time taken to do so; and 3) complications and reoperations. Two postoperative time points were defined: early (< 6 months) and late (≥ 6 months). RESULTS: A total of 345 patients (< 60 years: n = 94; 60-79 years: n = 208; ≥ 80 years: n = 43) were included in this study. The groups had significantly different average BMIs (least in patients aged ≥ 80 years), age-adjusted Charlson Comorbidity Indices (greatest in the ≥ 80-year age group), and operative times (greatest in 60- to 79-year age group). There was no difference in sex, number of operated levels, and estimated blood loss between groups. Compared with the preoperative values, the < 60-year and 60- to 79-year age groups showed a significant improvement in most PROMs at both the early and late time points. In contrast, the ≥ 80-year age group only showed significant improvement in PROMs at the late time point. Although there were significant differences between the groups in the magnitude of improvement (least improvement in ≥ 80-year age group) at the early time point in VAS back and leg, ODI, and SF-12 MCS, no significant difference was seen at the late time point except in ODI (least improvement in ≥ 80-year group). The overall MCID achievement rate decreased, moving from the < 60-year age group toward the ≥ 80-year age group at both the early (64% vs 51% vs 41% ) and late (72% vs 58% vs 52%) time points. The average time needed to achieve the MCID in pain and disability increased, moving from the < 60-year age group toward the ≥ 80-year age group (2 vs 3 vs 4 months). There was no significant difference seen between the groups in terms of complications and reoperations except in immediate postoperative complications (5.3% vs 4.8% vs 14%). CONCLUSIONS: Although in this study minimally invasive decompression led to less and slower improvement in patients ≥ 80 years of age compared with their younger counterparts, there was significant improvement compared with the preoperative baseline.

Reoperations after primary and revision lumbar discectomy: study of a national-level cohort with eight years follow-up.

BACKGROUND CONTEXT: Published rates for disc reherniation following primary discectomy are around 6%, but the ultimate reoperation outcomes in patients after receiving revision discectomy are not well understood. Additionally, any disparity in the outcomes of subsequent revision discectomy (SRD) versus subsequent lumbar fusion (SLF) following primary/revision discectomy remains poorly studied. PURPOSE: To determine the 8-year SRD/SLF rates and time until SRD/SLF after primary/revision discectomy respectively. STUDY DESIGN: Retrospective cohort study. PATIENT SAMPLE: Patients undergoing primary or revision discectomy, with records in the PearlDiver Patient Records Database from the years 2010 to 2019. OUTCOME MEASURES: Subsequent surgery type and time to subsequent surgery. METHODS: Patients were grouped into primary or revision discectomy cohorts based off of the nature of "index" procedure (primary or revision discectomy) using ICD9/10 and CPT procedure codes from 2010 to 19 insurance data sets in the PearlDiver Patient Records Database. Preoperative demographic data was collected. Outcome measures such as subsequent surgery type (fusion or discectomy) and time to subsequent surgery were collected prospectively in PearlDiver Mariner database. Statistical analysis was performed using BellWeather statistical software. A Kaplan-Meier survival analysis of time to SLF/SRD was performed on each cohort, and log-rank test was used to compare the rates of SLF/SRD between cohorts. RESULTS: A total of 20,147 patients were identified (17,849 primary discectomy, 2,298 revision discectomy). The 8-year rates of SRD (6.1% in revision cohort, 4.8% in primary cohort, p<.01) and SLF (10.4% in revision cohort, 6.2% in primary cohort, p<.01) were higher after revision versus primary discectomy. Time to SLF was shorter after revision versus primary discectomy (709 vs. 886 days, p<.01). After both primary and revision discectomy, the 8-year rate of SLF (10.4% in revision cohort, 6.2% in primary cohort, p<.01) is greater than SRD (6.1% in revision cohort, 4.8% in primary cohort, p<.01). CONCLUSIONS: Compared to primary discectomy, revision discectomy has higher rates of SLF (10.4% vs. 6.2%), and faster time to SLF (2.4 vs. 1.9 years) at 8-year follow up.

Association between muscle health and patient-reported outcomes after lumbar microdiscectomy: early results.

BACKGROUND CONTEXT: Poor muscle health has been implicated as a source of back pain among patients with lumbar spine pathology. Recently, a novel magnetic resonance imaging (MRI)-based lumbar muscle health grade was shown to correlate with health-related quality of life scores. However, the impact of muscle health on postoperative functional outcomes following spine surgery remains to be investigated. PURPOSE: To determine whether muscle health grade measured by preoperative psoas and paralumbar muscle cross-sectional areas impact the achievement of minimal clinically important difference (MCID) following lumbar microdiscectomy. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Consecutive patients who underwent 1-level lumbar microdiscectomy in a single institution between 2017 and 2021. OUTCOME MEASURES: Rate of MCID achievement, time to MCID achievement, PROMs including Oswestry Disability Index (ODI), visual analog scale for back pain (VAS back), VAS leg, Short Form 12 Physical Component Summary (SF-12 PCS), SF-12 Mental Component Summary (SF-12 MCS), and Patient Reported Outcomes Measurement Information System Physical Function (PROMIS PF). METHODS: Two previously validated methods for muscle health grading were applied. Axial T2 MRI were analyzed for muscle measurements. The psoas-based method utilized the normalized total psoas area (NTPA), which is the psoas cross-sectional area divided by the square of patient height (mm2/m2). Patients were divided into low and high NTPA groups based on sex-specific lowest quartile NTPA thresholds. The paralumbar-based method incorporated the paralumbar cross-sectional area normalized by body mass index (PL-CSA/BMI) and Goutallier classification. Score of 1 was added for either PL-CSA/BMI >130 or Goutallier class of ≤2. "Good" muscle health was defined as score of 2, and "poor" muscle health was defined as score of 0 to 1. Prospectively collected PROMs were analyzed at 2-week, 6-week, 3-month, 6-month, 1-year, and 2-year postoperative timepoints. The rate of and time to MCID achievement were compared among the cohorts. Bivariate analyses were performed to assess for correlations between psoas/paralumbar cross-sectional areas and change in PROM scores from baseline. RESULTS: The total cohort included 163 patients with minimum follow-up of 6 months and mean follow-up of 16.5 months. 40 patients (24.5%) were categorized into the low NTPA group, and 55 patients (33.7%) were categorized into the poor paralumbar muscle group. Low NTPA was associated with older age, lower BMI, and greater frequencies of Charlson Comorbidity Index (CCI) ≥1. Poor paralumbar muscle health was associated with older age, female sex, higher BMI, and CCI ≥1. There were no differences in rates of MCID achievement for any PROMs between low versus high NTPA groups or between poor versus good paralumbar groups. Low NTPA was associated with longer time to MCID achievement for ODI, VAS back, VAS leg, and SF-12 MCS. Poor paralumbar muscle health was associated with longer time to MCID achievement for VAS back, VAS leg, and SF-12 PCS. NTPA negatively correlated with change in VAS back (6-week, 12-week) and VAS leg (6-month). PL-CSA/BMI positively correlated with change in PROMIS-PF at 3 months follow-up. CONCLUSIONS: Among patients undergoing lumbar microdiscectomy, patients with worse muscle health grades achieved MCID at similar rates but required longer time to achieve MCID. Lower NTPA was weakly correlated with larger improvements in pain scores. PL-CSA/BMI positively correlated with change in PROMIS-PF. Our findings suggest that with regards to functional outcomes, patients with worse muscle health may take longer to recuperate postoperatively compared to those with better muscle health.

The Impact of Prior Bariatric Surgery on Outcomes After Spine Surgery: A Systematic Review and meta-Analysis.

STUDY DESIGN: Systematic review and meta-analysis. OBJECTIVE: To compare outcomes and complication rates in patients undergoing bariatric surgery (BS) prior to spine surgery. METHODS: A systematic review and meta-analysis were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines comparing the outcomes of spine surgery between subjects with prior bariatric surgery to those who were considered obese with no prior bariatric surgery. RESULTS: A total of 183, 570 patients were included in the 4 studies meeting inclusion criteria. The mean patient age was 52.9 years, and the majority were female (68%). The two groups consisted of a total of 36, 876 patients with prior BS and 146, 694 obese patients without prior BS. The overall rate of complications in the prior BS group was 6.4% (4.5%-38.7%) compared to 11.9% (11.2%-55.4%) in the non-prior BS obese group with a statistically significant difference between the two groups. The prior BS group had lower rates of renal, neurological, and thromboembolic complications, with a lower mortality and readmission rate. In a subgroup undergoing cervical spine surgery, patients with prior BS had fewer cardiac, GI, and total complications. For patients undergoing thoracolumbar spine surgery, patients with prior BS had fewer thromboembolic and total complications. CONCLUSION: Patients undergoing bariatric surgery prior to spine surgery had fewer renal, neurological, and thromboembolic complications as well as a decreased mortality and readmission rate.

Novel Lateral Approach for MIS Sacroiliac Joint Arthrodesis: An Assessment of Feasibility and Outcomes.

OBJECTIVE: The prevalence of physicians experiencing work-related musculoskeletal disorders is high. Traditionally, minimally invasive surgery (MIS) sacroiliac joint (SIJ) fusions are performed with the patient oriented in the prone position, with an incision made inferior to the iliac crest. However, a novel technique that orients the patient in the lateral decubitus position has the potential of significantly enhancing ergonomics and ease of approach. The primary objectives of this study were to quantify surgical parameters, describe this 'lateral-decubitus MIS' technique, and identify imaging angle parameters that predict feasibility. METHODS: A prospective cohort of patients who underwent MIS SIJ arthrodesis in the lateral decubitus position was evaluated at a single institution between 2017 and 2020. Medians and ranges of intraoperative blood loss, operative time, revision rate, infection, and total radiation dose were recorded. Sacral inlet and outlet angles were defined and collected to assess for operative candidacy. RESULTS: Thirty-nine cases were identified in 34 patients who underwent the technique with an age range of 31-78 years. Median blood loss was 22.5 mL, operating room time was 32.5 minutes, and radiation dose was 30.9 rads. Average sacral inlet was 24.51° and average sacral outlet was 65.44°. Median length of stay was 0.94 days. No cases were aborted or required revision. A total of 93% of study participants reported improvement in pain. Operative parameters were comparable to the traditional prone approach. CONCLUSIONS: The aim was to provide an insight into outcomes and metrics observed from pioneering this style of procedure. A future study comparing traditional perioperative parameters together with surgical ergonomics is needed.