Intra-Operative Hypotension is an Important Modifiable Risk Factor for Major Complications in Spinal Fusion Surgery.

STUDY DESIGN: Retrospective observational cohort. OBJECTIVES: This study explores the impact of Intraoperative hypotension (IOH)on post-op complications for major thoracolumbar spine fusion procedures. SUMMARY OF BACKGROUND DATA: IOH with mean arterial pressure (MAP) < 65 mmHg is associated with post-op acute kidney injury (AKI) in general surgery. In spinal deformity surgery, IOH is a contributing factor to MEP changes and spinal cord dysfunction with deformity correction. METHODS: 539 thoracolumbar fusion cases, > 6 surgical levels and > 3 hours duration were identified. Anesthetic/surgical data included OR time, fluid volume, blood loss, blood product replacement and use of vasopressors. Arterial-line based MAP data was collected at 1 min intervals. Cummulative duration of MAP < 65 mmHg was recorded. IOH within the first hour of surgery vs. the entire case was determined. Post-op course and complications including SSI, GI complications, pulmonary complications, MI, DVT, PE, AKI and encephalopathy were noted. Cumulative complications were grouped as none, 1-2 complications, or >3 complications. RESULTS: There was a significant association between occurrence of complications and duration of IOH within the first hour of surgery (8.2 vs. 5.6 min, P<0.001) and across the entire procedure (28.1 vs. 19.3 min, P=0.008). This association persisted for individual major complications including SSI, acute respiratory failure, PE, ileus requiring NGT and post-operative cognitive dysfunction. Comparison of patients with 0 vs. 1-2 vs. 3 or more complications demonstrated that patients with 3 or more complications had a longer duration of IOH in the first hour of the surgery and that patients who had no complications received less vasopressor than patients who had 1-2 or 3 or more complications. CONCLUSION: This study identifies duration of IOH during the first hour of surgery as a previously unrecognized modifiable risk associated with major complications for multi-level lumbar fusion surgery.

Risk Factors for Medial Breach During Robotic-Assisted Cortical Bone Trajectory Screw Insertion.

OBJECTIVE: We describe the incidence of, and identify the risk factors for, a medial breach of the pedicle wall during robotic-assisted cortical bone trajectory (RA-CBT) screw insertion. METHODS: We analyzed a consecutive series of adult patients who underwent RA-CBT screw placement from January 2019 to July 2022. To assess the pedicle wall medial breach, postoperative computed tomography (CT) images were analyzed. Patient demographic data and screw data were compared between patients with and without a medial breach. The Hounsfield units (HUs) on the L1 midvertebral axial CT scan was used to evaluate bone quality. RESULTS: Of 784 CBT screws in 145 patients, 30 (3.8%) had a medial breach in 23 patients (15.9%). One screw was grade 2, and the others were grade 1. Patients with a medial breach had a lower HU value compared with the patients without a medial breach (123.3 vs. 150.5; P = 0.027). A medial breach was more common in the right than left side (5.5% vs. 2.0%; P = 0.014). More than one half of the screws with a medial breach were found in the upper instrumented vertebra (UIV) compared with the middle construct or lowest instrumented vertebra (6.7% vs. 1.3% vs. 2.7%; P = 0.003). Binary logistic regression showed that low HU values, right-sided screw placement, and UIV were associated with a medial breach. No patients returned to the operating room for screw malposition. No differences were found in the clinical outcomes between patients with and without a medial breach. CONCLUSIONS: The incidence of pedicle wall medial breach was 3.8% of RA-CBT screws in the postoperative CT images. A low HU value measured in the L1 axial image, right-sided screw placement, and UIV were associated with an increased risk of medial breach for RA-CBT screw placement.

Staged circumferential lumbar fusions have less intraoperative complications and shorter operative time with no difference in 30-, 90-, and 1-year complications: a propensity-matched cohort analysis of 190 patients.

BACKGROUND CONTEXT: Circumferential lumbar fusions (cLFs) are becoming more common with increasing and more minimally invasive anterior access techniques. Staging allows reassessment of indirect decompression and alignment prior to the posterior approach, and optimization of OR time management. Safety of staging has been well documented in deformity surgery but has yet to be delineated in less extensive, degenerative cLFs. PURPOSE: The purpose of this study is to compare perioperative complications and outcomes between staged versus single-anesthetic circumferential fusions in the lumbar spine. STUDY DESIGN: Propensity-matched comparative observational cohort. PATIENT SAMPLE: Patients who underwent cLFs for lumbar degenerative disease. OUTCOME MEASURES: In-hospital, 30-day, 90-day, and 1-year complications. METHODS: From 123 patients undergoing single-anesthetic and 154 patients undergoing staged cLF, 95 patients in each group were propensity-matched based on age, sex, BMI, ASA score, smoking, revision, and number of levels. We compared perioperative, 30-day, 90-day, and 1-year complications between the two cohorts. RESULTS: Mean days between stages was 1.58. Single-anesthetic cLF had longer total surgery time (304 vs 240 minutes, p<.001) but shorter total PACU total time (133 vs 196 minutes, p<.001). However, there was no difference in total anesthesia time (368 vs 374 minutes, p=.661) and total EBL (357 vs 320cc, p=.313). Intraoperative complications were nine incidental durotomies in the single-anesthetic and one iliac vein injury in the staged group (9% vs 1%, p=.018). There was no difference of in-hospital (38 vs 31, p=.291), 30-day (16 vs 23, p=.281), 90-day (10 vs 15, p=.391), 1-year complications (9 vs 12, p=.644), and overall cumulative 1-year complications (54 vs 56, p=.883) between the two cohorts. CONCLUSIONS: There is a decrease in total surgical time and intraoperative complications during staged compared with single-anesthetic cLF with no difference in in-hospital, 30-day, 90-day, and 1-year complications between approaches.

Normative Bone Mineral Density Measured on Computed Tomography Scans in Children and Adolescents.

STUDY DESIGN: Retrospective chart review. OBJECTIVE: To provide reference values for Hounsfield unit (HU) measured on computed tomography (CT) scans of children and adolescents. SUMMARY OF BACKGROUND DATA: Spine surgeons increasingly use HU on spine CT as a measure of bone mineral density (BMD). This has not been described in children and adolescents. PATIENTS AND METHODS: Pediatric patients who had a spine CT between 2012 and 2022 were identified. Patients who had more than 1 comorbidity or were syndromic were excluded. Using the bone window, 3 axial images (cephalad, middle, and caudal) of each vertebra were selected. In each axial view, the HU was measured using a "region of interest" (ROI) that included the total cancellous bone area and an ROI excluding the radiolucency present in the posterior vertebral body ("total" vs . "limited"). HU values were compared between total and limited areas and between the axial images at the cephalad, middle, and caudal levels. Each age category data were estimated and stratified. RESULTS: A total of 144 patients (79 females and 65 males) from 2 to 17 years old were included. Mean limited HU was consistently lower than total HU across all images and lumbar levels except for L1. Limited HU taken mid-vertebral body was also consistently lower than those taken cephalad or caudad. Mean limited HU across all ages including all levels was 227 ± 50 (range: 109-357). Stratifying by age showed a gradual decrease in BMD from age 2 to 10 followed by an increase. CONCLUSIONS: This is the first study to measure HU on lumbar CTs in children and adolescents. The technique of measuring BMD in adults should be modified in children by using an ROI that excludes the rarefaction present in the posterior vertebral body. Further studies are needed to evaluate the age-dependent changes in BMD seen in this study.

Opioid-sparing Anesthesia Decreases In-hospital and 1-year Postoperative Opioid Consumption Compared With Traditional Anesthesia: A Propensity-matched Cohort Study.

STUDY DESIGN: Propensity-matched cohort. OBJECTIVE: The aim of this study was to determine if opioid-sparing anesthesia (OSA) reduces in-hospital and 1-year postoperative opioid consumption. SUMMARY OF BACKGROUND DATA: The recent opioid crisis highlights the need to reduce opioid exposure. We developed an OSA protocol for lumbar spinal fusion surgery to mitigate opioid exposure. MATERIALS AND METHODS: Patients undergoing lumbar fusion for degenerative conditions over one to four levels were identified. Patients taking opioids preoperatively were excluded. OSA patients were propensity-matched to non-OSA patients based on age, sex, smoking status, body mass index, American Society of Anesthesiologists grade, and revision versus primary procedure. Standard demographic and surgical data, daily in-hospital opioid consumption, and opioid prescriptions 1 year after surgery were compared. RESULTS: Of 296 OSA patients meeting inclusion criteria, 172 were propensity-matched to non-OSA patients. Demographics were similar between cohorts (OSA: 77 males, mean age=57.69 yr; non-OSA: 67 males, mean age=58.94 yr). OSA patients had lower blood loss (326 mL vs. 399 mL, P =0.014), surgical time (201 vs. 233 min, P <0.001) emergence to extubation time (9.1 vs. 14.2 min, P< 0.001), and recovery room time (119 vs. 140 min, P =0.0.012) compared with non-OSA patients. Fewer OSA patients required nonhome discharge (18 vs. 41, P =0.001) compared with the non-OSA cohort, but no difference in length of stay (90.3 vs. 98.5 h, P =0.204). Daily opioid consumption was lower in the OSA versus the non-OSA cohort from postoperative day 2 (223 vs. 185 morphine milligram equivalents, P =0.017) and maintained each day with lower total consumption (293 vs. 225 morphine milligram equivalents, P =0.003) throughout postoperative day 4. The number of patients with active opioid prescriptions at 1, 3, 6, and 12 months postoperative was statistically fewer in the OSA compared with the non-OSA patients. CONCLUSIONS: OSA for lumbar spinal fusion surgery decreases in-hospital and 1-year postoperative opioid consumption. The minimal use of opioids may also lead to shorter emergence to extubation times, shorter recovery room stays, and fewer discharges to nonhome facilities.

Comparison of Bone Mineral Density in Children and Adolescents on CT Versus DEXA Scan.

STUDY DESIGN: Retrospective cross-sectional. OBJECTIVES: To determine associations between Hounsfield Units (HU) within a Region of interest (ROI) on CT scans and Dual Energy X-ray Absorptiometry (DEXA) measurements in children and adolescents. SUMMARY OF BACKGROUND DATA: HU on CT scans as a proxy for bone mineral density (BMD) is widely used in adults. However, the utility of CT as a proxy for BMD have not been evaluated in children and adolescents. METHODS: Patients younger than 18 years with a lumbar spine CT scan and a DEXA within 6 months of each other were identified. A ROI was used to measure the HU at each lumbar vertebral body on mid-axial cuts. Charts were reviewed for demographics, medical co-morbidities and DEXA reports. Correlation coefficients were calculated between mean DEXA Z-score and HU value. Patients were also stratified by Z-score (≥ -1.0, between -1.0 and -2.0, and ≤-2.0) and matched by age and BMI to a cohort of healthy children and compared. RESULTS: A moderate correlation between mean DEXA Z-score and mean HU on CT was found (r2=0.42, P<0.001). After matching for age and BMI, 21 patients in each group between the age of 4 and 17 years were analyzed. The mean HU value of the control group was 231.69. When stratified by Z-score (≥ -1.0, between -1.0 and -2.0, and ≤-2.0), the mean HU values were 244.59, 216.50, and 176.54, respectively. Patients with a Z-score of ≤-2.0 had a significantly lower mean HU than age matched controls. CONCLUSIONS: HU on lumbar CT in children and adolescents with DEXA Z-scores less than -2.0, were lower when compared to healthy age and BMI matched controls. This study suggests that HU on opportunistic CT scans of the spine may be used as a reasonable proxy for BMD in the pediatric population.

Risk Factors of Screw Malposition in Robot-Assisted Cortical Bone Trajectory: Analysis of 1344 Consecutive Screws in 256 Patients.

STUDY DESIGN: Retrospective single-center study using prospectively collected data. OBJECTIVE: To describe the incidence of and identify risk factors for intraoperative screw malposition secondary to skive or shift during robot-assisted cortical bone trajectory (RA-CBT) insertion. SUMMARY OF BACKGROUND DATA: RA-CBT screw malposition occurs through two distinct modes, skive or shift. Skive occurs when a downward force applied to the cannula, drill, tap, or screw, causes the instrument to deflect relative to its bony landmark. Shift is a change in position of the robot-assisted system relative to the patient after registration. METHODS: A consecutive series of patients older than 18 years who underwent RA-CBT screw placement between January 2019 and July 2022 were enrolled. Baseline demographic and surgical data, Hounsfield Units (HU) at L1, and vertebral shape related to screw planning were collected. Skive or shift was recorded in the operating room on a data collection form. RESULTS: Of 1344 CBT screws in 256 patients, malposition was recognized intraoperatively in 33 screws (2.4%) in 27 patients (10.5%); 19 via skive in 17 and 14 via shift in 10 patients. These patients had higher BMI than patients without malposition (33.0 kg/m2 vs 30.5 kg/m2, P=0.037). Patients with skive had higher HU (178.2 vs 145.2, P=0.035), compared to patients with shift (139.2 vs 145.2, P=0.935) and patients without screw malposition. More than half of screw malposition was observed at the UIV. At the UIV, if the screw's overlap to the bone surface at the insertion point was decreased, skive was more likely (57% vs 87%, P<0.001). No patients were returned to the operating room for screw revision. CONCLUSIONS: Intraoperative screw malposition occurred in 2.4% of RA-CBT. High BMI was associated with screw malposition, regardless of etiology. Skive was associated with high HU and decreased screw overlap to bone surface at the insertion point.

Improved Resource Utilization Using WALANT Hand Surgery in Adolescents.

BACKGROUND: Cost, efficiency, patient preference, and safety have driven utilization of wide awake, local anesthesia, no tourniquet (WALANT) in hand surgery. This is not well documented in adolescents. We hypothesize that the use of WALANT with adolescents reduced time spent in the operating room (OR) and in the hospital when compared with patients who underwent surgery with traditional anesthesia (TA). METHODS: After institutional review board approval, we performed a retrospective review of patients aged 10 to 17 who underwent surgery at a regional hospital system including the level 1 pediatric trauma hospital. Operative notes were assessed for use of WALANT. We excluded those operations not traditionally amenable to WALANT. Using a propensity matched cohort, hospital time, OR time, and perioperative complications were recorded and compared to evaluate efficiency and perioperative safety. RESULTS: There were 28 cases in the WALANT group and 28 cases in the TA group after excluding cases not amenable to WALANT, and cases were propensity matched. Although the operative time (incision to closure) was similar, for WALANT patients, the in-room to procedure time (15 vs 22 minutes), procedure end to out-room time (5 vs 10 minutes), total room time (52.81 vs 63.68), and length of hospital stay (222 vs 342 minutes) were shorter than patients in the TA group. CONCLUSION: Our case series demonstrates time-savings both in the OR and in the hospital overall. Avoiding TA when WALANT is feasible may result in significant savings to hospital systems, patients, and payers while also freeing up anesthesia staff and perioperative nurses.

Quantitative Romberg using a force plate: an objective measure for cervical myelopathy.

BACKGROUND CONTEXT: Surgical decision making for cervical spondylotic myelopathy (CSM) relies on evaluation of symptoms and physical examination. The Romberg test is a clinical exam used to identify balance issues with CSM. However, the Romberg test has a subjective interpretation and has a binary (positive or negative) result. PURPOSE: This study aims to compare force plate pressure readings during a standard Romberg test in patients with CSM to age-matched normal healthy volunteers. STUDY DESIGN/SETTING: Prospective cross sectional observational comparative cohort from a single multi-surgeon spine center. PATIENT SAMPLE: Patients who were clinically diagnosed with CSM were compared to age-matched healthy volunteers without a clinical history of spine pathology. OUTCOME MEASURES: Quantitative Romberg Force Plate Measurements METHODS: Patients with CSM requiring surgery and healthy normal volunteers were asked to perform the Romberg test while on a force plate measuring the center of pressure (COP): standing up straight with arms extended for 30 seconds with eyes open, followed by 30 seconds with eyes closed. The change for total sway area, sway frequency and sway speed with eyes closed and eyes open were calculated and compared between patients with CSM and healthy volunteers. RESULTS: Thirty-four CSM patients were age-matched to 34 healthy volunteers. There was a larger change in quantitative Romberg measurements with eyes open versus eyes closed in CSM patients compared to normal volunteers for maximum lateral movement (10.79 cm vs. 0.94 cm, p=.003), maximum anterior-posterior movement (15.06 cm vs. 10.00 cm p=.201), total lateral CoP movement (89.82cm vs. 18.71cm, p=.007), total AP CoP movement (154.68 cm vs. 87.47 cm, p=.601), total CoP trace movement (199.79 cm vs. 88.44 cm, p=.014), sway area (284.74 cm2 vs. 57.76 cm2, p=.006), and average speed (7.00 cm/s vs. 2.91 cm/s, p=.006). DISCUSSION: Poor standing balance can be quantified in patients with CSM. Quantifying standing balance in patients with CSM shows significantly worse objective measures than age-matched healthy volunteers. The Romberg test on a force plate may help diagnose and evaluate patients with CSM, guide patient management and potentially grade the severity of spinal pathology. Further studies are needed to determine its utility in monitoring disease progression and measure treatment effectiveness.

Propensity-Matched Comparison of 90-Day Complications in Robotic-Assisted Versus Non-Robotic Assisted Lumbar Fusion.

STUDY DESIGN: Retrospective single center propensity-matched observational cohort study that included patients who underwent 1- to 3-level lumbar fusion surgery for degenerative conditions. OBJECTIVE: To compare 90-day complication rates between robotic-assisted and non-robotic-assisted lumbar spinal fusions in propensity-matched cohorts. SUMMARY OF BACKGROUND DATA: A recent administrative database (PearlDiver) study reported increased 30-day complications with the utilization of robotic-assisted enabling technology. METHODS: Of 146 robotic-assisted cases that met inclusion criteria, 114 were successfully propensity matched to 114 patients from 214 cases who had 1 to 3 level lumbar fusion without robotic assistance based on age, sex, body mass index, smoking status, American Society of Anesthesiologist grade, number of surgical levels, primary versus revision, and surgical approach (posterior-only or anterior-posterior). We excluded tumor, trauma, infection, or deformity cases. Outcomes included surgical and medical (major/minor) complications at intraoperative, immediately postoperative, 30- and 90-day postoperative intervals, including reoperations, and readmissions within 90 days. RESULTS: All cause intraoperative complication rates were similar between non-robotic-assisted (5.3%) and robotic-assisted groups (10.5%, P = 0.366). Immediate postoperative medical complication rate was also similar between non-robotic-assisted (6.1%) and robotic-assisted groups (1.8%, P = 0.089). Thirty-day complication rates, 90-day complication rates, reoperation rates, and readmission rates showed no difference between non-robotic-assisted and robotic-assisted groups. There was no difference between return to OR for infection between the cohorts (non-robotic-assisted: 6 [5%] vs. robotic-assisted: 1 [0.8%], P = 0.119). There was however improved length of stay (LOS) in the robotic-assisted group compared with non-robotic-assisted group (2.5 vs. 3.17 days, P = 0.018). CONCLUSION: In propensity-matched cohorts, patients undergoing 1- to 3-level robotic-assisted posterior lumbar fusion for degenerative conditions did not have increased 90-day complication rate, and had a shorter length of stay compared with non-robotic-assisted patients. There findings differ from a prior administrative database study as the robotic-assisted group in the current study had 0% return to OR for malpositioned screws and 0.8% return to OR for infection.Level of Evidence: 2.

Drivers of in-hospital opioid consumption in patients undergoing lumbar fusion surgery.

BACKGROUND: With the current opioid crisis, as many as 38% of patients are still on opioids one year after elective spine surgery. Identifying drivers of in-hospital opioid consumption may decrease subsequent opioid dependence. We aimed to identify the drivers of in-hospital opioid consumption in patients undergoing 1-2-level instrumented lumbar fusions. METHODS: This is a retrospective cohort study. Electronic medical record analysts identified consecutive patients undergoing 1-2 level instrumented lumbar fusions for degenerative lumbar conditions from 2016 to 2018 from a single-center hospital administrative database. Oral, intravenous, and transdermal opioid dose administrations were converted to morphine milligram equivalents (MME). Linear regression analysis was used to determine associations between postoperative day (POD) 4 cumulative in-hospital MMEs and the patients' baseline characteristics including body mass index (BMI), race, American Society of Anesthesiologists (ASA) grade, smoking status, marital status, insurance type, zip code, number of fused levels, approach and preoperative opioid use. RESULTS: A total of 1,502 patients were included. The mean cumulative MMEs at POD 4 was 251.5. Linear regression analysis yielded four drivers including younger age, preoperative opioid use, current smokers and more levels fused. There were no associations with surgical approach, zip code, ASA grade, marital status, BMI, race or insurance type. CONCLUSIONS: Use of preoperative opioids and smoking are modifiable risk factors for higher in-hospital opioid consumption and can be targets for intervention prior to surgery in order to decrease in-hospital opioid use.

Drivers for nonhome discharge in a consecutive series of 1502 patients undergoing 1- or 2-level lumbar fusion.

OBJECTIVE: Unexpected nonhome discharge causes additional costs in the current reimbursement models, especially to the payor. Nonhome discharge is also related to longer length of hospital stay and therefore higher healthcare costs to society. With increasing demand for spine surgery, it is important to minimize costs by streamlining discharges and reducing length of hospital stay. Identifying factors associated with nonhome discharge can be useful for early intervention for discharge planning. The authors aimed to identify the drivers of nonhome discharge in patients undergoing 1- or 2-level instrumented lumbar fusion. METHODS: The electronic medical records from a single-center hospital administrative database were analyzed for consecutive patients who underwent 1- to 2-level instrumented lumbar fusion for degenerative lumbar conditions during the period from 2016 to 2018. Discharge disposition was determined as home or nonhome. A logistic regression analysis was used to determine associations between nonhome discharge and age, sex, body mass index (BMI), race, American Society of Anesthesiologists grade, smoking status, marital status, insurance type, residence in an underserved zip code, and operative factors. RESULTS: A total of 1502 patients were included. The majority (81%) were discharged home. Factors associated with a nonhome discharge were older age, higher BMI, living in an underserved zip code, not being married, being on government insurance, and having more levels fused. Patients discharged to a nonhome facility had longer lengths of hospital stay (5.6 vs 3.0 days, p < 0.001) and significantly increased hospital costs ($21,204 vs $17,518, p < 0.001). CONCLUSIONS: Increased age, greater BMI, residence in an underserved zip code, not being married, and government insurance are drivers for discharge to a nonhome facility after a 1- to 2-level instrumented lumbar fusion. Early identification and intervention for these patients, even before admission, may decrease the length of hospital stay and medical costs.

Multi-modal pain control regimen for anterior lumbar fusion drastically reduces in-hospital opioid consumption.

BACKGROUND: The opioid epidemic is at epic proportions currently in the United States. Exposure to opioids for surgery and subsequent postoperative pain management is a known risk factor for opioid dependence. In addition, opioids can have a negative impact on multiple aspects including clinical outcomes, length of hospital stay, and overall cost of care. Thus, the greatest effort to reduce perioperative opioid use is necessary and a multimodal pain control (MMPC) has been gaining popularity. However, its efficacy in spine surgery is not well known. We aimed to evaluate the efficacy of a MMPC protocol in patients undergoing lumbar single-level anterior lumbar interbody fusion (ALIF). METHODS: This is a retrospective comparative study. From a prospective, single-surgeon, surgical database, consecutive patients undergoing single-level ALIF with or without subsequent posterior fusion for degenerative lumbar conditions were identified before and after initiation of the MMPC protocol. The MMPC protocol consisted of a preoperative oral regimen of cyclobenzaprine (10 mg), gabapentin (600 mg), acetaminophen (1 g), and methadone (10 mg). Postoperatively they received a bilateral transverse abdominis plane block with 0.5% Ropivacaine prior to extubation. We compared in-hospital opioid consumption between the MMPC and non-MMPC cohorts as well as baseline demographic, the length of hospital stay, cost, and rate of postoperative ileus. Opioid consumption was calculated and normalized to the morphine milligram equivalents (MMEs). RESULTS: In total, 68 patients in the MMPC cohort and 39 in the non-MMPC cohort were identified. There was no difference in baseline demographics including sex, body mass index, smoking status, or preoperative opioid use between the two groups. Although there was no difference in the MMEs on the day of surgery (58.5 vs. 66.9, P=0.387), cumulative MMEs each day after surgery was significantly lower in the MMPC cohort, with final cumulative MMEs being reduced by 62% (120.2 vs. 314.8, P<0.001). There was no difference in postoperative ileus, length of stay, and hospital costs. CONCLUSIONS: The use of a MMPC protocol in patients undergoing single-level ALIF for degenerative conditions reduced opioid consumption starting on the first day after surgery, resulting in a cumulative reduction of 62%.