What Is the Carbon Footprint of Adult Spinal Deformity Surgery?

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

Post-Operative Hyperextension Bracing Has the Potential to Reduce Proximal Junctional Kyphosis: A Propensity Matched Analysis of Braced versus Non-braced Cohorts.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: Determine effects of bracing on proximal junctional kyphosis (PJK) after adult deformity correction. METHODS: Patients were identified from a single-surgeon dataset of posterior-only fusions for ASD (pelvis to UIV of T9-12) with a minimum of 1-year follow up. Starting in 2021, all lower thoracic fusions were braced using a hyperextension brace. Patients wore the brace at all times (unless in bed) for the first 6 weeks after surgery. A 1:1 propensity-match was performed based on age, number of levels, 3 column osteotomies, and magnitude of correction to identify a comparative non-braced cohort. RESULTS: 141 patients (113 non-brace, 28 brace) were evaluated. After matching, 56 patients were identified to form similar cohorts. Non-matched and matched groups had no statistically significant differences in demographics, comorbid conditions, surgical characteristics (except shorter operative time and lower EBL in the braced group), and preoperative radiographic parameters. For the overall cohort, the change in proximal junctional angle at 1-year was higher in the non-braced group (7.6° vs 8.1°, P = .047), and non-braced patients had a higher incidence of PJK at 1-year in both the overall cohort (36% vs 14%, P = .045) and matched cohort (43% vs 14%, P = .038). There was no difference in proximal junctional failure between groups. CONCLUSION: This pilot study shows that our protocol for extension bracing may reduce rates of PJK. These findings can form the basis for future multi-center trials examining the effect of extension bracing on junctional complications.

Return to sporting activities following long fusions to the pelvis in adult spinal deformity.

BACKGROUND CONTEXT: Returning to recreational sporting activities after adult spinal deformity (ASD) correction may significantly impact the patient's perceived quality of life. PURPOSE: This study sought to characterize participation in sporting activities before and after ASD surgery, and to identify factors associated with impaired return to sports. STUDY DESIGN: Cross-sectional survey and retrospective review of prospectively collected data. PATIENT SAMPLE: Patients who underwent posterior-only thoracolumbar ASD surgery between 2016 and 2021 with ≥1 year follow-up and ≥3 levels of fusion to the pelvis were included. OUTCOME MEASURES: Preoperative and postoperative participation in sports, timing of return to these activities, and reasons for limited sports participation postoperatively were assessed. METHODS: A survey was used to evaluate outcome measures. Differences in demographic, surgical, and perioperative variables between patients who reported improved, unchanged, or worsened activity tolerance were evaluated. RESULTS: Ninety-five patients were included (mean age: 64.3±10.1 years; BMI: 27.3±6.1 kg/m2; median levels fused: 7). The survey was completed at an average of 43.5±15.9 months after surgery. Sixty-eight (72%) patients participated in sports preoperatively. The most common sports were swimming (n=33, 34.7%), yoga (n=23, 24.2%), weightlifting (n=20, 21.1%), elliptical (n=19, 20.0%), and golf (n=11, 11.6%). Fifty-seven (83.8%) returned to at least one sport postoperatively, most commonly 6-12 months after surgery (45%). Elliptical had the highest rate of equal or improved participation (53%). Patients generally returned below their preoperative level to all other sports. Reasons for reduced sporting activities included physical limitation (51.4%), fear (20.0%), pain (17.1%), and surgeon advice (8.6%). There were no differences in the demographic, surgical, or perioperative characteristics between those who returned to sports at the same or better level compared with those who returned at a lower level. CONCLUSIONS: About 84% of patients successfully resumed sporting activities after undergoing fusion to the sacrum/pelvis for ASD. However, this return is typically at a lower level of participation than their preoperative participation, particularly in higher demand sports. Understanding trends in sporting activity may be valuable for counseling patients and setting expectations.

Opening Side of Unilateral Open-Door Laminoplasty Does Not Impact Improvement in Arm Pain or Space Available for the Spinal Cord.

Background/Objectives: There exists limited data guiding open-door laminoplasty. The objective of this study is to determine if open-door laminoplasty affects radiographic decompression or arm pain outcomes. Methods: Adult patients who underwent unilateral open-door laminoplasty cervical myelopathy were included. The side opened was dependent on surgeon discretion. We recorded preoperative side of symptoms, side of radiographic compression, arm pain scores, and canal diameter. Patients with open-side ipsilateral or contralateral to dominant symptoms or compression were compared to determine any effect on arm pain outcomes or spinal canal diameter. If the symptoms were equal bilaterally, patients were neutral. Results: A total of 167 patients were included, with an average age of 64 ± 11 years and average follow-up time of 64.5 ± 72 weeks. The average preoperative arm pain visual analog score (VAS) was 2.13 ± 2.86, and the average arm VAS after 6 months was 1.52 ± 2.68. For dominant symptoms, the ipsilateral, contralateral, and neutral groups had a significant improvement in arm VAS at >6 months postoperatively. For dominant compression, the ipsilateral and contralateral groups had a significant improvement in both arm VASs and canal diameter at >6 months postoperatively. No differences were seen between groups for either. We observed a significant correlation between size of plate and change in canal diameter; however, no differences were noted for arm pain. Conclusions: Laminoplasty may be effective in addressing radicular arm pain by increasing the spinal canal's diameter and space available for the cord. The laterality of open-door laminoplasty did not affect arm pain improvement or canal expansion.

Preoperative Physical Therapy is Associated with Decreased Length of Stay and Improved Postoperative Mobility in Patients with Sarcopenia Undergoing Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine the relationship between preoperative physical therapy (PT) and postoperative mobility, adverse events (AEs), and length of stay (LOS) among patients with low normalized total psoas area (NTPA) undergoing ASD surgery. SUMMARY OF BACKGROUND DATA: Sarcopenia as defined by low NTPA has been shown to predict poor perioperative outcomes following adult spinal deformity (ASD) surgery. However, there is limited evidence correlating the benefits of PT within the sarcopenic patient population. METHODS: NTPA was analyzed at the L3 and L4 mid-vertebral body on preoperative magnetic resonance imaging (MRI). Receiver operating characteristic (ROC) curve analysis was used to determine gender-specific NTPA cut-off values for predicting perioperative AEs. Patients were categorized as having low NTPA if both L3 and L4 NTPA were below these cut-off values. Perioperative outcomes were compared between patients with low NTPA that underwent documented formal PT within 6 months prior to ASD surgery with those that did not. RESULTS: 103 patients (42 males, 61 females) met criteria for low NTPA for inclusion in the study, of which 42 underwent preoperative PT and 61 did not. The preoperative PT group had a shorter LOS (111.2±37.5 vs. 162.1±97.0 h, P<0.001), higher ambulation distances (feet) on postoperative day (POD) 1 (61.7±50.3 vs. 26.1±69.0, P<0.001), POD 2 (113.2±81.8 vs. 62.1±73.1, P=0.003), and POD 3 (126.0±61.2 vs. 91.2±72.6, P=0.029), and lower rates of total AEs (31.0% vs. 54.1%, P=0.003) when excluding anemia requiring transfusion. Multivariable analysis found preoperative PT to be the most significant predictor of decreased LOS (OR 0.32, P=0.013). CONCLUSION: Sarcopenic patients may benefit from formal preoperative PT prior to undergoing ASD surgery to improve early postoperative mobility, decrease AEs, and decrease LOS. LEVEL OF EVIDENCE: 3.

Left-digit bias in surgical decision-making for lumbar spinal stenosis.

BACKGROUND CONTEXT: Left-digit bias is a behavioral heuristic or cognitive "shortcut" in which the leftmost digit of a number, such as patient age, disproportionately influences surgical decisions. PURPOSE: To determine if left-digit bias in patient age influences the decision to perform arthrodesis with instrumentation vs decompression in lumbar spinal stenosis (LSS). DESIGN: Retrospective cohort. PATIENT SAMPLE: Patients with an ICD-10 diagnosis of lumbar stenosis or spondylolisthesis identified in the 2017-2021 National Surgical Quality Improvement Program (NSQIP) database. OUTCOME MEASURES: The primary outcome was the percent of patients who underwent arthrodesis with instrumentation (AwI). Matched age group comparisons without left-digit differences (ie, 76/77 vs 78/79, 80/81 vs 82/83, etc.) were performed to isolate the effect of the heuristic. Secondary outcomes including peri-operative events and complications were also compared within AwI and decompression cohorts. METHODS: Using CPT codes, procedures were classified as either AwI or decompression. Patients were grouped into 6 cohorts based on 2-year age windows (74/75, 76/77, 78/79, 80/81, 82/83, 84/85). The cohorts were propensity matched with neighboring age groups based on the presence of spondylolisthesis, demographics, and comorbidities. The primary comparison was between those aged 78/79 vs 80/81. RESULTS: After matching, the primary cohort consisted of two groups of 1,550 patients (aged 78/79 and 80/81). Patients aged 80/81 were less likely to undergo AwI than patients aged 78/79 (23.5% vs 27.2%, p=.021). AwI procedures occurred at similar rates between age groups with the same left digit. Within the decompression and AwI cohorts, there were no differences in secondary outcomes between patients aged 78/79 and 80/81. CONCLUSIONS: LSS patients aged 80/81 are less likely to undergo AwI than patients aged 78/79, regardless of comorbidities. This was not seen when comparing patients with similar left digits in age. Until objective measures of physiologic capacity are established, left-digit bias may influence clinical decisions.

Postoperative racial disparities following spine surgery are less pronounced in the outpatient setting.

BACKGROUND CONTEXT: Racial disparities in spine surgery have been thoroughly documented in the inpatient (IP) setting. However, despite an increasing proportion of procedures being performed as same-day surgeries, whether similar differences have developed in the outpatient (OP) setting remains to be elucidated. PURPOSE: This study aimed to investigate racial differences in postoperative outcomes between Black and White patients following OP and IP lumbar and cervical spine surgery. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Patients who underwent IP or OP microdiscectomy, laminectomy, anterior cervical discectomy and fusion (ACDF), or cervical disc replacement (CDR) between 2017 and 2021. OUTCOME MEASURES: Thirty-day rates of serious and minor adverse events, readmission, reoperation, non-home discharge, and mortality. METHODS: A retrospective review of patients who underwent IP or OP microdiscectomy, laminectomy, anterior cervical discectomy and fusion (ACDF), or cervical disc replacement (CDR) between 2017 and 2021 was conducted using the National Surgical Quality Improvement Program (NSQIP) database. Disparities between Black and White patients in (1) adverse event rates, (2) readmission rates, (3) reoperation rates, (4) non-home discharge rates, (5) mortality rates, (6) operative times, and (7) hospital LOS between Black and White patients were measured and compared between IP and OP surgical settings. Multivariable logistic regression analyses were used to adjust for potential effects of baseline demographic and clinical differences. RESULTS: Of 81,696 total surgeries, 49,351 (60.4%) were performed as IP and 32,345 (39.6%) were performed as OP procedures. White patients accounted for a greater proportion of IP (88.2% vs. 11.8%) and OP (92.7% vs. 7.3%) procedures than Black patients. Following IP surgery, Black patients experienced greater odds of serious (OR 1.214, 95% CI 1.077-1.370, p=.002) and minor adverse events (OR 1.377, 95% CI 1.113-1.705, p=.003), readmission (OR 1.284, 95% CI 1.130-1.459, p<.001), reoperation (OR 1.194, 95% CI 1.013-1.407, p=.035), and non-home discharge (OR 2.304, 95% CI 2.101-2.528, p<.001) after baseline adjustment. Disparities were less prominent in the OP setting, as Black patients exhibited greater odds of readmission (OR 1.341, 95% CI 1.036-1.735, p=0.026) but were no more likely than White patients to experience adverse events, reoperation, individual complications, non-home discharge, or death (p>.050 for all). CONCLUSIONS: Racial inequality in postoperative complications following spine surgery is evident, however disparities in complication rates are relatively less following OP compared to IP procedures. Further work may be beneficial in elucidating the causes of these differences to better understand and mitigate overall racial disparities within the inpatient setting. These decreased differences may also provide promising indication that progress towards reducing inequality is possible as spine care transitions to the OP setting.

Reliability of Vertebral Pelvic Angles in Assessment of Spinal Alignment.

STUDY DESIGN: Reliability analysis. OBJECTIVES: Vertebral pelvic angles (VPA) are gaining popularity given their ability to describe the shape of the spine. Understanding the reliability and minimal detectable change (MDC) is necessary to determine how these measurement tools should be used in the manual assessment of spine radiographs. Our aim is to assess intra- and interobserver intraclass correlation coefficients (ICC) and the MDC in the use of VPA for assessing alignment in adult spinal deformity (ASD). METHODS: Three independent examiners blindly measured T1, T4, T9, L1, and L4PA twice in ASD patients with a 4-week window after the initial measurements. Patients who had undergone hip or shoulder arthroplasty, fused or transitional vertebrae, or whose hip joints were not visible on radiographs were excluded. Power analysis calculated a minimum sample size of 19. Both intra- and interobserver ICC and MDC, which denotes the smallest detectable change in a true value with 95% confidence, were calculated. RESULTS: Out of the 193 patients, 39 were ultimately included in the study, and 390 measurements were performed by 3 raters. Intraobserver ICC values ranged from .90 to .99. The interobserver ICC was .97, .97, .96, .95, and .92, and the MDC was 5.3°, 5.1°, 4.8°, 4.9°, and 4.1° for T1, T4, T9, L1, and L4PA, respectively. CONCLUSION: All VPAs showed excellent intra- and interobserver reliability, however, the MDC is relatively high compared to typical ranges for VPA values. Therefore, surgeons must be aware that substantial alignment changes may not be detected by a single VPA.

Decisional regret following corrective adult spinal deformity surgery: a single institution study of incidence and risk factors.

PURPOSE: To assess the characteristics and risk factors for decisional regret following corrective adult spinal deformity (ASD) surgery at our hospital. METHODS: This is a retrospective cohort study of a single-surgeon ASD database. Adult patients (> 40 years) who underwent ASD surgery from May 2016 to December 2020 with minimum 2-year follow-up were included (posterior-only, ≥ 4 levels fused to the pelvis) (n = 120). Ottawa decision regret questionnaires, a validated and reliable 5-item Likert scale, were sent to patients postoperatively. Regret scores were defined as (1) low regret: 0-39 (2) medium to high regret: 40-100. Risk factors for medium or high decisional regret were identified using multivariate models. RESULTS: Ninety patients were successfully contacted and 77 patients consented to participate. Nonparticipants were older, had a higher incidence of anxiety, and higher ASA class. There were 7 patients that reported medium or high decisional regret (9%). Ninety percentage of patients believed that surgery was the right decision, 86% believed that surgery was a wise choice, and 87% would do it again. 8% of patients regretted the surgery and 14% believed that surgery did them harm. 88% of patients felt better after surgery. On multivariate analysis, revision fusion surgery was independently associated with an increased risk of medium or high decisional regret (adjusted odds ratio: 6.000, 95% confidence interval: 1.074-33.534, p = 0.041). CONCLUSIONS: At our institution, we found a 9% incidence of decisional regret. Revision fusion was associated with increased decisional regret. Estimates for decisional regret should be based on single-institution experiences given differences in patient populations.

Differences in total shoulder arthroplasty utilization and 30-day outcomes among White, Black, and Hispanic patients: do disparities exist in the outpatient setting?

BACKGROUND: In the United States, efforts to improve efficiency and reduce healthcare costs are shifting more total shoulder arthroplasty (TSA) surgeries to the outpatient setting. However, whether racial and ethnic disparities in access to high-quality outpatient TSA care exist remains to be elucidated. The purpose of this study was to assess racial/ethnic differences in relative outpatient TSA utilization and perioperative outcomes using a large national surgical database. METHODS: White, Black, and Hispanic patients who underwent TSA between 2017 and 2021 were identified from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database. Baseline demographic and clinical characteristics were collected, and rates of outpatient utilization, adverse events, readmission, reoperation, nonhome discharge, and mortality within 30 days of surgery were compared between racial/ethnic groups. Race/ethnicity-specific trends in utilization of outpatient TSA were assessed, and multivariable logistic regression was used to adjust for baseline demographic factors and comorbidities. RESULTS: A total of 21,186 patients were included, consisting of 19,135 (90.3%) White, 1093 (5.2%) Black, and 958 (4.5%) Hispanic patients and representing 17,649 (83.3%) inpatient and 3537 (16.7%) outpatient procedures. Black and Hispanic patients were generally younger and less healthy than White patients, yet incidences of complications, nonhome discharge, readmission, reoperation, and death within 30 days were similar across groups following outpatient TSA (P > .050 for all). Relative utilization of outpatient TSA increased by 28.7% among White patients, 29.5% among Black patients, and 38.6% among Hispanic patients (ptrend<0.001 for all). Hispanic patients were 64% more likely than White patients to undergo TSA as an outpatient procedure across the study period (OR: 1.64, 95% CI 1.40-1.92, P < .001), whereas odds did not differ between Black and White patients (OR: 1.04, 95% CI 0.87-1.23, P = .673). CONCLUSION: Relative utilization of outpatient TSA remains highest among Hispanic patients but has been significantly increasing across all racial and ethnic groups, now accounting for more than one-third of all TSA procedures. Considering outpatient TSA is associated with fewer complications and lower costs, increasing utilization may represent a promising avenue for reducing disparities in orthopedic shoulder surgery.

Pre-operative bone quality deficits and risk of complications following spine fusion surgery among postmenopausal women.

Poor bone quality is a risk factor for complications after spinal fusion surgery. This study investigated pre-operative bone quality in postmenopausal women undergoing spine fusion and found that those with small bones, thinner cortices and surgeries involving more vertebral levels were at highest risk for complications. PURPOSE: Spinal fusion is one of the most common surgeries performed worldwide. While skeletal complications are common, underlying skeletal deficits are often missed by pre-operative DXA due to artifact from spinal pathology. This prospective cohort study investigated pre-operative bone quality using high resolution peripheral CT (HRpQCT) and its relation to post-operative outcomes in postmenopausal women, a population that may be at particular risk for skeletal complications. We hypothesized that women with low volumetric BMD (vBMD) and abnormal microarchitecture would have higher rates of post-operative complications. METHODS: Pre-operative imaging included areal BMD (aBMD) by DXA, cortical and trabecular vBMD and microarchitecture of the radius and tibia by high resolution peripheral CT. Intra-operative bone quality was subjectively graded based on resistance to pedicle screw insertion. Post-operative complications were assessed by radiographs and CTs. RESULTS: Among 50 women enrolled (age 65 years), mean spine aBMD was normal and 35% had osteoporosis by DXA at any site. Low aBMD and vBMD were associated with "poor" subjective intra-operative quality. Skeletal complications occurred in 46% over a median follow-up of 15 months. In Cox proportional models, complications were associated with greater number of surgical levels (HR 1.19 95% CI 1.06-1.34), smaller tibia total area (HR 1.67 95% CI1.16-2.44) and lower tibial cortical thickness (HR 1.35 95% CI 1.05-1.75; model p < 0.01). CONCLUSION: Women with smaller bones, thinner cortices and procedures involving a greater number of vertebrae were at highest risk for post-operative complications, providing insights into surgical and skeletal risk factors for complications in this population.

Revision-Free Loss of Sagittal Correction Greater Than Three Years After Adult Spinal Deformity Surgery: Who and Why?

STUDY DESIGN: Multicenter retrospective cohort study. OBJECTIVE: To investigate risk factors for loss of correction within the instrumented lumbar spine after adult spinal deformity surgery. SUMMARY OF BACKGROUND DATA: The sustainability of adult spinal deformity surgery remains a health care challenge. Malalignment is a major reason for revision surgery. PATIENTS AND METHODS: A total of 321 patients who underwent fusion of the lumbar spine (≥5 levels, LIV pelvis) with a revision-free follow-up of ≥3 years were identified. Patients were stratified by a change in pelvic incidence-lumbar lordosis from 6 weeks to 3 years postoperative as "maintained" versus "loss" >5°. Those with instrumentation failure (broken rod, screw pullout, etc .) were excluded before comparisons. Demographics, surgical data, and radiographic alignment were compared. Repeated measure analysis of variance was performed to evaluate the maintenance of the correction for L1-L4 and L4-S1. Multivariate logistic regression was conducted to identify independent surgical predictors of correction loss. RESULTS: The cohort had a mean age of 64 years, a mean Body Mass Index of 28 kg/m 2 , and 80% females. Eighty-two patients (25.5%) lost >5° of pelvic incidence-lumbar lordosis correction (mean loss 10±5°). After the exclusion of patients with instrumentation failure, 52 losses were compared with 222 maintained. Demographics, osteotomies, 3CO, interbody fusion, use of bone morphogenetic protein, rod material, rod diameter, and fusion length were not significantly different. L1-S1 screw orientation angle was 1.3 ± 4.1 from early postoperative to 3 years ( P = 0.031), but not appreciably different at L4-S1 (-0.1 ± 2.9 P = 0.97). Lack of a supplemental rod (odds ratio: 4.0, P = 0.005) and fusion length (odds ratio 2.2, P = 0.004) were associated with loss of correction. CONCLUSIONS: Approximately, a quarter of revision-free patients lose an average of 10° of their 6-week correction by 3 years. Lordosis is lost proximally through the instrumentation ( i.e. tulip/shank angle shifts and/or rod bending). The use of supplemental rods and avoiding sagittal overcorrection may help mitigate this loss.

Why Didn't You Walk Yesterday? Factors Associated With Slow Early Recovery After Adult Spinal Deformity Surgery.

STUDY DESIGN: This is a retrospective case-control study. OBJECTIVES: The objectives of this study are to identify (1) risk factors for delayed ambulation following adult spinal deformity (ASD) surgery and (2) complications associated with delayed ambulation. METHODS: One-hundred and ninety-one patients with ASD who underwent posterior-only fusion (≥5 levels, LIV pelvis) were reviewed. Patients who ambulated with physical therapy (PT) on POD2 or later (LateAmb, n = 49) were propensity matched 1:1 to patients who ambulated on POD0-1 (NmlAmb, n = 49) based on the extent of fusion and surgical invasiveness score (ASD-S). Risk factors, as well as inpatient medical complications were compared. Logistic regressions were used to identify risk factors for late ambulation. RESULTS: Of the patients who did not ambulate on POD0-1, 32% declined participation secondary to pain or dizziness/fatigue, while 68% were restricted from participation by PT/nursing due to fatigue, inability to follow commands, nausea/dizziness, pain, or hypotension. Logistic regression showed that intraoperative estimated blood loss (EBL) >2L (OR = 5.57 [1.51-20.55], P = .010) was independently associated with an increased risk of delayed ambulation, with a 1.25 times higher risk for every 250 mL increase in EBL (P = .014). Modified 5-Item Frailty Index (mFI-5) was also independently associated with delayed ambulation (OR = 2.53 [1.14-5.63], P = .023). LateAmb demonstrated a higher hospital LOS (8.4 ± 4.0 vs 6.2 ± 2.6, P < .001). The LateAmb group trended toward an increase in medical complications on POD3+ (14.3% vs 26.5%, P = .210). CONCLUSIONS: EBL demonstrates a dose-response relationship with risk for delayed ambulation. Delayed ambulation increases LOS and may impact medical complications.

The Association of Lumbar Plexus Lengthening with Neurologic Deficit After Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: This study aimed to evaluate the association between nerve lengthening after adult deformity correction and motor deficits dervied from the upper lumbar plexus or femoral nerve. SUMMARY OF BACKGROUND DATA: Adult spinal deformity (ASD) surgery is associated with high rates of neurological deficits. Certain postoperative deficits may be related to lengthening of the upper lumbar plexus (ULP) and/or femoral nerve (FN) after correction of lumbar deformity. METHODS: Patients with ASD who underwent posterior-only corrective surgery from the sacrum to L3 or above were included. The length of each lumbar nerve root (NR) was calculated geometrically using the distance from the foramen to the midpoint between the anterosuperior iliac crest and pubic symphysis on AP and lateral radiographs. The mean lengths of the L1-3 and L2-4 NRs were used to define the lengths of the ULP and FN, respectively. Pre- to postoperative changes in nerve length were calculated. Neurological examination was performed at discharge. Proximal weakness (PW) was defined as the presence of weakness compared to baseline in either hip flexors or knee extensors. Multiple linear regression analysis was used for estimating the postoperative lengthening according to the magnitude of preoperative curvature and postoperative correction angles. RESULTS: A total of 202 sides were analyzed in 101 patients, and PW was present on 15 (7.4%) sides in 10 patients. Excluding the 10 cases with three-column osteotomies, those with PW had a significantly higher rate of pure sagittal deformity (P<.001) and greater nerve lengthening than those without PW (ULP 24 vs 15 mm, P=0.02; FN 18 vs 11 mm, P=0.05). No patient had advanced imaging showing neural compression, and complete recovery of PW occurred in 8 patients at 1-year follow-up. CONCLUSIONS: After ASD surgery, lengthening of the ULP was associated with PW. In preoperative planning, surgeons must consider how the type of correction may influence the risk for nerve lengthening, which may contribute to postoperative neurologic deficit. LEVEL OF EVIDENCE: 3.

Single-position Minimally Invasive Surgery for Correction of Adult Spinal Deformity.

Minimally invasive adult spinal deformity (MIS ASD) surgery may offer benefits over conventional techniques in select circumstances. The success of the procedure is based on proper patient selection, restoring adequate alignment, and optimizing fusion. In the past, MIS techniques were limited because of the need to reposition the patient-a source of increased surgical time and potentially patient risk. New developments now allow for single-position, MIS correction of adult deformity. Additional research will be needed to determine the ideal patient for minimally invasive adult spinal deformity surgery and whether prone or lateral single-position confers the best outcomes.

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.

Optimizing the Definition of Proximal Junctional Kyphosis: A Sensitivity Analysis.

STUDY DESIGN: Diagnostic binary threshold analysis. OBJECTIVE: (1) Perform a sensitivity analysis demonstrating the test performance metrics for any combination of proximal junctional angle (PJA) magnitude and change; (2) Propose a new proximal junctional kyphosis (PJK) criteria. SUMMARY OF BACKGROUND DATA: Previous definitions of PJK have been arbitrarily selected and then tested through retrospective case series, often showing little correlation with clinical outcomes. MATERIALS AND METHODS: Surgically treated adult spinal deformity patients (≥4 levels fused) enrolled into a prospective, multicenter database were evaluated at a minimum 2-year follow-up for proximal junctional failure (PJF). Using PJF as the outcome of interest, test performance metrics including sensitivity, positive predictive value, and F1 metrics (harmonic mean of precision and recall) were calculated for all combinations of PJA magnitude and change using different combinations of perijunctional vertebrae. The combination with the highest F1 score was selected as the new PJK criteria. Performance metrics of previous PJK definitions and the new PJK definition were compared. RESULTS: Of the total, 669 patients were reviewed. PJF rate was 10%. Overall, the highest F1 scores were achieved when the upper instrumented vertebrae -1 (UIV-1)/UIV+2 angle was measured. For lower thoracic cases, out of all the PJA and magnitude/change combinations tested, a UIV-1/UIV+2 magnitude of -28° and a change of -20° was associated with the highest F1 score. For upper thoracic cases, a UIV-1/UIV+2 magnitude of -30° and a change of -24° were associated with the highest F1 score. Using PJF as the outcome, patients meeting this new criterion (11.5%) at 6 weeks had the lowest survival rate (74.7%) at 2 years postoperative, compared with Glattes (84.4%) and Bridwell (77.4%). CONCLUSIONS: Out of all possible PJA magnitude and change combinations, without stratifying by upper thoracic versus lower thoracic fusions, a magnitude of ≤-28° and a change of ≤-22° provide the best test performance metrics for predicting PJF.

Is High-Dose Tranexamic Safe in Spine Surgery? A Systematic Review and Meta-Analysis.

STUDY DESIGN: Literature review and meta-analysis. OBJECTIVES: Single-center series may be underpowered to detect whether high-dose (HD) tranexamic acid (TXA) confers a higher risk of complications. We sought to determine the safety and efficacy of HD TXA as compared to low-dose (LD) or placebo. METHODS: A systematic literature review was performed to find studies where spine surgery patients were given HD TXA (loading dose ≥30 mg/kg). Complication rates were pooled, and meta-analyses performed on outcomes of interest. Articles were evaluated for risk of bias and a strength of evidence assessment was given for each conclusion. RESULTS: Twenty three studies (n = 2331) were included. The pooled medical complication rate was 3.2% in pediatric patients, 8.2% in adults. Using lower dose TXA or placebo as the reference, meta-analysis showed no difference in medical complications (n = 1,723, OR 1.22 [95% CI, .78 to 1.22]; P = .388; I2 = 0%) or thrombotic events (n = 1158 patients, OR 1.27 [95% CI, .71 to 2.63]; P = .528; I2 = 0%). Compared to LD, HD TXA was associated with less intraoperative blood loss (823 patients, WMD = -285 [95% CI, -564 to -5.90]; P = .0454; I2 = 86%), fewer perioperative transfusions (n = 505, OR .28 [95% CI, .082 to .96]; P = .043; I2 = 76%) and lower perioperative transfusion volumes (n = 434, WMD -227.7 mL [95% CI, -377.3 to -78.02]; P = .0029; I2 = 0%). CONCLUSION: Compared to LD TXA or placebo, there is moderate evidence that HD is not associated with an increased risk of medical complications. Compared to LD, there is moderate evidence that HD reduces transfusion requirements. High-Dose TXA can be safely utilized in healthy patients undergoing major spine surgery.

Complications and Revisions After Spine Surgery in Patients With Skeletal Dysplasia: Have We Improved?

STUDY DESIGN: Retrospective case series. OBJECTIVE: To report contemporary rates of complications and subsequent surgery after spinal surgery in patients with skeletal dysplasia. METHODS: A case series of 25 consecutive patients who underwent spinal surgery between 2007 and 2017 were identified from a single institution's skeletal dysplasia registry. Patient demographics, medical history, surgical indication, complications, and subsequent surgeries (revisions, extension to adjacent levels, or for pathology at a non-contiguous level) were collected. Charlson comorbidity indices were calculated as a composite measure of overall health. RESULTS: Achondroplasia was the most common skeletal dysplasia (76%) followed by spondyloepiphyseal dysplasia (20%); 1 patient had diastrophic dysplasia (4%). Average patient age was 53.2 ± 14.7 years and most patients were in excellent cardiovascular health (88% Charlson Comorbidity Index 0-4). Mean follow up after the index procedure was 57.4 ± 39.2 months (range). Indications for surgery were mostly for neurologic symptoms. The most commonly performed surgery was a multilevel thoracolumbar decompression without fusion (57%). Complications included durotomy (36%), neurologic complication (12%), and infection requiring irrigation and debridement (8%). Nine patients (36%) underwent a subsequent surgery. Three patients (12%) underwent a procedure at a non-contiguous anatomic zone, 3 (12%) underwent a revision of the previous surgery, and another 3 (12%) required extension of their previous decompression or fusion. CONCLUSIONS: Surgical complication rates remain high after spine surgery in patients with skeletal dysplasia, likely attributable to inherent characteristics of the disease. Patients should be counseled on their risk for complication and subsequent surgery.

How Does Gravity Influence the Distribution of Lordosis in Patients With Sagittal Malalignment?

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: Compare the supine vs standing radiographs of patients with adult spinal deformity against ideals defined by healthy standing alignment. METHODS: 56 patients with primary sagittal ASD (SRS-Schwab Type N) and 119 asymptomatic volunteers were included. Standing alignment of asymptomatic volunteers was used to calculate PI-based formulas for normative age-adjusted standing PI-LL, L4-S1, and L1-L4. These formulas were applied to the supine and standing alignment of ASD cohort. Analyses were repeated on a cohort of 25 patients with at least 5 degrees of lumbar flexibility (difference between supine and standing lordosis). RESULTS: The asymptomatic cohort yielded the following PI-based formulas: PI-LL = -38.3 + .41*PI + .21*Age, L4-S1 = 45.3-.18*Age, L1-L4 = -3 + .48*PI). PI-LL improved with supine positioning (mean 8.9 ± 18.7°, P < .001), though not enough to correct to age-matched norms (mean offset 12.2 ± 16.9°). Compared with mean normative alignment at L1-L4 (22.1 ± 6.2°), L1-L4 was flatter on standing (7.2 ± 17.0°, P < .001) and supine imaging (8.5 ± 15.0°, P < .001). L4-S1 lordosis of subjects with L1-S1 flexibility >5° corrected on supine imaging (33.9 ± 11.1°, P = 1.000), but L1-L4 did not (23.0 ± 6.2° norm vs 2.2 ± 14.4° standing, P < .001; vs 7.3 ± 12.9° supine, P < .001). CONCLUSIONS: When the effects of gravity are removed, the distal portion of the lumbar spine (i.e., below the apex of lordosis) corrects, suggesting that structural lumbar deformity is primarily proximal.