Faculty Bibliography

BACKGROUND CONTEXT/BACKGROUND:Lateral lumbar interbody fusion is a popular technique used in spine surgery. It is minimally invasive, provides indirect decompression, and allows for coronal plane deformity correction. Despite these benefits, the approach to lateral lumbar interbody fusion has been linked to complications associated with the lumbosacral plexus and vascular anatomy. As a result, vascular surgeons may be recruited for the exposure portion of the procedure. PURPOSE/OBJECTIVE:The purpose of this study was to compare exposure related complication and post-operative (postop) neuropraxia rates between exposure (EXP) and spine surgeon only (SSO) groups when performing the approach for lateral lumbar interbody fusion (LLIF). STUDY DESIGN/SETTING/METHODS:Retrospective analysis of patients treated at a single institution PATIENT SAMPLE: Patients undergoing LLIF procedures between 2012-2018 OUTCOME MEASURES: Operative time, estimated blood loss, fluoroscopy, length of stay, intra- and post-operative complications, and physiologic measures including pre- and post-operative motor examinations and unresolved neuropraxia METHODS: Patients who underwent LLIF were separated into EXP and SSO groups based on the presence or absence of vascular/general surgeon during the approach. The entire clinical history of patients with a decrease in pre and postop motor examination were reviewed for the presence of neuropraxia. All other intra- and postop exposure related complications were recorded for comparison. PSM was performed to account for age, Charlston Comorbity Index (CCI) % LLIFs including L4-L5, and number levels fused. Independent T-test and Chi-squared analyses were used to identify significant differences between EXP and SSO groups. Statistical significance was set at p<0.05. RESULTS:Two hundred seventy-five patients underwent LLIF procedures, 155 SSO and 120 EXP. Post-operatively, 26 patients (11.1%) experienced a drop in any MRC score, and two patients (0.7%) experience unresolved quadriceps palsies. The mean recovery time for MRC scores was 84.4 days. Other complications included 2 pneumothoraces (0.7%), 1 iliac vein injury (0.4%), 14 cases of ileus (5.1%), 3 pulmonary emboli (1.1%), 2 deep vein thrombosis (0.7%), 3 cases of abdominal wall paresis (1.1%), and one abdominal hematoma (0.4%). After PSM, demographics including age, gender, BMI, CCI, levels fused and operative time were similar between cohorts. Twenty patients had changes in pre- to postop motor scores (SSO 9.4%, EXP 12.4%, p>0.05). Iliopsoas motor scores decreased at the highest rate (EXP 12.4%, 8.2% SSO, p>0.05) followed by quadriceps (EXP 5.2%, SSO 4.7%, p>0.05). One SSO patient's postop course was complicated by a foot drop but returned to baseline within 1-year. One patient in EXP group developed an unresolved quadriceps palsy (EXP 1.0%, SSO 0.0% p>0.05). Intra-op exposure complications included one pneumothorax (EXP 1.0%, SSO 0.0%, p>0.05). There were no differences in PE/DVT, Ileus, or LOS. In the EXP cohort, three patients experienced abdominal wall paresis (EXP 2.9%, SSO 0.00%, p=0.246). CONCLUSIONS:Comparing the LLIF exposures performed by EXP and SSO, we found no significant difference in the rates of complications. Additional research is needed to determine the etiology of the abdominal wall complications. In conclusion, neuropraxia- and approach-related complications are similarly low between exposure and spine surgeons.

BACKGROUND:Lumbar herniated nucleus pulposus (HNP) is a common spinal pathology often treated by microscopic lumbar discectomy (MLD), though prior reports have not demonstrated which preoperative MRI factors may contribute to significant clinical improvement after MLD. PURPOSE/OBJECTIVE:To analyze the MRI characteristics in patients with HNP that predict meaningful clinical improvement in Health Related Quality of Life scores (HRQoL) after MLD. STUDY DESIGN/SETTING/METHODS:Retrospective clinical and radiological study of patients undergoing MLD for HNP at a single institution over a two-year period. PATIENT SAMPLE/METHODS:88 patients receiving MLD treatment for HNP. OUTCOME MEASURES/METHODS:Cephalocaudal Canal Migration; Canal & HNP Anterior-Posterior (AP) Lengths and Ratio; Canal & HNP Axial Areas and Ratio; Hemi-Canal & Hemi-HNP Axial Areas and Ratio; Disc appearance (black, grey or mixed), Baseline (BL) and 3-Month (3M) postoperative Health Related Quality of Life Scores. METHODS:Patients > 18 years old who received MLD for HNP with BL and 3M HRQoL scores of PROMIS (Physical Function, Pain Interference, and Pain Intensity), ODI, VAS Back, and VAS Leg scores were included. HNP and spinal canal measurements of cephalocaudal migration, AP length, area, hemi-area, and disc appearance were performed using T2 axial and sagittal MRI. HNP measurements were divided by corresponding canal measurements to calculate AP, Area, and Hemi-Area ratios. Using known minimal clinically important differences (MCID) for each ΔHRQoL score, patients were separated into two groups based on whether they reached MCID (MCID+) or did not reach MCID (MCID-). The MCID for PROMIS Pain Intensity was calculated using a decision tree. A linear regression illustrated correlations between PROMIS vs ODI and VAS Back/Leg scores. Independent t-tests and chi [2] tests were utilized to investigate significant differences in HNP measurements between the MCID+ and MCID- groups. RESULTS:± 43.2, p<.04). MCID+ patients had a greater Hemi-Area Ratio than MCID- patients had in 4 out of 6 HRQoL score comparisons (51.8% ± 14.7 vs 43.9% ± 14.9, p<.05). CONCLUSIONS:Patients who met MCID after MLD had larger HNP areas and larger Hemi-HNP Areas than those who did not meet MCID. These patients were also 2.7x more likely to have a grey MRI signal than a mixed or black MRI signal. When accounting for HNP area relative to canal area, patients who met MCID had greater Hemi-HNP canal occupation than patients who did not meet MCID. The results of this study suggest that preoperative MRI parameters can be useful in predicting patient reported improvement after MLD.

STUDY DESIGN/METHODS:Single-center retrospective study. OBJECTIVE:Investigate how differing degrees of PI modulate the recruitment of pelvic tilt (PT) in response to similar amounts of sagittal malalignment as measured by T1-Pelvic Angle (TPA). SUMMARY OF BACKGROUND DATA/BACKGROUND:Past research has shown that some patients do not recruit PT in response to sagittal malalignment. Given the anatomic relationship between PI and PT, we sought to determine whether differing PI is associated with variable recruitment of PT. METHODS:Single-center retrospective study of 2077 patients undergoing full body radiographs and TPA>10°. Five groups of patients (Very Low, Low, Average, High, and Very High PI) were defined utilizing PI ranges on a gaussian distribution. Linear regression (LR) evaluated correlation of TPA to PT within each PI group. Multivariate LR evaluated whether correlation between TPA and PT differed between each PI group. RESULTS:Mean PT increased with increasing levels of PI (p < 0.05). Within the full cohort, PT correlated with TPA (r = 0.80, p < 0.001). Multivariate LR revealed significant differences between slopes and intercepts of the linear relationship between PT and TPA within the PI groups. Compared to patients with an average PI, patients with Very Low PI had 3.4° lower PT while holding TPA constant (p < 0.001). Further, patients with Very High PI displayed a PT of 1.9° higher than patients with an Average PI while holding TPA constant (p = 0.01). A similar difference of -1.8°, and 1.2° with respect to the Average PI group was observed in the Low and High PI groups, respectively (p < 0.001). Means and standard deviations of PT at varying levels of TPA were defined for PI groups. CONCLUSIONS:This is the first study which demonstrated that PI is associated with varied recruitment of PT while maintaining constant sagittal malalignment. The results reported herein are intended to allow surgeons to assess a patient's magnitude of compensatory PT for an individual patient's PI. LEVEL OF EVIDENCE/METHODS:3.

BACKGROUND:The important relationship between sagittal spinal alignment and total hip arthroplasty (THA) is becoming well recognized. Prior research has shown a significant relationship between sagittal spinal deformity (SSD) and THA instability. This study aims at determining the prevalence of SSD among preoperative THA patients. METHODS:A multicenter database of preoperative THA patients was analyzed. Radiographic parameters measured from standing radiographs included anterior pelvic plane tilt, spinopelvic tilt, and lumbar lordosis (LL); pelvic incidence (PI) was measured from computed tomography scans. Lumbar flatback was defined as PI-LL mismatch >10°, balanced as PI-LL of -10° to 10°, and hyperlordosis as PI-LL <-10°. RESULTS:A total of 1088 patients were analyzed (mean, 64 years; 48% female). And 59% (n = 644) of patients had balanced alignment, 16% (n = 174) had a PI-LL > 10°, and 4% (n = 46) had a PI-LL > 20° (severe flatback deformity). The prevalence of hyperlordosis was 25% (n = 270). Flatback patients tended to be older than balanced and hyperlordotic patients (69.5 vs 64.0 vs 60.8 years, P < .001). Spinopelvic tilt was more posterior in flatback compared to balanced and hyperlordotic patients (24.7° vs 15.4° vs 7.0°) as was anterior pelvic plane tilt (-7.1° vs -2.0° vs 2.5°) and PI (64.1° vs 56.8° vs 49.0°), all P < .001. CONCLUSION/CONCLUSIONS:Only 59% of patients undergoing THA have normally aligned lumbar spines. Flatback SSD was observed in 16% (4% with severe flatback deformity) and there was a 25% prevalence of hyperlordosis. Lumbar flatback was associated with increasing age, posterior pelvic tilt, and larger PI. The relatively high prevalence of spinal deformity in this population reinforces the importance of considering spinopelvic alignment in THA planning and risk stratification.

STUDY DESIGN/METHODS:Retrospective analysis OBJECTIVE.: Determine whether deformity corrections should vary by pelvic incidence (PI). SUMMARY OF BACKGROUND DATA/BACKGROUND:Alignment targets for deformity correction have been reported for various radiographic parameters. The T1 pelvic-angle (TPA) has gained in applications for ASD surgical-planning since it directly measures spinal alignment separate from pelvic- and lower-extremity compensation. Recent studies have demonstrated that ASD corrections should be age specific. METHODS:A prospective database of consecutive ASD patients was analyzed in conjunction with a normative spine database. Clinical measures of disability included the Oswestry Disability Index (ODI) and SF-36 Physical Component Score (PCS). Baseline relationships between TPA, age, PI and ODI/SF-36 PCS scores were analyzed in the ASD and asymptomatic patients. Linear regression modeling was used to determine alignment targets based on PI and age-specific normative SF-36-PCS values. RESULTS:903 ASD patients (mean 53.7y) and 111 normative subjects (mean 50.7y) were included. Patients were subanalyzed by PI: low, medium, high (<40, 40-75, >75); and age: elderly(>65y, n = 375) middle age(45-65y, n = 387) and young(18-45y, n = 141). TPA and SRS-Schwab parameters correlated with age and PI in ASD and normative subjects (r = .42, p < .0001). ODI correlated with PCS(r = .71, p < .0001). Linear regression analysis using age-normative SF-36-PCS values demonstrated that ideal spinopelvic alignment is less strict with increasing PI and age. CONCLUSIONS:Targets for ASD correction should vary by age and PI. This is demonstrated in both asymptomatic and ASD subjects. Using age-normative SF-36 PCS values, alignment targets are described for different age and PI categories. High-PI patients do not require as rigorous realignments to attain age-specific normative levels of health status. As such, sagittal spinal alignment targets increase with increasing age as well as PI. LEVEL OF EVIDENCE/METHODS:3.

STUDY DESIGN:Retrospective review from a single institution. OBJECTIVE:To investigate the effect of hip osteoarthritis (OA) on spinopelvic compensatory mechanisms as a result of reduced hip range of motion (ROM) between sitting and standing. SUMMARY OF BACKGROUND DATA:Hip OA results in reduced hip ROM and contracture, causing pain during postural changes. Hip flexion contracture is known to reduce the ability to compensate for spinal deformity while standing; however, the effects of postural spinal alignment change between sitting and standing is not well understood. METHODS:Sit-stand radiographs of patients without prior spinal fusion or hip prosthesis were evaluated. Hip OA was graded by Kellgren-Lawrence grades and divided into low-grade (LOA; grade 0-2) and severe (SOA; grade 3 or 4) groups. Radiographic parameters evaluated were pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI-LL, thoracic kyphosis (TK), SVA, T1-pelvic angle (TPA), T10-L2, proximal femoral shaft angle (PFSA), and hip flexion (PT change-PFSA change). Changes in sit-stand parameters were compared between LOA and SOA groups. RESULTS:548 patients were included (LOA = 311; SOA = 237). After propensity score matching for age, body mass index, and PI, 183 LOA and 183 SOA patients were analyzed. Standing analysis demonstrated that SOA had higher SVA (31.1 vs. 21.7), lower TK (-36.2 vs. -41.1), and larger PFSA (9.1 vs. 7.4) (all p < .05). Sitting analysis demonstrated that SOA had higher PT (29.7 vs. 23.3), higher PI-LL (21.6 vs. 12.4), less LL (31.7 vs. 41.6), less TK (-33.2 vs. -38.6), and greater TPA (27.9 vs. 22.5) (all p < .05). SOA had less hip ROM from standing to sitting versus LOA (71.5 vs. 81.6) (p < .05). Therefore, SOA had more change in PT (15.2 vs. 7.3), PI-LL (20.6 vs. 13.7), LL (-21.4 vs. -13.1), and T10-L2 (-4.9 vs. -1.1) (all p < .001), allowing the femurs to change position despite reduced hip ROM. SOA had greater TPA reduction (15.1 vs. 9.6) and less PFSA change (86.7 vs. 88.8) compared with LOA (both p < .001). CONCLUSIONS:Spinopelvic compensatory mechanisms are adapted for reduced hip joint motion associated with hip OA in standing and sitting. LEVEL OF EVIDENCE:Level III.

STUDY DESIGN:Retrospective review from a single institution. OBJECTIVES:To evaluate intraoperative T1-pelvic angle (TPA), T4PA, and T9PA as predictors of postoperative global alignment after adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA:Malalignment following adult spinal surgery is associated with disability and correlates with health-related quality of life. Preoperative planning and intraoperative verification are crucial for optimal postoperative outcomes. Currently, only pelvic incidence minus lumbar lordosis (PI-LL) mismatch has been used to assess intraoperative correction. METHODS:Patients undergoing ≥4-level spinal fusion with full-length pre-, intra-, and first postoperative calibrated radiographs were included from a single institution. Alignment measurements were obtained for sagittal vertical axis (SVA), PI-LL, TPA, T4PA, and T9PA. The whole cohort was divided into upper thoracic (UT: UIV > T7) and lower thoracic fusions (LT: UIV < T7). Change was assessed between phases, and a subanalysis was included for UT and LT groups to compare alignment changes for differing extent of proximal fusion in the sagittal plane. RESULTS:Eighty patients (mean 63.4 years, 70% female, mean levels fused 11.9) underwent significant ASD correction (ΔPI-LL = 22.1°; ΔTPA = 13.8°). For all, intraoperative TPA, T4PA, and T9PA correlated with postoperative SVA (range, r = 0.41-0.59), whereas intraoperative PI-LL correlated less (r = 0.38). For UT (n = 49), all spinopelvic angles and LL were similar intraoperative to postoperatively (p > .09). For LT (n = 31), intraoperative and postoperative T9PA and LL were similar (p > .10) but TPA and T4PA differed (p < .02). For UT, all intraoperative and postoperative spinopelvic angles strongly correlated (r = 0.8-0.9). For LT, intraoperative to postoperative T9PA strongly correlated (r = 0.83) and TPA, T4PA, and LL correlated moderately (r = 0.65-0.70). LT trended toward more reciprocal kyphosis postoperatively (8.1° vs. 2.6°; p = .059). CONCLUSIONS:Intraoperative measurements of TPA, T4PA, and T9PA correlated better with postoperative global alignment than PI-LL, demonstrating their utility in confirming alignment goals. When comparing intraoperative to postoperative films, only T9PA was similar in LT whereas all spinopelvic angles were similar in UT. Reciprocal kyphosis in unfused segments of LT fusions may account for difference in TPA and T4PA from intraoperative to postoperative films. LEVEL OF EVIDENCE:Level III.

Background/UNASSIGNED:Outpatient anterior cervical discectomy and fusion (ACDF) is performed frequently, with studies demonstrating similar complication and readmission rates compared to traditional admission. Advantages include cost effectiveness, as well as lower risk of nosocomial infections and medical errors, which lead to quicker recovery and higher patient satisfaction. Protocols are needed to ensure that outpatient ACDF occurs safely. The objective of this study was to develop and implement a protocol with patient selection and discharge criteria for patients undergoing same-day discharge (SDD) ACDF and assess readmission rates. Methods/UNASSIGNED:A retrospective chart review was performed to identify patients undergoing 1 or 2 level primary ACDF between March 2016 and March 2017 who were eligible for SDD according to the institutional protocol (Figure 1, Table 2). Patients with identical surgery and discharge dates were grouped as SDD, and admitted patients were grouped as same-day admission (SDA). Using our electronic health record's analytics, readmissions in the 90-day postoperative period were identified. Results/UNASSIGNED:= .86). Conclusions/UNASSIGNED:The results of this study support the feasibility of outpatient ACDF and add a patient selection and discharge criteria to the literature. Proper identification of suitable patients using our protocol results in a noninferior readmission rate, allowing surgeons to continue to safely perform these surgeries with a low readmission rate. Level of Evidence/UNASSIGNED:3. Clinical Relevance/UNASSIGNED:SDD is safe in the appropriate patient population.

Background/UNASSIGNED:Robotic-guided navigation systems for pedicle screw placement has gained recent interest to ensure accuracy and safety and diminish radiation exposure. There have been no published studies using a new combined robotics and navigation system (Globus ExcelsiusGPS system). The purpose of this study was to demonstrate safety with this system. Methods/UNASSIGNED:This is a case series of consecutive patients at a single institution from February 1, 2018, to August 31, 2018. All patients who had planned placement of thoracic and lumbar pedicle screws using the combined robotics-navigation system were included. Chart review was performed for operative details. A subgroup analysis was performed on patients with postoperative computed tomography (CT) scans to assess screw placement accuracy using the Gertzbein and Robbins system. Acceptable pedicle screw position was defined as grade A or B. Results/UNASSIGNED:One hundred six patients were included, with 636 pedicle screws, 6 iliac screws, and 1 S2AI screw. Five cases were aborted for technical issues. In the remaining 101 patients, 88 patients had screws placed using preoperative CT planning and 13 patients using intraoperative fluoroscopy planning. All screws except for 5 pedicle screws in 2 patients were placed successfully using the robot (99%). These 5 pedicle screws were placed by converting to a fluoro-guided technique without robotic assistance. Eighty-six patients had screws placed using a percutaneous technique, and 15 patients had screws placed using an open technique. Ninety-eight patients underwent interbody placement: 28 anterior lumbar interbody fusions (ALIFs), 12 lateral lumbar interbody fusions (LLIFs), and 58 transforaminal lumbar interbody fusions (TLIFs). All ALIFs and LLIFs were performed prior to placement of the screws. Four LIF patients had screws placed in the lateral position. No patients had screw-related complications intraoperatively or postoperatively, and no patients returned to the operating room for screw revision. Thirteen patients underwent postoperative CT for various reasons. Of the 66 pedicle screws that were examined with postoperative CT, all screws (100%) had acceptable position. Conclusion/UNASSIGNED:This study demonstrates that the combined robotics and navigation system is a novel technology that can be utilized to place pedicle screws and pelvic screws safely and has the potential to reduce screw-related complications. Level of Evidence/UNASSIGNED:4 (case series).

Introduction/UNASSIGNED:The aim of this study was to evaluate the association of available cervical alignment components through the Ames cervical deformity (CD) classification parameters with the Patient-Reported Outcomes Measurement Information System (PROMIS) physical health domain metrics. Methods/UNASSIGNED:Surgical CD patients (C2-C7 Cobb >10° or C2-C7 sagittal vertical axis [cSVA] >4 cm or T1 slope minus cervical lordosis (TS-CL) >15°) ≥18 years with available baseline (BL) radiographic and PROMIS were isolated in a single-center spine database. Patients were classified according to the Ames CD modifiers for cSVA and TS-CL (low deformity [Low], moderate deformity [Mod], and severe deformity [Sev]). Descriptives and univariate analyses compared population-weighted PROMIS scores for Pain Intensity (PI), Physical Function (PF), and Pain Interference (Int) across CD modifiers. Conditional tree analysis with logistic regression sampling determined the threshold of PROMIS scores for which the correlation with Ames radiographic cutoffs was most significant. Reported cutoff values for Mod (cSVA: 4-8 cm; TS-CL: 15-20°) and Sev (cSVA: >8 cm; TS-CL: >20°) disabilities were used. Results/UNASSIGNED:, Charlson Comorbidity Index: 1.19). BL cSVA modifier by severity: 83.2% Low, 16.8% Mod. No patients met criteria for severe cSVA. BL TS-CL modifier by severity: 18.8% Low, 22.1% Mod, 59.1% Sev. Mean baseline PROMIS scores were as follows: PI score: 89.6 ± 15.4, PF score: 11.9 ± 13.1, Int score: 56.9 ± 6.8. PI did not differ between cSVA and TS-CL severity. Mod cSVA patients and Mod/Sev TS-CL modifier groups trended toward lower PF scores and higher Int scores. A PI score of >96 (odds ratio [OR]: 0.658 [0.303-1.430]), a PF score of <14 (OR: 1.864 [0.767-4.531]), and an Int score of > 57.4 (OR: 1.878 [0.889-3.967]) were predictors of Mod cSVA. A PI score of >87 (OR: 1.428 [0.767-2.659]), a PF score of <14 (OR: 1.551 [0.851-2.827]), and an Int score of >56.5 (OR: 1.689 [0.967-2.949]) were predictors of Sev TS-CL. Conclusions/UNASSIGNED:PROMIS physical health domains were related to the Ames CD classification. Certain BL PROMIS thresholds can be connected to the severity of CD.