Faculty Bibliography

Endoscopic spine surgery (ESS) is growing in popularity as a minimally invasive approach to a variety of spinal conditions. Similar to other types of minimally invasive spine surgery (MISS), ESS aims to address the underlying pathology while minimizing surrounding tissue disruption. Its use in the lumbar spine has progressed over the past 50 years and is now routinely used in cases of lumbar disc herniations and stenosis. This review defines common terminology, highlights important developments in the history of ESS, and discusses its current and future application in the lumbar spine.

Background/UNASSIGNED:The decision upper-most instrumented vertebrae (UIV) in a multi-level fusion procedure can dramatically influence outcomes of corrective spine surgery. We aimed to create an algorithm for selection of UIV based on surgeon selection/reasoning of sample cases. Methods/UNASSIGNED:The clinical/imaging data for 11 adult spinal deformity (ASD) patients were presented to 14 spine deformity surgeons who selected the UIV and provided reasons for avoidance of adjacent levels. The UIV chosen was grouped into either upper thoracic (UT, T1-T6), lower thoracic (LT, T7-T12), lumbar or cervical. Disagreement between surgeons was defined as ≥3 not agreeing. We performed a descriptive analysis of responses and created an algorithm for choosing UIV then applied this to a large database of ASD patients. Results/UNASSIGNED:. 38.9%, P=0.025). Conclusions/UNASSIGNED:Our algorithm for selection of UIV emphasizes the role of proximal and regional thoracic kyphosis. Failure to follow this consensus for UT fusion was associated with twice the rate of PJK.

STUDY DESIGN/UNASSIGNED:Retrospective review of a multicenter prospective registry. OBJECTIVES/UNASSIGNED:Our goal was to develop a method to risk-stratify adult spinal deformity (ASD) patients on the basis of their accumulated health deficits. We developed a novel comorbidity score (CS) specific to patients with ASD based on their preoperative health state and investigated whether it was associated with major complications, length of hospital stay (LOS), and self-reported outcomes after ASD surgery. METHODS/UNASSIGNED:We identified 273 operatively treated ASD patients with 2-year follow-up. We assessed associations between major complications and age, comorbidities, Charlson Comorbidity Index score, and Oswestry Disability Index score. Significant factors were used to construct the ASD-CS. Associations of ASD-CS with major complications, LOS, and patient-reported outcomes were analyzed. RESULTS/UNASSIGNED:< .01) in patients with ASD-CS of 7 or 8. Patients with ASD-CS of 7 or 8 had the longest mean LOS (10.7 days) and worst mean Scoliosis Research Society-22r total score at baseline; however, they experienced the greatest mean improvement (0.98 points) over 2 years. CONCLUSIONS/UNASSIGNED:The ASD-CS is significantly associated with major complications, LOS, and patient-reported outcomes in operatively treated ASD patients.

OBJECTIVE:Cervical deformity (CD) patients have severe disability and poor health status. However, little is known about how patients with rigid CD compare with those with flexible CD. The main objectives of this study were to 1) assess whether patients with rigid CD have worse baseline alignment and therefore require more aggressive surgical corrections and 2) determine whether patients with rigid CD have similar postoperative outcomes as those with flexible CD. METHODS:This is a retrospective review of a prospective, multicenter CD database. Rigid CD was defined as cervical lordosis (CL) change < 10° between flexion and extension radiographs, and flexible CD was defined as a CL change ≥ 10°. Patients with rigid CD were compared with those with flexible CD in terms of cervical alignment and health-related quality of life (HRQOL) at baseline and at multiple postoperative time points. The patients were also compared in terms of surgical and intraoperative factors such as operative time, blood loss, and number of levels fused. RESULTS:A total of 127 patients met inclusion criteria (32 with rigid and 95 with flexible CD, 63.4% of whom were females; mean age 60.8 years; mean BMI 27.4); 47.2% of cases were revisions. Rigid CD was associated with worse preoperative alignment in terms of T1 slope minus CL, T1 slope, C2-7 sagittal vertical axis (cSVA), and C2 slope (C2S; all p < 0.05). Postoperatively, patients with rigid CD had an increased mean C2S (29.1° vs 22.2°) at 3 months and increased cSVA (47.1 mm vs 37.5 mm) at 1 year (p < 0.05) compared with those with flexible CD. Patients with rigid CD had more posterior levels fused (9.5 vs 6.3), fewer anterior levels fused (1 vs 2.0), greater blood loss (1036.7 mL vs 698.5 mL), more 3-column osteotomies (40.6% vs 12.6%), greater total osteotomy grade (6.5 vs 4.5), and mean osteotomy grade per level (3.3 vs 2.1) (p < 0.05 for all). There were no significant differences in baseline HRQOL scores, the rate of distal junctional kyphosis, or major/minor complications between patients with rigid and flexible CD. Both rigid and flexible CD patients reported significant improvements from baseline to 1 year according to the numeric rating scale for the neck (-2.4 and -2.7, respectively), Neck Disability Index (-8.4 and -13.3, respectively), modified Japanese Orthopaedic Association score (0.1 and 0.6), and EQ-5D (0.01 and 0.05) (p < 0.05). However, HRQOL changes from baseline to 1 year did not differ between rigid and flexible CD patients. CONCLUSIONS:Patients with rigid CD have worse baseline cervical malalignment compared with those with flexible CD but do not significantly differ in terms of baseline disability. Rigid CD was associated with more invasive surgery and more aggressive corrections, resulting in increased operative time and blood loss. Despite more extensive surgeries, rigid CD patients had equivalent improvements in HRQOL compared with flexible CD patients. This study quantifies the importance of analyzing flexion-extension images, creating a prognostic tool for surgeons planning CD correction, and counseling patients who are considering CD surgery.

BACKGROUND:Surgical site infections are common and costly complications after spine surgery. Prophylactic antibiotics are the standard of care; however, the appropriate duration of antibiotics has yet to be adequately addressed. We sought to determine whether the duration of antibiotic administration (preoperatively only versus preoperatively and for 24 hours postoperatively) impacts postoperative infection rates. METHODS:All patients undergoing inpatient spinal procedures at a single institution from 2011 to 2018 were evaluated for inclusion. A minimum of 1 year of follow-up was used to adequately capture postoperative infections. The 1:1 nearest-neighbor propensity score matching technique was used between patients who did and did not receive postoperative antibiotics, and multivariable logistic regression analysis was conducted to control for confounding. RESULTS:A total of 4,454 patients were evaluated and, of those, 2,672 (60%) received 24 hours of postoperative antibiotics and 1,782 (40%) received no postoperative antibiotics. After propensity-matched analysis, there was no difference between patients who received postoperative antibiotics and those who did not in terms of the infection rate (1.8% compared with 1.5%). No significant decrease in the odds of postoperative infection was noted in association with the use of postoperative antibiotics (odds ratio = 1.17; 95% confidence interval, 0.620 to 2.23; p = 0.628). Additionally, there was no observed increase in the risk of Clostridium difficile infection or in the short-term rate of infection with multidrug-resistant organisms. CONCLUSIONS:There was no difference in the rate of surgical site infections between patients who received 24 hours of postoperative antibiotics and those who did not. Additionally, we found no observable risks, such as more antibiotic-resistant infections and C. difficile infections, with prolonged antibiotic use. LEVEL OF EVIDENCE/METHODS:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND CONTEXT/BACKGROUND:Numerous advances have been made in the field of spine fusion, such as minimally invasive (MIS) or robotic-assisted spine surgery. However, it is unknown how these advances have impacted the cost of care. PURPOSE/OBJECTIVE:Compare the economic outcomes of lumbar spine fusion between open, MIS, and robot-assisted surgery patients. STUDY DESIGN/SETTING/METHODS:Retrospective review of a single center spine surgery database. PATIENT SAMPLE/METHODS:360 propensity matched patients. OUTCOME MEASURES/METHODS:Costs, EuroQol-5D (EQ5D), cost per quality adjusted life years (QALY). METHODS:Inclusion criteria: surgical patients >18 years undergoing lumbar fusion surgery. Patients were categorized into 3 groups based on procedure type: open, MIS, or robotic. Open patients undergoing poster spinal fusion were considered as the control group. MIS patients included those undergoing transforaminal or lateral lumbar interbody fusion with percutaneous screws. Robotic patients were those undergoing robot-assisted fusion. Propensity score matching was performed between all groups for the number of levels fused. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims for ICD-9 codes. For robotic cases, costs were reflective of operational fees and initial purchase cost. Complications and comorbidities (CC) and major complications and comorbidities (MCC) were assessed according to CMS.gov manual definitions. QALYs and cost per QALY were calculated using a 3% discount rate to account for residual decline to life expectancy (78.7 years). Costs per QALY were calculated for both 1 year and life expectancy, assuming no loss of benefit. A 10,000 trial Monte Carlo simulation with probabilistic sensitivity analysis (PSA) assessed our model parameters and costs. RESULTS:360 propensity matched patients (120 open, 120 MIS, 120 robotic) met inclusion criteria. Descriptive statistics for the cohort were: age 58.8 ± 13.5, 50% women, BMI 29.4 ± 6.3, operative time 294.4 ± 119.0, LOS 4.56 ± 3.31 days, EBL 515.9 ± 670.0 cc, and 2.3 ± 2.2 average levels fused. Rates of post-op complications were significantly higher in robotic cases versus open and MIS (43% vs. 21% and 22% for open and MIS, p<0.05). However, revision rates were comparable between all groups (3% open, 3% MIS, 5% robotic, p>0.05). After factoring in complications, revisions, and purchasing and operating fees, the costs of robotic cases was significantly higher than both open and MIS surgery ($60,047.01 vs. $42,538.98 open and $41,471.21 MIS). In a subanalysis of 42 patients with baseline (BL) and 1Y EQ5D data, the cost per QALY at 1Y for open, MIS, and robot-assisted cases was $296,624.48, $115,911.69, and $592,734.30. If utility gained was sustained to life expectancy, the cost per QALY was $14,905.75, $5,824.71, $29,785.64 for open, MIS, and robot-assisted cases. Results of the PSA were consistent with MIS surgery having the most incremental cost effectiveness when compared to open and robotic surgery. CONCLUSIONS:Numerous advances have been made in the field of spine surgery, however, there has been limited discussion of the effect these advances have on economic outcomes. When matched for levels fused, robot-assisted surgery patients had significantly higher rates of complications and 30% higher costs of surgery compared to minimally invasive and open spine surgery patients. While 1 year economic outcomes weren't optimal for robotic surgery cases, the projected costs per quality adjusted life years at life expectancy were well below established acceptable thresholds. The above findings may be reflective of an educational learning curve and emerging surgical technologies undergoing progressive refinement.

BACKGROUND:Adult sagittal spinal deformity (SSD) leads to the recruitment of compensatory mechanisms to maintain standing balance. After regional spinal compensation is exhausted, lower extremity compensation is recruited. Knee flexion, ankle flexion, and sacrofemoral angle increase to drive pelvic shift posterior and increase pelvic tilt. We aim to describe 2 summary angles termed ankle-pelvic angle (APA) and global lower extremity angle (GLA) that incorporate all aspects of lower extremity and pelvic compensation in a comprehensive measurement that can simplify radiographic analysis. METHODS:Full-body sagittal stereotactic radiographs were retrospectively collected and digitally analyzed. Spinal and lower extremity alignment were quantified with existing measures. Two angles-APA and GLA-were drawn as geometrically complementary angles to T1-pelvic angle (TPA) and global sagittal axis (GSA), respectively. Regression analysis was used to represent the predictive relationship between TPA and APA and between GSA and GLA. RESULTS:= .005). CONCLUSIONS:TPA and GSA are measures of global spinal alignment and APA and GLA, respectively, and are geometrically complementary angles that vary proportionately to SSD and balance the body. APA and GLA increase in SSD patients with lower extremity compensation and decrease with corrective surgery. LEVEL OF EVIDENCE/METHODS:4. CLINICAL RELEVANCE/CONCLUSIONS:APA and GLA offer a concise and simple method of communicating pelvic and lower extremity compensation.

Background/UNASSIGNED:Age-adjusted alignment targets in the context of distal junctional kyphosis (DJK) development have yet to be investigated. Our aim was to assess age-adjusted alignment targets, reciprocal changes, and role of lowest instrumented level orientation in DJK development in cervical deformity (CD) patients. Methods/UNASSIGNED:CD patients were evaluated based on lowest fused level: cervical (C7 or above), upper thoracic (UT: T1-T6), and lower thoracic (LT: T7-T12). Age-adjusted alignment targets were calculated using published formulas for sagittal vertical axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), pelvic tilt (PT), T1 pelvic angle (TPA), and LL-thoracic kyphosis (TK). Outcome measures were cervical and global alignment parameters: Cervical SVA (cSVA), cervical lordosis, C2 slope, C2-T3 angle, C2-T3 SVA, TS-CL, PI-LL, PT, and SVA. Subanalysis matched baseline PI to assess age-adjusted alignment between DJK and non-DJK. Results/UNASSIGNED:< 0.05). The distribution of over/under corrected patients and the offset between actual and ideal alignment for SVA, PT, TPA, PI-LL, and LL-TK were similar between DJK and non-DJK patients. DJK patients requiring reoperation had worse postoperative changes in all cervical parameters and trended toward larger offsets for global parameters. Conclusion/UNASSIGNED:CD patients with severe baseline malalignment went on to develop postoperative DJK. Age-adjusted alignment targets did not capture differences in these populations, suggesting the need for cervical-specific goals.

OBJECTIVE:The impact of global coronal malalignment (GCM; C7 plumb line-midsacral offset) on adult spinal deformity (ASD) treatment outcomes is unclear. Here, the authors' primary objective was to assess surgical outcomes and complications in patients with severe GCM, with a secondary aim of investigating potential surgical target coronal thresholds for optimal outcomes. METHODS:This is a retrospective analysis of a prospective multicenter database. Operative patients with severe GCM (≥ 1 SD above the mean) and a minimum 2-year follow-up were identified. Demographic, surgical, radiographic, health-related quality of life (HRQOL), and complications data were analyzed. RESULTS:Of 691 potentially eligible operative patients (mean GCM 4 ± 3 cm), 80 met the criteria for severe GCM ≥ 7 cm. Of these, 62 (78%; mean age 63.7 ± 10.7 years, 81% women) had a minimum 2-year follow-up (mean follow-up 3.3 ± 1.1 years). The mean ASD-Frailty Index was 3.9 ± 1.5 (frail), 50% had undergone prior fusion, and 81% had concurrent severe sagittal spinopelvic deformity with GCM and C7-S1 sagittal vertical axis (SVA) positively correlated (r = 0.313, p = 0.015). Surgical characteristics included posterior-only (58%) versus anterior-posterior (42%) approach, mean fusion of 13.2 ± 3.8 levels, iliac fixation (90%), 3-column osteotomy (36%), operative duration of 8.3 ± 3.0 hours, and estimated blood loss of 2.3 ± 1.7 L. Final alignment and HRQOL significantly improved (p < 0.01): GCM, 11 to 4 cm; maximum coronal Cobb angle, 43° to 20°; SVA, 13 to 4 cm; pelvic tilt, 29° to 23°; pelvic incidence-lumbar lordosis mismatch, 31° to 5°; Oswestry Disability Index, 51 to 37; physical component summary of SF-36 (PCS), 29 to 37; 22-Item Scoliosis Research Society Patient Questionnaire (SRS-22r) Total, 2.6 to 3.5; and numeric rating scale score for back and leg pain, 7 to 4 and 5 to 3, respectively. Residual GCM ≥ 3 cm was associated with worse SRS-22r Appearance (p = 0.04) and SRS-22r Satisfaction (p = 0.02). The minimal clinically important difference and/or substantial clinical benefit (MCID/SCB) was met in 43%-83% (highest for SRS-22r Appearance [MCID 83%] and PCS [SCB 53%]). The severity of baseline GCM (≥ 2 SD above the mean) significantly impacted postoperative SRS-22r Satisfaction and MCID/SCB improvement for PCS. No significant partial correlations were demonstrated between GCM or SVA correction and HRQOL improvement. There were 89 total complications (34 minor and 55 major), 45 (73%) patients with ≥ 1 complication (most commonly rod fracture [19%] and proximal junctional kyphosis [PJK; 18%]), and 34 reoperations in 22 (35%) patients (most commonly for rod fracture and PJK). CONCLUSIONS:Study results demonstrated that ASD surgery in patients with substantial GCM was associated with significant radiographic and HRQOL improvement despite high complication rates. MCID improvement was highest for SRS-22r Appearance/Self-Image. A residual GCM ≥ 3 cm was associated with a worse outcome, suggesting a potential coronal realignment target threshold to assist surgical planning.