Faculty Bibliography

Total uncinate process resection or uncinectomy is often required in the setting of severe foraminal stenosis or cervical kyphosis correction. The proximity of the uncus to the vertebral artery, nerve root, and spinal cord makes this a challenging undertaking. Use of a high-speed burr or ultrasonic bone dissector can be associated with direct injury to the vertebral artery and thermal injury to the surrounding structures. The use of an osteotome is a safe and efficient method of uncinectomy. Here the authors describe their technique, which is illustrated with an intraoperative video.

OBJECTIVE:Obesity, a condition that is increasing in prevalence in the United States, has previously been associated with poorer outcomes following deformity surgery, including higher rates of perioperative complications such as deep and superficial infections. To date, however, no study has examined the relationship between preoperative BMI and outcomes of deformity surgery as measured by spine parameters such as the sagittal vertical axis (SVA), as well as health-related quality of life (HRQoL) measures such as the Oswestry Disability Index (ODI) and Scoliosis Research Society-22 patient questionnaire (SRS-22). To this end, the authors sought to clarify the relationship between BMI and postoperative change in SVA as well as HRQoL outcomes. METHODS:The authors performed a retrospective review of a prospectively managed multicenter adult spinal deformity database collected and maintained by the International Spine Study Group (ISSG) between 2009 and 2014. The primary independent variable considered was preoperative BMI. The primary outcome was the change in SVA at 1 year after deformity surgery. Postoperative ODI and SRS-22 outcome measures were evaluated as secondary outcomes. Generalized linear models were used to model the primary and secondary outcomes at 1 year as a function of BMI at baseline, while adjusting for potential measured confounders. RESULTS:Increasing BMI (compared to BMI < 18) was not associated with change of SVA at 1 year postsurgery. However, BMIs in the obese range of 30 to 34.9 kg/m2, compared to BMI < 18 at baseline, were associated with poorer outcomes as measured by the SRS-22 score (estimated change -0.47, 95% CI -0.93 to -0.01, p = 0.04). While BMIs > 30 appeared to be associated with poorer outcomes as determined by the ODI, this correlation did not reach statistical significance. CONCLUSIONS:Baseline BMI did not affect the achievable SVA at 1 year postsurgery. Further studies should evaluate whether even in the absence of a change in SVA, baseline BMIs in the obese range are associated with worsened HRQoL outcomes after spinal surgery.

Study Design/UNASSIGNED:Prospective cohort study. Objectives/UNASSIGNED:Most studies of dysphagia in the cervical spine have focused on a degenerative patient population; the rate of dysphagia following surgery for cervical deformity (CD) is unknown. This study aims to investigate if surgery for cervical deformity results in postoperative dysphagia. Methods/UNASSIGNED:tests, and bivariate Pearson correlations were performed. Results/UNASSIGNED:= .53). Surgical variables, including estimated blood loss (EBL), anterior or posterior fusion levels, steroid use, preoperative traction, staged surgery, surgical approach, anterior corpectomy, posterior osteotomy, and UIV (upper instrumented vertebrae) location, showed no impact on postoperative SWAL-QoL. Correction of cervical kyphosis was not correlated to 3-month SWAL-QoL scores or the change in SWAL-QoL scores. Conclusions/UNASSIGNED:While patients undergoing surgery for cervical deformity had swallowing dysfunction at baseline, we did not observe a significant decline in SWAL-QoL scores at 3 months. Patients with prior cervical surgery and higher BMI had a lower baseline SWAL-QoL. There were no surgical or radiographic variables correlated to a change in SWAL-QOL score.

MINI: The ability of PROMIS to capture disability from cervical sagittal malalignment is unknown. Correlations between PROMIS domains and legacy outcome metrics with cervical sagittal alignment parameters were analyzed. PROMIS domains correlated strongly with legacy outcomes and PROMIS Pain Intensity correlated with worsening sagittal alignment in patients with cervical sagittal deformity.

BACKGROUND:Patients undergoing multilevel spine surgery are at risk for delayed extubation. OBJECTIVE:To evaluate the impact of type and volume of intraoperative fluids administered during multilevel thoracic and/or lumbar spine surgery on postoperative extubation status. METHODS:Retrospective evaluation of medical records of patients ≥ 18 yr undergoing ≥ 4 levels of thoracic and/or lumbar spine fusions was performed. Patients were organized according to postoperative extubation status: immediate (IMEX; in OR/PACU) or delayed (DEX; outside OR/PACU). Propensity score matched (PSM) analysis was performed to compare IMEX and DEX groups. Volume, proportion, and ratios of intraoperative fluids administered were evaluated for the associated impact on extubation status. RESULTS:A total of 246 patients (198 IMEX, 48 DEX) were included. PSM analysis demonstrated that increased administration of non-cell saver blood products (NCSB) and increased ratio of crystalloid: colloids infused were independently associated with delayed extubation. With increasing EBL, IMEX had a proportionate reduction in crystalloid infusion (R = -0.5, P < .001), while the proportion of crystalloids infused remained relatively unchanged for DEX (R = -0.27; P = .06). Twenty-six percent of patients receiving crystalloid: colloid ratio > 3:1 had DEX compared to none of those receiving crystalloid: colloid ratio ≤ 3:1 (P = .009). DEX had greater cardiac and pulmonary complications, surgical site infections and prolonged intensive care unit and hospital stay (P < .05). CONCLUSION/CONCLUSIONS:PSM analysis of patients undergoing multilevel thoracic and/or lumbar spine fusion demonstrated that increased administration of crystalloid to colloid ratio is independently associated with delayed extubation. With increasing EBL, a proportionate reduction of crystalloids facilitates early extubation.

BACKGROUND:Limited data are available to objectively define what constitutes a "good" versus a "bad" recovery for operative cervical deformity (CD) patients. Furthermore, the recovery patterns of primary versus revision procedures for CD is poorly understood. OBJECTIVE:To define and compare the recovery profiles of CD patients undergoing primary or revision procedures, utilizing a novel area-under-the-curve normalization methodology. METHODS:CD patients undergoing primary or revision surgery with baseline to 1-yr health-related quality of life (HRQL) scores were included. Clinical symptoms and HRQL were compared among groups (primary/revision). Normalized HRQL scores at baseline and follow-up intervals (3M, 6M, 1Y) were generated. Normalized HRQLs were plotted and area under the curve was calculated, generating one number describing overall recovery (Integrated Health State). Subanalysis identified recovery patterns through 2-yr follow-up. RESULTS:Eighty-three patients were included (45 primary, 38 revision). Age (61.3 vs 61.9), gender (F: 66.7% vs 63.2%), body mass index (27.7 vs 29.3), Charlson Comorbidity Index, frailty, and osteoporosis (20% vs 13.2%) were similar between groups (P > .05). Primary patients were more preoperatively neurologically symptomatic (55.6% vs 31.6%), less sagittally malaligned (cervical sagittal vertical axis [cSVA]: 32.6 vs 46.6; T1 slope: 28.8 vs 36.8), underwent more anterior-only approaches (28.9% vs 7.9%), and less posterior-only approaches (37.8% vs 60.5%), all P < .05. Combined approaches, decompressions, osteotomies, and construct length were similar between groups (P > .05). Revisions had longer op-times (438.0 vs 734.4 min, P = .008). Following surgery, complication rate was similar between groups (66.6% vs 65.8%, P = .569). Revision patients remained more malaligned (cSVA, TS-CL; P < .05) than primary patients until 1-yr follow-up (P > .05). Normalized HRQLs determined primary patients to exhibit less neck pain (numeric rating scale [NRS]) and myelopathy (modified Japanese Orthopaedic Association) symptoms through 1-yr follow-up compared to revision patients (P < .05). These differences subsided when following patients through 2 yr (P > .05). Despite similar 2-yr HRQL outcomes, revision patients exhibited worse neck pain (NRS) Integrated Health State recovery (P < .05). CONCLUSION/CONCLUSIONS:Despite both primary and revision patients exhibiting similar HRQL outcomes at final follow-up, revision patients were in a greater state of postoperative neck pain for a greater amount of time.

S1 pedicle subtraction osteotomies (PSOs) are indicated in patients with fixed, high-grade L5-S1 spondylolisthesis or kyphosis secondary to a sacral fracture, who present with severe sagittal imbalance. Unlike lumbar PSOs, sacral osteotomies are rare, and there is a paucity of literature outlining techniques. Here, we present the indications, planning, technique, and outcomes for S1 PSOs.

STUDY DESIGN/METHODS:Retrospective cohort study. OBJECTIVE:The goals of this study were to (1) evaluate pre-operative bone quality assessment and intervention practice over time and (2) review the current evidence for bone evaluation in spine fusion surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND:Deformity spine surgery has demonstrated improved quality of life in patients however its cost has made it controversial. If pre-operative bone quality can be optimized then potentially these treatments could be more durable however, at present, no clinical practice guidelines have been published by professional spine surgical organizations. METHODS:A retrospective cohort review was performed on patients who underwent a minimum five-level primary or revision fusion. Pre-operative bone quality metrics were evaluated over time from 2012 - 2017 to find potential trends. Sub-group analysis was conducted based on age, gender, pre-operative diagnosis, and spine fusion region. RESULTS:Patient characteristics including pre-operative rates of pseudarthrosis and junctional failure did not change. An increasing trend of physician bone health documentation was noted (p = 0.045) but changes in other metrics were not significant. A gender bias favored females who had higher rates of pre-operative DXA studies (p = 0.001), Vitamin D 25-OH serum labs (p = 0.005), Vitamin D supplementation (p = 0.022), calcium supplementation (p < 0.001), antiresorptive therapy (p = 0.016), and surgeon clinical documentation of bone health (p = 0.008) compared to men. CONCLUSION/CONCLUSIONS:Our spine surgeons have increased documentation of bone health discussions but this has not affected bone quality interventions. A discrepancy exists favoring females over males in nearly all pre-operative bone quality assessment metrics. Pre-operative vitamin D level and BMD assessment should be considered in patients undergoing long fusion constructs however the data for bone anabolic and resorptive agents has less support. Clinical practice guidelines on pre-operative bone quality assessment spine patients should be defined. LEVEL OF EVIDENCE/METHODS:4.

Introduction/UNASSIGNED:Correction of cervical deformity (CD) often involves different types of osteotomies to address sagittal malalignment. This study assessed the relationship between osteotomy grade and vertebral level on alignment and clinical outcomes. Methods/UNASSIGNED:Retrospective review of a multi-center prospectively collected CD database. CD was defined as at least one of the following: C2-C7 Cobb >10°, cervical lordosis (CL) >10°, C2-C7 sagittal vertical axis (cSVA) >4 cm, and chin-brow vertical angle > 25°. Patients were evaluated for level and type of cervical osteotomy. Results/UNASSIGNED:= 0.058) due to lever arm effect. Conclusions/UNASSIGNED:CD patients undergoing osteotomies in the cervical and upper thoracic spine experienced improvement in TS--CL and C2 slope. In the upper thoracic spine, multiple minor osteotomies achieved similar alignment changes to major osteotomies at a single level, while a major osteotomy focused at T2 had the greatest overall impact in cervicothoracic and global alignment in CD patients.

OBJECTIVEProximal junctional kyphosis (PJK) is a structural complication of spinal fusion in 5%-61% of patients treated for adult spinal deformity. In nearly one-third of these cases, PJK is progressive and requires costly surgical revision. Previous studies have suggested that patient body habitus may predict risk for PJK. Here, the authors sought to investigate abdominal girth and paraspinal muscle size as risk factors for PJK.METHODSAll patients undergoing thoracolumbosacral fusion greater than 2 levels at a single institution over a 5-year period with ≥ 6 months of radiographic follow-up were considered for inclusion. PJK was defined as kyphosis ≥ 20° between the upper instrumented vertebra (UIV) and two supra-adjacent vertebrae. Operative and radiographic parameters were recorded, including pre- and postoperative sagittal vertical axis (SVA), sacral slope (SS), lumbar lordosis (LL), pelvic tilt, pelvic incidence (PI), and absolute value of the pelvic incidence-lumbar lordosis mismatch (|PI-LL|), as well as changes in LL, |PI-LL|, and SVA. The authors also considered relative abdominal girth and the size of the paraspinal muscles at the UIV.RESULTSOne hundred sixty-nine patients met inclusion criteria. On univariate analysis, PJK was associated with a larger preoperative SVA (p < 0.001) and |PI-LL| (p = 0.01), and smaller SS (p = 0.004) and LL (p = 0.001). PJK was also associated with more positive postoperative SVA (p = 0.01), ΔSVA (p = 0.01), Δ|PI-LL| (p < 0.001), and ΔLL (p < 0.001); longer construct length (p = 0.005); larger abdominal girth-to-muscle ratio (p = 0.007); and smaller paraspinal muscles at the UIV (p < 0.001). Higher postoperative SVA (OR 1.1 per cm), smaller paraspinal muscles at the UIV (OR 2.11), and more aggressive reduction in |PI-LL| (OR 1.03) were independent predictors of radiographic PJK on multivariate logistic regression.CONCLUSIONSA more positive postoperative global sagittal alignment and smaller paraspinal musculature at the UIV most strongly predicted PJK following thoracolumbosacral fusion.