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Han Jo Kim, Sohrab Virk, Jonathan Elysee, Peter Passias, Christopher Ames, Christopher I. Shaffrey, Gregory Mundis Jr., Themistocles Protopsaltis, Munish Gupta, Eric Klineberg, Justin S. Smith, Douglas Burton, Frank Schwab, Virginie Lafage, Renaud Lafage and the International Spine Study Group

OBJECTIVE

Cervical deformity (CD) is difficult to define due to the high variability in normal cervical alignment based on postural- and thoracolumbar-driven changes to cervical alignment. The purpose of this study was to identify whether patterns of sagittal deformity could be established based on neutral and dynamic alignment, as shown on radiographs.

METHODS

This study is a retrospective review of a prospective, multicenter database of CD patients who underwent surgery from 2013 to 2015. Their radiographs were reviewed by 12 individuals using a consensus-based method to identify severe sagittal CD. Radiographic parameters correlating with health-related quality of life were introduced in a two-step cluster analysis (a combination of hierarchical cluster and k-means cluster) to identify patterns of sagittal deformity. A comparison of lateral and lateral extension radiographs between clusters was performed using an ANOVA in a post hoc analysis.

RESULTS

Overall, 75 patients were identified as having severe CD due to sagittal malalignment, and they formed the basis of this study. Their mean age was 64 years, their body mass index was 29 kg/m2, and 66% were female. There were significant correlations between focal alignment/flexibility of maximum kyphosis, cervical lordosis, and thoracic slope minus cervical lordosis (TS-CL) flexibility (r = 0.27, 0.31, and −0.36, respectively). Cluster analysis revealed 3 distinct groups based on alignment and flexibility. Group 1 (a pattern involving a flat neck with lack of compensation) had a large TS-CL mismatch despite flexibility in cervical lordosis; group 2 (a pattern involving focal deformity) had focal kyphosis between 2 adjacent levels but no large regional cervical kyphosis under the setting of a low T1 slope (T1S); and group 3 (a pattern involving a cervicothoracic deformity) had a very large T1S with a compensatory hyperlordosis of the cervical spine.

CONCLUSIONS

Three distinct patterns of CD were identified in this cohort: flat neck, focal deformity, and cervicothoracic deformity. One key element to understanding the difference between these groups was the alignment seen on extension radiographs. This information is a first step in developing a classification system that can guide the surgical treatment for CD and the choice of fusion level.

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Nitin Agarwal, Federico Angriman, Ezequiel Goldschmidt, James Zhou, Adam S. Kanter, David O. Okonkwo, Peter G. Passias, Themistocles Protopsaltis, Virginie Lafage, Renaud Lafage, Frank Schwab, Shay Bess, Christopher Ames, Justin S. Smith, Christopher I. Shaffrey, Douglas Burton, D. Kojo Hamilton and the International Spine Study Group

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.

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Renaud Lafage, Ibrahim Obeid, Barthelemy Liabaud, Shay Bess, Douglas Burton, Justin S. Smith, Cyrus Jalai, Richard Hostin, Christopher I. Shaffrey, Christopher Ames, Han Jo Kim, Eric Klineberg, Frank Schwab, Virginie Lafage and the International Spine Study Group

OBJECTIVE

The surgical correction of adult spinal deformity (ASD) often involves modifying lumbar lordosis (LL) to restore ideal sagittal alignment. However, corrections that include large changes in LL increase the risk for development of proximal junctional kyphosis (PJK). Little is known about the impact of cranial versus caudal correction in the lumbar spine on the occurrence of PJK. The goal of this study was to investigate the impact of the location of the correction on acute PJK development.

METHODS

This study was a retrospective review of a prospective multicenter database. Surgically treated ASD patients with early follow-up evaluations (6 weeks) and fusions of the full lumbosacral spine were included. Radiographic parameters analyzed included the classic spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], PI−LL, and sagittal vertical axis [SVA]) and segmental correction. Using Glattes’ criteria, patients were stratified into PJK and noPJK groups and propensity matched by age and regional lumbar correction (ΔPI−LL). Radiographic parameters and segmental correction were compared between PJK and noPJK patients using independent t-tests.

RESULTS

After propensity matching, 312 of 483 patients were included in the analysis (mean age 64 years, 76% women, 40% with PJK). There were no significant differences between PJK and noPJK patients at baseline or postoperatively, or between changes in alignment, with the exception of thoracic kyphosis (TK) and ΔTK. PJK patients had a decrease in segmental lordosis at L4-L5-S1 (−0.6° vs 1.6°, p = 0.025), and larger increases in segmental correction at cranial levels L1-L2-L3 (9.9° vs 7.1°), T12-L1-L2 (7.3° vs 5.4°), and T11-T12-L1 (2.9° vs 0.7°) (all p < 0.05).

CONCLUSIONS

Although achievement of an optimal sagittal alignment is the goal of realignment surgery, dramatic lumbar corrections appear to increase the risk of PJK. This study was the first to demonstrate that patients who developed PJK underwent kyphotic changes in the L4–S1 segments while restoring LL at more cranial levels (T12–L3). These findings suggest that restoring lordosis at lower lumbar levels may result in a decreased risk of developing PJK.

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Blake N. Staub, Renaud Lafage, Han Jo Kim, Christopher I. Shaffrey, Gregory M. Mundis Jr., Richard Hostin, Douglas Burton, Lawrence Lenke, Munish C. Gupta, Christopher Ames, Eric Klineberg, Shay Bess, Frank Schwab, Virginie Lafage and the International Spine Study Group

OBJECTIVE

Numerous studies have attempted to delineate the normative value for T1S−CL (T1 slope minus cervical lordosis) as a marker for both cervical deformity and a goal for correction similar to how PI-LL (pelvic incidence–lumbar lordosis) mismatch informs decision making in thoracolumbar adult spinal deformity (ASD). The goal of this study was to define the relationship between T1 slope (T1S) and cervical lordosis (CL).

METHODS

This is a retrospective review of a prospective database. Surgical ASD cases were initially analyzed. Analysis across the sagittal parameters was performed. Linear regression analysis based on T1S was used to provide a clinically applicable equation to predict CL. Findings were validated using the postoperative alignment of the ASD patients. Further validation was then performed using a second, normative database. The range of normal alignment associated with horizontal gaze was derived from a multilinear regression on data from asymptomatic patients.

RESULTS

A total of 103 patients (mean age 54.7 years) were included. Analysis revealed a strong correlation between T1S and C0–7 lordosis (r = 0.886), C2–7 lordosis (r = 0.815), and C0–2 lordosis (r = 0.732). There was no significant correlation between T1S and T1S−CL. Linear regression analysis revealed that T1S−CL assumed a constant value of 16.5° (R2 = 0.664, standard error 2°). These findings were validated on the postoperative imaging (mean absolute error [MAE] 5.9°). The equation was then applied to the normative database (MAE 6.7° controlling for McGregor slope [MGS] between −5° and 15°). A multilinear regression between C2–7, T1S, and MGS demonstrated a range of T1S−CL between 14.5° and 26.5° was necessary to maintain horizontal gaze.

CONCLUSIONS

Normative CL can be predicted via the formula CL = T1S − 16.5° ± 2°. This implies a threshold of deformity and aids in providing a goal for surgical correction. Just as pelvic incidence (PI) can be used to determine the ideal LL, T1S can be used to predict ideal CL. This formula also implies that a kyphotic cervical alignment is to be expected for individuals with a T1S < 16.5°.

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Alexander A. Theologis, Gregory M. Mundis Jr., Stacie Nguyen, David O. Okonkwo, Praveen V. Mummaneni, Justin S. Smith, Christopher I. Shaffrey, Richard Fessler, Shay Bess, Frank Schwab, Bassel G. Diebo, Douglas Burton, Robert Hart, Vedat Deviren and Christopher Ames

OBJECTIVE

The aim of this study was to evaluate the utility of supplementing long thoracolumbar posterior instrumented fusion (posterior spinal fusion, PSF) with lateral interbody fusion (LIF) of the lumbar/thoracolumbar coronal curve apex in adult spinal deformity (ASD).

METHODS

Two multicenter databases were evaluated. Adults who had undergone multilevel LIF of the coronal curve apex in addition to PSF with L5–S1 interbody fusion (LS+Apex group) were matched by number of posterior levels fused with patients who had undergone PSF with L5–S1 interbody fusion without LIF (LS-Only group). All patients had at least 2 years of follow-up. Percutaneous PSF and 3-column osteotomy (3CO) were excluded. Demographics, perioperative details, radiographic spinal deformity measurements, and HRQoL data were analyzed.

RESULTS

Thirty-two patients were matched (LS+Apex: 16; LS: 16) (6 men, 26 women; mean age 63 ± 10 years). Overall, the average values for measures of deformity were as follows: Cobb angle > 40°, sagittal vertical axis (SVA) > 6 cm, pelvic tilt (PT) > 25°, and mismatch between pelvic incidence (PI) and lumbar lordosis (LL) > 15°. There were no significant intergroup differences in preoperative radiographic parameters, although patients in the LS+Apex group had greater Cobb angles and less LL. Patients in the LS+Apex group had significantly more anterior levels fused (4.6 vs 1), longer operative times (859 vs 379 minutes), and longer length of stay (12 vs 7.5 days) (all p < 0.01). For patients in the LS+Apex group, Cobb angle, pelvic tilt (PT), lumbar lordosis (LL), PI-LL (lumbopelvic mismatch), Oswestry Disability Index (ODI) scores, and visual analog scale (VAS) scores for back and leg pain improved significantly (p < 0.05). For patients in the LS-Only group, there were significant improvements in Cobb angle, ODI score, and VAS scores for back and leg pain. The LS+Apex group had better correction of Cobb angles (56% vs 33%, p = 0.02), SVA (43% vs 5%, p = 0.46), LL (62% vs 13%, p = 0.35), and PI-LL (68% vs 33%, p = 0.32). Despite more LS+Apex patients having major complications (56% vs 13%; p = 0.02) and postoperative leg weakness (31% vs 6%, p = 0.07), there were no intergroup differences in 2-year outcomes.

CONCLUSIONS

Long open posterior instrumented fusion with or without multilevel LIF is used to treat a variety of coronal and sagittal adult thoracolumbar deformities. The addition of multilevel LIF to open PSF with L5–S1 interbody support in this small cohort was often used in more severe coronal and/or lumbopelvic sagittal deformities and offered better correction of major Cobb angles, lumbopelvic parameters, and SVA than posterior-only operations. As these advantages came at the expense of more major complications, more leg weakness, greater blood loss, and longer operative times and hospital stays without an improvement in 2-year outcomes, future investigations should aim to more clearly define deformities that warrant the addition of multilevel LIF to open PSF and L5–S1 interbody fusion.

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Kristina Bianco, Robert Norton, Frank Schwab, Justin S. Smith, Eric Klineberg, Ibrahim Obeid, Gregory Mundis Jr., Christopher I. Shaffrey, Khaled Kebaish, Richard Hostin, Robert Hart, Munish C. Gupta, Douglas Burton, Christopher Ames, Oheneba Boachie-Adjei, Themistocles S. Protopsaltis and Virginie Lafage

Object

Three-column resection osteotomies (3COs) are commonly performed for sagittal deformity but have high rates of reported complications. Authors of this study aimed to examine the incidence of and intercenter variability in major intraoperative complications (IOCs), major postoperative complications (POCs) up to 6 weeks postsurgery, and overall complications (that is, both IOCs and POCs). They also aimed to investigate the incidence of and intercenter variability in blood loss during 3CO procedures.

Methods

The incidence of IOCs, POCs, and overall complications associated with 3COs were retrospectively determined for the study population and for each of 8 participating surgical centers. The incidence of major blood loss (MBL) over 4 L and the percentage of total blood volume lost were also determined for the study population and each surgical center. Complication rates and blood loss were compared between patients with one and those with two osteotomies, as well as between patients with one thoracic osteotomy (ThO) and those with one lumbar or sacral osteotomy (LSO). Risk factors for developing complications were determined.

Results

Retrospective review of prospectively acquired data for 423 consecutive patients who had undergone 3CO at 8 surgical centers was performed. The incidence of major IOCs, POCs, and overall complications was 7%, 39%, and 42%, respectively, for the study population overall. The most common IOC was spinal cord deficit (2.6%) and the most common POC was unplanned return to the operating room (19.4%). Patients with two osteotomies had more POCs (56% vs 38%, p = 0.04) than the patients with one osteotomy. Those with ThO had more IOCs (16% vs 6%, p = 0.03), POCs (58% vs 34%, p < 0.01), and overall complications (67% vs 37%, p < 0.01) than the patients with LSO. There was significant variation in the incidence of IOCs, POCs, and overall complications among the 8 sites (p < 0.01). The incidence of MBL was 24% for the study population, which varied significantly between sites (p < 0.01). Patients with MBL had a higher risk of IOCs, POCs, and overall complications (OR 2.15, 1.76, and 2.01, respectively). The average percentage of total blood volume lost was 55% for the study population, which also varied among sites (p < 0.01).

Conclusions

Given the complexity of 3COs for spinal deformity, it is important for spine surgeons to understand the risk factors and complication rates associated with these procedures. In this study, the overall incidence of major complications following 3CO procedures was 42%. Risks for developing complications included an older age (> 60 years), two osteotomies, ThO, and MBL.