Are Higher Global Alignment and Proportion Scores Associated With Increased Risks of Mechanical Complications After Adult Spinal Deformity Surgery? An External Validation.

dc.contributor.author

Kwan, Kenny Yat Hong

dc.contributor.author

Lenke, Lawrence G

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Shaffrey, Christopher I

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Carreon, Leah Y

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Dahl, Benny T

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Fehlings, Michael G

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Ames, Christopher P

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Boachie-Adjei, Oheneba

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Dekutoski, Mark B

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Kebaish, Khaled M

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Lewis, Stephen J

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Matsuyama, Yukihiro

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Mehdian, Hossein

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Qiu, Yong

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Schwab, Frank J

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Cheung, Kenneth Man Chee

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AO Spine Knowledge Forum Deformity

dc.date.accessioned

2023-06-19T18:48:51Z

dc.date.available

2023-06-19T18:48:51Z

dc.date.issued

2021-02

dc.date.updated

2023-06-19T18:48:51Z

dc.description.abstract

Background

The Global Alignment and Proportion (GAP) score, based on pelvic incidence-based proportional parameters, was recently developed to predict mechanical complications after surgery for spinal deformities in adults. However, this score has not been validated in an independent external dataset.

Questions/purposes

After adult spinal deformity surgery, is a higher GAP score associated with (1) an increased risk of mechanical complications, defined as rod fractures, implant-related complications, proximal or distal junctional kyphosis or failure; (2) a higher likelihood of undergoing revision surgery to treat a mechanical complication; and (3) is a lower (more proportioned) GAP score category associated with better validated outcomes scores using the Oswestry Disability Index (ODI), Scoliosis Research Society-22 (SRS-22) and the Short Form-36 questionnaires?

Methods

A total of 272 patients who had undergone corrective surgeries for complex spinal deformities were enrolled in the Scoli-RISK-1 prospective trial. Patients were included in this secondary analysis if they fulfilled the original inclusion criteria by Yilgor et al. From the original 272 patients, 14% (39) did not satisfy the radiographic inclusion criteria, the GAP score could not be calculated in 14% (37), and 24% (64) did not have radiographic assessment at postoperative 2 years, leaving 59% (159) for analysis in this review of data from the original trial. A total of 159 patients were included in this study,with a mean age of 58 ± 14 years at the time of surgery. Most patients were female (72%, 115 of 159), the mean number of levels involved in surgery was 12 ± 4, and three-column osteotomy was performed in 76% (120 of 159) of patients. The GAP score was calculated using parameters from early postoperative radiographs (between 3 and 12 weeks) including pelvic incidence, sacral slope, lumbar lordosis, lower arc lordosis and global tilt, which were independently obtained from a computer software based on centralized patient radiographs. The GAP score was categorized as proportional (scores of 0 to 2), moderately disproportional (scores of 3 to 6), or severely disproportional (scores higher than 7 to 13). Receiver operating characteristic area under curve (AUC) was used to assess associations between GAP score and risk of mechanical complications and risk of revision surgery. An AUC of 0.5 to 0.7 was classified as "no or low associative power", 0.7 to 0.9 as "moderate" and greater than 0.9 as "high". We analyzed differences in validated outcome scores between the GAP categories using Wilcoxon rank sum test.

Results

At a minimum of 2 years' follow-up, a higher GAP score was not associated with increased risks of mechanical complications (AUC = 0.60 [95% CI 0.50 to 0.70]). A higher GAP score was not associated with a higher likelihood of undergoing a revision surgery to treat a mechanical complication (AUC = 0.66 [95% 0.53 to 0.78]). However, a moderately disproportioned GAP score category was associated with better SF-36 physical component summary score (36 ± 10 versus 40 ± 11; p = 0.047), better SF-36 mental component summary score (46 ± 13 versus 51 ± 12; p = 0.01), better SRS-22 total score (3.4 ± 0.8 versus 3.7 ± 0.7, p = 0.02) and better ODI score (35 ± 21 versus 25 ± 20; p = 0.003) than severely disproportioned GAP score category.

Conclusion

Based on the findings of this external validation study, we found that alignment targets based on the GAP score alone were not associated with increased risks of mechanical complications and mechanical revisions in patients with complex adult spinal disorders. Parameters not included in the original GAP score needed to be considered to reduce the likelihood of mechanical complications.

Level of evidence

Level III, diagnostic study.
dc.identifier

00003086-202102000-00019

dc.identifier.issn

0009-921X

dc.identifier.issn

1528-1132

dc.identifier.uri

https://hdl.handle.net/10161/28117

dc.language

eng

dc.publisher

Ovid Technologies (Wolters Kluwer Health)

dc.relation.ispartof

Clinical orthopaedics and related research

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10.1097/corr.0000000000001521

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AO Spine Knowledge Forum Deformity

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Humans

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Spinal Curvatures

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Postoperative Complications

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Disability Evaluation

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Reoperation

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Risk

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Retrospective Studies

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Predictive Value of Tests

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Adolescent

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Adult

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Aged

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Aged, 80 and over

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Middle Aged

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Female

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Male

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Surveys and Questionnaires

dc.title

Are Higher Global Alignment and Proportion Scores Associated With Increased Risks of Mechanical Complications After Adult Spinal Deformity Surgery? An External Validation.

dc.type

Journal article

duke.contributor.orcid

Shaffrey, Christopher I|0000-0001-9760-8386

pubs.begin-page

312

pubs.end-page

320

pubs.issue

2

pubs.organisational-group

Duke

pubs.organisational-group

School of Medicine

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Clinical Science Departments

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Orthopaedic Surgery

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Neurosurgery

pubs.publication-status

Published

pubs.volume

479

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