Ability of the Global Alignment and Proportion Score to Predict Mechanical Failure Following Adult Spinal Deformity Surgery—Validation in 149 Patients With Two-Year Follow-up

Bari, Tanvir Johanning; Ohrt-Nissen, Søren; Hansen, Lars Valentin; Dahl, Benny; Gehrchen, Martin

doi:10.1016/j.jspd.2018.08.002

Cited by 61 publications

(45 citation statements)

References 31 publications

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“…Bari et al reports no significant correlation between postoperative GAP scores and mechanical failure in their cohort of 149 patients with minimum 2-year follow-up, which questions the validity of the GAP score even with the presence of all 4 radiographic parameters. 16 Similarly, Baum et al 17 recently reported that the predicted rate of mechanical complications from the GAP score overestimated the observed rate in patients with disproportioned alignment. The current literature has mixed results on the validity of the GAP score and a further simplification of this score to use as an intraoperative tool may not be feasible.…”

Section: Discussionmentioning

confidence: 99%

Partial Intraoperative Global Alignment and Proportion Scores Do Not Reliably Predict Postoperative Mechanical Failure in Adult Spinal Deformity Surgery

Hong

Coury

et al. 2020

Global Spine Journal

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Study Design: Retrospective radiographic review. Objectives: The Global Alignment and Proportion (GAP) score allows sagittal plane analysis for deformity patients and may be predictive of mechanical complications. This study aims to assess the effectiveness of predicting mechanical failure based on partial intraoperative GAP (iGAP) scores. Methods: A retrospective radiographic review was performed on 48 deformity patients between July 2015 to January 2017 with a 2-year follow-up. Using the same methodology as the original GAP study, the partial iGAP score was calculated with the sum of the scores for age, relative lumbar lordosis (RLL), and lordosis distribution index (LDI). Therefore, the iGAP score (0-7) was grouped into proportional (0-2), mildly disproportionate (3-5), and severely disproportionate (6-7). Logistic regression was performed to assess the ability of the partial iGAP score to predict postoperative mechanical failure. Results: The mean iGAP for patients with a mechanical failure was 3.54, whereas the iGAP for those without a mechanical failure was 3.46 ( P = .90). The overall mechanical failure rate was 27.1%. The mechanical failures included 8 proximal junctional kyphosis, 7 rod fractures, and 1 rod slippage from the distal end of the construct. Logistic regression analysis revealed that the partial iGAP score was not able to predict postoperative mechanical failure (χ2 = 1.4; P = .49). Conclusion: The iGAP scores for RLL or LDI did not show any significant correlation to postoperative mechanical failure. Ultimately, the proposed partial iGAP score did not predict postoperative mechanical failure and thus, cannot be used as an intraoperative alignment assessment to avoid postoperative mechanical complications.

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Section: Discussionmentioning

confidence: 99%

Partial Intraoperative Global Alignment and Proportion Scores Do Not Reliably Predict Postoperative Mechanical Failure in Adult Spinal Deformity Surgery

Hong

Coury

et al. 2020

Global Spine Journal

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“…Jacobs et al 6 performed a two-center, retrospective cohort study of 39 patients and concluded that both the GAP score and the Schwab-SRS classification were capable of predicting radiographic evidence of mechanical failure, yet the GAP score performed better with higher correlation. 3 Another single-center study performed by Bari and colleagues 7 attempted to validate the GAP score with their retrospective cohort of 149 consecutive patients who underwent deformity correction. With an overall mechanical complication rate of 51% and reoperation rate of 35%, the authors reported an AUC of 0.50 and no linear association between GAP score and occurrence of mechanical failure (p = 0.28) or revision surgery (p = 0.58).…”

Section: Discussionmentioning

confidence: 99%

“…Whereas some groups have shown good correlation between the GAP score and predicting clinical and radiographic outcomes, 5,6 others have reported weak predictive value. 7 The current objective was to examine the ability of the GAP score to predict mechanical complications after ASD surgery at a high-volume single center for spinal deformity surgery. We hypothesized that the GAP score would accurately predict the risk of mechanical complications after ASD surgery at our center.…”

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confidence: 99%

Does the Global Alignment and Proportion score overestimate mechanical complications after adult spinal deformity correction?

Baum

Cerpa

et al. 2021

Journal of Neurosurgery: Spine

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OBJECTIVEThe goal of this study was to validate the Global Alignment and Proportion (GAP) score in a cohort of patients undergoing adult spinal deformity (ASD) surgery. The GAP score is a novel measure that uses sagittal parameters relative to each patient’s lumbosacral anatomy to predict mechanical complications after ASD surgery. External validation is required.METHODSAdult ASD patients undergoing > 4 levels of posterior fusion with a minimum 2-year follow-up were included. Six-week postoperative standing radiographs were used to calculate the GAP score, classified into a spinopelvic state as proportioned (P), moderately disproportioned (MD), or severely disproportioned (SD). A chi-square analysis, receiver operating characteristic curve, and Cochran-Armitage analysis were performed to assess the relationship between the GAP score and mechanical complications.RESULTSSixty-seven patients with a mean age of 52.5 years (range 18–75 years) and a mean follow-up of 2.04 years were included. Patients with < 2 years of follow-up were included only if they had an early mechanical complication. Twenty of 67 patients (29.8%) had a mechanical complication. The spinopelvic state breakdown was as follows: P group, 21/67 (31.3%); MD group, 23/67 (34.3%); and SD group, 23/67 (34.3%). Mechanical complication rates were not significantly different among all groups: P group, 19.0%; MD group, 30.3%; and SD group, 39.1% (χ2 = 1.70, p = 0.19). The rates of mechanical complications between the MD and SD groups (30.4% and 39.1%) were less than those observed in the original GAP study (MD group 36.4%–57.1% and SD group 72.7%–100%). Within the P group, the rates in this study were higher than in the original study (19.0% vs 4.0%, respectively).CONCLUSIONSThe authors found no statistically significant difference in the rate of mechanical complications between the P, MD, and SD groups. The current validation study revealed poor generalizability toward the authors’ patient population.

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“…Kwan et al 4 have recently reported that a higher GAP score does not predict mechanical complications after ASD surgery using 272 patients from the Scoli-RISK-1 prospective trial data. As mentioned above, Bari et al 2 also could not find an association with the GAP score and mechanical complications. Given that large studies could not find a direct correlation with the GAP score and mechanical complications, the study performed by the current authors sheds new light and insight onto the GAP score.…”

mentioning

confidence: 85%

Commentary on “Modified Global Alignment and Proportion Scoring With Body Mass Index and Bone Mineral Density Analysis in Global Alignment and Proportion Score of Each 3 Categories for Predicting Mechanical Complications After Adult Spinal Deformity Surgery”

Chou

2021

Neurospine

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The authors have performed a retrospective review of 203 patients who underwent adult spinal deformity (ASD) surgery with minimum 2-year follow-up. 1 The authors have analyzed the global alignment and proportion (GAP) score, incorporating bone mineral density (BMD) and body mass index (BMI). The authors found that when incorporating BMI and BMI into the GAP score (GAPB), the GAPB score correlates with mechanical failure in patients when they are moderately or severe disproportioned in their alignment.I commend the authors for their work in incorporating BMI and BMD into the evaluation of mechanical failures in ASD surgery. This represents important work because Bari et al. 2 had reported that the GAP score alone-without the incorporation of BMI and BMDhas been unable to predict mechanical failure in ASD patients undergoing 4 or more levels of fusion. However, the original GAP score alone does not incorporate the BMI and BMD. Many mechanical failures can be related to poor bone quality because of the implant-bone junction interface failure. In our practice, all patient's bone densities are check prior to any fusion surgery, and by incorporating bone density into decision making, we have anecdotally seen fewer screw pull-out failures. Thus, it makes sense that the current authors' findings of incorporating BMD in the form of the GAPB score create a more accurate predictor of mechanical failure. In addition, the incorporation of BMI as a predictor makes sense. In patients with high BMI, the failure of mainly posterior-based constructs in the face of significant anterior trunk weight can potentially be predicted using the GAPB score instead of the GAP score. By incorporating BMI and BMD into the GAP score, the current authors have shown that incorporation of these 2 elements has made the GAP score more accurate by converting it into the GAPB score.The original GAP score takes into account age, pelvic incidence, sacral slope (SS), L4-S1

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Ability of the Global Alignment and Proportion Score to Predict Mechanical Failure Following Adult Spinal Deformity Surgery—Validation in 149 Patients With Two-Year Follow-up

Cited by 61 publications

References 31 publications

Partial Intraoperative Global Alignment and Proportion Scores Do Not Reliably Predict Postoperative Mechanical Failure in Adult Spinal Deformity Surgery

Partial Intraoperative Global Alignment and Proportion Scores Do Not Reliably Predict Postoperative Mechanical Failure in Adult Spinal Deformity Surgery

Does the Global Alignment and Proportion score overestimate mechanical complications after adult spinal deformity correction?

Commentary on “Modified Global Alignment and Proportion Scoring With Body Mass Index and Bone Mineral Density Analysis in Global Alignment and Proportion Score of Each 3 Categories for Predicting Mechanical Complications After Adult Spinal Deformity Surgery”

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