P94. Global alignment and proportion (GAP) score with modified RLL parameter: GAP-L score

Abstract

BACKGROUND CONTEXT The Global Alignment and Proportion (GAP) score was thus developed to predict such mechanical complications following spinal correction surgery. The GAP score is a pelvic-incidence based method of analyzing the sagittal plane. GAP scores of 0∼2 are classified as proportioned, 3∼6 as moderately proportioned, and >=7 as severely disproportioned. GAP parameters include relative pelvic version, relative lumbar lordosis (RLL), lordosis distribution index, age factor of 60, and relative spinopelvic alignment. RLL categories include: 11° receiving a score of 3. PURPOSE The aim of the study was to adjust the RLL parameter in calculation of GAP scores among US adult volunteers with no prior spinal pathology, in order to compensate for high GAP scores in otherwise healthy individuals. STUDY DESIGN/SETTING Retrospective review of prospectively collected data. PATIENT SAMPLE A total of 87 healthy volunteers were included in the study. Mean age was 54.9±15.1 (20-84) years. Exclusion criteria included any major spinal pathology or surgery, terminal illness, morbid obesity, or any significant comorbid condition. OUTCOME MEASURES GAP scores with RSA parameter removed and GAP-L scores. METHODS Preliminary GAP scores with the RLL parameter removed were assessed in 87 healthy volunteers that met inclusion criteria. The preliminary GAP scores were grouped based on the original GAP system's RLL parameters, and these scores were analyzed to search for discrepancies from the baseline trend. Original GAP scores were calculated for the same 87 healthy volunteers. GAP-L scores were calculated with the same parameters as the GAP score, with the exception of the RLL factor. In GAP-L scores, the number of points were subtracted from each RLL group in the same amount that showed discrepancies in the Preliminary GAP score trend. The percentages of Proportioned, Moderately Disproportioned, and Severely Disproportioned volunteers were then compared between the two scoring systems. RESULTS Preliminary GAP scores shows a 3-point discrepancy point in the CONCLUSIONS Our study examined the RLL parameter in calculation of GAP scores in a healthy US population. In this study, we analyzed how the GAP score system may be attributing a high score to otherwise healthy individuals. We found the percentage of proportioned volunteers increases in the Original GAP score by subtractions at RLL group FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.