GAP Score Calculator

This App allows calculation of the Global Alignment and Proportion (GAP) Score using Pelvic Incidence (PI) and measured sagittal plane parameters. Simply type in the measured PI, and obtain its ideal values. Then, put in measured Sacral Slope, L1-S1 Lordosis, L4-S1 Lordosis and the Global Tilt to obtain scores per domain as well as the Total GAP Score.

Please note the obtained data provided to you by the GAP Score calculator are only estimates. There may be other factors that are not included in the estimate which may not be representative of the actual spinal alignment. This tool does not substitute clinical judgment. JSDI is not responsible for medical decisions that may be made based on the calculation that this app estimates, since these estimates are provided for informational purposes only.

Original GAP Score formulae and research that this app is based upon:

Yilgor, C., Sogunmez, N., Boissiere, L., Yavuz, Y., Obeid, I., Kleinstück, F., … European Spine Study Group (ESSG). (2017). Global Alignment and Proportion (GAP) Score: Development and Validation of a New Method of Analyzing Spinopelvic Alignment to Predict Mechanical Complications After Adult Spinal Deformity Surgery. The Journal of Bone and Joint Surgery. American Volume, 99(19), 1661–1672. https://doi.org/10.2106/JBJS.16.01594