The measures reflects the percent of patients receiving spine surgery for whom there is medical record evidence of ambulation (actual movement out of the bed, not just feet dangling out of bed) on the day of surgery. Analysis of MSSIC data in 2016 showed the early ambulation is a significant protective factor for a variety of complications, and that there is currently significant variability among hospitals and surgeons in terms of the percent of patients who do have ambulation on the day of surgery.