The Oswestry Disability Index (ODI) is a widely used spine-specific PRO instrument in orthopedics to assess disability related to back pain and functional improvement from treatment (Fairbank & Pynsent, 2000). The ODI has 10 patient-completed questions in which the response options are presented as 6-point Likert scales. Scores range from 0% (no disability) to 100% (most severe disability).