The EQ-5D-3L will be collected at each follow up visit. It consists of two pages - the EQ-5D descriptive system (page one) and the EQ visual analogue scale (EQ VAS) (page two). The descriptive system consists of five dimensions (mobility, self-care, usual activities, pain/discomfort, anxiety/depression) each of which takes one of three responses. The responses record three levels of severity (no problems/some or moderate problems/extreme problems) within a particular dimension. The EQ VAS records the respondent's self-rated health on a vertical, visual analogue scale where the endpoints are labelled 'Best imaginable health state' and 'Worst imaginable health state'. This information can be used as a quantitative measure of health outcome as judged by the individual respondents.

Combines an objective physician-derived component with a subjective subject-derived component. The objective section rates alignment, instability, joint motion and symptoms. Patient reported expectations and satisfaction questions evaluate pain relief, functional abilities, satisfaction and fulfillment of expectations using a subjective perspective. A functional score is derived from assessments of walking and standing, standard activities, advanced activities and discretionary activities.