Fig 2. Knee -Mean trajectories^a for WOMAC-pain and WOMAC-function (Unstandardized outcomes) by high vs. low pre-operative pain/function^b.

A. The mean trajectories are derived from the fixed effects of linear mixed model stratified on high-low profile and regressing each outcome on the time of assessment parameterised as two linear splines. B. High/low function status defined on pre-operative WOMAC-function or -pain using their median scores (51 and 45) as cut-points.