The Graphs show the comparisons between the groups. A. Passive knee flexion range of motion (ROM). B. Active knee flexion ROM. The dark grey line represents the sling exercise training group (ST) and the light grey line the continuous passive motion group (CPM). Data are presented as estimated marginal means and standard deviation (ANCOVA: posttest adjusted for baseline, sex, weight, age, pain and physical activity; follow-up adjusted for baseline, sex, weight, age and physical activity. * denotes a significant difference (P ≤ 0.025).