Arnold Huurnink

Chapter 3 3 34 Abstract Background . Diminished postural stability is a risk factor for ankle sprain occurrence and ankle sprains result in impaired postural stability. To date, ankle sprain history has not been taken into account as a determinant of postural stability, while it could possibly specify subgroups of interest. Methods . Postural stability was compared between 18 field hockey athletes who had recovered from an ankle sprain (mean (SD); 3.6 (1.5) months post-injury), and 16 uninjured controls. Force plate and kinematics parameters were calculated during single-leg standing: mean center of pressure speed, mean absolute horizontal ground reaction force, mean absolute ankle angular velocity, and mean absolute hip angular velocity. Additionally, cluster analysis was applied to the ‘injured’ participants, and the cluster with diminished postural stability was compared to the other participants with respect to ankle sprain history. Findings . MANCOVA showed no significant difference between groups in postural stability (P=0.68). A self-reported history of an (partial) ankle ligament rupturewas typically present in the cluster with diminished postural stability. Subsequently, a ‘preceding rupture’ was added as a factor in the MANCOVA, which showed a significant association between diminished postural stability and a ‘preceding rupture’ (P=0.01), for all four individual parameters (P: 0.001-0.029; Cohen’s d: 0.93-2.23). Interpretation . Diminished postural stability is not apparent in all previously injured athletes. However, our analysis suggests that a (mild) ankle sprain with a preceding severe ankle sprain is associated with impaired balance ability. Therefore, sensorimotor training may be emphasized in this particular group and caution is warranted in return to play decisions.