The Effect of Joint Mobilisation Treatment Dose on Dynamic Balance in Those With Chronic Ankle Instability

Introduction: Talocrural joint-mobilisations improve postural control in those with chronic ankle instability (CAI) (1). However, the effects of different treatment durations over multiple sessions have not been investigated. The study aim was to examine the effect of varying treatment durations over three treatment sessions on dynamic postural control in those with CAI.

Methods: 48 female athletes with unilateral CAI (22.8 ±4.8yrs) were randomly assigned to balanced treatment groups (30, 60 or 120 seconds) and received three anterior-to-posterior talocrural joint mobilisation treatments equally spaced over a 5-day period. Dynamic postural control was measured prior to and immediately following each treatment session using the anterior (ANT), posterolateral (PL) and posteromedial (PM) directions of the star excursion balance test (SEBT). The uninjured extremity was used as a control for all measurements.

Results: Interaction effects between group and treatment session for each reach direction were evidenced (p ≤ 0.001). ANT improved for all treatment durations when compared to their control for all sessions (p ≤ 0.001) with effect sizes being ‘huge’ (≥2.0). Longer treatment sessions produced significantly greater ANT improvements than shorter durations (p ≤ 0.005). In contrast, there was no improvement (p ≥ 0.05) in PL or PM for any treatment group when compared to their control. However, both treated and control limb showed evidence of improvement after each session. The 30s group (PL) and the 60s (PM) did show improvements over their control following session 1 (p ≤ 0.05). Improvements in PL and PM reach distances were superior in the longer treatment groups than shorter duration treatment groups (p ≤ 0.05).

Conclusion: Anteroposterior talar joint mobilisations improve postural control in ANT, with longer treatment durations conferring greater increases. This can be attributed to the associated increases in dorsiflexion seen following joint mobilisations, with around 28% of the variance in ANT being credited to improvements in dorsiflexion (2). For PM and PL, longer treatments appear to produce greater results, although the benefit does not seem limited to only the treated limb. This suggests a central processing mechanism is at play through increases in afferent transmission (3). This adds clarity to the use of joint mobilisations in the treatment of CAI, although further investigation of the potential ‘cross-over’ effect is warranted.