Study Design Case-control.

Objectives Our purpose was to identify sagittal thigh angular motion deficits during a stepping-in-place task between healthy controls and participants with a history of recurrent ankle sprains.

Background Ligamentous laxity and self-reported ankle ‘giving way’ resulting in modified proximal joint movement patterns have been noted in individuals with recurrent ankle sprains and instability. However, few clinical evaluation tools are used to assess potential altered movement patterns. We propose using smartphone technology to identify sagittal thigh motion deficiencies.

Methods and Measures Subjects with (22±3 year, 171±10 cm, 76±11 kg; 14 females, 8 males; Cumberland Ankle Instability Tool=21±5) and without (23±4 year, 168±2 cm, 69±12 kg; 14 females, 8 males; Cumberland Ankle Instability Tool=29±1) a history of ankle sprains. Participants were outfitted with a smartphone on each thigh. Healthy participants were matched to ankle sprain participants and were assigned an affected and unaffected limb. Three trials of a stepping-in-place task were performed for 70 s. The angular thigh position in the sagittal plane was collected by a customised App on a smartphone. Two repeated measures ANOVAs (alpha=0.05) with one between factor (group: sprain, no sprain) and one within factor (limb: affected, unaffected) analysed maximum and average sagittal thigh angular motion (degrees).

Results Significant interactions (maximum: F_(1,42)=5.016; p=0.03; average: F_(1,42)=6.17; p=0.02) were found that indicated the unaffected limb of the ankle sprain group (maximum=40.73±11.33°; average=13.06±4.01°) had less motion than its affected limb (maximum=44.26±12.52°; average=15.02±5.78°) and the unaffected limb of the healthy group (maximum=46.29±14.78°; average=16.41±6.01°).

Conclusions We established that a smartphone App identifies thigh motion deficits for a clinical pathology. A history of ankle sprains may facilitate compensatory thigh movement strategies when stepping-in-place. This novel finding demonstrates the need to examine the role that the unaffected proximal extremity might have in recurrent sprains of the contralateral ankle.