CAN PROXIMAL HIP STRENGTH AND DYNAMIC CONTROL DIFFERENTIATE FUNCTIONAL ANKLE STABILITY CLASSIFICATIONS?

Background: Ankle instability can be problematic in an active population with multiple risk factors associated with recurrence.

Purpose: The aim of this study was to determine if deficits in weight-bearing and non-weight bearing assessment of hip strength or dynamic balance in lower extremity reaching tasks from flat and inclined surfaces can differentiate subjects classified as controls, ankle sprain copers, or those with chronic, recurrent ankle sprains.

Study Design: Quasiexperimental, Ex post facto.

Methods: A convenience sample of 60 subjects was classified into control, coper, or chronic ankle sprain groups based on the results of the Identification of Functional Ankle Instability Questionnaire. Subjects were tested for peak force production of their hip extensors, hip abductors, and a composite of hip extension and external rotation while in a standing position using a hand-held dynamometer. Additionally, each subject performed a modified Star Excursion Balance Test in anterior, posterolateral, and posteromedial directions from both a flat and 15 ° inverted stance position. One-way analysis of variance was calculated for between group differences of hip strength and balance reach ability and ankle stability classification. Pearson product-moment correlation coefficients were derived to evaluate relationships between hip strength and dynamic balance tests.

Results: Twenty-one subjects were assigned to the control group, 23 to the coper group, and 16 to the chronic group. There were no significant differences between groups in self-report of Foot and Ankle Ability Measures or Tegner activity levels. Mean hip strength was not significantly different between ankle sprain classification groups (p = 0.66 - 0.82). The mean limb symmetry index for hip strength comparing injured and uninjured ankles was nearly symmetrical in all ankle stability groups (p = 0.34 - 0.97). The same symmetry was present when comparing injured and uninjured abilities for all dynamic balance reach tasks from both flat and inclined surfaces. (p = 0.16 - 0.62). There was a fair relationship between hip extension and weight-bearing hip extension/external rotation strength and the posteromedial and posterolateral reach tasks with correlation coefficients in the range of 0.33 - 0.43.

Conclusion: Performance measures of tri-planar, static, isometric hip strength and lower extremity reach in dynamic balance tasks could not differentiate subjects without a history of injury from those subjects with one or more lateral ligamentous ankle sprains.

Level Of Evidence: 2b; Ex post facto.