Effect of Sex and Ankle Brace Design on Knee Biomechanics During a Single-Leg Cut.

BACKGROUND

Despite success at preventing ankle sprain, prophylactics that restrict ankle plantarflexion motion may produce deleterious knee biomechanics and increase injury risk.

PURPOSE

To determine if ankle prophylactics that restrict plantar- and dorsiflexion motion produce changes in knee biomechanics during a single-leg cut and whether those changes differ between sexes.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 17 male and 17 female participants performed a single-leg cut with 4 conditions: Ankle Roll Guard (ARG), lace-up brace, nonelastic tape, and an unbraced control. Peak stance knee flexion, abduction, and internal rotation joint angle and moment; total knee reaction moment (TKM) and its components (sagittal, frontal, and transverse); and ankle plantarflexion and inversion range of motion (ROM) and peak stance joint moments were tested with a repeated measures analysis of variance to determine the main effect and interaction of condition and sex.

RESULTS

Brace and tape restricted plantarflexion ROM as compared with ARG and control (all < .001). With the brace, women had increased peak knee abduction angle versus ARG ( = .012) and control ( = .009), and men had decreased peak knee internal rotation moment as compared with ARG ( = .032), control ( = .006), and tape ( = .003). Although the restrictive tape decreased inversion ROM when compared with ARG ( = .004) and brace ( = .017), it did not change knee biomechanics. Neither brace nor tape produced significant changes in TKM or components, yet sagittal TKM increased with ARG versus control ( = .016). Women exhibited less ankle inversion ROM ( = .003) and moment ( = .049) than men, while men exhibited significantly greater frontal TKM ( = .022) and knee internal rotation moment with the ARG ( = .029), control ( = .007), and tape ( = .016).

CONCLUSION

Prophylactics that restrict ankle plantarflexion motion may elicit knee biomechanical changes during a single-leg cut, but these changes may depend on prophylactic design and user's sex and may increase women's injury risk.

CLINICAL RELEVANCE

Sex-specific ankle prophylactic designs may be warranted to reduce knee injury during sports.