The Role of Ankle Strength in Functional Ankle Instability

Abstract

The purpose of this study was to determine if there were any differences in ankle range of motion, strength, or work between persons with normal ankles (Normal,n= 14), those with functional ankle instability (FAI,n= 15), and those with a history of FAI who have been through formal proprioceptive rehabilitation (Rehab,n= 14). A second puipose was to determine normative values for ankle strength and work measurements using the Biodex® isokinetic system. There were no significant differences between groups for ankle range of motion or for any strength or work measurements. The overall strength/work averages were 11.75/3.42 for plantar flexion, 339/1.48 for dorsiflexion, 3.30/2.40 for inversion, and 2.62/1.79 for eversion. Dorsiflexion torque overall was 31.43% of plantar flexion, and the evertors produced 75.42% of the torque produced by the invertors. It is recommended that clinicians continue to rehabilitate ankles with strength and proprioceptive exercises but do not rely on ankle strength/work testing as the only criteria for determining an athlete's readiness to return to full activity.

Eccentric Plantar-Flexor Torque Deficits in Participants With Functional Ankle Instability

“…6 However, the previous literature related to the presence of peroneal deficits in individuals with functionally unstable ankles is conflicting. 5,8,[13][14][15] Some investigators have identified both concentric 4,13,15 and eccentric 4,15 eversion torque deficits, whereas others have concluded that no eversion deficit exists, regardless of mode or speed of contraction. [7][8][9] Additionally, while the evertor muscles can counter a varus force, 6 proper dynamic stabilization of the ankle can only be achieved through a coordinated effort of all the surrounding muscles.…”

“…Significant torque deficits have been noted during both concentric 5,11 and eccentric 9,15 muscle contractions, whereas others found no significant invertor deficits. 4,7,10,14,17 Research investigating plantar-flexor and dorsiflexor muscles is very limited. One group 18 studying the plantar flexors reported concentric torque deficits in participants with a history of a lateral ankle sprain; other authors 14 found no significant difference in plantar-flexion or dorsiflexion torque between FAI and control participants.…”

Ankle Stability and Movement Coordination Impairments: Ankle Ligament Sprains

“…Some studies have identified invertor strength deficits, 107,187,202,218,278 whereas others have not. 156,180 Evertor strength deficits have also been identified in some studies 107,202,242 but not others. 156,180,218,278 Single-Limb Balance…”

“…156,180 Evertor strength deficits have also been identified in some studies 107,202,242 but not others. 156,180,218,278 Single-Limb Balance…”

Eccentric Peak Torque Analysis of Subjects Suffering from Chronic Ankle Instability

“…[15] McKnight and Armstrong [16] and Baumhauer et al [17] found no significant invertor deficits. Termansen et al [18] studying the plantar-flexors reported concentric torque deficits in participants with a history of a lateral ankle sprain.…”