Chronic ankle instability alters eccentric eversion/inversion and dorsiflexion/plantarflexion ratio.
OBJECTIVE
To determine if the eccentric evertor/invertor and dorsiflexor/plantar-flexor ratio are altered in subjects with chronic ankle instability.


METHODS
Twenty chronic ankle instability (CAI) subjects as an experimental group, and twenty healthy subjects as a control group, were matched in age, gender, and activity level. CAI subjects have a history of at least one ankle sprain and repeated episodes of giving way were included in CAI group. Subjects with no prior history of ankle injury were included in the control group. Ankle evertor/invertor and dorsiflexor/plantar-flexor muscles eccentric torque ratios were measured using the eccentric muscle contraction at angular velocities 60 and 120°/s.


RESULTS
Analysis of variance revealed that the eccentric contraction eversion/inversion ratio of CAI group was significantly lower than normal group ratio at angular velocities 60 and 120°/s (p=0.041 and 0.012) respectively. The eccentric contraction dorsiflexion/plantarflexion ratio of CAI group was significantly higher than normal group ratio at both angular velocities (p=0.036 and 0.013) respectively. Moreover, at angular velocities of 60°/s and 120°/s a deficit in inversion and eversion eccentric torques were identified in CAI group (p=0.000), plantarflexion torque deficit of CAI group (p=0.034 and 0.028), respectively, and no deficit was identified for dorsiflexion torque of CAI group (p=0.595 and 0.696) respectively.


CONCLUSIONS
Chronic ankle instability increases the dorsiflexion/plantarflexion muscles torque ratio and decreases the eversion/inversion ratio at angular velocities 60 and 120°/s. Therefore, the restoration of a normal eccentric inversion, eversion, and plantarflexion strength may prevent recurrent lateral ankle ligament sprain.
Department of Biomechanics, Faculty of Physical Therapy, Cairo University, Giza, Egypt.
Amr Almaz
AA
Abdel-aziem
Department of Basic Sciences, Faculty of Physical Therapy, Cairo University, Giza, Egypt.
Amira Hussin
AH
Draz
D000328:Adult; D000842:Ankle / Q000503:physiopathology*; D000843:Ankle Joint / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D019415:Torque; D055815:Young Adult
Eccentric contraction; ankle muscles; chronic ankle instability