Biomechanics and Intrinsic Foot Muscle Roles in Subjects With Chronic Ankle Instability

Three groups of participants : Chronic ankle instability, lateral ankle sprain copers andhealthy controls. INCLUSION CRITERIA:

1. For all three groups :

• Physically active male subjects between 18 and 44 years of age
• Able to run at low speed.
• For homogeneity purposes, the investigators will only recruit subjects whoperform a regular physical activity on a weekly basis, including competitionparticipation.

2. Chronic ankle instability :

• A history of at least one significant ankle sprain that occurred at least 12months before study enrolment, associated with inflammatory symptoms, creating atleast 1 interrupted day of desired physical activity;
• The most recent injury occurred more than 3 months prior to study enrolment;
• At least two episodes of giving way in the 6 months prior to study enrolment,recurrent sprain, and/or "feelings of instability"; and
• Poor disability status according to the Cumberland Ankle Instability Tool (CAIT) (score ≤ 24/30).

3. Lateral ankle sprain copers :

• A history of one significant ankle sprain that occurred at least 12 months beforestudy enrolment, associated with inflammatory symptoms, creating at least 1interrupted day of desired physical activity;
• A return to at least moderate levels of weight-bearing physical activity lessthan 12 months after initial sprain without recurrent injury, episodes of givingway, and/or feelings of instability;
• Minimal, if any, level of self-reported disability (CAIT score ≥ 28/30); and
• Minimal, if any, alteration in self-reported function (ADL- and Sport-subscales ≥95%).

4. Healthy controls :

• The same inclusion criteria as the LAS coper group, with the exception reportedin the exclusion criteria.

EXCLUSION CRITERIA:

1. For all three groups :

• Being younger than 18 years
• Any medical contraindication to physical exertion,
• Any systemic or neurological disease,
• A recent surgery,
• A difference in leg length of more than 3 cm,
• Pregnancy,
• A body mass index higher than 30kg/m² (due to less accurate motion analysis byabsence of anatomical landmarks).
• LAS copers and controls will also be excluded if: constant or intermittent anklepain, ankle fractures, or surgeries, and recent participation in a physicalrevalidation programme.
• Healthy participants must never have suffered an inversion trauma resulting indisability.

2. For healthy controls : the healthy control subjects may not have suffered from anankle sprain.