Background and aim: Chronic ankle instability (CAI) is a current disability that can affect on activity daily living of the patients. Many studies have indicated postural control deficits in these patients but the effect of a dual task on postural control has not been examined yet.

Materials and methods: Postural stability in CAI patients and healthy subjects was measured using the Force Plate. Eight positions concluded two different stances (double & single) with closed or opened eyes. All positions concurrently were done with a cognitive task. Anterior/posterior (Rfa) and medial/lateral (Rsw) mean sway quantified static postural stability.

Results: Mean sway significantly increased in patients in the anterior/posterior (single and double leg stance) and medial/lateral (single leg stance) directions (P<0.05). While performing a dual task anterior/posterior mean sway decreases within the patients group on the impaired leg stance (P<0.05). No difference is seen in the healthy subjects.

Conclusion: Postural control deficits were identified in participants with chronic ankle instability. In view of the fact that a cognitive task resulted in decreasing displacement of center of pressure in patients, this method may identify as an examination and a plan of treatment for affecting on ankle stabilizing factors.

Background and Aim: Forces which applied to ankle joint for control of stability can cause damage to joint if it does not have suitable control. Chronic ankle instability (CAI) is a current disability that can affect on activity daily living of the patients. The aim of this study is to evaluate forces which contribute to control of posture in difficult conditions.

Material and Methods: Postural control was measured by force plate in two groups of CAI and healthy subjects. Eight positions were selected , including of double stances with closed or opened eyes, and single stances with opened eyes (right/ left) with and without a cognitive task. Force changes in two direction medial/lateral and anterior/posterior were evaluated with fractal time series analysis.

Results: Fractal dimension of force in two groups, following dual task in all of conditions reduced significantly (P<0.05). There was not significant different between two groups in double stance with or without dual task. Single stance in patients indicated significant increase of fractal dimension in affected ankle joint (P<0.05) but comparison of two side in healthy subjects did not have difference. Also there was significant increase of fractal in affected ankle joint of patients in comparison with similar side of healthy subjects (P<0.05).

Conclusion: Patients with (CAI) have a problem in regulation of force for control of posture. This difficulty increased and clearly indicated by dual task condition, which can cause susceptible qualifications for recurrent injuries. Fractal dimension is a suitable factor for analysis of control of posture in difficult situations.

Background and Aim: In recent years, introducing the quantitative methods for diagnosing the joints injuries and its level of severity, surveying the recovery progress and effectiveness of rehabilitation methods are important for clinical practice. Using the inertial sensors is one of the custom methods for quantifying joints motion. The purpose of this study is to quantify injuries in ankle joint.

Materials and Methods: By setting the Sharif-HMIS inertial sensors on the leg and ankle of patients and control subjects, the motion of their ankle was evaluated and the amount of velocity and acceleration in 8 distinct motions were measured.

Results: Using the gathered data from the sensors in different motions and by implementing the assumed criterions, several parameters are calculated that can give a rather precise and quantitative distinction between injured people and control subjects. The results showed that RAV, M and P scores indicate the differences between patients and control subjects clearly, although their performance as a parameter for qualifying the level of ankle injuries is not good.

Conclusion: Motion analysis of ankle and comparing the results of patients and control subjects showed that the assumed criterions are valid and can be used for diagnosing the ankle injury. Also, this method is utilized to measure the ankle motion of both elderly and young groups and the results showed that this method is suitable for indicating the ankle motion differences between two groups.

Key words: Ankle sprain, Motion measurement, Arthritis, Inertial sensors.