Background and aim: In physical evaluations, measuring the joint angle is one of the most important outcomes to assess the patient's progress, the effectiveness of various treatment techniques and to delineate the need for future treatments. The aim of this study is to study the reliability of a system consists of skin markers, digital photography, and AutoCAD software for measuring the knee joint angles.

 Materials and methods: In first section, reliability of markers placement was evaluated within three different intervals (five minutes, two days, and twenty days). At second section, reliability of digital photography was evaluated while position of the skin markers and subjects was the same. At the end, in third section, reliability of angle measurement by means of AutoCAD software was assessed.

Results: In first section, the ICC for test-retest reliability of markers placement between first and second sessions, first and third sessions, and also first and forth sessions were 0.97, 0.94, and 0.73, respectively. In second section, the ICC for test-retest reliability of digital photography was 0.99 and in third section, the ICC for intra-rater reliability of angle measurement by means of AutoCAD software was 0.99 (p=0.05).

Conclusion: It was noted that the introduced system was highly reliable, so it could be utilized to measure the knee joint angles.

Background and Aim: The rapid growth of the athletic training profession has been accompanied by an equally rapid increase in focus on basic and clinical research. Lateral ankle sprain (LAS) is an extremely common athletic injury. Despite extensive clinical and basic science research, the recurrence rate remains high. Chronic ankle instability (CAI) following LAS is hypothesized to predispose individuals to re-injury because of neuromuscular control deficits which result following injury. No investigation has been carried out on the existence of joint position deficits in the knee joint of patients with CAI. In this study, joint position sense (JPS) was evaluated in patients with CAI.

Materials and Methods: Ten female patients with CAI and ten healthy control subjects participated in this study. JPS was evaluated by reproduction of the angles in two standing and sitting positions, and in each position two target angles were tested. The knee joints in both lower limbs of patients and the dominant knee-limb of healthy subjects were evaluated. The knee angles were measured by using a system comprised of skin markers, digital photography, and Auto CAD software. Absolute error was considered as a dependant variable.

Result: There were no significant differences between the knee JPS of dominant leg in healthy subjects and both knee joints of patients. There were also no significant differences between knee JPS in two standing and sitting positions and in two different target angles (p>0/05).

Conclusion: The result of this study suggests that subjects who have CAI do not have deficit in knee JPS when tested in sitting position and also under functional weight bearing conditions.