Kenney, Megan (2003) Functional instability of the ankle and its relationship to the Q angle. Coursework Master thesis, Victoria University.

Abstract

Ankle ligament injuries are common, and the majority of ankle sprains can be treated successfully. However ankles that demonstrate recurrent sprains or have the tendency to give way are known to be functionally unstable. Functional Instability (FI) can present with three pathophysiological factors; mechanical instability, proprioceptive deficits and peroneal muscle weakness. Clinical examination reveals that with increased inwards rotation and forward displacement of the calcareous, the subtalar joint will be held in supinated position resulting in compensatory tibial, femoral and pelvic external rotation. To evaluate functional instability a number of tests were carried out bilaterally on all participants, in order to compare their control and symptomatic ankles. The participant stated on the information sheet which of their ankles was symptomatic. Two mechanical tests were conducted, the anterior draw test and the talar tilt. Postural sway was mapped using the Force Vector Visualisation System and peroneal muscle strength was measured using a kinetic dynamometer. Following these tests the Q angles of each participant were measured and calculated. Peak peroneal concentric torque demonstrated a significant negative relationship with Q angle in subjects experiencing FI of the ankle. FI of the ankle may result in hyper supination of the foot, with compensatory external rotation of the tibia and femur, accounting for a decrease in Q angle as found in this study, altering patellofemoral kinematics. From the results obtained, it can be said that with a maximum effort of the Q angle. Further investigation is needed into the relationship between the components of FI and the kinematics of the entire lower limb. This minor thesis was written by a post-graduate student as part of the requirements of the Master of Health Science (Osteopathy) program.

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