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Rehab Advised to Prevent Recurring Ankle Sprains

This is the first study to look at patterns of muscle activity and joint motion at the same time in patients with ankle functional instability (FI). FI refers to the fact that these individuals twist their ankle easily. Sometimes it happens without warning or cause.

A group of adults with FI were tested using EMG (electromyography) while walking on a treadmill. The results of the tests were compared to a control group of men and women who did not have an ankle problem.

The FI group all had at least two inversion injuries severe enough to keep them off their foot for a period of time. In an inversion injury, the outer edge of the ankle gives way.

A special 3-D motion tracking system was used during walking. Infrared light-emitting markers were attached to the leg in several places. This device measured joint angles during motion. At the same time, surface electrodes were used to measure the electrical activity of the muscles.

The authors report increased ankle inversion and decreased foot clearance during walking for the FI group compared to the control group. The inverted position was held during the final swing phase of the lower leg. It was also present when the heel touched the ground and weight was accepted onto the foot and ankle.

The peroneus muscle in the ankle/foot showed increased electrical activity after heel strike in the walking sequence for the FI group. This may be a way the ankle has to offset the inverted position of the ankle joint. The pull from the muscle may offer some natural protection from further inversion injury to the ankle.

The findings in this study support the idea that hyperinversion injuries are biomechanical in nature. If the ankle isn't positioned properly before heel strike, risk of inversion injury increases.

Rehab may be the answer to this problem. Exercises to retrain muscle control and correct position of the ankle should come first before agility drills and jump landing. Bracing and taping may help hold the joint in a neutral position as part of the retraining process.

References: Eamonn Delahunt, BSc, et al. Altered Neuromuscular Control and Ankle Joint Kinematics During Walking in Subjects with Functional Instability of the Ankle Joint. In The American Journal of Sports Medicine. December 2006. Vol. 34. No. 12. Pp. 1970-1976.

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