Limited ankle mobility is a common finding in people with flat feet and over pronation problems. When the ankle joint is stiff, the body has to compensate for the lost motion by increasing movement at other locations. This compensation often happens in the joints below the ankle leading to excessive pronation and a collapsing of the arch.
Ankle joint stiffness usually takes years to develop. It involves both inflexibility of the calf muscles and Achilles tendon as well as limited movement between the bones of the ankle. Decreased ankle dorsiflexion is a risk factor for several overuse type injuries of the leg. The three factors most likely to contribute to limited ankle mobility are:
1. Modern Footwear
The average shoe has a heel of between 1 and 2 cm. This is the difference in elevation between the back of the shoe and the front. This holds true for all types of footwear from dress shoes to boots and even running sneakers. High-heel shoes take this to an extreme, and can have a heel-to-toe differential of over several inches. An elevated heel holds the ankle in a plantar flexed position and over time this causes the person wearing the shoe to lose motion in the opposite direction, dorsiflexion.
2. Poor Posture
Ideal posture is usually described in terms of the location of landmarks on the body to a vertical plumb line. When the spine is in alignment, the head, shoulders, hips, and ankles will form a straight line traveling up and down. Slight variance from this alignment is not likely to be a problem. However, certain postures like forward head carriage or anterior pelvic tilting significantly alter that alignment and causes the body’s center of gravity to fall in front of the line. In order to stay balanced the body must find a way to move the center of gravity back over the feet, and this is achieved by plantar flexion at the ankles.
3. Limited Activity Requiring Dorsiflexion
Certain activities like deep squatting or plyometric jumping can only be performed properly with good ankle range of motion. People have a tendency to avoid these activities, particularly as they age. This keeps us from using the full range of motion of the ankle. Use it or lose it. Limited dorsiflexion has been linked to increased risk of falls in the elderly and overuse injuries in athletes. Restoring range of motion is one way to decrease these risks.
The foot is not the only place that the effects of ankle stiffness will be seen. The knee and hip are other joints where the body will try to make up for limited ankle motion. Altered alignment of joints (e.g. knock knees, toe out walking) can be the result of ankle stiffness. If dorsiflexion range of motion is limited more on one side than the other, asymmetries in posture and movement can develop.
How To Test For Limited Dorsiflexion
One of the measures I like the most for dorsiflexion range of motion is the lunge test:
- Stand facing a wall with foot of the leg being tested about 10 cm (4 inches) away from the wall
- Place the other foot about a foot’s distance away from the one being tested
- Bend the front knee forward until it touches the wall without lifting the heel off the ground
- If the knee does not touch the wall without the heel coming off the ground, move the foot closer to the wall and repeat
- If the knee can touch the wall, move the foot farther away and repeat
- At the maximum distance at which the knee is able to touch without lifting the heel, measure the distance between the wall and the end of the big toe lunge test dorsiflexion
A distance of less than 10 cm between the wall and toe is considered restricted ankle dorsiflexion.
One of the problems that I have with the test as described above is that there is no control for pronation of the foot. Because this test is done weight bearing, it’s actually a measure of both ankle and foot mobility.
When I initially performed the test myself, I could touch the wall with my knee at 10 cm but my arch was completely collapsed and the alignment looked horrible.
If I held my foot supinated, essentially recreating the arch, that distance was less than half. My ankle mobility was really bad, but going about my daily activities I would never have realized this because I was excessively pronating to compensate.
So one of the fundamentals of correcting limited dorsiflexion is knowing how to properly supinate the foot to limit the amount of pronation. This can be achieved with the short foot exercise (description). Stretching the calf or mobilizing the ankle without attempting to maintain an arch will just be furthering the pronation problem and make the arch even more likely to collapse.
The position used for the lunge test, in conjunction with the short foot position, can be used as a treatment as long as there is no associated pain in the ankle or knee going into the movement and the foot is held in supination. Calf stretching and ankle mobility drills can also be used to increase ankle dorsiflexion range of motion.