If assessing ankle mobility is not on your checklist of assessments to complete with a new or existing client, you might consider adding it to your repertoire. Adequate ankle mobility is paramount for proper exercise mechanics through a wide range of motions, from deep squats to simply walking. Find out why assessing ankle mobility is so important, how to do it, and what to do to improve it.
There are several considerations when assessing ankle mobility. Do you assess your client while weight-bearing, or not? Do you consider subtalar position? Do you measure with a goniometer, an inclinometer, a tape measurer, or otherwise? What range should a client typically fall into?
Overwhelmed? Don’t worry, we will cover all of these here.
Ankle Anatomy and Biomechanics
The foot and ankle are made up of 26 individual bones of the foot, together with the long bones of the lower limb to form a total of 33 joints! Ankle mobility becomes not so “simple” when we consider this. The ankle joint is complex and made up of:
- talocalcaneal (subtalar) joint
- tibiotalar (talocrural) joint
- transverse-tarsal (talocalcaneoclavicular) joint
Due to this complexity, and the scope of this article, we will be simplifying the joints and focusing on range of motion as opposed to discussing all joint articulations, as well as muscular and tendonous attachments.
Ankle Range of Motion
Ankle range of motion occurs primarily in the sagittal plane and is comprised of dorsiflexion and plantar flexion. However, abduction and adduction may occur in the transverse plane, as well as inversion and eversion occurring in the frontal plane. Combinations of these motions may create three-dimensional motions called supination and pronation.
Once again, due to the scope of this article, and the complexity of these three-dimensional movements, we will focus primarily on sagittal plane motion (i.e. plantar and dorsiflexion). There are many sources that report conflicting “normal” ranges for these common ranges of motion. They range anywhere from 30° to 75+° total motion, broken down into (most typically) 10-20° of dorsiflexion and 40-65° in plantar flexion.
These ranges vary widely and are a complex combination of age, sex, background, geographical and cultural differences, and more.
What can we do with all of this?
Since normal daily activities tend not to challenge the range of plantar flexion healthy adults exhibit, ankle dorsiflexion will be further investigated. Limited ankle dorsiflexion may be linked to limited ranges of motion in other compound movements, additional stresses on the knee, and overall compensatory aberrant movement patterns.
It should be noted, however, that there is no “perfect” range for ankle dorsiflexion either. As previously stated, with such a large range of “normal” and accessible dorsiflexion, any assessment should be relative to the client and their overall movement patterns, as part of a larger picture assessment.
Ankle dorsiflexion is typically assessed up against a wall or other object, where the client assumes either a half-kneeling (non-weight bearing) or a partial lunge stance (weight-bearing) where the subject touches their knee to the wall whilst keeping their heel down (on the front foot).
They advance the foot away from the wall gradually, continuing to touch their knee to the wall, until they can no longer maintain heel contact. This is their maximum amount of ankle dorsiflexion on that side, and may be recorded. Repeat on the other side, and note difference between the two, as a large disparity may be indicative (or explanatory) of additional dysfunction.
Weight bearing vs. Non-weight bearing
Assuming a normal, healthy population, it is typically more functionally applicable to assess ankle mobility using a weight-bearing assessment. This is simply because, in typical functional movements, the joint will be loaded with at least the bodyweight of the subject. To assess the range half-kneeling, additional accessible range may not be realized.
Using Measurement Tools
These methods, which include a goniometer, inclinometer, or tape measure, may all be used to measure either the angle of the joint at maximum dorsiflexion, or the maximum distance of the big toe from the wall at terminal dorsiflexion. All have been shown to be reliable and repeatable, so use the method you are most comfortable with and/or have ready access to. For most, this will be the tape measurement method. Because this does not yield an angle, a “normal” range of 9.5-14 cm away from the wall may be utilized as a gauge.
Subtalar position (is the ankle, pronating, supination, or neutral?) may be considered during the dorsiflexion assessment, but does not need to be. It is likely that should the foot pronate during dorsiflexion, additional range may be accessed that is not functionally relevant.
In other words, the additional range of motion permitted by pronation is not accessible during functional movements or exercises that the client performs because they are unlikely to pronate during those movements (and if they are, it is likely not desirable).
This may be considered by placing a wedge (or otherwise) under the arch of the subject during the assessment to mechanically prevent pronation. You may also instruct the client to track the knee over the second toe to minimize this effect. Evaluate this on a case-by-case basis and use your best judgment during the assessment.
Putting it all together
The ankle is a complex joint comprising numerous joint articulations and motions. Most typically, coaches will assess ankle dorsiflexion, as the majority of ankle motion occurs in the sagittal plane, and dorsiflexion is usually the most limited/problematic range. Based on client population, cultural background, age, sex, and a number of other factors, there exists a large range of acceptable dorsiflexion, and their assessment results should be taken into consideration along with their functional presentation and other assessments completed. The simplest and most reliable assessment is the standing, partial lunge, dorsiflexion assessment where the measurement of the big toe is taken from the wall (or other object) when the heel can no longer maintain contact with the ground and the knee is in contact with the wall.
This assessment should be part of a larger picture assessment of the client to determine if ankle dorsiflexion is in fact limited and/or significantly different from one side to the other.
Best methods for improving ankle mobility will be in a follow-up article coming soon!
Gray H. Arcturus Publishing; 2009. Gray’s anatomy: with original illustrations by Henry Carter