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4 July 2009
Normal range of motion for the subtalar joint

For years we believed the normal range of motion of the subtalar joint was 10 degrees of eversion and 20 degrees of inversion from subtalar joint neutral. I used to religiously draw the bisections down the back of the leg and calcaneus and measure this angle.

After a while I came to the realisation that:
1. Many studies were showing that the measurements were not reliable
2. Once I got the number (assuming that I was actually reliable!), I did nothing with the number
3. 20 and 10 were probably not the normal range of motion

What is the normal range of motion? For straight ahead walking on a hard surface, we probably only need 4 degrees of eversion and no inversion. If we want to turn a corner, we going to need more. If you going to play tennis, you going to need a huge amount more. I have seen a slow motion video of a high jump foot plant and take off and the STJ/rearfoot complex everted (pronated), something like 50-60 degrees.

What is the normal range? There isn't one because it activity dependent. I suggest its simply a matter of checking the range and noting if its adequate or inadequate for the activity of the person – that’s all that is needed. What is the normal range came up in this thread on Podiatry Arena on foot pronation.

Craig Payne


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