A female runner came in today, who hasn’t been able to run for the past two weeks because of increasingly severe left ankle pain. She has been wearing a pair of Mizuno Wave Alchemy running shoes for the past 6 months and when I set the shoes on a flat table, this is what I found.
Notice how the back of the left shoe is tilted outward and the right shoe is more upright?
In this case, the shoes outsole is made of soft EVA (ethylene vinyl acetate), whereas this person should have hard EVA to support heel strike, especially on her left side. EVA is made soft by pumping in air, which is great for shock absorption, but accelerates outsole wear because of compression.
In this case, because the outsole compressed unevenly, this runner sustained significant peroneal tendon injury. At this point I’ve ordered an MRI to determine the extent of the tendon damage…A big price to pay for an excessively worn shoe.
This injury could have been completed avoided, had this runner known how to evaluate her running shoes. Lots of runners have rules when it comes to replacing shoes. The most common ones I hear are replace your shoes every 500 miles or every 6 months.
Unfortunately, because shoes vary so much in construction, an arbitrary rule can lead to injury. Instead, place your running shoes on a flat surface monthly and when they start to tilt, it’s time for a replacement pair.
Dr. Jenny Sanders Shoe Blog 
Thank you for this post — I had the exactly same thing happen to me with my Wave Alchemy’s. I used them for 5 1/2 months and was shocked that they might have worn out so quickly (It was only about 200 miles) but I had a similar minor tendon injury from them as one shoe wore more quickly on the outside! Now I’ve reevaluated and am looking for a non-motion control shoe that allows a more natural stride. Your anatomy of a shoe is helpful. Keep posting as it helps us out there.