I. Hate. Sounding like a salesman.
But that is exactly what happens when, at a clients request, I explain the rationale for custom inserts in the management of plantar fascia pain. The most common question goes something like, "How are custom inserts going to be any different than the inserts I bought at the shoe store?"
All the discussion is for good reason. Custom inserts are often used and abused as a treatment option, and many clients pay cash if their health insurance does not cover them. Thankfully, the rationale is far more science than marketing hype. When used with attention to detail, they are often effective in dealing with this common, stubborn problem.
Without getting too geeky about ankle/foot biomechanics and the function of the plantar fascia (PF), we'll just say that there are many causes of plantar fascitis. The function of the achilles tendon and great toe are intimately connected to the plantar fascia, and inflexibility or weakness at either point can place undue strain across it. People with high arches typically have PF for different reasons than those with low arches.
The most important thing that you need to understand about plantar fascitis is that the problem is not due to ground pressure into the foot, but from abnormal strain ACROSS the length of the foot. The chronic pain, inflammation, and degenerative changes are coming from the PF being pulled apart and/or twisted, not from being pressed into.
This is why squishy shoes, gel heel cups, and soft cushioning inserts rarely provide long-term relief. In fact, fluffy footwear like Crocs may make the problem worse since most provide inadequate rigidity to counter the forces that are pulling the plantar fascia apart.
Some quality shoe stores and Walmart offer off-the-shelf inserts that are "prescribed" based on pressure measures taken when standing on a computer-interfaced mat. That information is somewhat limited:
1. The computer does not identify what takes place when you walk or run.
2. Even the best off-the-shelf inserts are shooting for the average foot. To accommodate a large subset of the population, they must necessarily be fairly pliable and thus provide insufficient rigidity and control. Off-the-shelf rigid orthotics are rarely well tolerated because appropriate contour is nearly impossible to achieve with one or three orthotics for every foot type.
3. Footwear makes a difference. The computer doesn't know what shoes you typically need for work, what you prefer, or what is good to "marry" to the right insert.
Now don't get me wrong. When the plantar fascia is acutely inflamed and swollen it will feel better to have just about anything soft between your foot and the ground. And if you bought a $12 Doctor Scholls or other over-the-counter insert and it relieved the pain, then that's great. Really, why not try it?
When those fail, here is what custom inserts have to offer:
1. Based off a static and dynamic (you move!) ankle and foot evaluation, they can specifically facilitate the "help" of the achilles tendon and great toe, thus taking some of the strain off the plantar fascia.
2. They can provide some rigidity to help resist the strain and twisting forces. We have found that in reality, a custom insert made with a semi-rigid shell is better tolerated and just as effective as a rock hard, crush-your-foot-to-smithereens rigid shell.
3. They can promote more even distribution of pressure throughout the length of the foot (including ON the plantar fascia) sparing the typical high pressure areas on the heel bone and the ball of the foot that twists and pulls the plantar fascia apart. Based off a plaster cast of the foot, custom inserts truly stand out as the only option for pressure redistribution.