Why CUSTOM Orthotics?
These are good questions. My informal on-line search reveals a lack of quality advice on this topic. Those who manufacture and sell off-the-shelf inserts portray their product as pure nirvana for any and every foot condition. On the other hand, many medical professionals promote custom orthotics as if they are the only treatment option.
Not every person with a foot issue needs a custom orthotic (or an orthotic at all). Some will do perfectly fine in the right off-the-shelf insert while others clearly need custom inserts. And the Dr. Scholl's (and other) gel liners? If that's all it takes to clear up your chronic leg or foot problems, consider yourself fortunate.
Which type of insert is best for you? First a disclaimer!
Everyone has a unique set of circumstances. Some of the more obvious variables to consider include foot structure, movement quality (strength, flexibility, etc), and activity level. But there are an equal number of soft variables. What kind of shoes do you wear and are you willing to wear? How compliant will you be with instructions regarding orthotics, exercises, and a slow return to desired activities? How sensitive is your foot (really your entire being) to change?
Given the disclaimer, here are a few important considerations regarding off-the-shelf versus custom orthotics.
1. Soft off-the-shelf inserts:
There is a reason why most off-the-shelf inserts are made of gel or other squishy material: they will hurt people far less often than a more rigid off-the-shelf insert. The problem with gel inserts is that the treatment effect is minimal. While almost everyone will tolerate a gel or soft foamy insert, very few will see actual change in terms of pain and functional ability.
Take plantar fasciitis, for example. This 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 caused by 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.
2. Rigid off-the-shelf inserts:
Rigid inserts have greater potential for providing support and relief as compared to gel inserts. They stiffen the shoe and help the entire leg function with improved leverage. The problem with off-the-shelf rigid inserts is that they are constructed according to the average, most probable foot. So if your foot is a little wider or narrower, higher or lower in the arches, or the proportions and contours vary from the norm, the insert will often cause more grief than relief. This is an issue because it's those without "average" feet who have the most problems.
An easy way to see if you can get by with a rigid off-the-shelf insert rather than a rigid custom orthotic is to simply stand in them. Place them on the ground and then in your shoes. Walk around for 5 or 10 minutes if you can. If you feel contoured support but no ridges, abrupt creases, or edges, then it's probably worth the time and cost to give them a try.
3. Rigid custom orthotics:
These are constructed from a foam impression or a plaster cast that enables the clinician to capture the exact width, length, contour, and proportion of the feet. This allows for improved tolerance to a fairly rigid device. The clinician can also more easily identify high-pressure areas and perform various custom accommodations. Do you need a little or lot more arch fill than the norm? Do you need a metatarsal pad just proximal to (but not on) the a neuroma? Custom orthotics leave out any guesswork as to where various modifications should be placed.
It's important to keep in mind that orthotics are not magic. All inserts are most helpful when used in conjunction with other treatments that can help alleviate swelling and inflammation, improve strength, mobility, and gait pattern, and a skilled eye that can help you "marry" the appropriate orthotic to the right footwear.