Tendonitis which is inflammation of a tendon, can occur any where on the body, but perhaps the most common place for it to occur is on the achilles tendon.
Usually repeated over stretching of the achilles tendon or trauma to the tendon will cause the tendonitis. Most cases of achilles tendonitis, in the mild to moderate range will dissipate over the course of a week or two with a minimal amount of treatment.
However, there are the cases of resistant achilles tendonitis which just seems to stay around regardless of what the patient does. In these instances an orthotic can be very helpful for a couple of different reasons.
As described with other foot and leg issues, the simple act of every day walking on the injured foot or leg keeps aggravating the problem and so the ailment never has a chance to heel. That explains why some people need crutches or a walking cast in order to rest an area for healing to occur. In the case of achilles tendonitis an orthotic many times can do the same thing.
Some people exhibit what is known as a tight heel cord or an equinus where the tightness of the heel cord, essentially a shortened heel cord, does not allow the foot to bend upwards as far as it needs to in order to ambulate. So, what happens is the achilles tendon (heel cord) is over worked and thus over stretched and becomes inflamed and painful.
When people have a tight heel cord, one of the ways they compensate for that is to pronate the foot. Pronation actually reduces the strain on the achilles tendon by shortening the distance between the origin of the muscles that make up the achilles tendon and where the tendon inserts into the heel and thus gives it a little more relative length. So in a situation where there is a tight heel cord not only can that lead to tendonitis but it can also lead to other problems associated with excessive pronation.
We then can use an orthotic to accomplish two things. If the orthotic is built with a heel lift in it, that will take the strain off the achilles tendon and allow the tendon to heal. Secondly, by controlling excess pronation with the orthotic, we can relieve some of the other potential problems that may be occurring.
The caveat here is that we try and stay away from the hard plastic orthotics in these situations because if we over control pronation and do not allow for some, that will add more strain to the achilles tendon.
In general we use an orthotic of the accommodative nature which tend to have a thick heel as well as enough "softness" to control some of the pronation.
The second situation where we can use an orthotic for achilles tendonitis is in instances where there has been some sort of injury to the tendon either from participation in a sport or even a lot of excess walking.
For many the pain just does not want to go away on its own and thus the achilles tendon needs to some how be "rested". Yes, in severe cases we can put people on crutches or apply a walking cast, but for most of these cases by adding an orthotic we can reduce the tension on the achilles tendon so that the tendon does not continually over stretch during gait and this will allow the tendon to get progressively better.
Once again, as I have repeated through out this site, orthotics are not the only treatment for achilles tendonitis and in fact may not even be the first treatment of choice in this tendonitis but if other treatements fail to alleviate the pain , or if this is a recurring problem, than an orthotic is something that should be considered.
store bought arch support may be helpful as long as back of orthotic has a heel lift component to it or the back portion is just thick as so many store bought arch supports appear to be
medical grade off the shelf orthotic generally I find these not to be the best choice, simply because the heel is too thin. You can look at the ones that have external rearfoot posts, but I do not like those for other reasons. Mainly they are too narrow and too rigid..
prescription orthotic for more severe cases, this may be your best bet as the heel can be customized as well as the flexibility of the arch itself.