Clinical Biomechanics for Podiatry (Post #5): Think about Pain Syndromes and Mechanical Causes

     Certain mechanics produce certain pain patterns or syndromes. The 4 common types of mechanical faults which can produce predictable pain patterns are:

1. Over Pronation
2. Over Supination
3. Poor Shock Absorption
4. Limb Length Discrepancies

     Every bio mechanical oriented practitioner looks at these 4 areas when initially evaluating an injury for cause. Could it be from Over Pronation? Could it be from Over Supination (also called Under Pronation)? Could it be Poor Shock Absorption? Could it be tied into one leg being longer than the other?

     It is important to note here that there can be more than one issue going on at once causing symptoms, or confusing the treatment plan? Since 80% of patients have one leg longer (either structurally, functionally, or both), and 99% of patients are have dominant right or left sides (right handed vs left handed), and 10% or so of patients I see have a past injury which affects mechanics (ie. old knee injury), the complexity can be intense, but treatment can logically work through the issues.

     The treatment of these 4 common areas can also be complete or partial for many reasons. Some injuries need 100% correction of the mechanical fault to get better, another injury requiring 20% or so. I tend to personally shoot to correct a problem close to 100% if I think it is the cause or major contributor to the pain syndrome. I can give you hundreds of examples when treatment  near the 100% level was extremely important, but also hundreds of examples when 20 to 30% correction of the mechanics was all that was needed. An easy example of this is low back pain and short legs. If a patient has an 1 inch short right leg with lower back pain, they normally present to my office with 1/4 inch heel lifts. Patients tend to say it was helpful, but they still have back pain. Why are they left with this 25% correction? Because it is much more difficult going to the next level of lift therapy when some or all is placed in the mid sole or on to the outer sole of the shoe.  This same problem is seen in the treatment of over pronation, over supination, and poor shock absorption.

With the onset of very unprotected shoes, we may see a new category arise of Poor Foot Protection, or over protected shoes that weaken our feet!! . I have 3 patients now injured in these less protective shoes that I am unsure if the cause was poor protection, over pronation, or poor shock absorption. Perhaps each factor played a role in the injuries and they all had to be present for the injury to occur. And perhaps it was poor training techniques, the jury is out at this time.

Clinical Biomechanics for Podiatry Series (Post #4):Taking a Good (Biomechanics) History

This is where it all begins in the doctor/patient or therapist/patient relationship. The time spent here discussing the historical facts of an injury or pain syndrome, and important contributing factors, can be vital in the success or failure of treatment. Why is it so vital? Followup visits work off the success or failure of the treatment plan set on that first visit. If the information collected is inadequate, the entire sequence of events following may be subpar. I refer the reader to a post I did earlier on giving a good history. Please review it now before we go further.

http://www.drblakeshealingsole.com/2010/06/giving-good-medical-history-for-pain.html

The biomechanics history related to injuries is looking for patterns or facts that can cause injuries to occur. Here are some of the many questions that normally get asked, or at least you should add to your thoughts prior to seeing a doctor or therapist. These include:

1. Do you know if you have a short leg?
2. Do you believe you have weak or tight muscles in general, or around the injured part?
3. Do you have loose ligaments in general?
4. Are you right or left-handed?
5. When you were a child did you have to wear braces or shoe inserts?
6. Have you ever been prescribed shoe inserts?
7. Have people told you that you walk or run funny?
8. What has your history been of overuse injuries (nontraumatic)?
9. How all or most of your injuries been to one side of your body?
10. Do you have high arches, flat feet, bow legs, knock knees, bunions, hammertoes, or other abnormalities?
11. Do you have any arthritis from your hips downward and wear?
12. Do you feel unstable in any joints?

A skilled practitioner knows the relevancy of the answers. The answers will help point the course of treatment in the right direction. 

Clinical Biomechanics for Podiatry (Post #2): Foot Orthotic Devices: General Principles

There are many types of foot orthotic devices for the consumer. They fall into 5 categories based on the needs of the patient. These 5 categories are:

1. Corrective (or Controlling)
2. Stabilizing (or Balancing)
3. Shock Absorbing (or Cushioning)
4. Accommodative (or Weight Transferring)
5. Combination (or Multi-Functional)

How is the correct orthotic device ordered or purchased? The orthotic device that you prescribe, or that you recommend purchasing in a store, may or may not help if it is not the correct type. At its best, the correct orthotic device will successfully make the necessary change in mechanics, but it may still be crucial to work on all the other aspects of rehabilitation (anti-inflammatory, flexibility, strengthening, etc.) in order to relieve all your symptoms. It is important when prescribing the orthotic device that you are familiar with the many different types of orthotic devices available. It is also important for the patient/customer to be somewhat clear on what type of orthotic device is needed. And, unfortunately, the type of orthotic device required today may change in the future with different sports, different symptoms, different shoe types, and different age. You need to be willing to change to a different type of orthotic device if the patient's symptoms are not improving with the present pair of orthotics, and if there is another type available that may help them. Sometimes, practitioners don’t like discussing this type of change due to the added cost to the patient, but it is important that they know there are options.

Corrective or Controlling Orthotic Devices do what they say---correct or control excessive pronation or supination (the inward collapse of the arch, or the outside roll of the ankle, respectively). This type of orthotic device produces the most dramatic change in function, and may take the most time to get used to wearing.

Stabilizing or Balancing Orthotic Devices normally do not change foot position much, but the patient/customer feels more centered, more balanced. The weight of any point can become so distributed that only a small fraction of the original weight bearing still exists. This can be vital for heel pain, some arch pain, fifth metatarsal base pain, and many metatarsal problems.

Shock Absorbing or Cushioning Orthotic Devices take the stress out of the pounding of heel impact. Runner’s versions need to have equal cushion at the heel and forefoot. These can dramatically reduce the stresses which cause or aggravate stress fractures, joint pains (knee and hip), and heel pain. One of the best shock absorbing orthotic devices is the Hannaford which will be discussed later.

Accommodative or Weight Transferring Orthotic Devices try to transfer weight from a painful area to a non-painful area. These orthotic devices have probably been around the longest of all orthotic devices prescribed by podiatrists. If you have heel pain, you need an orthotic device that transfers weight into the arch. If you have sesamoid pain, you need an orthotic to transfer weight back into the arch and onto the 2nd and 3rd metatarsal heads.

Combination or Multi-Functional Orthotic Devices are probably the most prescribed type of orthotic device. The prescribing practitioner attempts to accomplish multiple tasks with one type of orthotic device. This is why there are so many types of orthotic devices out there. When you really study them, most primarily do one of the 4 basic functions really well, and then 1 to 3 of the other functions somewhat or not at all. A good practitioner will try to get the most out of orthotic therapy. This means that the practitioner tries to combine different functions into each orthotic device on a routine basis. Sometimes, however, doing too much sacrificing the most important function.

Hopefully, this post helped you understand some of the basics of orthotic therapy. When discussing with a patient, try to understand what we want the orthotic device to do. Ask yourself these questions:

1. Do I need to order a corrective device to change foot positioning?
2. Does the patient primarily need to feel more centered and stable?
3. Do they need cushion/shock absorption as they walk or run?
4. Do they need to transfer weight from a painful area to a non-painful area?
5. Do they need a multi-purpose orthotic device with many functions to help the problems at hand?

Perhaps the patient will need several orthotic versions since their activities, shoe gear, etc. vary so much. The doctor and patient must be on the same relative page, and the patient must be aware that there may be a plan B. 

Clinical Biomechanics for Podiatry (Post # 1): Orthotic Designs: Positive Casts before Balancing

In designing orthotic devices, to achieve positive functional changes, and positive symptom outcomes, the prescribing health care provider needs to be fluent in orthotic casting, orthotic prescription variables, etc. I took 20 casts of my wife Pat's left foot to show common variables in orthotic prescription writing. The first cast I poured with plaster and left it uncorrected (the yellow positive cast below). The other 19 casts of her left foot I corrected various ways to achieve various functional results. I will try to show you that even though a good cast is taken (podiatry's Gold Standard in Root Biomechanics), your goals of what you are trying to achieve functionally and symptomatically may require a wide range of orthotic variables.

These 3 positive casts were made for 3 different patients: Orange for high degree of Forefoot Varus, Pink for high degree of Forefoot Valgus, and Yellow (my wife Pat) for a Neutral to Slight Varus forefoot to rearfoot relationship. 

Here are these 3 feet seen from the back of the heel. These represent the negative cast which were taken of three left feet. The Orange cast of a high Forefoot Varus deformity shows the heel collapsing into valgus to get the front of the foot to the ground. The Pink cast of a high Forefoot Valgus foot type shows the heel falls into varus to bring the forefoot to the ground. The Yellow cast (my wife) represents the more Neutral Forefoot to Rearfoot showing the heel position more near a vertical position. The orange and pink foot types are simple to analyze and correct and untreated can lead to devastating foot compensations and pain syndromes. 

Here is a blow up photo of two left feet positive casts. The one on the left shows FF Varus where the forefoot is inverted on the rearfoot. 20 to 50% of patients have this problem. After the foot lands on the ground, to get the big toe to the ground, the arch must collapse and the heel roll into valgus causing severe over pronation. The cast on the right (pink) shows a left foot of FF Valgus. This foot type must roll the heel out to get the metatarsal weight evenly spread and the foot stable. However, this outward roll of the heel, also called over supination, under pronation, or lateral instability, causes a very unstable foot. Try standing on the outside edge of your foot and see how stable you feel. The goal of orthotic devices with these 2 foot types is to get the feet balanced, centered, with the heel straight up and down. This is the goal for what is called Root Balance Technique. 

The Yellow cast of my wife's left foot shows a very Neutral foot. It is very stable. All the negative casts are poured with the heel vertical by propping up one side or the other to get the vertical heel position marked on the cast to be perpendicular to the top of the foot. This is the Gold Standard of Root Balanced Orthotic Devices, but can be your reference in other cast corrections such as the Inverted Orthotic Technique. 

This is a soft based orthotic device made directly off the uncorrected positive cast. By uncorrected, I mean no attempt was made to change the position of the foot. I will demonstrate in some of the upcoming posts, how simple changes to the positive cast correction can make powerful changes in the foot position. This soft based orthotic device is called an Accommodative Device and more correctly called a Hannaford Device (as first invented by Dr. David Hannaford).