It is fairly common knowledge that the human foot was not designed to maneuver in high heel shoes. Because of the abnormal angle in which it places the foot, numerous problems can develop both in the foot and ankle joint.
Did you ever stop to think of the impact that high heels can have on the knee joint? In this article we will discuss how the elevation of the foot from this type of dress shoe may adversely affect the function of the knee joint.
Those that develop osteoarthritis (wear and tear arthritis) of the knee include:
women twice as much as men
people who are overweight
those with muscle weakness in the leg
those with a history of knee trauma
the biomechanics of knee osteoarthritis
The area of the knee that is most affected appears to be the medial, or inside, portion of the knee. Cartilage damage as well as deterioration of the surrounding soft tissue occurs over time. This damage occurs from both a combination of direct impact on the knee when walking, as well as torsional forces (twisting forces) within the knee joint. The combination of these two forces is known as KAM-knee adduction moment. The greater the KAM measurement, the more varus rotation, the more the tibia jams into the femur on the inside of the knee. The question then became one of does shoes increase the KAM and to what extent.
Research into this problem began in the 1990's lead primarily by Casey Kerrigan MD, an orthopedist, who wondered why women get knee osteoarthritis at a greater incident then men. Certainly, since women wear high heels and men do not, that would seem to be an area that needed to be researched.
In "normal" gait, when your heel first hits the ground, you land on the outside of your heel. As your foot hits the ground your body weight travels along the outside of the foot and then at the level of the ball of your foot, the weight is transferred across the front of the foot and as your foot leaves the ground, you "push off" with your big toe.
In her research, Dr. Kerrigan found that stilettos altered the ability of the foot to adapt to the changes necessary to function in a "normal" gait. She even found that high heel shoes with a broader base were even worse. Both shoes increased the varus torsional (twisting) forces on the inside of the knee. One would think that stilettos would be worse then broad heel shoes, but Dr. Kerrigan conjectured that with stilettos, women walk in a more guarded gait simply because of the clumsiness of this type of shoe, whereas in a broader heel women walked in a more normal gait and thus the negative effects of the broad high heel was more pronounced.
In further studies she and her colleagues found that even running shoes with a thick heel increased KAM to a greater extent then wearing flat heeled shoes or walking barefoot. They even found that wearing an arch support was also counter productive. It should be noted that other studies have contradicted these findings.
pronation and knee osteoarthritis
For the most part, the purpose of an arch support is to reduce pronation
and there are numerous foot and ankle problems that require a reduction in pronation to alleviate pain. However. some researchers have found that this same reduction in pronation may increase KAM, so much so that some studies claim that by increasing pronation in individuals, by adding a lateral heel wedge to their shoes, actually improved knee pain in their studies.
This appears to be contrary to my training and observations over the years. One of the things that excessive pronation does is increase the torsion at the level of the knee joint. With excess pronation the lower leg excessively internally rotates, while the upper leg begins to externally rotate and you are left with a twisting motion (torsion) at the level of the knee joint.
These same researchers have advocated wearing hyper-mobile shoes for knee pain which of course will allow the feet to pronate. These shoes are similar to minimalist shoes which have become popular over the last few years. What they do is allow the foot the maximum amount of motion, almost the same as walking barefoot.
shoes and knee osteoarthritis-what should you do?
If you suffer from knee arthritis, particularly on the inside of the knee, certainly considering a change in shoe selection may go a long way in improving your quality of life. The problem with most of the research that has been done so far is:
1. The studies for the most part were done on small samplings of people.
2. Other considerations such as being over-weight or having suffered trauma to the knee years ago may not have been taken into account.
3. Foot structure and skeletal make-up varies from person to person and there can be great variabilities in this aspect.
4. Most people do not wear the same shoes day in and day out and certainly shoe styles (heel height) change over the years.
The biggest concern is that by drastically changing your shoe style, even though your knee may feel better, you may actually be exacerbating some other problems.
Such examples would include:
wearing high heels for many years has the consequence of shortening the Achilles tendon. Trying to switch from a diet of high heels to low heel shoes or even hyper-mobilty shoes can lead to Achilles tendonitis in many women.
people with biomechanical foot and ankle problems may be adversely affected by a switch to a more flexible shoe or no longer wearing an orthotic.
diabetics have to be particularly careful of not wearing shoes that adequately support their feet. Hypermobile shoes or lack of wearing an orthotic may increase pressure points in the foot and increase the risk of ulceration.
The takeaway point from this article is that if you suffer from knee pain or are beginning to suffer from knee pain, changing the shoes you wear may have a positive impact in reducing your knee pain and reduce the damage going forward. Just make sure you do not end up creating other problems. The pain may be in the knee but the problem is coming from the feet.