Do My Flat Feet Affect My Arthritis?

I get many patients each day who come in with knee or hip pain from arthritis. The diagnosis is clear, but the causative factors aren't always. Sometimes the patient is young, relatively healthy, and without obvious risk factors like previous injury or obesity. How do I explain the "early onset" arthritis they are experiencing? Well, let's look at the question from a broader perspective. What are risk factors for arthritis in general?

The most obvious risk factor is previous injury or trauma to a joint. If you were in a car wreck ten years ago that caused you to fracture or break the bone in the portion which bears cartilage (we use the phrase, intra-articular fracture), then you're far more likely to develop what we call post-traumatic arthritis. Even with an excellent surgeon to fix the fracture pieces, odds are that someone will have a higher chance of developing arthritis in that joint.

The next most clear reason someone might get arthritis is that they are carrying too much weight around. Whether it's clinical obesity (a body mass index of greater than 30) or simply that "freshman fifteen" that steadily grew over time, arthritis has a clear correlation with body weight. Clinicians like to call osteoarthritis "wear and tear" arthritis, likening it to the tread on your tires. The heavier the car is, the quicker the tread wears out. Similarly, the more someone weighs, the more likely they are to have arthritis and more severe arthritis as well as at an earlier age. Now, the caveat to this is that weight which (to a degree) comes with muscle. If you're 210 lbs and 6'2" as a male, and it's all muscle, you're likely not suffering from much arthritis. If you're 6'2" an 210 lbs at 25% body fat, then your extra weight is working against you. Both men weigh the same and thus have the same BMI, but the more muscular male will generally not become arthritic nearly as quickly despite their same weight. There are several reasons for this.

- First, fat is pro-inflammatory. Meaning that inflammatory conditions like heart disease, arthritis, and blood clots are more likely with more fat weight.

- Second, the act of building muscle requires resistance training, which has been shown to be chondroprotective in moderate. Chondroprotective means cartilage protecting.

- Third, leaner individuals tend to consume healthful foods like lean meats, vegetables, and fruits and generally consume fewer processes foods, fat, and sugar.

The third most common reason for developing early arthritis is biomechanical imbalances. Ask anyone who has had scoliosis for decades, and they'll tell you that it affects not only their back but their hips and their knees and maybe even their ankles too. Similarly, problems and the foot and ankle can also affect the degree to which joints above experience mechanical stress and thus manifest wear in the form of arthritis. One of the most common biomechanical imbalances is the flat foot and it's associated ankle collapse. The medical terminology for these are pes planus (flat foot) and equinovalgus (ankle collapse toward each other). How does this affect your knees and hips? As your arch collapses and your foot flattens, your knees tend to also collapse inward, making someone's stance more knock-kneed.

Genu Valgum, Genu Varum, Arthritis, knock kneed, bow legged
Figure 1. Normal Knee alignment, genu varum (bow legged), and genu valgum (knock kneed) denoted by A, B, and C respectively.

As you can tell, knock kneed stance increases pressure on the cartilage on the outside of the knee. There is some data to suggest that in individuals with arthritis present on the outside of the knee, that flat feet worsens their pain. Similarly, correction of that flat foot deformity can improve the pain.

Newer research suggests that the presence of a flat foot, prior to the onset of arthritis, might increase the risk of arthritis on the inside of the knee. This would be because the outside of the knee is the pivot point around which the inside of the knee swings with walking. See the figure to the left; click to view the study from which the image was borrowed.

Over time, the inside compartment of the knee experiences more shear stress and, likely producing early arthritic change and more medial knee pain. So what should be done about this if you have flat feet and either have arthritis in the knee or are concerned about knee arthritis? Well, the first thing to do would be to try and get evaluated by a sports medicine or orthopedic physician.

The second thing would be, if advised by your physician, to address the need for a supported arch and ankle. I prefer orthotics which not only are comfortable but can be slipped into tennis shoes or work shoes. I have had excellent results with inserts made by Powerstep, particularly their Protech line. Should these not provide sufficient correct, custom inserts can be made by a qualified orthotist. Pedorthists and some physical therapists can also be trained to properly fit and produce a custom orthotic. I would ask your sports physician or orthopedist for their referral.

The last recommendation I make make to nearly all individuals is to establish yourself with a qualified orthopedics-oriented physical therapist. Within physical therapy, as within medicine, there are therapists who either hold a residency in a particular field (neurological, orthopedics and sports, etc) or have expertise through practice in a field. I would look for a therapist with lots of experience in evaluation and rehabilitation of the flat foot and its associated conditions. If you're not sure whom to see, again, ask your physician for their recommendation.

While there are many more biomechanical issues than flat fleet and collapsed ankles, these maladies are by far some of the most common and easily addressed. Feel free to shoot me an email at or leave a comment if you want to share your experience or ask a question!

Keep Moving!


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P.S. Some of the links above are sponsored links in which I either have used in my practice with good efficacy or those which I have tried personally and in which I believe there to be benefit. If you choose to purchase through these links, there is no increased cost to you, but I may receive a small commission.

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