San Francisco Podiatry Video


Wednesday, March 20, 2013

SF Tri Run Clinic: Foot Issues

Thanks to everyone from the SF Tri Club who joined us Monday evening for the Run Clinic. This was the second clinic in a series designed by Dino and Katie (our fearless Run Coordinators).

The point of the clinic was to discuss some of the keys to training that might help one avoid injury, particularly those running injuries that can wreck a triathlon season. We talked about running shoe selection, common training errors and barefoot running biomechanics.

There were many great questions from our Peeps. I will be posting those questions here, with answers, for all those who could not make to the Presidio Sports Basement for the clinic.

In fact, here's one now...

Question: What ARE the most common preventable running injuries?

Answer: The most common injuries I see in San Francisco runners and triathletes (that are preventable) are:
1. Stress Fractures
2. Achilles Tendinitis
3. Plantar Plate Injuries
4. Peroneal Tendintis
5. Sesamoiditis

See you out in the water, on the track, or on the road!

Dr. Christopher Segler is an SFTRi Club member, 10-time Ironman Finisher and Sports Medicine Podiatrist. He is Board Certified, American Board of Podiatric Medicine. His practice caters to active runners and triathletes in San Francisco, Berkeley, and Mill Valley. If you have a question about a running injury, you can call him directly at 415-308-0833.

Tuesday, March 5, 2013

Should I drain a liquid nitrogen wart blister?


I got a blister when I recently tried the liquid nitrogen treatment to freeze a wart on my foot. It is tender and so I stopped running. Should I try to drain the blister so I can run?


The idea with treating a wart with liquid nitrogen is in fact to cause a blister. The way this treatment works is that when liquid nitrogen freezes the skin fluid collects between the dermis and the underlying subcutaneous layer of the skin creating the blister. The blister separates the skin layers. Here is how it cures a wart...

The wart is a thick callus covering an encapsulated collection of viral wart particles, which is within then the living layer of skin called the dermis. By creating a blister beneath the dermis (under the wart) the wart essentially gets lifted off of the underlying skin as the blister swells up.

The fluid within the blister will resorb over the next several days. As the blister heals and flattens out, it forms a scab-like structure that doesn’t fully re-adhere to the tissue underneath. Eventually the dried up skin of the blister peels off, and the wart goes with it. If all goes according to plan, you are left with new healthy skin underneath. 

There are many different blistering agents that can be used to cure plantar warts. Here are three of the most common wart treatments that work by blistering:

Liquid Nitrogen - creates a blister with a carefully placed frostbite-type injury. 

Bleomyocin - is a chemical blistering agent injected directly into the wart.

Canthacur - is a topical chemical blistering agent applied to the surface of the wart.

As every runner knows, blisters on the feet can be irritating enough to force one to limit their run mileage or stop running altogether. So it is not surprising that a runner may consider popping a painful blister to lessen the discomfort, promote healing and get back to running. 

This may be a reasonable strategy with friction blisters sustained during a marathon or other long run. But not so with warts treatment blisters.

The problem with warts is that they are caused by a viral infection of the skin. If you poke a needle through the blister (and through the wart containing all of those viral particles) you just might seed the surrounding healthy, non-infected skin with the wart virus. In this way, by attempting to drain the blister under the wart, you may actually infect other areas of the foot and cause a new wart to start growing nearby. 

Then, after the original wart (and its associated treatment blister) have gone away, you may have a brand new nasty little wart rearing its ugly head. Then you have to repeat this process all over again.

Another issue is that the fluid inside the blister is sterile. As soon as you poke a hole the blister fluid can drain out, but bacteria can also get in. So when you pop a blister the risk of bacterial infection goes up. 

If you have a wart that is being treated by a podiatrist, and the blister is large enough to interfere with your activities, you should follow-up with the treating physician. After all the doctor is being paid to treat the wart, so let the doctor finish what he started. Let your podiatrist decide whether or not to drain the blister, and do the draining if needed. That is the safest way to remedy the blister AND make sure that there isn’t any risk of causing a bigger problem long-term.

Heal fast and get back to running! 

Dr. Christopher Segler is a podiatrist who focuses on the rapid treatment of running injuries. He is a runner himself and 10-time Ironman Triathlon finisher. You can learn more about warts, blisters and running injuries at and  If you have a question about a running injury, you can reach him directly at 415-308-0833.

Saturday, March 2, 2013

Marathon Blisters Related to Pronation?

Blister left foot.jpg


Hi Doc,

I have just finished a marathon qualifier for an ultra coming up here in South Africa. I have always been pretty neutral footed, but with the tendency to pronate slightly. I have always had the odd blister after a very long run, but lately they seem to be worse and I am wondering if I am beginning to pronate more (can this happen over time?). I have taken a photo of some blisters that occur after a marathon. I don't like to get rid of them, I sorta let them callous for the season so its not so sore :-). Should I try pronation shoes? What are your thoughts? I use Nike Pegasus +28's. Really hope you can shed some light on this for me :-) 

Many thanks
Blister right foot.jpg

Blisters that pop up anywhere on the foot during/after a marathon are always the result of excessive pressure and friction. With excess friction the underlying layers of the skin begin to separate. Fluid accumulates and collects between the dermis and epidermis creating the fluid filled bubble that runners know as a blister. In the pictures here we can see that one blister has clear fluid and the other is dark. The dark blister implies that this is a collection of blood. This kind of blister is of course often referred to as a "blood blister." 

A blood blister insinuates more pressure or increased trauma, not just friction.

The location of the blister is important and helps a podiatrist figure out the cause. These blisters and calluses forming at the inside of the big toe joint. The medical term for this location is the "medial and plantar-medial aspect of the first metatarsophalangeal joint." 

All runners know the basic causes of blisters.  To be clear we will review:
1. Running shoes that are loose. The feet slide around with every foot strike and push off while running. The result of 26.2 miles of this is excessive friction producing blisters. 
2. Running shoes that are too tight. The feet are compressed against the inside of the shoes, increasing the risk of excess friction (with increased pressure) at parts of the shoe that move (such as the tips of the toes or ball of the foot where the break in the shoe occurs).  
3. Wet feet. Think twice about running through those garden hoses on the marathon course. Moisture in the skin can weaken the structure between the layers of skin, making blisters form with less friction that usually required. 
4. Starting and Stopping too much. If you are running with a walk/run approach, all of the starting and stopping actually takes more force (and produces more friction) than running at an even pace. This can increase your risk of blisters.  

There are other certain circumstances that can contribute to blister formation at the medial big toe joint. 
1. Pronation. As the foot pronates, the foot rolls inward, unlocking the joints in the mid-foot. The first metatarsal bone gets pushed up by the ground and the running shoe effectively twists right around the inside of the big toe joint. This of course creates excess friction and stimulated the formation of blisters during longs runs such as marathons. 

2. Bunions. Same forces at work as in excess pronation, with the added pressure at the bunion stick out and presses against the inside of the shoe. 

1. Blister-prevention socks that have 2 layers that can glide past each other. In effect, you beat up the socks instead of the skin.
2. Custom orthotics or over-the-counter inserts that support the foot, stabilize the subtalar joint and decrease pronation. If properly fitted and constructed, inserts can slow the pronation that contributes to the problem. 
3. Motions control running shoes. Stability running shoes decrease pronation with aggressive medial posting on a stable platform.  They are heavier, and stiffer. Beware-if you have high arches they can increase your risk of shin splints and stress fractures. 
4. Build mileage gradually. This gives the skin a chance to toughen up and form protective calluses without blistering.  

When in doubt. See a local podiatrist for a complete evaluation, running shoe analysis and gait exam to assess your running biomechanics. 

Dr. Christopher Segler, DPM a marathon runner, podiatrist and 10-time Ironman Triathlon finisher who is is Board Certified, American Board of Podiatric Medicine.  He believes the best podiatry practice combines cutting edge technology with the old-school convenience of house calls. He makes podiatry house calls for runners in San Francisco, Palo Alto, Sausalito, Pacifica, and Corte Madera. He also does remote consults for runners who live outside of the United States. If you have a question, you can reach him directly at 415-308-0833. You can learn more about running injuries at