pain in 5th metatarsal head when weight bearing

by Karen
(Greensboro, NC)

Several months ago I started to have pain in my right foot behind my little toe at the head of the 5th metatarsal. A podiatrist diagnosed me with "inflammation" and prescribed ibuprofen for 2 weeks and new walking shoes - both of which I did. She insisted that I not stop walking so I continued. (I have been walking 3 miles per day, 6 days per week for a couple of years.)

After a week, the pain was so bad that I did stop walking and rested for about 3 weeks with no real improvement.

I decided to see my primary care physician and she ordered an MRI. A stress fracture at the tip of the 5th metatarsal was diagnosed. Specifically, the MRI showed, "There is abnormal bone marrow signal from the distal fifth metatarsal, specifically the metatarsal head extending to the distal metaphysis. On T1-weighted imaging, there is a subtle transverse line of low signal along the plantar margin of the fifth metatatarsal head, surrounded by edema. There is also soft tissue edema adjacent to the fifth metatarsal head. THis suggests an incomplete stress fracture."

I wore a walking boot for 4 weeks and then switched to a post-op shoe for 1 week. X-Rays revealed no evidence of the stress fracture. My doctor could not produce pain by palpating the foot, so she ordered me back to regular shoes (no heels). After a couple of days of wearing regular shoes, the tenderness has returned and the pain is present when weight-bearing or applying pressure such as would occur when crossing your legs with the affected foot on the floor.

My exercise program has been de-railed and even though the doctor told me I could return to walking - initially for 10 minutes with gradual increase over time, I can see that I'll be back in the same predicament before long.

What else could produce these MRI results besides a stress fracture?

I am a 54 year old female who has just entered menopause. I am otherwise healthy.

RESPONSE

Hi Karen,

I do not think the diagnosis is the problem as much as the time you have been "nursing" this problem. Between the walking boot and surgical shoe you have spent five weeks total trying to immobilize the fifth metatarsal head and allowing it to heal. Quite simply, this may not be enough time.

Most fractures, in general, take between six to eight weeks to heal, so you did not even reach the thresh hold of six weeks so if you were my patient I do not know if I would have been concerned that you were still having some degree of pain at five weeks.

At this point I would not call this delayed healing as much as not enough healing. There can be mitigating factors as well that may slow down the healing process.

The first that comes to mind in your particular case may be osteoporosis or de-mineralization of bone that is common in post menopause women. If your bones are somewhat osteoporotic than this may increase the amount of time for the bone to fully heal.

Another factor is smoking. I do not know if you are a smoker or not, but smoking definitely slows down the healing process in broken bones simply because it decreases the amount of oxygen that gets to the fracture site.

Your weight, if you are over-weight, may also play a role.

Circulation to your feet may also be a factor. All things being equal, most people in their mid-fifties should still have adequate circulation going into their feet but it would not be a bad idea for your doctor to check your circulation just to make sure.

As you point out a stress fracture in many instances will not show up on x-ray, so taking another x-ray at this point may not be of any value. Your only options would be another MRI which is expensive, or perhaps a bone scan which is also helpful in detecting fractures that do not show up on x-ray. But, in my opinion it may still be too early for that.

I would suggest to you that perhaps your primary care doctor may not be the best one to handle this going forward even though I recognize that she did a better job of diagnosing the problem than your podiatrist. If you were my patient, at this point I would recommend going back in to the walking boot, not the surgical shoe for at least another two weeks because as I have already stated time may be the biggest issue here.

If after two weeks you are still having pain then another MRI or bone scan might be indicated to measure the amount of healing that has transpired.

If there is still an indication that the fracture has not completely healed then the next course of action might be the use of a bone stimulator. A bone stimulator is a device that creates a "current" between both sides of the fracture line that helps the remaining fracture line to heal.

As a final thought and it is just a thought since I do not have the luxury of actually examining you, your doctor might want to check you for the possibility of what is known as a sub metatarsal bursitis. I mention this because it is a very common problem under the fifth metatarsal head and both a stress fracture and bursitis can be caused by the same factor, which is primarily excessive pressure under the fifth metatarsal head. So, in theory at least, you may have both problems and so there is a possibility that the fracture is actually healed, but the pain you are experiencing may be from the bursitis. Something to think about.

Marc Mitnick DPM
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