sprain, swelling, 5th metatarsal, electric shock lateral heel

by Maggie
(Cape Town, South Africa)

I sprained my left ankle 3 months ago, and experienced swelling and bruising on the lateral (outside) side of my foot in the 5th metatarsal region. Although the bruising healed, the swelling remained and I currently can't flex my ankle towards the right hand side. Whenever I do, I experience a sharp, electric shock that radiates from the outside of the heel (adjacent to the cuboid region) that spread across the top of the foot together with mild pain. It does subside very quickly, but is very unsettling and restricts movement. This started about a month ago and the swelling in the 5th metatarsal region is still present. I currently wear an ankle brace which helps to limit movement but doesn't seem to improve either the swelling or the electric shock. When resting I do still experience some pain, but this is very mild. Can you please advice whether I should see a doctor and if this might be caused by a fracture?

RESPONSE

Hi Maggie,

Assuming you were experiencing pain along the fifth metatarsal bone of your left foot right after your trauma three months ago, you probably should have seen a doctor back then. The reason being is that in many instances of inversion sprains where the foot turns inward, there is a high incidence of associated fracture of the fifth metatarsal base.

What happens is you end up with an ankle sprain and a fracture of the fifth metatarsal base. Over time the pain on the outside of the ankle (the ankle sprain) will heal but the pain does not resolve in the area of the fifth metatarsal because it is broken and is not being treated as a broken bone.

The fact that you mention you still have swelling in the area of the fifth metatarsal bone does concern me as a possibility that there is a fracture in that area.

The problem with fractures of the fifth metatarsal bone, particularly the fifth metatarsal base is that portion of bone has a very poor blood supply and with a poor blood supply goes the increased chance of a fracture not healing.

All fractures, but in particular fractures of poorly vascularized bone are best treated as soon as possible. The quicker the site is immobilized, the better the chances of healing. This is predicated on a number of factors such as the space, if any, between the broken bone fragments, whether or not there is a complete fracture or just a "crack" in the bone.

Additionally, factors such as smoking or some metabolic diseases will delay if not prevent broken bones from healing.

In cases such as yours where you have been walking around for three months with no true immobilization, or even non-weightbearing for that matter, there is a chance either the bone is still completely broken or you may have what is known as a non-union where fibrous tissue has bridged the broken bone, rather than osseous (bone) tissue. Because fibrous tissue is not healthy tissue and not structurally sound, there could be some degree of motion in the fracture site which would then cause some degree of pain and swelling.

Short of having broken the fifth metatarsal bone, there are other considerations as to what may be causing your continued discomfort.

Secondary to the inversion sprain, you may have dislodged (subluxed) the cuboid bone which is the bone just behind the fifth metatarsal. This is a tough diagnosis to make just by x-ray and is made by the exact location of the pain. Sometime a CT scan needs to be performed to confirm the diagnosis.

Additionally, there is also the possibility that you damaged the peroneal tendons which come down the outside of the ankle. Damage could range from a strain to a partial tear and because you have been continually walking of the foot, the area has not had the opportunity to heal. In fact the sharp, electric shock you experience when you invert your foot (move it to the right) may be due to further stretching of the damaged peroneal tendons.

Since "electric shock" is usually associated with nerve pain, damage to the sural nerve which passes in the same area would also have to be ruled out.

So, in answer to your question about whether you should see a doctor, I would think that would be a great idea. Three months is way to long for you to still be having these issues and it is safe to say they apparently are not going to disappear on their own.

Marc Mitnick DPM
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