My 3 year old daughter got her pinky finger closed in the door last night. It broke the skin. We took her to urgent care and they did an x-ray. While waiting for the results, the tech said that if there was a fracture they would put her on antibiotics. The way I understood it, they would skip the antibiotics if there was no fracture.

She ended up having a hairline fracture and is now on Keflex. Why would they only prescribe the antibiotics if the bone was broken?

1 Answer 1


This is known as antibiotic prophylaxis. It is to prevent infection in the bone (osteomyelitis).

If the bone surface is intact, pathogens like bacteria cannot penetrate it easily, but in the presence of an open fracture (when the bony injury is exposed to the environment due to skin and subcutaneous tissue damage) antibiotics are used to prevent infection.

In some countries, an open fracture may be known as a compound fracture.


  • I understand the need in the case of a compound fracture, but the was a completely enclosed hairline fracture. No bone was exposed - the skin was broken but not even deeply enough to reach muscle
    – Drew
    Sep 9, 2018 at 12:53
  • True that’s not an open fracture, but some clinicians will be cautious even if only the skin is broken, as it is still a source of potential infection near a fracture, which could spread through the relatively intact tissues under the skin.
    – Chris
    Sep 9, 2018 at 13:01
  • 1
    @Drew I would add that the tissue between the skin and bone on a 3-year old's little finger is only a few millimeters thick. It wouldn't take much for an otherwise minor infection to make it to the bone.
    – Carey Gregory
    Sep 10, 2018 at 3:59

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