The Shulhan Aruch (Orah Haim 328) rules that if a bone became entirely dislocated on Shabbat, it is permissible to put it back into place, and this does not fall under the category of Refu’a – medical procedures which are forbidden on Shabbat. However, the Aruch Ha’shulan (Rav Yechiel Michel Epstein of Nevarduk, 1829-1908) writes that modern medical science has found that broken or dislocated bones could pose a potential danger to the patient’s life, and so one may even violate Shabbat if this is necessary to receive treatment in such cases. This is the ruling of Hacham Ovadia Yosef. Therefore, if one suffers from a dislocated or broken bone on Shabbat, everything necessary should be done to ensure that the patient receives proper treatment, including driving the patient to a hospital and taking x-rays, if the doctor feels this is required.
One may place a non-medicated band-aid on a wound on Shabbat, and it is permissible to tear open the wrapper and remove the stickers. Hacham Bension Abba Shaul (Israel, 1924-1998) explained that since the stickers were placed from the outset with the intention that they would be removed, removing them does not violate the prohibition of “Kore’a” (tearing on Shabbat). However, Hacham Bension added that one may not remove a band-aid from his skin if this is certain to result in hairs being pulled out from the skin. In his view, removing a band-aid is allowed only if it is uncertain whether hairs will be pulled out as a result. Hacham Ovadia disagreed, noting that pulling out hairs is forbidden on Shabbat only by force of Rabbinic enactment, as opposed to Torah law, and thus it is permissible to do an action that would unintentionally result in the removal of hair. According to Hacham Ovadia, then, it is permissible under all conditions to remove a band-aid on Shabbat, even if this will definitely cause hairs to be removed, though he adds that if this can be done after Shabbat, it is preferable to wait until Shabbat ends.
Hacham Ovadia ruled that it is permissible on Shabbat to use powder to stop bleeding. Such powders are commonly used, for example, by Mohalim after a Berit Mila, and Hacham Ovadia maintained that they may be used on Shabbat, since they do not actually heal the wound, but simply stop the bleeding from continuing. Likewise, Hacham Ovadia permitted pouring iodine on a wound to disinfect the area, since the iodine is used not for healing, but to prevent infection.
Summary: A broken or dislocated bone is considered a potentially dangerous situation, and thus one may desecrate Shabbat if necessary to treat such a condition. It is permissible to use non-medicated band-aids on Shabbat – this includes tearing open the wrapper, removing the stickers, and applying the band-aid. It is also permissible to remove a band-aid on Shabbat, though if this is certain to cause hairs to be pulled out from the skin, it is preferable to wait until after Shabbat, if possible. It is permissible to apply powder to wounds to stop bleeding, and to pour iodine on a wound to disinfect it.