It is narrated from Qatadah (may Allah have mercy on him) that bandages and splints are not to be placed on a wound or a fracture, if it is in a place of ablution, until he has performed his ablution for prayer and washed the place of that wound because of the blood that has appeared from it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1088