How did Sai Baba's Udi cure the seemingly incurable disease of the doctor's nephew from Malegaon?

In a story from Chapter 34 of the Shri Sai Satcharitra, a doctor's nephew from Malegaon suffered from a severe bone-cyst, also known as Hadyavran. Despite the boy's uncle being a doctor and consulting with many expert surgeons, all native and foreign treatments, including surgery, failed to provide any relief. The family, having exhausted all medical options, heard about the great saint Sai Baba in Shirdi. They traveled to see Him as a last resort. Upon hearing their plea, Sai, the embodiment of compassion, reassured them. He gave them His Udi and instructed them to smear it on the wound. As Chapter 34 narrates, this simple act of applying the sacred ash completely uprooted the pain and cured the ailment that no medical remedy could touch.