Tiny Tim is believed to have had rickets, tuberculosis (TB), polio, and/or cerebral palsy.

What is Tiny Tim's affliction?

According to Russell Chesney, a physician at Le Bonheur Children's Hospital at the University of Tennessee Health Science Center in Memphis, Tiny Tim suffered from a combination of rickets and tuberculosis.

Why did Tiny Tim have a crutch?

She wondered what was wrong with Tiny Tim. ... Second, Tiny Tim "bore a little crutch, and had his limbs supported by an iron frame," a reference to leg braces that were used to manage bowing of the legs. The single crutch also implied that he was affected on only one side of his body.