What are the signs that a fractured metacarpal needs reduction?

Deformity: The only way to know if a fracture needs reduction, is with x-rays. If the bone is obviously displaced or the finger is crooked, there is a good chance that the fracture needs to be reduced. See a board certified orthopaedic hand surgeon for evaluation and treatment.

Rotational Deformity: The most common metacarpal fracture is that of the little finger. When you make a fist the contour of the knuckles may be different. A small depression is probably ok. Any change in rotation of the finger usually requires reduction.