1. A method for automatically identifying a three-dimensional (3-D) central axis of a bone of interest in a 3-D image, the method comprising: receiving, by a processor of a computing device, the 3-D image of one or more bones, comprising at least a portion of the bone of interest, of a mammal; isolating, by the processor, the bone of interest from the one or more bones in the 3-D image; generating, by the processor (e.g., after the isolating of the bone of interest), a binary bone mask of the bone of interest; generating, by the processor, a filled bone mask for the bone of interest using the binary bone mask; generating, by the processor, a skeleton of the bone of interest; and generating, by the processor, a pruned skeleton to reduce the skeleton to a branch (e.g., a single branch, central branch, and/or main branch) corresponding to the 3-D central axis of the bone of interest.