Did you know that the CIA and also the Russian KGB teaches their spies to put rocks in their shoes to cause them to slightly limp.
Do you know why they do this? You see, when someone is limping your mind is watching their body as it limps along and that takes quite a bit of visual bandwidth in the human mind.
This causes any normal human with only normal observation skills to forget everything else about the person except for the limp.
Most people will not remember their face only that a limping individual walked by (most people, I didn't say me).
This means the spy is safe from being given away by facial features.
All they have to do then is wear a pair of sunglasses for their identity to be concealed.
Now then, if it takes quite a bit of bandwidth for the human mind to process all this information, then you can understand it is going to take an animator a little extra time, and planning to draw someone walking with a limp.
So, let's talk a little bit about how we would draw someone walk in with a limp.
You must remember that your sketches must include side-to-side movement where the figure is moving on an "S-like" path, but it should not be exact, more like the beginning of an "S-path" with an abrupt angle, then back to the "S-Path" after a contact of the limping leg with the ground.
Meanwhile, you must also realize the changes in the height of the figure, as the head changes height as it moves forward so a lateral "S-curve" above also, thus, you have "S-lines" that are both horizontal, one flat, the other laterally vertical.
Everything else will remain the same as drawing a normal person with a normal gait that might be walking along the sidewalk.
Please consider this.
References: "The Animator's Survival Kit; a Manual of Methods, Principles, and Formulas for Classical, Computer, Games, Stop Motion and Internet Animators" by Richard Williams (director of animation "Who Framed Roger Rabbit"), Published by Faber and Faber, New York; 2001.
ISBN: 0-571-21268-9 And "3D Graphics & Animation; from Starting Up to Standing Out," by Mark Giambruno; New Riders Publishing; Indianapolis, IN; 1997.
ISBN: 1-56205-698-0