A walking stick or a cane. Every lame person should have one.
Basic canes and walking sticks can be purchased at stores like Walmart or Target. Higher end canes and walking sticks can be purchased online at Ebay or Amazon. Going through the classified section of Craigslist might also locate what you are looking for.
a cane
A cane is meant to be leaned apon and assist to take weight off the legas as one walks. It will have a curved handle at the top or a "T" shape or one of several designs, but with the top able to support the weight of a person leaning against it palm down. A well fitting cane to be useful to the user is slightly longer than the distance between the ground and their palm with the arm hanging down at their side. A walking stick is much longer. Sometimes it can be as tall or taller than the user. It is a straight pole, usually round wood, or a long tappered branch. The walking stick is usefull for walking uneven terrain and is gripped toward the upper end with the hand higher than the elbow.
In the story, Willy Wonka is known for carrying a cane in one hand and a top hat in the other.
Here is the name of one breed. A good place to start researchign them. Diapheromera femorata
Amazon, is an online retailer, which offers many products. Amazon is where a wooden walking cane can be purchased and delivered right to the door of the customer. The product is reasonably priced and the shipping and handling is not to outrageous for the quality of the item.
I don't believe that the book specifies. However, a cane or walking stick was a common accessory for all gentlemen in the Victorian Era, it would have been unusual for him not to have one. Add in the fact that he may have been wounded in the leg (or possibly the shoulder), it would have been something he may have needed on occasion.
There are many board games in which one might use stick figures in their drawings. Examples of board games where one might use stick figures in their drawings include Cranium and Who? What? Where?, a drawing game.
This answer depends on mobility needs and comfort. Some can get by with a straight, one-leg cain with a rounded top. Others find a cane with a handle offers more support. If more stability is required, a quad cain with 4 legs can be used.
I do not know myself, but I have some stick insects myself and one of them spat out green slime. Maybe this shows he is sick????
Michael McCary has scoliosis. So he needed it for chronic back problems.