How are the worn knees on trousers of pawnbrokers assistance to a clueto mystery in redheaded league?

In Arthur Conan Doyle's short story "The Red-Headed League," the worn knees on the trousers of Jabez Wilson, a pawnbroker, do not directly assist in solving the mystery. The worn knees on Wilson's trousers have to do with his habit of crawling under counters and tables in his shop to examine various items. Therefore, the knee holes are only mentioned in the very beginning to add extra detail to the character and are irrelevant to the solving of the mystery.