Denis ‘Mac’ Maguire, the main character in The Mac Maguire Detective Mysteries by Patrick Walsh, has a chronic spinal condition, which causes him chronic pain and mobility issues.
From the author:
All of my crime books feature a character called Dennis ‘Mac’ Maguire. He’s an ex-policeman and murder specialist who was forced to retire from the force because of a spinal disability. His disability was brought to light after his wife had died and he could no longer cover up the fact that he was constantly in pain. The books chart Mac’s progress back into work as a private detective, and then as a consultant to his local Major Crime Unit, where he once again discovers the unique gifts that help him solve the most puzzling crimes.
UK publisher: Garden City Ink