There are a lot of bundled payment programs, but the best known one is the Center for Medicare and Medicaid Services’ (CMS) Comprehensive Care Joint Replacement (CJR) program. It’s complex, but Medicare essentially sets a target for the total cost of a hip or knee replacement (including the physician, hospital, and rehabilitation fees), and pays a bonus if costs are kept down and quality measures are met.

More than 23,000 of the men and women lined up in Hopkinton for the start of the 2019 Boston Marathon will be there having run under an age-specific time threshold in another marathon, which shows just how unremarkable qualifying for the Boston Marathon really is. And yet, if you ask any of the 500,000 Americans who will run a marathon this year (and many of the million-plus marathoners in other countries), qualifying for Boston - a ‘BQ’ - can be a bit of an obsession.