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.

We leave the parking lot, riding side-by-side up a short stretch of fire road before cutting left onto a rock-strewn creek bed that climbed sharply. Making it to the top requires choosing a path that navigates boulders, gravel, damp leaves, and roots - and then executing. Gravel can spin; boulders may be insurmountable; leaves and roots are slippery when damp. The hill is steep enough that the wrong choice would bring me to a halt. I carefully select a good line and push forward, breathing hard.

In the 15 years I have practiced obstetrics, I have been the surgical assistant on hundreds of cesarean deliveries that seemed to me, at the time, to be unnecessary, and I’ve been the surgeon of record for a handful of unnecessary cesarean deliveries myself. I know firsthand how difficult it is for physicians, nurses, policy makers, and administrators, all of whom are well aware that the United States has a cesarean epidemic, to wrestle with it.