The same knee, from $9,350 to $44,187.

Same city. Same operation. Nearly five times the price.

Six hospitals in Dallas replace knees. Your plan pays $9,350 at one of them and $44,187 at another.

Medicare grades all six on how often a joint replacement goes wrong there. All six came back the same. Not one better. Not one worse.

And the hospital Medicare has watched most closely, 640 operations, is the cheapest one on the list.

Somebody put the expensive hospital in your network. Nobody checked whether it was better.

That is the part that should bother you. Not that prices vary, everyone knows prices vary. That the difference was never tested. We have all assumed the costly hospital is the careful one, and it turns out to be an assumption nobody ever went and looked at.

Those are middle prices, and the range behind each one is wide. Your own plan sits somewhere in it. That is worth knowing before you renew.

Both halves of this are public. The prices come from files hospitals are required by law to publish. The results come from Medicare. Anyone could have put them next to each other. Nobody had.

At $44,187 your plan is not buying a better knee. There is no evidence it is buying anything but a bigger number.