In fact, he has and says it doesn't hurt. I am worried something is going to go wrong and he will end up crippled. It sounds like your husband is not likely to listen to reason or gentle persuasion. Maybe a slap will get his attention. But deliver it gently - you wouldn't want to knock him off his crutches if he is still using them.
Men can be peculiar creatures.
In this capacity, they resemble a brontosaurus with attitude. Just plain dumb but not much you can do about it. Bribery might work. If the usual inducements to good behavior fail, you might offer a golf package in Myrtle Beach or a satellite dish pulling in 250 24-hour sports channels. You know him better than I do.