My commute is only a few miles each way, but includes an annoying climb which, during a typical ride, wouldn't be such a big deal. However, first thing in the morning or first thing at the end of a work day, it's a bit of a nuisance. I find there's a big difference based on the weather. On a cold or excessively hot morning, it's a lot more of a challenge than on a perfect Spring or Fall day.

My preparation is mostly psychological, and like Buzzatronic, I won't ever get off the saddle. However, if that's what you need to do to complete your commute without doing additional damage to your knee, then it's a no-brainer. Walk it, call a cab for half the trip, or do whatever you have to do to stay out of your car!