Wedges are a lot comfier and easier on the joints than heels, if having a heel is absolutely necessary. But imo, flats are fine in a corporate environment provided they're 'dressy' flats and don't look out of place with tailored clothes I would find it very hard to accept that women MUST wear some form of heel as part of a work uniform in a corporate setting, I'd consider it discrimination on the basis of gender - blokes don't have to wear heels so why should women be forced to risk damaging their feet and joints?
If you need some ideas, Wanted Shoes and Style Tread offer lots of really gorgeous, high-quality flats in all different styles. (Psst: big sales on atm, too!) If I were working in an office where the dress code is quite strict, I'd see absolutely no problem with some dressy flats - especially if you have a bad ankle or knee (or just don't like torturing the balls of your feet by wearing heels constantly!).