I don't see anything that screams "breed me" but there isn't anything terrible about her either. I don't think her age or the changes to her joints would prohibit breeding. Doc O Lena was foundered so bad she could barely walk and she had two foals. You might have heard of them Dry Doc and Smart Little Lena!
I'm kind of the opinion that there are a lot of horses to choose from right now and it would be much cheaper and faster to find one you liked and buy it rather than trying to raise one yourself. It takes much less time and you get to pick the color and the gender.
Evidently you're mixing up your quarter horses. Poco Lena was the mother of Doc O Lena and Dry Doc. Her founder was made so horrid because of an incident where her previous owner had died and the hauler left the horses in a trailer, with no food in water in the desert. Doc O Lena sired sons like Smart Little Lena and Tap O Lena.
As for the mare, she has very good cutting lines, and if her resulting foal was a good one, I'd say that it wouldn't hurt to breed her if you breed her to a stud with cow sense and nice cutting lines.
Notable horses I saw in her lines were Doc O Lena, King and Peppy.
So she's got some good lines for breeding, and even though foals take a long time to raise, it's always rewarding to start them from the ground up, and see them grow. That way you always know what the horse has done and been through. The choice is yours but I'd say it'd be worth a try.