Had a knee injury on 7/31 occasionaly my feet swell. took a ultrasound no clots. walked a lot yesterday on my feet all day swell came back. is serious?

Swollen feet: Your knee injury is not the cause of your swollen feet. From your description, it sounds as if you're forming edema in your legs. Some causes of this edema formation are cardiac and kidney disease. Another cause may be varicose veins. See a cardiologist for evaluation and if your cardiac and kidney function are normal, ask for a venous doppler study of your legs to see if you have varicose veins.

Feet swell: Some knee surgeries get no assistance with postoperative edema. This may be your case , but there aren't enough specifics to know form your description. See your surgeon sooner rather than later so you can get the assistance you need. Good luck.