<s>[INST] i was riding a bike and met with an accident, my left leg toes except the big toe got fractured and there is a swelling on my feet around this location. Initially i was bandaged with casting and later i was suggested with a aircast shoe. Iam wearing this shoe but over a period of time my swelling turns to black colour. what is the reason? [/INST] Rest assured your swelling turning to black color is just part of the entire inflammatory response to your injury. What you have my friend is ecchymosishere is how it happened to you :) for your question what is the reason:after you injured your left foot, structures underneath your skin gets damaged (bone ligament fat small blood vessels)they bleed temporarily, but since you don't have a break in your skin (external cuts, open wound) the blood is trapped underneath your skin. Even if you did not ask I would like to tell you this as well, because you probably would like to know this and save u some time of asking another question:overtime this blood would slowly be reabsorbed by your body but some of them will find their way to your skin hence giving the appearance of black or darkening of the injured body part. They temporarily "stain" your skin. But through time they will also get reabsorbed by your body.till go away on its own so relax. Merry Christmas in advance Chat Doctor.  </s>