What is the probability of skin necrosis if I want to do facelift surgery after head and neck radiotherapy?

Radiation therapy can cause microvascular changes in the area that was treated. These are likely permanent changes that can adversely impact the outcomes of facelift surgery.The effect it will have will depend upon:1) What kind of radiation you had/how deep it penetrated2) Total dose of radiation3) How long ago it was done4) Where the beam was focusedAll in all you do have a potentially increased risk of having issues with your facelift flap that can result in some scarring issues.  It does not mean that this will definitely happen, but the risk is higher.  The factors above will influence this as the type of facelift you are considering will as well.There is no study that can give you an exact percentage of increased risk of skin necrosis.  It would be very hard to get a large enough sample size in this type of a population to ascertain this information. 

High. Radiation causes a permanent vasculitis that impairs the circulation to the skin. If you undermine that skin as in a facelift, the skin may die from inadequate blood supply.One could consider other treatments, such as fat grafting to restore volume to the aging face. This may also improve the quality and texture of the skin appearance, as stem cells exert their effect.Consider non-invasive treatments that restore volume. Should any procedure be done, it would have to be a highly modified facelift with limited skin undermining. 

Is impossible to comment on your specific situation. However, radiation creates a progressive decrease in blood flow to the skin which influences wound healing. You should pursue a facelift only with a plastic surgeon familiar with the aesthetic operation as well as head and neck cancer.