What happens if the Alloderm isn't incorporated on the lower breast skin flap? If it is free floating in the breast pocket?

If the AlloDerm graft does not incorporate to the tissues, it will be free floating. The AlloDerm graft will not be reabsorbed and will eventually "ball up" and turn into thickened scar tissue. If the graft does not take and become vascularized, there is also a higher risk of infection. Good luck.

Yes, if  for some reason the acellular dermal matrix doesn't incorporate as planned, it can be "free-floating". Unfortunately, if this does occur, it can be a potential source of infection.  On the other hand, it may not cause a problem. Best wishes.

Though rare, non-incorporation happens. The alloderm does not develop cellular integration and new blood vessels within the tissue to which it was transferred. In this case, the graft can be sterile and in the same capsule as the breast implant or tissue expander. Sometimes this can be a problem, but most of the time doctors and patients are unaware.In most cases, there is only a portion of the alloderm that is not incorporated and when I encounter this in breast reconstruction patients, for example when the expanders are changed for implants, I will remove the portion that is not integrated.