The AlloDerm and DermaMatrix groups had similar rates of complications ( 33.6 percent versus 38.8 percent ; p = 0.52 ) , consisting mostly of skin necrosis ( 17.8 percent versus 21.4 percent ; p = 0.66 ) and infections ( 13.9 percent versus 16.3 percent ; p = 0.29 ) , both of which led to tissue expander losses ( 5 percent versus 11.2 percent ; p = 0.11 ) .