1 The results of prophylactic measures for femoral head AVN have considerable variation, but certain generalizations can safely be stated. 2  Namely, the clinical results of core decompression alone deteriorate with more advanced lesions.
1 Melasma is very common skin ailment. It can occur to anyone, but young women with brownish tone are more likely to contract with it.  The condition is often linked with female hormonal changes. Change in level of estrogen and progesterone may cause melasma.
From the research I've done, it seems that some birth control pills cause melasma and the only way to (attempt to) prevent it is to use sunscreen. I use sunscreen every day (SPF 30) and have used an age spot/dark spots facial cream for the past 6 months.