SYLMAR (CBSLA.com) — Rare, conjoined twins separated surgically nearly 10 years ago are back in the news Tuesday as one of the girls needs to undergo major surgery to remedy complications from being fused to her sister.

Doctors are expected to perform surgery on Renata Salinas Fierros at 5 a.m. Wednesday to ease her scoliosis and the severe complications she endures that keep her from standing tall.

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The operation is also expected to ease the pain and pressure she feels from a condition that compresses her chest, too.

“They want to straighten my back a little bit more ‘cause it’s like getting more crooked and that’s bad for my body,” she said.

Renata’s mother says she’s been told the operation will be the second biggest of her young daughter’s life.

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The twins first made headlines at birth in 2005. The girls were born conjoined facing one another and fused at the pelvis and stomach.

A year later, a medical team of 80 people at Children’s Hospital Los Angeles successfully separated the sisters.

Of the two, Renata’s sister, Regina, has more daily complications that require a wheelchair and multiple breathing machines but the fourth graders are generally happy and healthy.

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The twin’s parents say the girl’s will likely face many more operations but they are expected to live full and healthy lives.