Surgeons at Le Bonheur Children's Hospital operated for 13 hours to separate the twins in what hospital officials called the most complex procedure every performed in the history of the facility, The Memphis Commercial Appeal reported Wednesday.
Joshua and Jacob Spates of Memphis, though joined at the lower spine and pelvis, have separate hearts, heads and limbs.
Doctors said the twins have health problems that will require ongoing treatment, but said they hope both will be able to walk with braces.
In 2009 the hospital launched the Le Bonheur Fetal Center to monitor and handle high-risk pregnancies involving congenital abnormalities.
Occurring about once every 200,000 live births, conjoined twins are extremely rare, health experts said.