Spanish surgeon Pedro Cavadas concluded here Monday the world's first-ever double leg transplant.

The operation performed by Cavadas and his medical team at Valencia's La Fe Hospital got underway Sunday night.

This was a "highly complex" operation that had never been done before, according to hospital authorities, who did not provide information about the patient receiving the transplant.

They said that Cavadas considered it necessary to wait for at least 48 hours before giving out information and asked both patient and donor to keep the matter confidential.

Cavadas previously performed on Aug. 18, 2009, the world's first face implant to include both jaw and tongue, on a 43-year-old man who was released from hospital close to a month after his operation.

The surgeon also did the first double transplant of forearms and hands on a Colombian woman, Alba Lucia, who was operated in November 2006 and was able to go home 18 months later.

In November 2006 he successfully reimplanted a 20-year-old man's right leg that was amputated in an accident at work.

In that case, in order to save the extremity while the stump was still in usable condition, he provisionally reimplanted it in the left leg, first in the groin and then in the ankle.