Former Guantanamo Bay inmate Omar Khadr is recovering from a 19-hour operation on a shoulder that was badly injured in Afghanistan 15 years ago, his lawyer, Dennis Edney, said Monday.

The Toronto-born Khadr remained in intensive care at the University of Alberta hospital and it was not clear when he might be able to go home, Edney said in an interview from Edmonton.

Three surgeons were involved in Friday's complicated surgery — first reported by the Globe and Mail — that Edney said should have been done years ago.

"What they did was take bone from different parts of his legs and muscles from other parts of his body to try to rebuild his right shoulder," Edney said. "There's no prognosis — it's almost experimental in some ways, and hoping that it works."

Khadr had gone into hospital expecting minor surgery that would have seen him back at school on Tuesday, Edney chuckled.

Now 30, Khadr was horrifically injured as a 15-year-old in a four-hour bombardment and firefight with American soldiers, who captured him in Afghanistan in July 2002. In addition to the shoulder injuries, he was blinded in one eye and still has shrapnel in the other that threatens his sight.

Could go completely blind

"There are times when you can see that the shrapnel has moved in the eye, which is always scary for me because he could go completely blind," said Edney, who has given lectures about his client all over the world. The lawyer said it might take a military surgeon with experience in shrapnel wounds to salvage Khadr's sight.

After his capture, the teenager was sent to Guantanamo Bay later in 2002, where authorities accused him of throwing a grenade that killed an American special forces soldier during the Afghanistan firefight. He pleaded guilty in October 2010 before a widely discredited military commission to five war crimes, and was sentenced to a further eight years in prison.

Khadr, who afterwards said he only pleaded guilty to get out of Guantanamo Bay, transferred to Canada in 2012 to serve out his sentence and was subsequently granted bail in May 2015 pending an appeal of his U.S. conviction.

Despite the pressing need and multiple infections over the years, Khadr received little treatment at Guantanamo Bay or in Canada. Three years ago, however, while he was still in detention, surgeons at the Edmonton hospital scraped bone and flesh in an effort to remove festering tissue.

Aiming for nursing school

Since his release on bail, Khadr has completed his high school diploma and was taking courses — as an honours student — in the hopes of being accepted into nursing school in the fall.

"It would be great for him to get into medicine in some form," Edney said.

Initially stiff bail restrictions have been eased over the last three years — although he is still barred from any contact with one of his sisters. For the most part, however, he lives a largely solitary lifestyle out of the glare of the public spotlight that once tracked his every move. He moved out of the Edney home where he had been living since his release and has been on his own in a small apartment for the past several months.

In addition to the stalled appeal in the U.S., Khadr is suing the federal government for violating his rights.