For months, Linda Moss and her two sisters took shifts at their father's bedside in a hospital in Burlington, Ont.

But while they sat and held his hand nearly every day, an unseen wound festered beneath his bed sheets.

A bedsore had been silently forming on Bob Wilson's backside, eating away at his flesh until it left a gaping hole bigger than a football.

"We couldn't believe what we saw," Moss said.

"It was ... so massive. It was black, dead, rotted skin. He was basically rotting alive, and we had no idea."

Eric Vandewall, president of Joseph Brant Hospital in Burlington, located about 60 kilometres southwest of Toronto, said he personally apologized to Wilson and his family for what happened, and staff are investigating.

"We are currently conducting a comprehensive and thorough review of Mr. Wilson's care while he was at Joseph Brant Hospital and we will hold further meetings with Mr. Wilson's family to share and discuss the results of our review," he said.

'It's to the bone, and it's pretty horrific'

Wilson, who is 77, fell in November and suffered a brain injury.

During his time in hospital, he started showing signs of improvement, playing games, shaking hands and even talking, but his recovery seemed to stop suddenly in February and the family couldn't figure out why.

It wasn't until the end of April, when he was ready to be transferred to nearby Hamilton General Hospital for surgery to re-attach part of his skull, that Wilson's family learned of the wound.

Moss said the family was told the surgery couldn't happen because her father had an infection. Then they were shown a picture that made their jaws drop.

What baffles us is how could a medical team … put a Band-Aid over black, dead, rotted skin and not raise the flag? - Linda Moss

A photo of the wound shows a large hole on Wilson's backside, with only a few clumps of skin and tissue remaining.

The image is so graphic, CBC decided not to share it, instead relying on the family's description, which accurately illustrates the sore.

Moss said staff at the Hamilton hospital told them the bedsore was one of the worst they've ever seen.

It was classified as unstageable, meaning the ulcer is covered in skin or dead tissue at the bottom of the wound.

"It's to the bone, and it's pretty horrific," she said.

Bedsores — also known as pressure ulcers — happen when a patient lies or sits in one place for a long time. As a result of pressure or friction, injuries to skin and tissue form over bony parts of the body.

Family struggles with feelings of guilt

The Canadian Patient Safety Institute (CPSI) says bedsores are preventable, but thousands of patients across Canada suffer from them every year, risking dangerous infection as a result.

A Hospital Harm Indicators report prepared by the CPSI points to best practices to stop bedsores before they start, including daily inspections of a patient's skin, monitoring it for moisture, and moving the patient carefully and often.

"We really encourage patients to be turned and repositioned at least every two hours," said Anne MacLaurin, a senior program manager with the CPSI.

Bob Wilson poses for a photo with his daughters before a fall that sent him to hospital. (Supplied by Linda Moss)

Families should also be included in a patient's care plan, she said.

Moss said her family was told her father was developing some redness and irritation, but that it was being treated.

They liked the hospital staff and trusted them to care for their father, but now they're left with complicated emotions, and wonder if they could have done something differently.

"It's devastating," said Moss. "It's torture, and we felt a sense of guilt, because if [we'd known], we could have helped turn him, or something.

"What baffles us is how could a medical team and several people … put a Band-Aid over black, dead, rotted skin and not raise the flag?"

Hospital promises to post bedsore rates

Vandewall said the hospital's routine for immobile patients includes turning them daily and checking for pressure ulcers.

He declined to discuss the details of Wilson's case, but said an incident like his is rare.

The family is sharing their story to raise awareness of what questions other families should ask about a loved one, and how they can be involved in his or her care.

Linda Moss does exercises with her father before the family found out about the bedsore. (Supplied by Linda Moss)

After what happened to Wilson, Vandewall said the hospital will voluntarily publish the rates of hospital-acquired pressure ulcers and surgical-site infections on its website, starting in June.

"We [want] to join Mr. Wilson and his family in taking a leadership position in bringing greater awareness to the issue, and public reporting is one of the ways to do that," said Vandewall.

'He could lose his life'

Moss said doctors have told them her father's infection has reached his bones, and he's resistant to many of the antibiotics that could treat it. She said her father's chances of surviving are slim.

Before the hospital stay and bedsore, Moss said her father was an avid bowler who loved golfing. She's still trying to wrap her head around what happened to the man she loves.

"It's hard to believe this happened and he could lose his life, not because of major brain surgery, but because of a preventable bedsore," she said. "That's what is so heartbreaking."