Rockliff's 2021 season was derailed in early May when he damaged both of his knees during a game in the SANFL.

After undergoing surgery on both knees, Rockliff was rushed back to hospital a few days later when he developed deep vein thrombosis.

It was then that a series of blood clots on Rockliff's lungs were discovered.

The former Lions skipper has been on blood thinning medication since, and he was barred from taking part in any contact drills when he returned to training duties several weeks ago.

The 31-year-old made the decision to retire after a recent discussion with his specialist.

"I spoke with the specialist and the clot is still there," Rockliff said.

"They can't guarantee it'll go away and if you get hit where that clot is, it can transport up to your lungs, so the risk factor was too high and it's not really worth risking your life over.

"It is the best thing in the end for me to call time on my career.

"The people I have spoken to have celebrated with me but there have been a few tears shed.

"It's been emotional but also the right thing to do."

Rockliff informed his teammates of his retirement on Tuesday morning, bringing an end to his 208-game career.

The two-time Lions best-and-fairest winner moved to Port as a restricted free agent before the 2018 season but his career never took off at the Power, despite being able to string together a series of strong displays in 2019 and 2020.

Power coach Ken Hinkley was saddened by Rockliff's retirement.

"Tom is outstanding person to have around the group, as much as sometimes he annoys the hell out of us," Hinkley said.

"He would have to be one of the smartest players I have come across in my time in the game and it is a shame he has been unable to get back on the park following a very unusual and frankly pretty unfortunate set of injuries.

"It is telling of his character that he didn't sit there and get down about his bad luck and instead continued to bring energy to the group and help guide our younger players."

Australian Associated Press