Former New England Patriots tight end Rob Gronkowski, who announced his retirement in March, said in an interview that he absorbed about 20 concussions in a lifetime on the gridiron.

Gronkowski, 30, told CBS News correspondent Reena Ninan that he would only allow a future son to play football after educating him about the suffering he endured during nearly a decade in the trenches.

“I truly believe that any injury that you receive is fixable,” Gronkowski said. “I went through it. I had nine surgeries, probably had like 20 concussions in my life, no lie. I remember five blackout ones.”

Gronkowski, a three-time Super Bowl champion, established himself as one of the most dominant tight ends in NFL history and was named to the All-Pro first team on four occasions. But he was dogged in his final seasons by back, knee, ankle and arm injuries that limited his ability to stay on the field.

.@RobGronkowski told CBSN's @reenaninan that he'd let his son play football ––only after educating him about what he went through in the game.



He said he had about "nine surgeries, probably had 20 concussions" playing football. https://t.co/CYw25maOgo pic.twitter.com/dltWn6Y4k2 — CBS News (@CBSNews) September 12, 2019

He finished his career with 521 receptions for 7,861 yards and 79 touchdowns and was one of the most dominant receivers in the game when he was fully fit. He was also known for his colorful personality on and off the field.

Last month Gronkowski reflected on the hours after Super Bowl LIII – the final game of his career – saying he was in bed in tears after playing a vital role in the Patriots’ 13-3 victory over the Los Angeles Rams.

He couldn’t enjoy it because of the pain.

Gronkowski was hit in the quadriceps during the game, leaving him with the deepest bruise he had ever had in his life. He spent weeks unable to walk properly, sleeping just 20 minutes per night.

His mood was volatile – one moment, he’d be feeling fine, as if he overcame the discomfort. The next moment, he’d be aching, unable to even sit down without focusing on the pain. Over the next month, he had to drain a liter of blood from his thigh.

That’s when he knew it was time to retire.

“I was like all right. This is a sign,” he told the Associated Press in August. “I was saying to my friends that this is a goodbye present from the NFL.”