Tommy John had an extensive Major League Baseball career. One that lasted nearly 30 years. Although it very well could've been about half that length, had it not been for a historical medical procedure.

In more recent medical news, many current and former athletes have been stricken hard by COVID-19, including Hall of Fame pitcher Tom Seaver, who died of the disease. The novel Coronavirus remains a dangerous problem for others.

Tommy John was admitted to the hospital

Tommy John has been an in-patient at a California hospital since mid-December, USA Today reports.

At one point, he is receiving breathing assistance and had pneumonia.

John has indicated that he's no longer getting assistance to breathe. However, he's still dealing with other significant issues, including serious weakness in his legs. He indicated that he would need to have physical therapy at some point to regain his strength.

Some reports had apparently erroneously named John as a COVID-19 skeptic. Something that he himself has outspokenly denied. His son, who shares his name, Tommy John III, is a different story, reports ESPN. Likely leading to confusion between the two Tommy Johns. The elder Tommy John also has three other children. A son-in-law, Patrick Mannelly, was a long-time player in the National Football League.

Ligament replacement surgery nicknamed for him

As a Los Angeles Dodger, John suffered a catastrophic injury in a game against the Montreal Expos in 1974. During the game, he lost control of his throwing arm. As it turned out, he'd torn his ulnar collateral ligament—a triangle-shaped ligament located in the elbow.

At the time, the injury probably would've ended the playing careers for most pitchers.

However, John opted to undergo a groundbreaking surgery by Dr. Frank Jobe. A tendon was removed from John's forearm and was used to replace the UCL in his elbow. Similar procedures had been done for other people but John's specific situation was the first of its kind.

It was considered highly unlikely that John would be able to pitch again.

Most pitchers who'd had major surgery on their arms at the time ended up retiring. John underwent a second surgery to reroute a nerve. But eventually, after more than a year of rehab and recovery, he returned to playing.

In fact, he continued playing for more than a decade. The operation John underwent, now popularly known as 'Tommy John surgery,' has become commonplace in baseball. It's also been performed on athletes from other sports.

Frequently mentioned as a Hall of Fame candidate, John played for six MLB teams. He retired with the eighth-most games started in MLB history. John was a four-time All-Star selection, three of which came after his surgery. He helped the Dodgers win three NL Championships, also helping the New York Yankees win an AL Championship. After finishing his playing career, he went into broadcasting and coaching.