Shaquille O'Neal won four NBA titles during his 19-year career in basketball.

STORY HIGHLIGHTS

• Shaquille O'Neal announces his retirement from basketball
• Known as "Shaq," O'Neal had a 19-year career in the sport, winning four NBA titles
• He has struggled with injury and played just 37 games for the Boston Celtics last year
• The 39-year-old is fifth on the all-time NBA scoring list

(CNN) -- Four-time NBA champion Shaquille O'Neal has announced he is retiring from basketball after a 19-year career in the sport.

The 39-year-old posted a link to a video on his Twitter account that confirmed he is to hang up his boots.

In a brief message he said: "We did it. Nineteen years, baby. I want to thank you very much. That's why I'm telling you first. I'm about to retire. Love you. Talk to you soon."

O'Neal has been dogged by injuries in the latter stages of his career and played only 37 games for the Boston Celtics this season after struggling with an Achilles tendon problem.

He returned for two playoff games against the Miami Heat but managed just 12 minutes, and he told an ESPN reporter that he didn't want to let Celtics fans down.

I didn't want to let people down two years in a row. I didn't want to hold Boston hostage again
--Shaquille O'Neal

RELATED TOPICS

He was quoted by AFP as saying: "I really thought about coming back but this Achilles is very damaged and if I had it done the recovery would be so long we'd have the same outcome as this last year -- everyone sitting around and waiting for me.

"I didn't want to let people down two years in a row. I didn't want to hold Boston hostage again.

"I'm letting everybody know now so the organization can try to get younger talent. I would love to come back, but they say once the Achilles is damaged it's never the same. I don't want to take that chance."

O'Neal won three titles with the LA Lakers after forming a devastating partnership with Kobe Bryant, and added to his haul with a fourth in 2006 when at the Miami Heat.

With 28,596 points, O'Neal is fifth on the all-time NBA scoring list and is second only to Michael Jordan on the all-time list of NBA Finals Most Valuable Player Awards.

He began his career in 1992 when the Orlando Magic picked him first in the NBA Draft. The following season he was named rookie of the year.

He took the NBA scoring title in 1995 as he led the Magic to the NBA finals in 1995, but they were beaten by Houston. He won the accolade again in 2000, when the Lakers won the finals.