Yao Ming is calling it quits at age 30. Reuters

Houston Rockets' center Yao Ming has called it quits after a long battle with injuries.

Over the last six years, the 7'6 China-born star had multiple injuries and surgeries over the course of his career, including a toe infection, a broken bone in his left foot, a broken right knee, a stress fracture on his left foot, a hairline fracture in his left foot, and a stress fracture in his left ankle.

Plenty of professional athletes suffer injuries, but it's very possible that Ming's injuries, and his inability to fully recover from them, contributed to his retirement.

The fact that Ming is retiring at age 30 might be what separated him from other players who were extremely tall, and weren't able to have long careers. He was a physical presence and both a threat on offense and defense.

Unlike Rik Smits, a 7'4 center for the Indiana Pacers, most players who are taller than average centers, have had troubles maintaining a presence on both ends of the court and having a long career. Ralph Sampson, Mark Eaton, Manute Bol, Gheorge Muresan, and Shawn Bradley each were all 7'4 or taller, and only Eaton was able to stay in the NBA more than 12 seasons under steady minutes, though the Utah Jazz big man was mainly used for his defensive presence.

LIke Sampson, Ming was a former first pick in the NBA Draft. In Sampson's case, he had back and knee problems that derailed his career. Sampson was only effective for three NBA seasons, while Ming was effective for about seven.

Ming put up solid numbers when he was healthy. He averaged 19 points and 9.2 rebounds a game after nine NBA seasons.

MUST READ: Yao Ming Retired: Rumor, Says Agent Zhang Jiming

MUST READ: Yao Ming to Retired: Did Injuries Overcome the Gentle Giant? [PHOTO]