Edgar Sosa, the starting point guard for the New Zealand Breakers of Australia’s National Basketball League, was changing after practice one morning last month when he heard a commotion coming from the coach’s office, where his teammates were watching the Boston Celtics play the Cleveland Cavaliers in the N.B.A.’s season opener.

Sosa soon learned what his teammates had seen — that the Celtics’ Gordon Hayward had crumpled to the court at Quicken Loans Arena with a grisly injury that contorted the lower part of his left leg into the shape of an ampersand. From his safe remove on the far side of the world, Sosa watched the aftermath unfold on television, and part of it was eerily familiar. He spotted the Celtics’ Al Horford.

“I saw Al’s face,” Sosa said in a recent telephone interview, “and it was the same face he made when it happened to me.”

In 2011, while he and Horford were playing for the Dominican Republic in an Olympic qualifier in Argentina, Sosa crashed under the basket and, in clinical terms, sustained compound — or open — fractures of his right tibia and fibula.