Islanders coach Jack Capuano announced on Jan. 26 that Okposo would be sidelined six to eight weeks but did not disclose the nature of the injury.
Okposo played in New York's first 46 games this season and is the Islanders' second-leading scorer with 44 points, four behind All-Star center John Tavares.
"I kind of had an idea before the break, but it definitely comes as a shock," Capuano said on Jan. 26. "Kyle's play is dictating how we go and the pace we play with."
The Islanders (32-16-1) have lost two of their three games without Okposo but lead the Metropolitan Division with 65 points, one point ahead of the Penguins.
Information from The Associated Press contributed to this report.