DiPietro, who was placed on injured reserve retroactive to Feb. 28 because of the swelling, has not played since the Islanders' 3-1 loss to Carolina Feb. 6.
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Even if the swelling subsides and DiPietro shows significant improvement, the 28-year-old does not have enough practice time remaining to get back into game shape. With seven games left, the Islanders are eight points behind the Flyers and Bruins, who are tied for seventh in the Eastern Conference, so a place in the postseason is highly unlikely.
Considering the long, grueling road DiPietro has taken to rehab his surgically repaired knee, the team does not want to rush him back and risk aggravating the injury.
DiPietro will resume practicing if he makes strides in rehab, if only to allow the medical staff an opportunity to learn more about the condition.
Given the nature of DiPietro's injury and his medical history - multiple surgeries during the past three years - the Islanders want to pinpoint what causes the swelling and how the condition can be treated or prevented.
The Islanders' regular season ends April 11, but questions about DiPietro's future will persist.
DiPietro, who was 2-5-0 with a .900 save percentage and 2.60 goals-against average in eight games this season, still has 11 years remaining on his 15-year, $67.5-million contract and has played only 13 games in the past two seasons.
Despite DiPietro's injury struggles, Islanders general manager Garth Snow said he's optimistic that DiPietro can have a productive future.
"We feel that working with our goaltending coaches this summer, Rick will return to top form," Snow said.
This past week, DiPietro told reporters he was encouraged by his return to the Islanders in January, but he remained uncertain whether he'd play again this season.
"It's not a wasted year," he said. "I proved I could come back and play in the NHL. I know I can play. I've already proved it. I'm in the best shape I've ever been in."
When asked about his most recent stint on injured reserve, DiPietro said: "It's not even a setback. You can't turn back time. I did what the doctor said to do. Is it frustrating? Yeah. But it's part of what happens to athletes."