"As we understand, they were at, they have these kids' places where you jump on trampolines and stuff like that," Yankees general manager Brian Cashman said Friday.
Chamberlain had surgery on Thursday night at St. Joseph's Hospital and is expected to remain in the hospital for several days for the injury, which resulted in an open flesh wound around the ankle.
"I know he did it on the trampoline, that he was bouncing," manager Joe
Girardi said on Saturday.
Girardi was at the hospital early Friday morning, visiting with Chamberlain
for roughly 30 minutes and said both got a little emotional.
"(Joba) was OK. What he's going through is very difficult, because you work your rear end off for nine months, and you get real close to doing what you wanna do again, and you have a setback," Girardi said Friday. "And it's crushing for him. It's difficult for him. My heart goes out to him.
"We're behind him, we're gonna take care of him, we'll get him back. But right now, he's going through a hard time."
According to the New York Daily News, Chamberlain lost a significant amount of blood and was taken by ambulance to the hospital. When asked specifically about the report, Cashman said he was "not in a position to answer that."
There was no timetable for Chamberlain's return, but Cashman labeled it a "significant injury." Chamberlain already was working his way back from Tommy John surgery last June.
Cashman did not have the results Saturday morning on Chamberlain's MRI exam and CT scan, which were done on Friday. Cashman had said he would visit the pitcher after the tests were administered.
"I just feel for him as an individual, as a member of our family," Cashman said. "We care a great deal about him, and we're just right now gonna be there (for him).
"From a team standpoint, it's a massive loss, because he's really good. But right now the most important thing is not what it means to the team, but what it means to him personally, in the present and the future. Right now, I don't have any answers for anything."
When asked if the injury could be career-threatening, Cashman said: "I couldn't say; I just couldn't say. I'd like to say no. My heart and my gut tells me no, that's not the case."
According to Dr. Michael Kaplan, ESPN's medical analyst, Chamberlain likely will miss most of the season, as the injury leaves him unable to put weight on the leg for four to six weeks. A lengthy rehabilitation that includes range-of-motion and strengthening exercises will be needed.
The wound in an ankle open fracture/dislocation typically is treated promptly to prevent infection before a fracture reduction is performed with plate and screw fixation carried out, according to Kaplan.
During his early recovery, Chamberlain will be on crutches and wear a walking boot.
"I think you all know Joba is someone who has a history of healing very well. But at the same time, this is unfortunately the news of the day," Cashman said.
The Yankees were not expecting Chamberlain to return from elbow surgery until June at the earliest. Chamberlain's rehabilitation was progressing so well, he thought it could be sooner.
"We thought it was realistic to get him back around June, and I don't think that's so realistic now," Girardi said. "It's a power arm that was gonna come back strong. We were thrilled to death the way he was throwing the ball."
News of Chamberlain's injury was tempered -- to a degree -- by Derek Jeter's return to the lineup after missing eight days because of a stiff left calf.
Jeter was listed as the leadoff hitter for a Yankees' split-squad, spring training game against the Minnesota Twins on Friday. The team captain first felt stiffness during a game on March 14.
"I feel extremely bad for him," Jeter said of Chamberlain. "He's worked extremely hard to get his arm back in shape -- and seemed as though he was ahead of schedule on that, and that's because he worked extremely hard. To have something like this, a fluke accident, I just feel really bad for him."
Information from ESPNNewYork.com's Andrew Marchand and The Associated Press was used in this report.