Holder broke his left shoulder, left hip and right heel when crashing at Brandon on Friday and has already undergone surgery to repair a dislocated hip.
The Australian is now scheduled to undergo further procedures after the incident that has wrecked his season.
Poole manager Neil Middleditch told the Coventry Telegraph: “Dare I say Chris is as laid-back as ever, he’s fairly philosophical about it although he’s in a great deal of pain, and the hospital did a great job in looking after him and making him comfortable.
“It’s going to be a long road to recovery for Chris, but I’ve been in the sport all my life and I’ve seen this far too many times. As a rider you accept it as part of the career path you’ve chosen, and difficult as it sounds you have to put these things behind you.
“Chris has got some nasty injuries, but he will recover and he will be back. He’s got such a great mind-set and is so laid-back even in the condition he’s in now.”