Physiotherapist Brien Seeney identified Nathan Cleary's intact tibia as the "single best piece of news" about the injury, and said a Round 1 return next year remained possible.
Speaking on the Magic Sponge podcast on Monday night, Seeney said tibia fractures can mean "long, complicated recoveries", while fibula fractures are more straightforward to treat.
"Fibula fractures by themselves heal really, really well with surgical fixation," Seeney said.
He cited Dylan Lucas, who returned after eight weeks, saying, "They return really well and really predictably. Dylan Lucas recently returned after only eight weeks and that's effectively what we've got here (with Cleary)."
His assessment followed Penrith chairman Greg Alexander's clarification on SEN radio Monday that reports of fractures in both bones of Cleary's left leg were incorrect.
"The reporting kept saying it was a double fracture. It wasn't a double fracture," Alexander said.
Alexander said Cleary broke his fibula, while pressure from that bone displaced the unbroken tibia and pushed the ankle bone through the skin.
Cleary also suffered a syndesmosis rupture, and two screws were inserted in his ankle, Alexander said.
Cleary is recovering from a second surgery, this time for a stress fracture in his other foot. His first operation treated a broken, dislocated ankle.
Seeney called the injury severe but said it was not career-threatening. "There is a scenario in which he could be back doing really, really well by Round 1," he said.