Horne suffered the injury in November’s fiery Federation Shield final at the Halton Stadium which saw a brawl on the final hooter between Tonga and England after the home side’s comprehensive victory.
Assistant coach Richard Agar said that the injury will not stop Horne from preparing adequately for the upcoming engage Super League season, with last year’s beaten Grand Finalists looking to go one better.
Agar said: "The fracture was a slight hairline one and it will not hinder his pre-season.
"Graeme is due back at training next Monday after his break and he will be able to go straight into everything we are doing at this stage of our preparations."
The Tongans had to players sent off in the Federation Shield final, with three more sent to the bin in a hard-fought encounter.