McCullough injured both his anterior cruciate ligament and medial collateral ligament following friendly fire from Adam Blair in Round 21 last season.
The 28-year-old is healing well though and is now running freely with the extended Brisbane squad in pre-season training.
“It is good to be out there running with the boys again today,” McCullough told broncos.com.au.
“I am not stuck back at the club riding a bike or doing something else.
“It is tough but a good feeling.”
It’s unlikely McCullough will take part in any trial matches before the start of the 2018 season but the veteran rake is on target for Round 1.
“I just have to nail this February – the next month of training,” said McCullough.
“I’ll be doing a bit more contact, tackling, and game situations to test the leg out.
“But it feels good and to be out there with the boys – it is something I have definitely missed.”