Four months ago the 29-year-old former Wallaby underwent neck surgery in a desperate effort to keep his rugby union career alive.

But on Saturday night he made his long-awaited return playing off the bench in the Brumbies' 40-16 demolition of the NSW Waratahs at Canberra Stadium, and said he's never felt better.

"It feels like I'm 23 again, so I've gotten a few years back," McInerney told The Canberra Times post-game.

"We'll just monitor it. The important thing now is keeping it strong so it doesn't happen again."

The neck injury came while the Brumbies were playing in Japan late last year, but it wasn't until about a month after McInerney returned that it became clear it was a serious setback impacting his arms and back as well as his neck.

"It was a wear and tear injury but it took one incident in Japan which was the straw that broke the camel's back," he explained.

"It was the last scrum of the game, my chin got stuck to my chest and it stretched and pissed off those nerves.

"It settled down on holidays for four weeks, but when I came back a lot of strength was gone in my arms."

"I had a couple of bulging discs - C6 and C7 - so they trimmed those away and I had some other damage like bone spurs - they said I had the neck of a 70-year-old," he added.

After a long but dedicated four months of rehabilitation, McInerney said he returned earlier than expected after Lachlan Lonergan's surgery for a fractured and dislocated ankle suffered against Queensland last week.

But McInerney was glad to shake off any cobwebs after getting "a new lease on life", especially against Brumbies rivals the Waratahs in a game that always seems to deliver an extra level of physicality.

"It's good to be back. I can't think of doing my rehab with better support staff," he said.

"My neck strength is even better than what it was before, which gives me a lot of confidence.

"There's nothing like crunching your head or neck in a scrum, so to test that in the game, it was good to get through it.

"The coaches gave me a few more minutes than I expected first game back but I feel like I needed that.

"I was pretty nervous during the week, so to get out there and play footy was very important."

With the recent surgery helping remedy his neck issues and allowed him to play, train and even sleep more comfortably, McInerney now has his sights set on a new Super Rugby contract.

His contract finishes at the end of June but with Lonergan out long-term, Billy Pollard and McInerney are set to keep the position depth solid, and give the latter a chance to pen another deal - whether at the Brumbies or another club.

"There's a lot of moving parts at the moment especially with what's happening with the Rebels which could see 40 more guys off-contract," McInerney said.

"Now I'm playing it's a lot better than sitting on the sidelines and have clubs forget about you. I'm in the nicest place now mentally to try and pick up a contract somewhere.

"Nothing's been said yet [from the Brumbies regarding contracts]. They're waiting to see how everything pans out.

"I'm just looking at every game to get better, and after a few more games I'll be back to my best."