Saints hooker Hartley discusses his injury situation

But the hooker admits there is still no time frame for his comeback.

Hartley has not played since the win at Worcester Warriors on December 21 last year due to what Saints boss Chris Boyd previously called 'a grumbly knee'.

And it remains unclear when Hartley will be back as the 33-year-old continues his recovery.

"If you break your leg or hurt a shoulder, you usually get a time frame, but unfortunately with my knee at the moment it's open-ended," Hartley said on BT Sport's Rugby Tonight programme.

"I can't put a time on it, which is frustrating because I can't train towards something.

"I basically give it a go every day, see how I react and if I can progress and up my training load and I don't get a blow-back that keeps me out of training for a couple of days it's a positive.

"At the moment, I'm making incremental improvements in my rehab.

"Ultimately, just to play again would be nice, let alone playing at Twickenham, because that is the dream.

"Just playing club footy or being able to run around the garden with my little one would be the dream actually.

"I'm sticking at it."

Saints, who finished fourth last season, will start their Gallagher Premiership season at Saracens on Saturday.

And Hartley said: "There is more expectation.

"We obviously blooded a lot of young guys last year and if you took Tom Wood, Ben Franks and myself out of the team, the average age would be about 20. We kind of drag it up if we're near it.

"But in terms of our back line, the guys we've blooded there have been really encouraging.

"Last year was a year to find their feet with no real expectation but guys like Rory Hutchinson, Fraser Dingwall and James Grayson have done alright.

"Now they need to back it up because a lot of young guys can have a good first season and a good second season, but it's about sustaining that and improving on your game when you're chasing higher honours.

"It comes down to playing well for your club week in, week out - consistency of performance."