All Blacks midfielder Charlie Ngatai still on sideline

Former All Blacks Charlie Ngatai and James Broadhurst are still in the same boat.

That boat is charting uncertain waters and no one knows for sure when it will come back to shore for them to resume their rugby careers after long-term concussion symptoms have prevented them from taking any training contact.

"He's getting better. It's been an incredibly slow process. He's not back in full training but is starting to ramp things up a bit. There is a bit of light at the end of the tunnel, but we are not going to rush that. His health is the most important," says Chiefs coach Dave Rennie of Ngatai. "It's been a frustrating time for him."

Tasman's Alex Nankivell has trained as cover for Ngatai, who was a shoe-in for the All Blacks until a head knock in May last year. Other options for the No 12 jersey include Anton Lienert-Brown, Stephen Donald, Johnny Fa'auli and the versatile Tim Nanai-Williams

Former Chiefs such as Ben Afeaki and Craig Clarke were forced into premature retirement due to concussions that never allowed them to regain full fitness and, in particular, the ability to train at a high level and take contact or lift their pulse rate without headaches.

Former loose forward Sean Polwart has not announced his retirement as such, but has not played since taking a bad head knock nearly two years ago at Chiefs training, and has since helped run the Auckland defence.

Hurricanes assistant coach John Plumtree said the outlook for lock Broadhurst, still battling concussion symptoms, is unchanged. After missing all of the 2016 season, Broadhurst is still a contracted Hurricane, but is rehabbing under his own steam, though with full access to the facilities at the home base of Rugby League Park.

"Nothing has really changed with James. He hasn't taken part in anything physically. He's still part of our group and is going through the process of coming back, but when that will be, just not sure. It's not something you can put a timeline on. It's bloody hard for him and hard for us, as we'd love to have him back, but there is no pressure from our side to get him back in," Plumtree says.

The Hurricanes will still have plentiful locking options in Mark Abbott, James Blackwell, Geoff Cridge, Michael Fatialofa, Vaea Fifita, Sam Lousi and Blade Thomson.

Rennie, in his sixth and final year at the helm of the Chiefs, did confirm that the franchise will persist with its co-captains policy, with Sam Cane and Aaron Cruden again leading the side. Cruden will have his final season in New Zealand rugby before joining Montpellier, while Cane is touch and go for the February 24 Super Rugby against the Highlanders due to an ankle issue. The returning Mitch Karpik is a more than adequate replacement should Cane not be ready.