Ratumaitavuki-Kneepkens had emergency surgery after injuring his neck while playing for Taranaki in their successful Ranfurly Shield challenge against Tasman in Nelson on October 6.
The 23-year-old suffered a hyperflexion injury to his cervical spine and scans showed a C5/6 joint dislocation.
A Highlanders spokesman yesterday said the talented fullback was "doing well and currently in a rigid collar".
His next key date was November 28, when he would have a review with a surgeon.
Ratumaitavuki-Kneepkens shared a post-operation photo on social media and thanked everyone who had sent their support.
"The price of progress is pain. Through tough times, seeing the good in situations has been made easy through human acts."
Ratumaitavuki-Kneepkens became a popular and influential member of the Highlanders soon after transferring south from the Blues.
He was defensively sound and his attacking prowess dovetailed nicely at the back with the explosiveness of another new recruit, winger Timoci Tavatavanawai.
He played all 15 of the Highlanders’ games, starting 13 of them.
The summer will go quickly, and it appears to be a reasonable assumption that Ratumaitavuki-Kneepkens will not be ready to start the new season, so attention turns to who will line up in the No 15 jersey.
Finn Hurley appears to be the leading contender.
He is still just 21 and his Super Rugby experience is limited to a single start and four cameos off the bench.
But Hurley played wonderfully well in that start, against the Hurricanes this year, and had another excellent season at fullback for Otago.
The only other obvious option for Highlanders coach Jamie Joseph — unless he has a surprise up his sleeve — is the experienced Sam Gilbert, though he has now settled into life as a second five after starting as a fullback or winger.
Meanwhile, the Highlanders are also certain to be in the market for a new lock or two following the announcement Max Hicks is off to France.
Hicks, who started seven games at lock and one at blindside in 21 appearances for the Highlanders over three seasons, is joining the Perpignan club.
He joins fellow lock Pari Pari Parkinson at the departure gate.
The Highlanders have a good incumbent locking pair in All Blacks XV star Fabian Holland and the experienced Mitch Dunshea, presumably with the injury-plagued Will Tucker as a back-up, but will certainly need some reinforcement in that position.
The Highlanders name their squad on Tuesday.
