Noel Fehily fears he might miss both the Cheltenham and Aintree Festivals after aggravating an old shoulder injury at Cheltenham on Saturday.
The Irish-born rider could need an operation after seeing a specialist on Monday following his tumble from Den Of Iniquity at Cheltenham on Saturday.
"There's tendon damage to my shoulder. I'm probably going to have an operation, but that's still a bit up in the air," said Fehily.
"I could be out for a couple of months. If I'm going to have an operation it will be in the next week. We'll see what the doctors say after that.
"At the moment it's looking doubtful for Cheltenham and Aintree. I'm hoping there might be some light at the end of the tunnel but it's not looking that way at present."
Fehily is stable jockey to trainer Charlie Mann, who has the difficult job of finding replacements for his horses.
"It's very bad news, a disaster basically. There's nothing much we can do about it, we'll just have to make the best of it," said the Upper Lambourn handler.
"Peter Toole (conditional jockey) will get a few rides and we'll see what we can do."
Charlie Mann is looking for the best option to get his smart staying chaser Air Force One back on the track in the near future.
The Grade One winner has not run since being pulled up in the Guinness Gold Cup at Punchestown in April.
However, he is ready to return to action with Mann trying to find the ideal start to get his Cheltenham Gold Cup entry back in the groove.
Air Force One holds entries in the Althrey Handicap Hurdle at Bangor on Friday and in the totesport.com Masters Handicap Chase at Sandown on Saturday. He is also a possible for the Aon Chase at Newbury on Saturday week.
"He has those two entries this week, but the plan actually was to run him in the Aon against Denman because it will be a small field," said the Upper Lambourn trainer.
"Really though he wants a confidence booster and a nice run round.
Zaynar is unlikely to wear cheekpieces in his prep race for the Smurfit Kappa Champion Hurdle.
The grey has worn the headgear only once, when winning the Triumph Hurdle last season.
Successful at Ascot and Cheltenham this term, he will bid to take his unbeaten record over hurdles to six in the Victor Chandler Morebattle Hurdle at Kelso on February 18.
It is an appropriate race to go for as bookmaker Victor Chandler sponsors the race and heads the Men In Our Position syndicate that own the five-year-old.
"My initial reaction would be not to put cheekpieces on him at Kelso and keep them up our sleeve," Henderson said. "He can hit flat spots and he does genuinely stay.
"It just keeps him on the bridle and focusing on what is ahead of him and keeps him sharper."
Zaynar is a best-priced 5/1 for the Champion Hurdle on day one of the Cheltenham Festival on March 16.
Arkle favourite Captain Cee Bee is due to have his final run before the Cheltenham Festival in Saturday's BBA Ireland Ltd Opera Hat Novice Chase at Naas.
Captain Cee Bee is one of 10 entries that also include Fosters Cross, Dancing Tornado and Major Finnegan.