Lizzy Yarnold was diagnosed with the rare condition in November ©Getty Images

The British Bobsleigh and Skeleton Association have announced that double Olympic gold medallist Lizzy Yarnold has undergone knee surgery to treat a rare genetic condition.

Yarnold, the first Birton to successfully defend a Winter Olympic title when she won the gold medal in the skeleton at last month's Games in Pyeongchang, was diagnosed with pigmented villonodular synovitis (PVNS) in November.

PVNS is characterised by inflammation and overgrowth of a joint lining.

The lining creates extra fluid, causing swelling which makes movement painful.

The 29-year-old is currently on crutches but should return to training within the next few weeks.

Lizzy Yarnold, the first Briton to defend a Winter Olympic title when she won the skeleton at Pyeongchang 2018 last month, has undergone an operation on her knee to treat a rare genetic condition ©Getty Images
Lizzy Yarnold, the first Briton to defend a Winter Olympic title when she won the skeleton at Pyeongchang 2018 last month, has undergone an operation on her knee to treat a rare genetic condition ©Getty Images

"The operation went well, which is great, and I'm pleased to have got it out of the way," Yarnold said, according to the BBC.

"I'd always had tightness problems with my left quad and last summer it swelled up unusually.

"I'm grateful the medical team started investigating and found out about the PVNS.

"It was another health distraction for me but I can't thank the team enough, who monitored everything and operated on me."

Yarnold had been advised by specialists last November that she could wait until the end of the season before having the operation.