Lindsey Vonn, the Olympic downhill champion and one of the biggest names in winter sport, will miss next month's Sochi Games because she requires surgery on her injured knee.

The 29-year-old American broke the news on her Facebook page yesterday. "I am devastated to announce I will not be able to compete in Sochi," said Vonn, the girlfriend of world No.1 golfer Tiger Woods. "I did everything I possibly could to somehow get strong enough to overcome having no ACL [anterior cruciate ligament] but the reality has sunk in that my knee is just too unstable to compete at this level."

Vonn, a four-times overall World Cup champion and the standout name in women's Alpine skiing, badly injured her right knee in a world championship super-G in February. She hurt the knee again while training for the season-opening World Cup downhill at Beaver Creek, Colorado but appeared to be back on track after racing at Lake Louise, Alberta.

Vonn then travelled with the US team to Europe and, with Woods watching her for the first time at a World Cup race, injured her knee once more in Val d'Isere, France.

"It was Tiger's first time at a World Cup race and I was really hoping to win my 60th as a present for him," said Vonn, who had hoped she could recover in time for Sochi, aiming to compete at her fourth straight Olympics, but faced the reality yesterday. "After the incident in Val d'Isere an MRI showed an MCL [medial collateral ligament] sprain which, coupled with the torn ACL, has made it impossible to stabilise her knee and be ready to safely ski again next month," Vonn's team said in a statement. "She will have surgery shortly and is expected to make a full recovery in time for the 2014/15 World Cup season and the 2015 world championship."

Vonn tried to put an optimistic spin on her personal disappointment. "On a positive note this means there will be an additional spot so that one of my teammates can go for gold," she said. "Thank you all so much for all of the love and support. I will be cheering for all of the Olympians and especially team USA."

Vonn is a six-times World Cup downhill champion, a four-times World Cup super-G winner and a triple World Cup super combined champion. She won downhill gold and super-G bronze at the Vancouver Games four years ago.