A boom in short skiing holidays abroad is leading to a rapid increase in knee injuries, particularly to women, claims a top specialist.
Steve Bollen, president of the British Orthopaedic Sports Trauma Association, blames poor fitness among beginners.
He describes many of the serious ligament injuries which he sees as "half-term syndrome".
The number of UK people who ski or snowboard is also rising - more than 1.3 million in 2007.
Damage to the ligaments which hold the knee together can require surgery to repair, and if left untreated, can cause irrepairable damage to the joint.
However, this is one of the most common injuries caused by falls or twisting during skiing, partly due to the design of modern ski boots, said Mr Bollen, an orthopaedic surgeon at Bradford Royal Infirmary.
"If, when you fall, the ski bindings do not release, the rigid, high boots mean that all that force can go straight through the knee, which can be very damaging."
His study of more than 200 patients with anterior cruciate or medial ligament injuries passing through his own clinic reveals that while rugby and football were still the biggest culprits, the percentage linked to skiing had soared, from 9% in 1994 to 28% in 2004.
More than nine out of ten of the injured skiers were women, with an average age of 40.
"Skiing is a strange sport which requires no intrinsic strength or skill - anyone can walk into a ski hire shop and hire the kit.
"Then they set off down the hill, and if anything goes wrong they may not have the strength or fitness to do anything about it."
"I call this 'half-term syndrome' - women who are perhaps not physically as fit as they could be going on a skiing trip with no prior preparation.
"I always try to improve my fitness for several weeks before I go skiing."
Statistics revealed by the Ski Club of Great Britain show that the vast majority of skiing trips are for seven days or less, and 28% of skiers class themselves as "beginners".
Mr Bollen said that knee ligament damage could be hard for GPs to diagnose, and that it was important for people who needed surgery to get their operation within six months to avoid permanent damage.
Betony Garner, at the Ski Club of Great Britain, said that a common mistake was to treat skiing as a holiday, rather than a sport.
"It's certainly a good idea to prepare physically for a skiing trip perhaps six weeks, or even three months, beforehand, with cardiovascular exercise and work to strengthen leg muscles, and improve core strength.
"While you're there, you should also make sure you keep hydrated, eat the right things and perhaps even consider taking a day off from skiing at some point to let your body recover."