The use of skis has a long, 5,000-year history. Even though skis were used for transportation in this country in the 19th century, especially during the gold rush years, the modern era of recreational skiing in the United States goes back only 60 to 70 years. The number of participants in downhill skiing has increased enormously.

Injury data from ski areas' clinics and ski patrol records show that 3 to 6 injuries occur per 1,000 skier-days. However, as many as 40 percent of downhill skiing injuries may go unreported. Some researchers have estimated an incidence as high as 10 injuries per 1,000 skier days. This means 200,000 to 500,000 injuries a year in the U.S. (or 14 to 35 injuries per 1,000 participants). For comparison, football has an incidence of 810 injuries per 1,000 participants and tennis an incidence of 30 per 1,000 participants.The injury rate since the 1960s has actually decreased. Most of the reduction was due to a decrease in ankle sprains and other lower extremity injuries. This has been attributed to improved grooming of slopes, use of snowmaking equipment, ski instruction, safety innovations in ski areas, and improved ski equipment.

Most injuries occur between noon and 1 p.m. and between 2 and 4 p.m.. Factors such as snow conditions, visibility, number of skiers on the slope, and skier fatigue affect injury rates. The most critical factors for sustaining an injury, however, are skier ability, relation of speed to ability, and improper adjustment or poor functioning of equipment.

Studies show that failure of ski bindings to release may be responsible for 44 percent of all downhill ski injuries and is usually due to improper maintenance.

The injury rate in beginners is two to three time that in experienced skiers. One-third of all skiing injuries occur in persons who are 16 years of age or less.

The injury rate in women exceeds that in men, and women have more upper-extremity injuries. Injury distribution by types appear below:

- Sprains, strains - 45 percent of all injuries.

- Lacerations, abrasions - 11.5 percent.

- Fractures - 9.5 percent.

- Contusions - 5 percent.

- Dislocations - 3 percent.

- Cold injury - 20 percent.

As the ski boot has become higherand more rigid, ski binding technology has become more advanced.

About 90 percent of tibia and fibular fractures are due to falls. Since the 1960s, the incidence of spiral fracture, which suggests a torque injury, has diminished from 71 percent to 51 percent. Boot-top fractures, which account for 35 to 50 percent of tibia fractures, are typically due to bending injuries and are not prevented by improved bindings.

Knee injuries account for about 50 percent of all acute injuries in downhill skiers.

Skiing deaths are uncommon. They are typically related to collisions with stationary objects, such as rocks or trees. Some of these deaths result when skiers combine drinking of alcoholic beverages with skiing.