''Our major concern is not so much that the shaped skis themselves may increase knee injuries,'' Ettlinger said. ''But they do require proper training. With the right orientation and practice, skiers could have a wonderful new product. There's good hope the skis could help reduce injuries over all as people understand the skis' limitations.''

Indeed, new equipment in the past has greatly reduced injuries. Broken legs were common in skiing until the 1970's, when better binding adjustments made for safer release mechanisms. Since then, broken leg injuries have been reduced by 95 percent, Ettlinger said. Over all, he added, ski injuries have decreased by 44 percent in the last 24 years.

The new skis do take to the hill differently than conventional models. ''Going straight can be difficult on the shaped skis,'' Ettlinger said. ''Skiers are going to have to change their style and learn they have to be making a turn almost all the time. They have to learn that these skis don't go straight, or run flat.''

Snowboarders are well aware of that technique. If a snowboard in motion isn't up on its edge, the board will shimmy and slide willy-nilly. It is the big, deeply grooved turns of snowboards that set them apart from traditional skis.

Whether skiers can make the transition, regardless of training and practice, remains to be seen. David MacPhail, director of research for a Canadian company that develops new sports technology, said yesterday that he believed that shaped skis ''defy the laws of physics.''

''When the shaped ski goes on edge,'' MacPhail said, ''the tail and tip exert pressure on the snow first. That force extends outside the limits of the foot, and puts a twisting stress on the knee, which has the potential to cause injury.''

Ettlinger and Dr. Robert Johnson, an orthopedic surgeon, and Dr. Jasper Healy, an industrial engineer, have not yet had enough time to compile meaningful statistics on the new skis. But they agree with other equipment analysts that shaped skis are too new to be responsible for the current spate of knee injuries.