We have studied 46,173 cases of ski injuries in recently twenty-five years.
　At first, we have examined them statistically, in order to know the relationship between these injuries and the changing or development of the ski equipments. Secondary, we have examined the questionnaire study for the patients, in order to know the factors or the causes of the ski injuries. Thirdly, we have examined two dimensional photo-elastic experiments, in order to know the causes and mechanism of the boot top level fractures of the lower legs by biomechanically. And fourthly, we have examined the arthrography of the dislocated sholder joints, in order to know the mechanism of the recurrent shoulder dislocation.
　Results
　1) Our ski injuries are classified by these types of trauma; 19,512 cases (42.3%) of sprains, 12,311 cases (26.7%) of fractures, 10,063 cases (21.8%) of lacerations, 2,982 cases (6.4%) of contusions, 814 cases (1.7%) of dislocations, and 491 cases (1.0%) of others.
　2) And they are classified by regions; 34,632 cases (75.0%) in the lower extremities, especially, 15,554 cases (33.7%) in the ankle joints, 9,939 cases (21.5%) in the knee, 8,063 cases (17.5%) in the lower legs, and 5,766 cases (12.6%) in the arms, 4,550 cases (9.9%) in the head and face, and 1,225 cases (2.7%) in the trunk.
　3) These formations of the percentages of these types of trauma have been changed year by year, according to the development and change of the ski equipments. Namely, because of the safety-bindings and the plastic-made-ski-boots, the sprains and fractures of the ankle joints were decreasing, but, the lacerations of the head and face and the knee sprains and the lower leg fractures, especially, the boot top fractures were increasing.
　4) We have examined the questionnaire study for the patients, the questions are those, the ski-technique of the patient, the body-conditions of the patient, the environmental conditions, the other conditions, the ski equipments of the patients, and the treatments. We have examined them and classified into the lacerations and LEERI (Lower Extremity Equipment Related Injury). And we recognize that the ski equipments have largely effected on the ski injuries.
　5) By the two dimensional photo-elastic experiments, when loading at dorsal flexion of ankle joint, great compressive stress acts upon the level of 1/6 downward of the frontal margin of tibia. And, furthermore, when overturned to forward, the top end of the boot acts as a fulcrum, the bending stress acts upon the lower leg. So, they are the mechanism of the boot top fracture.
　6) By the arthrography of the dislocated shoulder joints, in the capsular detachment type, 37.5% of them were re-dislocated, but in the capsular tear type, there were no re-dislocation in them. So, three weeks fixation are required to prevent re-dislocation to the capsular detachment type after diagnosed by the arthrography of the dislocated shoulder joint.

DESCENTE SPORTS SCIENCE Vol.3/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE