Minoru Kijima

Analysis of the Questionnaire on the Sport Injury to High-school Baseball Pitchers.

Background: In this study, we attempted to determine the connection between throwing injuries, especially to the shoulder or elbow, and the amount of pitching practice, in high-school pitchers. Methods: We distributed questionnaires to 67 high-school baseball pitchers and had them answer questions on the following: their sports career, past sport-related injuries, the amount of baseball practice per day and per week, the number of throws per day, and the number of non-throwing day per week. Using an unpaired T-test, we looked for statistical relationships between throwing injuries and the above factors. Results: Of the 67 cases that answered our questionnaire, 53 (79.1%) answered that they had suffered sports-related injuries in their careers. Of these, 48 (71.6%) had suffered throwing injuries to the shoulder or elbow. Our examination showed that 34 pitchers (50.7%) currently had derangement of the shoulder or elbow, and the questionnaires showed that these pitchers had spent much more time practicing throwing in elementary school and junior high school than those without these problems. Conclusion: Excessive throwing practice in elementary school and junior high school may lead to derangement of the shoulder or elbow.

Dynamic Analysis of the Harrington System Using a Spinal Simulator

The authors constructed a spinal simulator for the thoracolumbar spine with mechanical properties similar to those of cadaver specimens, and studied the effectiveness of the Harrington system in unstable fractures of the thoracolumbar spine. Distraction and compression rods were applied under various conditions. External bending moment was applied to the model to measure the internal bending moment on the vertebral body and ligaments. Optimal spinal stability was obtained when the distraction system was combined with the compression system with hooks at laminas three levels above and below the fracture.