投球傷害肩におけるゼロポジション外旋筋力評価の意義

-ボール投げ上げ動作に見られる特徴との関連-

抄録

The zero position with external rotation is similar to the important skill in the throwing movement. We examined the correlation between the muscle strength of external rotation at zero position and the characteristics of the throwing motion in throwing shoulders. A prospective study of 17 throwing shoulders and 15 normal shoulders were examined. We evaluated the muscle strength of external rotation at zero position using MICRO FET by puppy position. We also examined the throwing motion using MOTUS (3D analysis system). From these examinations, we investigated the correlation between the muscle strength of external rotation at zero position and the characteristics of a throwing motion in throwing shoulders. The muscle strength of external rotation at zero position was 35.3N ± 8.4 in normal shoulders. The muscle strength was 19.8N ± 6.4 and under 30N in the majority of throwing shoulders compared with normal shoulders. We investigated the characteristics of the throwing motion in each group. They throw a ball using an extended motion on the elbow in the normal group. The majority of patients throw a ball using a rotated motion on the shoulder. Insufficient muscular strength of external rotation at zero position was the cause of the wrong motion of a throw. As a result in this study, the evaluation of the muscle strength of external rotation at zero position for the throwing shoulders was important.