[Developmental changes in the Collis horizontal reaction analyzed using a three-dimensional video motion analysis system. I. Examination of techniques for inducing Collis horizontal reaction].
We used a three-dimensional video motion analysis system to evaluate techniques for inducing the Collis horizontal reaction in 46 infants (total 217 times) from 1-9 months old. Additionally, we examined the safety of different techniques for inducing the Collis horizontal reaction in 20 infants (total 66 times), from 1-3 months old, 40 times by holding the shoulder joint and 26 times by not holding the shoulder joint. Regardless of who performed the examination, the average height that induced the reaction increased from 24.3 to 34.6 cm and the average speed of reaction increased from 28.2 to 43.4 m/s as the age of the infants increased. Additionally, when the Collis horizontal reaction was induced in infants 1-3 months old by holding the shoulder joint of infants, the average fall angle of the head was 7.291 degrees and was not significantly larger than when the reaction was induced by not holding the shoulder joint, which resulted is an average fall angle of the head was 19.302 degrees. However, although the average speed to support the body increased, the fall angle of the head did not increase when the shoulder joint was held. The Collis horizontal reaction is usually not performed in early infancy before head control is acquired, because of the burden to neck caused by the fall of the head and the excess expansion of shoulder joint capsule. However these results suggest that when performing the Collis horizontal reaction in early infancy before head control is acquired, the Collis horizontal reaction can be safely performed by holding the shoulder joint, regardless of the skill of the diagnostician. Therefore, the Collis horizontal reaction is an excellent method to assess infant development, and can be performed at the usual infant health examinations.