Effects of frontal, sagittal, and scapular surfaces on the upper and upper scapular surfaces of the scapula and the scapular rhythm

Backgroundm: Scapulohumeral rhythm (SHR) has been established as the kinematic hallmark indicating motion of the shoulder joint. Numerous studies have investigated the effect of different factors on SHR. The purpose of the present study was to determine the scapular upward rotation and scapulohumeral rhythm ratio among frontal, sagittal, and scapular planes in different humeral abduction angles. In the curremnt experimental study, conducted at the University of Kurdistan in 2018, 35 healthy male individuals participated. Two inclinometers were used to measure humeral abduction
and scapular upward rotation in scapular rest position, 45°, 90°, and 135° shoulder abduction in frontal, sagittal, and scapular planes. Participants performed humeral abduction with dominant shoulder in different planes. The scapular motility rhythm was calculated from the distribution of glenohumeral abduction rate on the upper scapular rotation from the rest position of the scapula to 45, 90 and 135 degrees of shoulder abduction at different levels. No significant difference was found in scapular upward rotation (p=0.07) and scapulohumeral rhythm (p=0.48) among frontal, sagittal, and scapular planes in 45° humeral abduction, but the scapula had more upward rotation in 90° humeral abduction in frontal plane compared with sagittal plane (p<0.05). Also, the scapula had more upward rotation in 135° humeral abduction in frontal plane compared with scapular and sagittal planes (p<0.05). On the other hand, findings showed that scapulohumaral rhythm ratio from scapular rest position to 45°, 90°, and 135° humeral abduction in frontal plane was less compared with that of sagittal and scapular planes (p<0.05). On the other hand, findings showed that scapulohumaral rhythm ratio from scapular rest position to 90° humeral abduction in sagittal plane was more as compared with frontal plane while scapulohumaral rhythm ratio from scapular rest position to 135° humeral abduction in sagittal plane was more than those of the two other planes (p<0.05). Conclusion It seems that there are significant differences in scapular upward rotation and scapulohumaral
rhythm ratio among frontal, sagittal, and scapular planes. These findings can be useful in clinical assessments and future studies.