A Morphologic Study of the Upper Limb in Baseball Players

Abstract

[Purpose]The aim of this study is to report on the morphologic change of the upper limb by measuring the length of the humerus, forearm and between the proximal end of the humerus and the deltoid tuberosity.
[Materials and methods]Bilateral anteroposterior radiograph of the humerus, radius and ulna were performed on 80 upper limbs of forty baseball players, with an average age of 23.3 years old. The radiographic examination was performed with the elbow in extension and the forearm in supination. In each radioglaph, we measured the longest length of the humerus, radius and the distance between the proximal end of the humerus and the top of the deltoid tuberosity.
[Results]The average length of the humerus was 33.52cm on the throwing side and 33.57cm on the non-throwing side. The average length of the forearm was 26.88cm on the throwing side and 26.78cm on the non-throwing side. There was no statistically significant difference between the throwing and nonthrowing side. The ratio between the proximal end of humerus and the deltoid tuberosity to the length of the humerus was 45.59% on the throwing side and 46.27% on the non-throwing side. There was a statistically significant difference between the throwing and non-throwing sides.
[Conclusion]These results suggested the morphologic change of the humerus resulted from excessive stress to the attachment of the muscle tendon.