Analysis on the Variation of Medial Rotation Values According to the Position of the Humeral Diaphysis

Abstract

Objective: To analyze the validity of measurements of medial rotation (MR) of the shoulder, using vertebral levels, according to the variation in the position of the humeral diaphysis, and to test the bi-goniometer as a new measuring instrument. Methods: 140 shoulders (70 patients) were prospectively evaluated in cases presenting unilateral shoulder MR limitation. The vertebral level was evaluated by means of a visual scale and was correlated with the angle obtained according to the position of the humeral diaphysis, using the bi-goniometer developed with the Department of Mechanical Engineering of Mackenzie University. Results: The maximum vertebral level reached through MR on the unaffected side ranged from T3 to T12, and on the affected side, from T6 to the trochanter. Repositioning of the affected limb in MR according to the angular values on the normal side showed that 57.13% of the patients reached lower levels, between the sacrum, gluteus and trochanter. From analysis on the maximum vertebral level attained and the variation between the affected angle x (frontal plane: abduction and MR of the shoulder) and the unaffected angle x in MR, we observed that the greater the angle of the diaphyseal axis was, the lower the variation in the vertebral level attained was. From evaluating the linear correlation between the variables of difference in maximum vertebral level reached and variation in the affected angle y (extension and abduction of the shoulder) and the unaffected angle y in MR, we observed that there was no well-established linear relationship between these variables. Conclusion: Measurement of MR using vertebral levels does not correspond to the real values, since it varies according to the positioning of the humeral diaphysis.

Normalized hand-behind-back for the measurement of shoulder internal rotation

“… 9 In this regard, reliability of the HBB method improves by limiting the palpation site to one location, using the distance between this site and the tip of the subject's thumb as a parameter of the range of internal rotation. 19 This approach has been referred to as the measuring tape method. 10 However, concern remains regarding the obstruction of the comparison between individuals of different physiques when using the measuring tape method.…”

“…This method comprises the movement of the scapula and scapulohumeral, elbow, and wrist joints; therefore, previous studies have questioned the validity of the HBB method in measuring the true range of shoulder internal rotation. 9 , 14 , 17 , 19 , 26 Despite the satisfactory intraobserver reliability, the HBB method has poor interobserver reliability 7 ; in addition, constraints may be observed because of categorical data. 25 Nevertheless, the HBB method remains as an important measure of shoulder function as it has been related to personal functions, such as toileting and dressing, and the detection of motion loss, which is an early sign of pathology.…”