Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Science

Program

Physical Therapy

Supervisor

Dr. Trevor Birmingham

Second Advisor

Robert Werstine

Third Advisor

Shawn Robbins

Abstract

Objectives: 1) to estimate the intra and inter-rater reliability of measures of relative humeral head position based on the palpation of two bony landmarks (operationally defined as the distance between the most anterior border of the acromion to the most anterior aspect of the humeral head), 2) to compare the humerus-to-acromion distance in the dominant and non-dominant shoulders of baseball players and controls, and 3) to compare external and internal range of motion in the dominant and non-dominant shoulders of baseball players and controls. Methods: Sixty healthy participants (30 controls and 30 baseball players) were assessed by two experienced physical therapists in a biomechanics lab. Three-dimensional positions of palpated shoulder landmarks were captured with a motion analysis system with subjects tested in two positions: 1) arm at side, and 2) shoulder abduction and external rotation. Range of motion was measured using a universal goniometer. Results: ICC values ranged from 0.80 to 0.91 for intra-rater reliability and from 0.25 to 0.65 for inter-rater reliability. SEM values ranged from 2.68 to 5.65mm for intra-rater reliability and from 4.66 to 8.34mm for inter-rater reliability. Consistent with the literature, range of motion in the dominant side of baseball players was significantly larger for external rotation, and significantly smaller for internal rotation, than their nondominant side and both sides of the controls. The humerus-to-acromion distance, however, was not significantly different between sides in the baseball players for either the arm at side or abduction/external rotation position. Additionally, in the arm at side position, the humerus-to-acromion distance in the dominant side of controls was significantly larger than their non-dominant side and both sides of baseball players. iii Conclusion: The described method of measuring humerus-to-acromion distances from palpation of bony landmarks has high intra-rater, but poor inter-rater reliability. Based on the observed ICCs and SEMs, this measure is appropriate for use in studies comparing groups, but likely not appropriate for assessing individual patients. Overall, the comparisons within and between groups suggest change in shoulder range of motion observed in participants of single arm dominant sports is not accompanied by change in humerus-to-acromion distance demonstrable by palpation.

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