The purpose of this study is to describe a clinically feasible method for measuring the thickness of the serratus anterior (SA) muscle using rehabilitative ultrasound imaging (RUSI) and to determine the reliability of repeated measures of that method. An exploratory clinical measurement study using a test-retest methodology was utilized to determine the reliability of the measurements in a sample of 20 healthy subjects. While sitting with the arm flexed 120°, the SA of each subject was imaged at rest, during an active hold and while holding a three pound weight. On Day 1, images were repeated three times for each condition by the same examiner. On Day 2, Examiner 1 and Examiner 2 repeated the scans. Images were examined offline by Examiner 1 with SA thickness measured superior to the most distal rib in the image. Reliability was evaluated using intraclass correlation coefficients (ICCs) and Bland-Altman plots. The intra-examiner reliability (same day) during rest, active hold and active hold with resistance was ICC3,3  = 0·892; ICC3,3  = 0·951; and ICC3,3  = 0·869-0·971, respectively. Intra-examiner reliability between days ranged from ICC3,2  = 0·613 at rest to ICC3,2  = 0·736 during active hold with resistance. Interexaminer reliability was moderate during active hold (ICC2,2  = 0·526) and active hold with resistance (ICC2,2  = 0·535) and poor during rest (ICC2,2  = 0·425). This study demonstrates that SA thickness can be measured reliably using RUSI by the same examiner and suggests that active movements may increase that reliability.

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Findings of this study document the high reliability of ultrasound imaging in determining SA muscle thickness and thickness changes at rest and during contraction of the SA. Clinicians should be aware that resistance may need to be added to active scapular protraction in a side-lying position to produce a significant change in SA thickness from the rest position. This information can be used by clinicians who assess the SA and treat scapular dysfunction when activation or facilitation of the SA is required.

Objectives: The purpose of this study was to quantify in vivo posterior translational movements occurring in the glenohumeral joint during posterior mobilizations and to determine the intratester reliability of those posterior translational movements. Methods: Twenty-eight individuals (17 females, 11 males) participated in this study. One physical therapist utilized a Kaltenborn approach to apply three grades of posterior humeral mobilization. A hand held dynamometer was used to quantify the force used during each grade of mobilization. Ultrasound imaging was used to visualize and measure posterior humeral movement. Statistical analysis included descriptive statistics for force and posterior movement, intraclass correlation coefficient (ICC) for intrarater reliability of force and posterior movement during each grade of mobilization and paired t-tests to compare movement and force between grades of mobilization. Results: Mean posterior movement (mm) measurements were 3.0, 8.2 and 10.7 for grade I, grade II and grade III mobilizations, respectively. Mean force (Newtons) measurements used during mobilization were 41.7, 121.5 and 209.4 for grade I, grade II and grade III mobilizations, respectively. The ICCs ranged from 0.849 to 0.905 for movement and from 0.717 to 0.889 for force. Force and measurement values were significantly different between grades of mobilization and between dominant and non-dominant arms. Gender was found to be significantly associated with force. Discussion: Mean movements and mean forces occurring during posterior mobilization increased with increasing grades. Intratester reliability was high for all grades of manual mobilization supporting the use of subjective feedback to determine appropriate force application. Quantification of forces and movements helps to clarify parameters that can serve as a reference for clinical practice.

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