2012 TPTA Poster Abstracts
COMPARISON OF SUPRASPINATUS MUSCLE THICKNESS CHANGES IN PERSONS WITH SUBACROMIAL IMPINGEMENT SYNDROME AND ASYMPTOMATIC ADULTS
Presenter's Name - Last Name First
Blume, Christiana
Presenter's Affiliation, City, State
Texas Woman's University, School of Physical Therapy, Dallas, Texas
Purpose
Among various shoulder disorders, subacromial impingement syndrome (SAIS) is one of most frequently treated shoulder problems in physical therapy clinics. Rehabilitative ultrasound imaging (RUSI) offers a non-invasive alternative method to fine-wire electromyography (EMG) for the study of the deep rotator cuff muscles and can be used more readily in the clinic. The main purpose of this study was to compare supraspinatus muscle thickness change using RUSI in persons with SAIS compared to persons without shoulder symptoms. The study also investigated the reliability of the ultrasound (US) protocol used in the study.
Subjects
Twenty-two age- and gender-matched pairs participated in the comparison study (13 men). Mean age was 39.4 ± 14 years for asymptomatic participants and 39.5 ± 12 years for those with SAIS. A concurrent reliability study included 16 adults with SAIS and 36 adults without shoulder pathology.
Methods
A Sonosite US machine with a linear transducer (8-13 MHz) was used to measure thickness of the supraspinatus muscle at rest and with contraction at four angles of scapular plane elevation. The average of 3 trials in each condition was used in data analysis. Percentage change of muscle thickness was calculated by dividing the difference between the average contracted thickness and the average resting thickness by the average resting thickness. Ten participants per group were randomly selected to assess between-day reliability. Image-J software was used for off-line imaging analysis.
Results
A 2 x 4 mixed model analysis of variance (ANOVA) revealed a significant interaction effect between the angle of scapular elevation and group (p < .05). Post-hoc pairwise comparisons revealed a significant difference at the 0° condition (p < .05). The mean supraspinatus thickness at the 0° condition was found to be larger in persons with SAIS. The asymptomatic shoulders demonstrated a negative change value at the 0° condition from the rest condition, indicating a thinner muscle at 0°. The same-day intratester reliability of the US protocol was found to be good with ICC (2,3) = 0.75 to 0.92 for asymptomatic adults and ICC (2,3) = 0.71 to 0.91 for persons with SAIS across the rest and four contracted conditions.
Conclusion(s)
The results suggest that the supraspinatus muscle behaves differently in the shoulders of persons with SAIS than in asymptomatic shoulders. This alteration in supraspinatus thickness with SAIS might contribute to the impingement of the subacromial contents during shoulder elevation. In addition, the results indicate that the ultrasound protocol used in this study may be useful for assessing supraspinatus muscle thickness.