Musculotendinous architecture of pathological supraspinatus: a pilot in vivo ultrasonography study.
The supraspinatus muscle (SSP) can be divided in an anterior and posterior region. SSP tears are frequent cause of pain and loss of function in the shoulder region. Morphological changes resulting from tears have been described mostly in terms of muscle atrophy and fat infiltration. Nevertheless, other parameters such as muscle thickness (MT), fiber bundle length (FBL) and pennation angle (PA) can also be affected.
In this study, 12 SSPs were assessed using ultrasonography (US) in eight participants in order to investigate the intrarater and inter-rater reliability of US to quantify MT, FBL and PA in the different SSP regions. On top of that, subjects were divided in three groups: 1) tears with a retracted tendon; 2) tears without retraction; and 3) an intact tendon, and subsequently matched to controls according to age and gender, to determine architectural differences between SSPs with tears and healthy SSPs.
Both intrarater and inter-rater measurements of FBL and PA were strongly correlated and showed no significant difference between measurements. For the anterior SSP region, FBL did not differ significantly between the pathologic and control condition but PA was smaller in the pathologic compared to the control condition. FBL was significantly shorter in the pathologic condition for the posterior SSP region. MT of patients with tears but no retraction was significantly larger compared to healthy controls.
It seems rehabilitation protocols should address impairments associated with the posterior region, which functionally acts as an external rotator. > From: Kim et al., Clin Anat 26 (2013) 228-235. All rights reserved to Wiley Periodicals, Inc.
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