J Korean Orthop Assoc.  2019 Aug;54(4):343-352. 10.4055/jkoa.2019.54.4.343.

Descriptive Study for Sonographic Morphology of the 1st Facet of Subscapularis Footprint

• Sohn HS
• Wi CK
• Shon MS

• KMID: 2455503
• DOI: http://doi.org/10.4055/jkoa.2019.54.4.343

Abstract

PURPOSE
The purpose of this study was to document the sonographic morphology of the subscapularis footprint, particularly the 1st facet, of the non-pathologic subscapularis tendon and footprint, and analyze the correlation between the size of the 1st facet and the demographic variables.
MATERIALS AND METHODS
Between March 2015 and December 2017, retrospectively data analysis was performed for the ultrasound (US) scans of 115 consecutive shoulder (mean age 53.4 years, range 23-74 years) with non-pathologic subscapularis tendon and footprint. The sonographic findings of the 1st facet of the subscapularis footprint was a very unique, flat, broad, and plane angle in the upward direction, which were distinguished from the other facets. On US, the transverse (medio-lateral) and longitudinal (superior-inferior) length of the 1st facet on axis of the humerus shaft were recorded. The demographic variables, including age, site, body height, weight, body mass index (BMI), and arm length, were reviewed.
RESULTS
On US, the mean transverse length of the 1st facet was 12.75 mm (range 10.54-14.50 mm, standard deviation [SD] 0.712) and the mean longitudinal length was 12.22 mm (range 9.20-13.30 mm, SD 0.888). The transverse and longitudinal length of the size of the 1st facet were significantly greater in males than in females (p<0.001, p=0.001). Of the demographic data (body height, weight, BMI, arm length) that showed a significant positive linear correlation, the correlation with body height (transverse r=0.749, p<0.001; longitudinal r=0.642, p<0.001) showed the strongest relationship, and the correlation with the BMI was weakly related. The relationships between the size of the 1st facet to site/age were not statistically significant or appeared to have no linear correlation.
CONCLUSION
The structural and morphologic features of the 1st facet of the subscapularis footprint on the US were identified. This will provide anatomic knowledge of an US examination for subscapularis tendon pathology.

Keyword

shoulder; subscapularis; diagnostic ultrasound

MeSH Terms

Arm
Body Height
Body Weight
Female
Humans
Humerus
Male
Pathology
Retrospective Studies
Shoulder
Statistics as Topic
Tendons
Ultrasonography*

Figure

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  Figure 1. (A) Transverse scans of the subscapularis footprint (same as longitudinal scan of subscapularis tendon) tracing from superior to inferior (B-E) on the axis of humerus shaft. The sonographic morphology of the 1st facet of subscapularis footprint was unique with its flat and broad shape, which were distinguished from the other facets. The longest length was measured on a transverse scan of the 1st facet (transverse or medio-lateral length).

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  Figure 2. (A) Longitudinal scans of the subscapularis footprint (same as transverse scan of subscapularis tendon) tracing from medial to lateral (B-D) on axis of humerus shaft. The shapes of the tendinous portion of the subscapularis have undergone gradual echogenic and morphologic changes. On the medial portion (A, B), the corresponding ultrasound images of the subscapularis tendon revealed its multipennate appearance showing areas of hyper- and hypo-echogenicity. The echogenicity of the subscapularis tendon became denser and more hyperechoic as the tendon was closer to the 1st facet of the subscapularis footprint. The 1st facet of the subscapularis footprint also has a plane angle in the upward direction, which was distinguished from other facets with the plane angle in the anterior direction.

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  Figure 3. Longitudinal scans of subscapularis 1st facet tracing from longitudinal scan of biceps long the head tendon (A) to just medial on the axis of humerus shaft (B).

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  Figure 4. Correlation analysis between the demographic data and the medio-lateral (M-L) length of the subscapularis 1st facet on ultrasound. r, Pearson correlation coefficient; BMI, body mass index.

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  Figure 5. Correlation analysis between the demographic data and the superior-inferior (S-I) length of the subscapularis 1st facet on ultrasound. r, Pearson correlation coefficient; BMI, body mass index.

Reference

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