Aponeurotic expansion of the supraspinatus tendon: sonographic spectrum and proposed classifications

Saulius Rutkauskas

doi:10.15557/jou.2026.0003

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Aponeurotic expansion of the supraspinatus tendon: sonographic spectrum and proposed classifications

Journal of Ultrasonography

Volume 26 (2026): Issue 104 (April 2026)

By: Saulius Rutkauskas

Open Access

|Mar 2026

Figures & Tables

Schematic representation of aponeurotic expansion of the supraspinatus tendon (AEST) in relation to the supraspinatus tendon, long head of the biceps tendon (LHBT), and subscapularis tendon; the coracoacromial ligament is indicated as a supraspinatus landmark

Ultrasound image showing normal aponeurotic expansion of supraspinatus tendon (AEST) anterolateral to the long head of the biceps tendon (LHBT) at the intertubercular groove

Anatomy drawing of aponeurotic expansion of the supraspinatus tendon (AEST) within the rotator interval. Subluxation is defined as displacement above or medial to the long head of the biceps tendon (LHBT); dislocation occurs when positioned over the subscapularis tendon. Supr – supraspinatus; Subs – subscapularis

Evaluation of aponeurotic expansion of the supraspinatus tendon (AEST) at the intertubercular groove: normally lateral to the long head of the biceps tendon (LHBT); in intragroove subluxation, over or medial to LHBT; in subluxation, on the edge of the lesser tubercle; in dislocation, on the facet of the lesser tubercle at the subscapularis insertion (S); and in medial dislocation within the glenohumeral joint capsule (C)

Pseudo-double long head of the biceps tendon (LHBT). A. Longitudinal view mimicking a bifid tendon. B. Transverse view showing a narrow intratendinous fibrous band accentuated by degenerative changes

Residual echogenic fibers within the long head of the biceps tendon (LHBT) with surrounding fluid and degenerative changes

Long head of the biceps tendon (LHBT) hypoplasia in the left shoulder of a 28-year-old female; absent on the contralateral side

Proposed classification of the supraspinatus–AEST relationship. Type I: intrasubstance AEST tears (Ia <20%, Ib <50%, Ic >50%). Type II: partial supraspinatus tears (IIa medial full-thickness, IIb lateral full-thickness, IIc PASTA/rePASTA or intrasubstance). Type III: complete tears (IIIa supraspinatus, IIIb AEST, IIIc both). AEST – aponeurotic expansion of the supraspinatus tendon; LHBT – long head of the biceps tendon

Mild intrasubstance tear of aponeurotic expansion of the supraspinatus tendon (AEST) at the base of the supraspinatus tendon in the right shoulder (AEST–supraspinatus classification: Ia, case 1)

Small intra-aponeurotic ganglion in the left shoulder. A. Transverse view of aponeurotic expansion of the supraspinatus tendon (AEST). B. Longitudinal view (AEST–supraspinatus classification: Ia, case 19)

Variants of aponeurotic expansion of the supraspinatus tendon (AEST) subluxation in the rotator interval: A. intragroove subluxation, B. intrainterval and intragroove subluxation, C. intrainterval subluxation with intragroove dislocation, D. intrainterval subluxation with intragroove medial dislocation

Aponeurotic expansion of the supraspinatus tendon (AEST) subluxation over the long head of the biceps tendon (LHBT) at the midline of the rotator interval in the left shoulder (case 17)

Aponeurotic expansion of the supraspinatus tendon (AEST) subluxation medial to the long head of the biceps tendon (LHBT) with a full-thickness supraspinatus tear in the right shoulder (case 7)

Proposed classification of the AEST–LHBT relationship at the intertubercular groove. Five major types are defined by LHBT position: Type I – intragroove LHBT (Ia intragroove subluxation, Ib subluxation, Ic dislocation, Id medial dislocation); Type II – LHBT subluxation (IIa intragroove AEST, IIb both subluxated, IIc AEST dislocation, IId AEST medial dislocation); Type III – LHBT dislocation (IIIa intragroove AEST, IIIb AEST subluxation, IIIc+ both dislocated, IIIc– reciprocal dislocation, IIId AEST medial dislocation); Type IV – LHBT medial dislocation (IVa isolated, IVb AEST subluxation, IVc AEST dislocation, IVd+ AEST medial dislocation, IVd– reciprocal medial dislocation); Type V – LHBT tear (Va intragroove AEST, Vb subluxation, Vc dislocation, Vd medial dislocation). A – AEST; S – subscapularis; C – capsule. AEST – aponeurotic expansion of the supraspinatus tendon; LHBT – long head of the biceps tendon

Aponeurotic expansion of the supraspinatus tendon (AEST) dislocation with preserved intragroove long head of the biceps tendon (LHBT) in the right shoulder (AEST–LHBT classification: Ic, case 12)

Intragroove aponeurotic expansion of the supraspinatus tendon (AEST) with long head of the biceps tendon (LHBT) dislocation in the right shoulder (AEST–LHBT classification: IIIa, case 1)

Aponeurotic expansion of the supraspinatus tendon (AEST) intragroove subluxation with preserved long head of the biceps tendon (LHBT) alignment in the right shoulder (AEST–LHBT classification: Ia, case 11)

Combined aponeurotic expansion of the supraspinatus tendon (AEST) and long head of the biceps tendon (LHBT) dislocation in the left shoulder (AEST–LHBT classification: IIIc+, case 5)

Concomitant aponeurotic expansion of the supraspinatus tendon (AEST) and long head of the biceps tendon (LHBT) subluxation in the right shoulder (AEST–LHBT classification: IIb, case 15)

Medial course of aponeurotic expansion of the supraspinatus tendon (AEST) over the short head of biceps toward the retracted pectoralis major stump (not shown), with preserved long head of the biceps tendon (LHBT) alignment in the right shoulder (AEST–LHBT classification: Ia, case 2)

Demographic and clinical characteristics of patients with atypical or pathologically altered aponeurotic expansion of the supraspinatus tendon (AEST), summarized according to the proposed classification systems

Case No.	Age	Gender	Side	Presenting complaints	AEST-supraspinatus relation	AEST at rotator interval	AEST-LHBT relation	Additional findings
1	24	W	Right	Shoulder pain	Ia Mild intrasubstance tear at the basis of AEST	No subluxation	IIIa AEST intragroove position, LHBT dislocation	Unremarkable
2	48	M	Right	Acute trauma	Unremarkable	No subluxation	Ia AEST intragroove subluxation with dislocation below subscapularis, LHBT intragroove position	Complete tear of the pectoralis major tendon with retraction
3	57	M	Left	Shoulder pain	Unremarkable	No subluxation	Ia AEST intragroove subluxation, LHBT intragroove position	Complete tear of the subscapularis tendon
4	78	W	Left	Post-traumatic shoulder pain	IIb Partial tear of the lateral supraspinatus insertion	Subluxation	Ia↔Ib↔Ic AEST dislocation with instability, LHBT intragroove position	Full-width tear of the common supraspinatus and infraspinatus insertion, with preserved medial supraspinatus and lateral infraspinatus portions
5	82	W	Left	Persistent shoulder pain	IIIa Complete tear with retraction of the supraspinatus with severe retraction	Subluxation	IIIc+ AEST dislocation, LHBT dislocation	Severe tendinosis of the long head of the biceps tendon. Moderate tendinosis of the infraspinatus tendon with a partial tear at the cranial margin of the insertion
6	74	M	Left	Shoulder pain	Unremarkable	No subluxation	Ia AEST intragroove subluxation, LHBT intragroove position	Long head of biceps tendon – moderate tendinosis. Rotator cuff – severe diffuse tendinosis with microtears and microcalcifications. Status post greater tuberosity fracture without displacement
7	53	W	Right	Shoulder pain	IIIa Complete tear of the supraspinatus insertion with mild retraction	Subluxation	Ic AEST dislocation, LHBT intragroove position	Long head of biceps tendon – mild tendinosis. Complete tear of the supraspinatus tendon insertion with 2–3 mm retraction
8	65	W	Left	Shoulder pain	Unremarkable	No subluxation	IIIa AEST intragroove position, LHBT dislocation	Mild supraspinatus tendinosis with erosive changes at the insertion
9	52	W	Right	Shoulder pain	Ia Mild intrasubstance tear at the basis of AEST	No subluxation	Unremarkable	Unremarkable
10	62	W	Right	Shoulder pain	IIb Tear of the lateral supraspinatus margin, slightly distal to the insertion	No subluxation	IIIa AEST intragroove position, LHBT dislocation	Severe tendinosis of the long head of the biceps tendon. Severe supraspinatus tendinosis with a full-thickness tear at the lateral margin, ~1 cm from the insertion, with 8 mm retraction
11	70	W	Right	Shoulder pain	IIIa Complete tear with retraction of the supraspinatus with severe retraction	Subluxation	Ia↔Ib↔Ic↔IIc↔IIIc-↔IIIc+ AESTdislocation with instability, LHBT dislocation with instability	Severe tendinosis of the long head of the biceps tendon. Massive chronic rotator cuff tear (supraspinatus, infraspinatus, and teres minor), with marked retraction. Increased fluid in the glenohumeral joint
12	66	M	Right	Shoulder pain	IIIa Complete tear with retraction of the supraspinatus with severe retraction	Subluxation	Ic AEST dislocation, LHBT intragroove position	Moderate tendinosis of the long head of the biceps tendon. Complete supraspinatus tendon tear with retraction. Narrowed bicipital groove. Subscapularis tendon – mildly degenerated echotexture
13	74	W	Right	Shoulder pain	IIb Tear of the lateral supraspinatus margin	No subluxation	IIa AEST intragroove position, LHBT subluxation	Severe tendinosis of the long head of the biceps tendon with subluxation. Full-thickness tear of the lateral supraspinatus (~10 mm wide), without retraction. Moderate subscapularis tendinosis with partial tears at the cranial insertion
14	52	W	Left	Shoulder pain	Ia Mild intrasubstance tear at the basis of AEST	No subluxation	Unremarkable	At the mid-portion of the supraspinatus tendon insertion, the bony contour appears irregular and eroded, with locally pronounced tendon calcification
15	77	W	Right	Shoulder pain	Ia Mild intrasubstance tear at the basis of AEST	No subluxation	IIb AEST subluxation, LHBT subluxation	Moderate tendinosis of the long head of the biceps tendon at the rotator interval segment with microtears. Moderate supraspinatus tendinosis with marked degenerative changes
16	53	W	Right	Shoulder pain	IIb and Ia Narrow full-thickness supraspinatus tear in the lateral region, distal to the insertion and intrasubstance tear of AEST with ganglion formation	No subluxation	Unremarkable	Supraspinatus – markedly degenerated echotexture. At the lateral region, ~1.2 cm from the insertion, a 4 mm full-thickness tear with fatty infiltration is observed
17	54	W	Left	Shoulder pain	Ic Moderate intrasubstance tear	Subluxation	Ic AEST dislocation, LHBT intragroove position	Mild supraspinatus tendinosis
18	54	W	Right	Shoulder pain	Ib Severe intrasubstance tear	Subluxation	Ic AEST dislocation, LHBT intragroove position	Mild supraspinatus tendinosis
19	58	W	Left	Shoulder pain	Ia Intrasubstance tear of AEST with ganglion formation	No subluxation	Unremarkable	Moderate supraspinatus tendinosis

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DOI: https://doi.org/10.15557/jou.2026.0003 | Journal eISSN: 2451-070X | Journal ISSN: 2084-8404

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Language: English

Submitted on: Nov 1, 2025

Accepted on: Dec 18, 2025

Published on: Mar 17, 2026

Published by: MEDICAL COMMUNICATIONS Sp. z o.o.

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

aponeurotic expansion of the supraspinatus tendon (AEST)

Related subjects:

Medicine,

Basic medical science,

Basic medical science, other

© 2026 Saulius Rutkauskas, published by MEDICAL COMMUNICATIONS Sp. z o.o.
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Volume 26 (2026): Issue 104 (April 2026)

Aponeurotic expansion of the supraspinatus tendon: sonographic spectrum and proposed classifications

Figures & Tables

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Demographic and clinical characteristics of patients with atypical or pathologically altered aponeurotic expansion of the supraspinatus tendon (AEST), summarized according to the proposed classification systems

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