J Korean Soc Radiol.  2017 Jul;77(1):47-52. 10.3348/jksr.2017.77.1.47.

Subscapularis Injuries Associated with Acromiohumeral Instability in Patients with Shoulder Impingement Syndrome

• Moon TY
• Jeong HS
• Lee SJ
• Jeong YJ

• KMID: 2384735
• DOI: http://doi.org/10.3348/jksr.2017.77.1.47

Abstract

PURPOSE
To evaluate the association of subscapularis (SSC) injuries with acromiohumeral instability (AHI) in patients with shoulder impingement syndrome with supraspinatus (SSP) tears.
MATERIALS AND METHODS
Pre-operative shoulder magnetic resonance images of 106 patients with subsequent arthroscopic confirmation of shoulder impingement syndrome were reviewed retrospectively. Patients with SSC injuries were divided into the following 3 groups: 1) those with no injury symbolized to the SSC[0] (n = 38), 2) those with partial injuries to the SSC[1] (n = 41), and 3) those with complete disruption of the SSC[2] (n = 27). AHI was categorized into 5 stages depending on the SSP lesions: partial tear or pretear tendinosis symbolized to the SSP[0] (n = 24) and according to retraction severity of the SSP tendon with complete tear such as SSP[1] (n = 19), SSP[2] (n = 27), SSP[3] (n = 29), and SSP[4] (n = 7). Also, AHI was divided into two groups such as the mild group summed with SSP plus SSP plus SSP and the severe group summed with SSP plus SSP, including 70 patients and 36 patients, respectively.
RESULTS
Twenty-nine patients (63.0%) among 46 patients with SSC[0] and thirty-two patients (78.0%) among 41 patients with SSC[1] were related to mild AHI. Eighteen patients (66.7%) among 27 patients with SSC[2] were associated with severe AHI. The SSC injury groups were statistically significantly associated with AHI (estimate 0.207, standard error 0.057, p < 0.01).
CONCLUSION
SSC injuries could be related to AHI in patients with shoulder impingement syndrome.

MeSH Terms

Arthroscopy
Humans
Magnetic Resonance Imaging
Retrospective Studies
Rotator Cuff
Shoulder Impingement Syndrome*
Shoulder*
Tears
Tendinopathy
Tendons

Figure

• 

  Fig. 1 Schematic images explaning mechanical SSC tendon injuries in patients with subacromial impingement syndrome. A. The oblique sagittal image at the level of the coracoid process illustrates a normal anatomical structure of the SSP and SSC (small arrows) in the absence of subacromial impingement. B. In subacromial impingement with acromiohumeral instability, the oblique sagittal image demonstrates acromiohumeral joint space narrowing and elevated position of the humeral head resulting in SSC tendon injury (large arrows) caused by dynamic force of subcoracoid impingement between the coracoid process and the anterior convexity of the humeral head. C. The coronal image with a center of the coracoid process illustrates the normal anatomical position of the SSP and SSC (small arrows). D. In subacromial impingement with acromiohumeral instability, the coronal image reveals acromiohumeral joint space narrowing and elevated position of the humeral head (large arrows) resulting in SSC tendon tears caused by shearing force of the coracoid process. Also, medial subluxation of the LHBT could result in injury to the LT insertion portion of the SSC. A = acromion, GT = greater tuberosity, ISP = infraspinatus, LHBT = long head of biceps tendon, LT = lesser tuberosity, SSC = subscapularis, SSP = supraspinatus

• 

  Fig. 2 A 54-year-old female patient was arthroscopically confirmed to have complete tears of the SSP[3] and the SSC[2]. A. The T2 fat saturation (FS) coronal MR image demonstrates stage complete tear of the SSP with retracted portion on the medial side of the humeral head (white arrows). B. The T2 FS axial MR image depicts complete tear of the proximal portion of the SSC (black arrows). C. The T2 FS oblique-sagittal MR image illustrates marked narrowing of the acromiohumeral space due to full-thickness tear of the SSP (white arrow) and absence of the SSC on the medial side of the lesser tuberosity suggestive of full-thickness tear of the SSC (black arrows). D. Arthroscopy shows SSC stump due to its complete disruption (black arrows). A = acromion, GL = glenoid, H = humeral head, SSC = subscapularis, SSP = supraspinatus

• 

  Fig. 3 Regression analysis (A) and correspondence analysis (B) related between 5 stages of SSP lesions and 3 groups of SSC injuries (SSC = 0.529 + 0.207 SSP, regression coefficient estimate 0.207). SSC = subscapularis, SSP = supraspinatus

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