Posterosuperior Rotator Cuff Tears and Associated Pathologies

Bullet Points

• The rotator cable explains why patients with most rotator cuff tears can maintain active forward flexion, and also why even after only a partial rotator cuff repair, good functional results can be achieved.
• The most important negative prognostic factor is high-grade fatty infiltration of the rotator cuff muscle bellies (grade 3 or 4 fatty infiltration).
• The tangent sign is an indicator of advanced fatty infiltration and is a predictor of whether a rotator cuff tear will be reparable.
• Full thickness disruption of the lateral tendon stump (B1) is the most frequent type of rotator cuff lesion, comprising approximately 90% of all surgically treated lesions.
• Musculotendinous junction lesions (C-type) or rare and characterized by an edema of the muscle belly. They are associated to calcific deposit (infraspinatus) or trauma (supraspinatus). Unrepaired, grade III lesions lead rapidly to grade 4 fatty infiltration of the muscle.
• Tendon retraction is classified according to Patte. Overreduction and lateral transposition of the tendon over the greater tuberosity may be unphysiological.
• Massive rotator cuff has different definitions in the literature, each having potential benefits or drawbacks.
• Massive rotator cuff tears comprise approximately 20% of all cuff tears and 80% of recurrent tears.
• The classification of Collin not only subclassifies massive tears but has also been linked to function, particularly the maintenance of active elevation.
• Non-surgical treatment is effective in patient with massive rotator cuff if the tear involves less than three tendons and do not involves the subscapularis (D-type).
• Biomechanical testing has consistently demonstrated the superiority of double-row constructs over single-row. However, there is no obvious difference clinically.
• There is actually no support for routine suprascapular nerve release when massive rotator cuff repair is performed.
• Functional outcome improved after revision rotator cuff repair and 70% or more of patients were satisfied or very satisfied. However, the prevalence of persistent defect (retear or non-healing) is 28% at six months and 40% at two years.
• Rotator cuff are irreparable when associated to true pseudoparalysis with the presence of lag signs (external rotation lag, drop, dropping, hornblower signs), femoralization of the humerus or acetabulization of the acromion, grade 3 or 4 fatty infiltration and tangent sign.
• The current literature does not support the initial use of complex and expensive techniques in the management of posterosuperior irreparable rotator cuff tears.

Key Words

Shoulder arthroscopy; Rotator cuff lesion; Partial repair; Tear pattern; Classification; Massive; Reparable and non-repairable; Irreparable; Imaging; Recurrent; Failed; Revision surgery; Open and arthroscopic approach; Conservative or non-operative treatment; Physiotherapy; Functional outcomes; Prognostic factors; Latissimus dorsi transfer; Subacromial spacer interposition; Balloon; Biceps tenotomy; Superior capsular reconstruction; Reverse arthroplasty; Magnetic resonance imaging (MRI) arthrography (MRA); Fosbury flop tear; New tear pattern; FUSSI; SAM.

Biomechanics of the Posterosuperior Rotator Cuff

A primary function of the rotator cuff is to work synergistically with the deltoid to maintain a balanced force couple about the glenohumeral joint. A force couple is a pair of forces that act on an object and tend to cause it to rotate. For any object to be in equilibrium, the forces must create moments about a center of rotation that are equal in magnitude and opposite in direction. Coronal and transverse plane force couples exist between the subscapularis anteriorly and infraspinatus and teres minor posteriorly. The rotator cuff force across the glenoid provides concavity compression, which creates a stable fulcrum and allows the periscapular muscles to move the humerus around the glenoid.

The rotator cable is a thickening of the rotator cuff that has been likened to a suspension bridge in which force is distributed through cables that are supported by pillars (the anterior and posterior attachments). The anterior rotator cable attachment bifurcates to attach to bone just anterior and posterior to the proximal aspect of the bicipital groove. The posterior attachment comprises the inferior 50% of the infraspinatus. With small central tears the cable attachments often stay intact and forces are transmitted along the rotator cable. The rotator cable also explains why patients with most rotator cuff tears can maintain active forward flexion, and also why even after only a partial rotator cuff repair, good functional results can be achieved.

However, in the setting of massive rotator cuff with rotator cable disruption and non-compensation by other humeral head stabilizers (i.e pectoralis major and latissimus dorsi), the moments created by the opposing muscular forces are insufficient to maintain equilibrium in the coronal plane, resulting in altered kinematics, instability, and ultimately in pseudoparalysis. Interestingly, only few patients with an irreparable rotator cuff tears developed pseudoparalysis and arthritis.This finding has at least two potential explanations. First, the subscapularis that may not be involved in these tears is the key factor of active forward flexion.

Second, the rotator cable, has still an intact anterior attachment which is important for elevation. This may explain why patients can maintain active mobility, and also why even after only a partial rotator cuff repair, good functional results can be achieved.

Consequently, all the conditions for an imbalance in the force couples are not always met and subsequently loss of function is only occasionally seen.

Clinical examination

Supraspinatus

Superior rotator cuff insufficiency, present in complete tears, is usually associated with a positive Jobe manoeuver and decreased strength in the external resistance of the elbow at the side.

Figure. 1 Jobe manoeuver: the examiner push both arms down at the level of the wrists. Reproduce from Liotard J, Walch G. Test de Jobe. Recherche d'une atteinte du tendon supraépineux. In: Rodineau J, ed. 33 tests incontournables en traumatologie du sport. Paris: Éd. scientifiques; 2009, with permission.

Testing of abduction strength in the champagne toast position, i.e., 30° of abduction, mild external rotation, and 30° of flexion, better isolates the activity of the supraspinatus from the deltoid than Jobe's “empty can” position (Figure).

Figure. 2 Testing at 30° of abduction, 30° of forward elevation, 90° of elbow flexion, and mild external rotation replicates a “toast” position.

Infraspinatus and Teres Minor

Strength in External Rotation Elbow at the Side

Strength in external rotation elbow at the side of the supraspinatus, infraspinatus and teres minor represents approximately 10%, 70% and 20% of total external rotation strength, respectively.

However, the function of the teres minor may become more important in the setting of a chronic infraspinatus tear, as its hypertrophy is commonly observed in these cases and probably compensates for external rotation weakness.

External Rotation Lag Sign

The external rotation lag sign (Figure and Video), described by Hertel, was designed to test the integrity of infraspinatus and supraspinatus tendons.

The extent of internal rotation is recorded to the nearest 10 degrees degrees (10, 20, 30 and 40 degrees or above). An external rotation lag sign > 40 degrees seems to be the most reliable test for the teres minor.

Figure. 3 A) The external rotation lag sign is performed seated with the elbow flexed to 90 degrees and the shoulder elevated 20 degrees in the scapular plane. The arm is passively taken to maximal external rotation minus 5 degrees to allow for elastic recoil. B) The patient was asked to maintain that position as the clinician released the wrist. A positive test is defined as any internal rotation of more than 10 degrees. Reproduce from Collin et al., with permission.

Drop Sign

The drop sign (Figure and Video), also described by Hertel, is designed to assess the function of the infraspinatus.

Figure. 4
A) The drop sign is a lag sign beginning from 90 degrees of abduction in the scapular plane, with elbow flexion of 90 degrees, and external rotation of the shoulder to 90 degrees. From this position, the patient is asked to maintain the position against gravity (MRC Grade 3).
B) Failure to resist gravity and internal rotation of the arm is considered a positive drop sign. Reproduce from Collin et al., with permission.

Hornblower sign

The patient is asked to bring both hands to his mouth, but is unable to do so without abducting the affected arm (Video).

Patte Test

The Patte test (Figure and Video) is the only test that allowed to analyze the muscular strength of the teres minor in case of deficient infraspinatus.

Figure. 5
A) The Patte test is performed by passively taking from a starting point of 90 degrees of abduction in the scapular plane, an elbow flexion of 90 degrees without external rotation.
B) The patient is asked to perform external rotation of the shoulder from this position against resistance. A positive Patte test is defined as external rotation power less than MRC Grade 4. Reproduce from Collin et al., with permission.

Walch et al. reported a 100% sensitivity and 93% specificity with the Patte test and teres minor fatty atrophy Grade 3 or greater.

Dropping Sign

The dropping sign of Neer had a 100% sensitivity and 66% specificity for teres minor involvement.

Imaging

X-rays

The analysis should always begin with plain radiographic views to determine the morphology and status of the glenohumeral joint to exclude glenohumeral arthritis:

Anteroposterior True anteroposterior X-ray with the arm in neutral rotation, and the patient relaxed is obtained to evaluate the shape of the acromion and greater tuberosity, the critical shoulder angle, and the acromiohumeral distance. A decreased acromiohumeral distance < 7 mm in a standard antero-posterior radiograph indicates superior migration of the humeral head which increases the probability of finding an irreparable cuff tear. Such distance is correlated to 1) tears of the infraspinatus that mainly acts in lowering the humeral head, and 2) varying degrees of fatty infiltration.

Nevertheless, such criteria should be interpreted with parsimony. First, it is difficult in clinical practice to obtain standardized X-rays making measurement aleatory. Second, this distance has not been associated with an inability to obtain an intra-operative complete repair of the supraspinatus (18.2% irreparable, OR = 0.55, P = 0.610).

At the end of the spectrum, acetabularization of the acromion and femoralization of the humeral head are pre-operative adapting factors reflecting significant chronic static superior instability and are a contraindication for repair.

Lateral Y-view (Lamy)

Lateral Y-view (Lamy) is used to analyze the presence of a spur, the shape of the acromion on this view is less accurate to detect full-thickness rotator cuff tear.

Axillary lateral

An axillary lateral view can exclude static anterior subluxation or os acromialis.

If pathology of the acromioclavicular joint is suspected, a Zanca view is additionally acquired.

Ultrasound (US)

Following X-ray evaluation, advanced imaging modalities are obtained to confirm and plan treatment. Ultrasonography is an excellent cost-effective screening tool in the office but does not allow evaluation of intra-articular pathology or easy evaluation of muscle quality.

Rotator Cuff Interval

The space through which the long head of the biceps passes as it leaves the glenohumeral joint is called the rotator cuff interval. The patient position is the same as for evaluation of the long head of the biceps, with the probe being placed slightly superiorly to the bicipital groove and in the axial plane (Figure). The long head of the biceps is thus visualized with the subscapularis medially and the supraspinatus laterally, while the coracohumeral and superior glenohumeral ligaments surround it.

Figure. 6 Rotator cuff interval, containing the long head of the biceps, with a longitudinal view of the subscapularis medially and transverse view of the supraspinatus laterally, while the coracohumeral and superior glenohumeral ligaments surround it. Ultrasound image (a) with superimposed anatomy (b) and patient/probe position (c). Reproduced from Plomb-Holmes et al., with permission.

Supraspinatus Tendon and Subacromial-Subdeltoid Bursa

The supraspinatus tendon is best visualized with the shoulder in abduction and internal rotation, by asking the patient to place the palm of their hand on their back pocket, elbow pointed backwards (Figure). In patients presenting with reduced range of motion (adhesive capsulitis for example), maximal internal rotation with the arm hanging by the side of the thorax can be sufficient. The long axis of the tendon is most useful for analyzing integrity of the tendon on the footprint (measuring approx. 2 cm medially to laterally), and is visualized by holding the probe in a tilted position (therefore not a true coronal plane but at an approx. 45 degree angle, following the line of the humerus (Figure)).

This position also allows visualization of two other structures: the subacromial-subdeltoid bursa (and the presence of excessive liquid, see below) and the humeral head along with its articular cartilage (and possible surface defects). In the axial plane (again not truly axial but at 90 degrees to the previous plane), the leading edge of the supraspinatus can be identified laterally to the biceps tendon. Moving the probe laterally will reveal the mid-portion of the tendon, with the anterior part of the infraspinatus eventually coming into view as an anisotropic and dark image (as the fibers run in a different plane).

Figure. 7 Supraspinatus tendon, visualized on its longitudinal axis, and the subacromial-subdeltoid bursa lying superficially to it.
Ultrasound image (a) with superimposed anatomy (b), patient/probe position (c), and landmarks for measurement of these two structures (d). Reproduced from Plomb-Holmes et al., with permission

Infraspinatus and teres minor tendon, glenohumeral joint, spinoglenoid notch

The infraspinatus tendon, which inserts posteriorly to the supraspinatus tendon, is best examined in its long axis by elongating it (the patient placing his or her hand on the opposite shoulder) and placing the probe on the posterior part of the patient’s shoulder (Figure). The insertion of the tendon on the humeral head can be analyzed, as well as the musculotendinous junction by sliding the probe medially. At this point, the glenohumeral joint line and posterior labrum can be visualized in thin patients, and even more medially, the spinoglenoid notch containing the suprascapular neurovascular bundle (and the possible presence of a ganglion cyst arising from the posterior labrum which can compress the bundle) (Figure). The teres minor tendon can be difficult to separate from the infraspinatus tendon; it is located inferiorly and has a similar aspect, but can be distinguished by the fact that deeper to it lies bone whereas the infraspinatus lies on articular cartilage, and its insertion is primarily muscular (vs. tendinous).

Figure. 8 Infraspinatus tendon, visualized on its longitudinal axis. Ultrasound image (a) with superimposed anatomy (b) and patient/probe position (c). Reproduced from Plomb-Holmes et al., with permission.

Magnetic Resonance Imaging (MRI) and Computer Tomography (CT)

Magnetic resonance imaging accurately estimates tear pattern, muscle fatty infiltration and atrophy, tendon length and retraction, and is thus obtained to plan repair or reconstructive surgeries. The muscle bellies of the rotator cuff are assessed, if available, on T1-weighted axial, coronal, sagittal views with cuts sufficiently medial on the scapula to allow proper assessment regardless of retraction. Finally, computer tomography (CT) scans are used if magnetic resonance imaging is contraindicated or if joint replacement is planned, particularly in the setting of glenoid deformity. Additionally, computer tomography (CT) scan can be conducted with intra-articular contrast to assess the cuff. It should be noted that the magnetic resonance imaging and computer tomography are not reliable to analyze the acromiohumeral distance as they are performed in lying position.

Fatty Infiltration

The most important negative prognostic factor is high-grade fatty infiltration of the rotator cuff muscle bellies (grade 3 or 4 fatty infiltration) (Figure).

Figure. 9 Sagittal view of a left shoulder computed tomography (CT) arthrogram that show a Grade 4 fatty infiltration of infraspinatus and teres minor.

Fatty infiltration is irreversible even with repair and leads to reduced function of the rotator cuff musculature.
If pathology of the acromioclavicular joint is suspected, a Zanca view is additionally acquired.

Atrophy

The presence or absence of supraspinatus atrophy is determined using the tangent sign of Zanetti et al. (Figure).