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.