Rotator cuff Tears

Rotator cuff tears

Anatomy and Biomechanics:

• The rotator cuff is formed from the tendinous insertions of the subscapularis, supraspinatus, infraspinatus, and teres minor muscles.
• Traditionally these musculotendinous units have been described as discrete anatomic structures, the tendons of the rotator cuff fuse as one continuous band near their insertions into the tuberosities of the humerus
• The primary mechanical function of the rotator cuff is to balance the force couples about the glenohumeral joint to provide a stable fulcrum of motion and functional glenohumeral kinematics
• Importance of transverse plane force couple: Here the anterior cuff (subscapularis) is balanced by the posterior cuff (infraspinatus and teres minor)
• Rotator cuff tears involving most of the anterior cuff or most of the posterior rotator cuff may result in unstable kinematic patterns
• coronal plane force couple: Here the deltoid is balanced by the inferior portion of the rotator cuff
• a rotator cuff tear can also be likened to a suspension bridge, with the free margin of the tear corresponding to the cable, and the anterior and posterior attachments of the tear corresponding to the supports at each end of the cable’s span
• Such a model would predict that despite a tear of the supraspinatus tendon, the supraspinatus muscle can still exert a force on the humerus by means of its distributed load along the span of the suspension bridge configuration
• This explains why certain rotator cuff tears (termed functional rotator cuff tears), despite being massive in size, may demonstrate “normal” kinematic patterns

 

Maybe Acute or chronic, partial or full thickness, and traumatic or degenerative.

Ellman’s staging of partial-thickness tears may help in guiding management:

• Grade I: Tear up to a quarter of the tendon thickness

• Grade II: Tear between a quarter and half the thickness

• Grade III: Tear more than half the thickness of the cuff

 Clinical Features:

• Pain on the lateral aspect of the shoulder which may radiate distally to the deltoid insertion.
• The pain may also localize to the anterior aspect of the acromion and shoulder if there is impingement from a subacromial spur or biceps tendinitis
• Pain and weakness are consistent complaints and night pain is a very characteristic symptom.
• Patient would have felt or heard a pop.

       The Drop arm Sign:

–       The examiner abducts the arm to maximum degree.

–       Then the patient is asked to lower the arm gradually.

–       When a drop arm sign is present the patient is able to lower his arm around 100 degree after, which he suddenly loses control of his arm and his arm drops down.

–       It is indicative of a full thickness tear.

       The Dropping sign (external rotation lag sign):

–       The patient is asked to flex the elbow to 90 degree with arms by the side.

–       The shoulder is then passively externally rotated to the maximum and then released.

–       A normal individual will be able to maintain the arm in full external rotation, but patients with an infraspinatus tear will not be able to maintain their arm in external rotation

       Patte Test. (“horn blower’s sign”) is performed with the patient in sitting or standing.

–       The patient’s arm is supported in 90 degrees of abduction in the scapular plane, with the elbow flexed to 90 degrees.

–       The patient is then asked to rotate the forearm externally against the resistance of the clinician’s hand.

–       If the patient is unable to externally rotate the shoulder in this position, the horn blower’s sign is said to be present. It is highly suggestive of tears of the teres minor

X-rays:

AP view in the plane of the scapula, AP view in the coronal plane, and an axillary view of the shoulder.

Specialized views:

• Supraspinatus outlet view (10- to 15 degree caudal-tilt lateral scapular view) to assess supraspinatus outlet narrowing.
• AP coronal 10- to 30-degree cephalic-tilt view to evaluate the acromioclavicular joint for acromioclavicular arthritis

 

X-ray:

• Acromiohumeral interval less than 7 mm
• Subacromial calcification
• Greater tuberosity sclerosis or irregularity
• Cysts at greater tuberosity
• Subacromial spur
• Concave acromion
• Degenerative changes at the acromioclavicular joint
• Distally pointing acromioclavicular spur greater than 2 mm in diameter
• Degenerative changes at the glenohumeral joint
• Exaggerated groove between the greater tuberosity and the humeral articular surface

 

 Ultrasound Imaging: The most consistent ultrasound findings of a rotator cuff tear are nonvisualization, focal thinning, and discontinuity of the cuff.

MRI is diagnostic

Treatment

Conservative initially with analgesics, physiotherapy, ultrasound therapy

Indications for surgery:      Full thickness tears

                                                     Tears in younger patients

                                                     Not responding to conservative measures

Surgery

–      Arthroscopic Rotator cuff repair has become the gold standard to treat full thickness rotator cuff tears.

–      Tuberoplasty may done simultaneously:  this is a procedure in which the bony excrescences of the greater tuberosity are débrided such that the humeral head conforms to the rounded undersurface of the acromion. This is useful only in the elderly patients

–      A mini-open repair is an alternative if all arthroscopic repair is difficult to perform.

–        Full thickness tears are (if possible) repaired and reattached to bone using tissue anchors or drill holes. Mobilization of the relevant tendon is required, and relaxing incisions made within the rotator interval may be helpful.

–        The management of partial- thickness tears is controversial. A reasonable approach is simply to debride tears of less than half the tendon thickness (Grades I and II), and to repair more severe injuries (Grade III).

–        Some authors have advocated converting them to complete tears and repairing them.

–      The final option for treatment of a massive rotator cuff tear is a muscle transfer.

–      A transfer of the pectoralis major is performed for a chronic irreparable subscapularis tear, and a latissimus transfer is used for posterior and superior cuff insufficiency. The deltoid must also be intact and functioning well