Rotator Cuff Tear Case File

Rotator Cuff Tear Case File

Eugene C. Toy, MD, Lawrence M. Ross, MD, PhD, Han Zhang, MD, Cristo Papasakelariou, MD, FACOG

CASE 57

A 64-year-old man complains of pain and weakness in his right shoulder for the previous 2 months. He states that the pain is worse when he tries to lift his arm and he has difficulty keeping his arm elevated for more than a few seconds. He denies any falls or trauma to the arm or shoulder. His right hand is dominant. On examination, he has minor pain on palpation of the right shoulder. The pain is increased with abduction of his arm greater than 90°. Additionally, he is unable to hold his arm in an abducted position and has weakness with external rotation. Following injection of lidocaine in the joint, his pain disappears, but the weakness continues.

⯈ What is the most likely diagnosis?

⯈ What anatomical structure is involved?

ANSWER TO CASE 57:

Rotator Cuff Tear

Summary: A 64-year-old man with no previous trauma is complaining of chronic pain and weakness in his dominant arm. He has pain with abduction in addition to weakness with external rotation on examination. Injection of a local anesthetic relieves his pain but not help the weakness that he has been experiencing.

• Most likely diagnosis: Rotator cuff tear

• Anatomical structure likely involved: The rotator cuff, which consists of the supraspinatus, infraspinatus, teres minor, and subscapularis muscles

CLINICAL CORRELATION

This elderly man has the typical findings of a rotator cuff tear. Although some patients may be asymptomatic, common complaints include pain and weakness with abduction. Rotator cuff injuries are very common, especially in patients over the age of 40. The rotator cuff may be torn acutely, such as with trauma, or it may be a chronic issue, with both degeneration secondary to age and repetitive stress contributing. The rotator cuff stabilizes the glenohumeral joint and facilitates various arm movements. The supraspinatus contributes to abduction of the arm, especially early abduction. The infraspinatus and teres minor are external rotators. The subscapularis rotates the arm internally. Lidocaine injection is helpful for diagnosis as it distinguishes rotator cuff tendinopathy from a tear. Lidocaine relieves pain in both injuries, but will improve strength in only tendinopathy.

APPROACH TO:

Scapulohumeral Muscles (Intrinsic Shoulder Muscles)

OBJECTIVES

1. Be able to describe the arrangement of intrinsic shoulder muscles

2. Be able to describe the actions of the rotator cuff muscles

3. Be able to understand the features of the shoulder joint

DISCUSSION

There are two groups of muscles surrounding the glenohumeral (shoulder) joint: axioappendicular muscles (extrinsic shoulder muscles) and scapulohumeral muscles (intrinsic shoulder muscles). The extrinsic muscles (total nine muscles) connect the upper limb to the trunk; the six intrinsic shoulder muscles (deltoid, teres major, supraspinatus, infraspinatus, teres minor, and subscapularis) originate from the pectoral girdle (scapula and clavicle), insert to the

Table 57-1 • ROTATOR CUFF MUSCLES
Muscle	Origin	Insertion	Nerve Innervation	Main Action
Supraspinatus	Supraspinal fossa of scapula	Superior facet of greater tubercle of humerus	Suprascapular	Initiates abduction of arm
Infraspinatus	Infraspinal fossa of scapula	Middle facet of greater tubercle of humerus	Suprascapular	Laterally rotate arm
Teres minor	Lateral border of scapula	Inferior facet of greater tubercle of humerus	Axillary	Laterally rotate arm
Subscapularis	Subscapular fossa of scapula	Lesser tubercle of humerus	Upper and lower subscapular	Medially rotate arm

humerus, and act on the shoulder joint. Four of the intrinsic shoulder muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) are referred to as rotator cuff muscles (see Table 57-1) because their muscle fibers and tendons surround the capsule of the shoulder joint to form the musculotendinous rotator cuff (see Figure 57-1).

Figure 57-1. Muscles, tendons, and ligaments of the shoulder joint (lateral view). [Reproduced, with permission, from Lindner HH. Clinical Anatomy. East Norwalk, CT: Appleton & Lange, 1989:528 (Figure 41-3).]

The shoulder joint is a ball-and-socket synovial joint consisting of the large head of the humerus and small glenoid fossa of the scapula that fosters the mobility of the joint but also makes it relatively unstable.

The tendon of the supraspinatus crosses over the capsule superiorly, the tendons of the infraspinatus and the teres minor cross over the capsule posteriorly, and the tendon of the subscapularis crosses over the capsule anteriorly; these tendons (SITS) reinforce the joint capsule from three directions to protect the joint and give it stability.

Between the tendons of the rotator cuff muscles and the joint capsule are the bursae, which contain synovial fluid to reduce friction during muscle contractions. Most of the bursae directly communicate with the cavity of the shoulder joint.

Lesions or degeneration of the rotator cuff and related bursae are common causes of pain in the shoulder area.

COMPREHENSION QUESTIONS

57.1 A 44-year-old swimmer is seen in the physician’s office for right shoulder pain for 1 year. A radiograph of the shoulder indicates that the supraspinatus tendon is calcified. What movement is most likely to cause discomfort in this patient?

    A. Medial rotation of the humerus

    B. Lateral rotation of the humerus

    C. Adduction of the humerus

    D. Abduction of the humerus

57.2 A 19-year-old man is involved in a motor vehicle accident and suffers a right proximal humeral fracture. The patient is noted to have numbness of the right lateral upper arm and also inability to abduct his arm. Which of following muscles is likely affected by this nerve injury?

    A. Teres minor

    B. Supraspinatus

    C. Subscapularis

    D. Teres major

    E. Infraspinatus

57.3 An important function of the rotator cuff is

    A. Depression of the clavicle

    B. Elevation of the clavicle

    C. Costoclavicular support

    D. Stabilization of the humeral head

    E. Protraction of the acromial angle

ANSWERS

57.1 D. This patient likely has rotator cuff syndrome due to repetitive wearand- tear of the rotator cuff muscles. The rotator cuff consists of the supraspinatus, infraspinatus, teres minor, and subcapsularis muscles. The rotator cuff muscles act on abduction of the humerus. The other motions do not involve the rotator cuff muscles.

57.2 A. This patient likely has axillary nerve injury from blunt trauma to the quadrangular space. The quadrangular space is where the axillary nerve travels from anterior to posterior. It is bounded by the subscapularis muscle and teres minor, teres major, surgical neck of the humerus, and the long head of the triceps muscle. Injury to the axillary nerve affects the teres minor and deltoid muscles. The suprascapular nerve innervates the supraspinatus and infraspinatus muscles, and the subscapular nerve innervates the teres major and infraspinatus muscles.

57.3 D. Besides rotatory movement of the humerus in specific directions, the rotator cuff is an important stabilized of the shoulder.

ANATOMY PEARLS

⯈ The rotator cuff is the musculotendinous structure that surrounds the shoulder joint. It is composed of four muscles and their tendons (SITS) that cross over the shoulder joint from three directions and contributes to the stabilization of the joint.

⯈ Rotator cuff injury and degeneration in older people are common causes of shoulder pain.

References

Gilroy AM, MacPherson BR, Ross LM. Atlas of Anatomy, 2nd ed. New York, NY: Thieme Medical Publishers; 2012:286−287, 290−297. 

Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy, 7th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014:706−707, 712. 

Netter FH. Atlas of Human Anatomy, 6th ed. Philadelphia, PA: Saunders; 2014: plates 405−408, 411, 413, 418.

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