Rotator Cuff DysfuctionDz

Synonyms: Rotator cuff tendinitis, impingement syndrome.

ICD-9 Codes: Rotator cuff tear, 727.61; rotator cuff dysfunction NOS, 726.10.

Definition: Rotator cuff dysfunction refers to a spectrum of pathologic changes in the rotator cuff tendons, ranging from mild inflammation or tendinitis to a complete tear. Associated pathologic changes have given rise to names such as impingement syndrome and frozen shoulder. Many patients also have subacromial bursitis in conjunction with rotator cuff dysfunction. Rotator cuff dysfunction is the most common cause of shoulder complaints among the elderly, accounting for >75% of cases. This is notable because shoulder problems are the second most common musculoskeletal complaint in general practice.

Anatomic Considerations: Four muscles and their tendons constitute the rotator cuff apparatus. These muscles (the supraspinatus, infraspinatus, subscapularis, and teres minor) originate on the scapula, pass through a tunnel of ligaments on the underside of the acromion process, and insert on the trochanters of the humerus. They function to abduct, internally rotate, and externally rotate the humeral head. This allows free upper extremity movement in many different planes. The rotator cuff tendons also form the roof of the glenohumeral joint, being contiguous with its fibrous capsule. The rotator cuff tendons are separated from the overlying deltoid muscle by the subacromial bursa.

Pathology: Pathologically, it can be demonstrated that the rotator cuff tendons tend to degenerate with advancing age, which provides some explanation for the increasing prevalence of rotator cuff problems with advancing age. Intrinsic degeneration may be exacerbated by chronic overuse (e.g., manual labor involving repetitive shoulder movements against force) or by arthritis in adjacent joints (e.g., RA affecting the acromioclavicular or glenohumeral joints). Rotator cuff dysfunction in many persons represents a continuum of disease. Initial involvement with mild tendinitis may progress, resulting in a complete tear of the rotator cuff tendons. In addition, mild tendinitis may cause the patient to favor the affected arm, diminishing movements of the affected muscles. This allows the deltoid to pull the humeral head higher in the glenohumeral fossa, which in turn reduces the area of the space through which the rotator cuff tendons must pass. This may result in impingement of the rotator cuff against the acromion, which can cause further pain and worsen the entire process. If this is allowed to become chronic, tendon shortening may ensue, greatly diminishing movement of the shoulder. This frozen shoulder syndrome has also been referred to as adhesive capsulitis. However, because adhesions are not typically a part of the pathologic process, restrictive capsulitis has become the preferred term.

Demographics: Those at risk include the elderly, those with inflammatory arthritis of the shoulder (e.g., RA), diabetics, alcoholics, athletes with repetitive over-head or throwing movement, carpenters, welders, and painters.

Cardinal Findings: In some cases, particularly in younger persons (e.g., baseball pitchers), injury to the rotator cuff is acute. More commonly, pain related to rotator cuff dysfunction arises insidiously and often becomes chronic.
Patients with rotator cuff dysfunction characteristically complain of shoulder pain. The pain is usually somewhat difficult for the patient to localize more specifically, other than perhaps saying it is deep. Many patients complain of waking at night because of the pain. It is often worsened by movements that require specific use of the affected muscles. However, patients may compensate and perform movements that normally use the rotator cuff muscles by using other motions. For example, patients may avoid upper extremity abduction while hair brushing. Patients often report pain performing activities that require rotator cuff muscles (e.g., tying an apron behind the back or tucking a shirt into the back of the pants).
Physical examination for rotator cuff function should assess active and passive range of motion of the shoulder and test the muscles individually for pain or weakness. Patients with rotator cuff dysfunction typically have no difficulty with forward flexion or extension of the shoulder. Many have problems with abduction. Normally, the first 15 degrees of abduction is initiated by the deltoid. Abduction from there through 90 degrees depends mostly on the supraspinatus. (Above 90 degrees there is little further abduction; rather, the trapezius and rhomboid muscles tilt the scapula and bring it toward the midline.) Patients with rotator cuff dysfunction frequently have pain on, or limited range of, active abduction. If it is severe, e.g., in someone with long-standing disease and restrictive capsulitis, passive movements (i.e., done by the examiner) may be limited or result in pain. Some consider patients with impaired range of active motion but normal range of passive motion to have evidence of impingement. The other rotator cuff muscles can also be a source of pain and should be assessed. The subscapularis internally rotates the humeral head. This can be tested by having the patient hold the elbow against the side, with 90 degrees of elbow flexion, and try to move the hand medially against the examiner’s resistance. External rotation is mediated by the infraspinatus and teres minor. It can be tested as for internal rotation, except the examiner provides resistance against the patient’s attempt to move the hand laterally. In some cases, it may be possible to differentiate tendon inflammation from a complete tendon tear; the former being associated with pain, the latter with both pain and weakness. However, in practicality, it is difficult to differentiate between the two.

Complete tear of the rotator cuff is usually an acute posttraumatic event. Patients also complain of shoulder pain and weakness and may have a positive drop arm test.

Diagnostic Tests: No laboratory tests are helpful in diagnosing rotator cuff disease.

Imaging: Imaging modalities, although usually unnecessary to establish rotator cuff dysfunction as the cause of shoulder pain, may be helpful in determining the need for surgery or in unusual cases. Plain radiographs are not usually helpful because bony abnormalities are not commonly a critical part of the pathology. Commonly, the humeral head appears to be displaced slightly superiorly in the glenohumeral fossa. Some patients have acromioclavicular joint hypertrophy, which may contribute to impingement. Ultrasonography may define abnormalities in the rotator cuff, but the interpretation and utility of the study depend to a large extent on the experience of the ultrasonographer. MRI allows exquisite detail of the relevant tissues. It has replaced arthrography in the diagnosis of complete rotator cuff tendon tears.

Treatment: The treatment of rotator cuff disease may incorporate rest in acute settings. The use of hot packs, ice packs, ultrasonography, analgesic agents, or NSAIDs may be helpful in some individuals. However, aggressive physiotherapy with range-of-motion exercises and strengthening of the rotator cuff muscles is a critical component of therapy for all. Injection of the subacromial bursa with corticosteroids can provide substantial relief, particularly in patients with evidence of subacromial bursitis.

Surgery: Surgery is indicated in particular circumstances. For example, in patients with evidence of impingement, acromioplasty can increase the available space and decrease symptoms. In past years, some patients with frozen shoulder underwent surgical release. However, because this intervention did not appear to affect the ultimate outcome for these patients, most patients are now treated conservatively.

BIBLIOGRAPHY

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