Practice Essentials
Rupture of the rotator cuff tendon was first described by Smith in 1834. Subsequently, degenerative changes of the rotator cuff have been better characterized by Duplay (1872), Von Meyer (1924), Codman (1934), and Neer (1972). [1] The exact mechanisms leading to the degeneration of the rotator cuff, however, are still being debated.
Shoulder pain is the third most common cause of musculoskeletal disorders (MSDs), after low back and neck pain. Although rotator cuff tendinitis is considered a benign condition, a study of its long-term outcome found that 61% of patients were still symptomatic at 18 months, despite receiving what was considered sufficient conservative treatment, and 26% rated their symptoms as severe. MSDs are the primary disabling conditions of working adults. The prevalence of rotator cuff tendinitis has been found to be as high as 18% in certain workers who performed heavy manual labor.
Webster and Snook estimated that the mean compensation cost per case of upper-extremity work-related MSD was $8070 in 1993; the total US compensable cost for upper extremity, work-related MSDs was $563 million in the 1993 workforce. [2] The compensable cost is limited to the medical expenses and indemnity costs (lost wages). When other expenses (eg, full lost wages, lost production, cost of recruiting and training replacement workers, cost of rehabilitating the affected workers) are considered, the total cost to the national economy becomes much greater.
The impact of rotator cuff disease on quality of life is even more difficult to assess than its cost. Further studies using valid methods that measure the impact of the disorder on general health (eg, the Medical Outcomes Study [MOS] Short-Form [SF]-36 health survey) should help in the evaluation of this issue. Some of these studies have already been done, especially with SF-12.
Conservative treatment of the degenerative rotator cuff may be effective. (See Treatment.) However, patients with more advanced rotator cuff disease or a more significant injury may not respond to conservative therapies. If the patient believes that his or her quality of life is being significantly impacted by the shoulder dysfunction, then surgical intervention is a reasonable consideration.
Anatomy
The rotator cuff is composed of four muscles—subscapularis, supraspinatus, infraspinatus, and teres minor—and their musculotendinous attachments (see the image below).
The subscapularis is innervated by the subscapular nerve and originates on the scapula. It inserts on the lesser tuberosity of the humerus. The supraspinatus and the infraspinatus are both innervated by the suprascapular nerve, originate in the scapula, and insert on the greater tuberosity. The teres minor is innervated by the axillary nerve, originates on the scapula, and inserts on the greater tuberosity.
The subacromial space lies underneath the acromion, the coracoid process, the acromioclavicular joint, and the coracoacromial ligament. A bursa in the subacromial space provides lubrication for the rotator cuff. [3, 4]
A solid knowledge of the functional anatomy of the rotator cuff makes it easier to understand the disorder that affect this structure. The rotator cuff is the dynamic stabilizer of the glenohumeral joint; the static stabilizers are the capsule and the labrum complex, including the glenohumeral ligaments. Although the rotator cuff muscles generate torque, they also depress the humeral head. The deltoid abducts the shoulder. Without an intact rotator cuff, particularly during the first 60° of humeral elevation, the unopposed deltoid would cause cephalad migration of the humeral head, with resulting subacromial impingement.
Pathophysiology
Rotator cuff pathology can result from extrinsic or intrinsic factors. Extrinsic examples include a traumatic tear in tendons from a fall or accident. Overuse injuries from repetitive lifting, pushing, pulling, or throwing are also extrinsic in nature. Intrinsic factors include poor blood supply, normal attrition or degeneration with aging, and calcific invasion of tendons. [3, 5, 6, 7, 8, 9]
Rotator cuff tendinitis is the term used to describe irritation of tendons either from excessive pressure on the acromion or, less commonly, from intrinsic tendon pathology. Irritation of the adjacent bursa is known as subdeltoid or subacromial bursitis. The condition that develops when repetitive overhead activities result in irritation of tendons and bursae from repeated contact with the undersurface of the acromion is termed impingement syndrome.
Rotator cuff dysfunction is typically a continuum of pathology ranging from tendinitis and bursitis to partial tearing to complete tearing in one or more of the tendons. Although the earlier stages may resolve with conservative care, actual tearing of the tendon can be more problematic. These tears most commonly occur at the tenoperiosteal (tendon-to-bone) junction. Because this area has a relatively poor blood supply, injury to the tendon at this location is very unlikely to heal well.
Additionally, the constant resting tension in the muscle-tendon unit, or muscle tone, pulls any detached fibers away from the bone, preventing their reattachment. Finally, joint fluid from within the shoulder may seep into the gap created by the tear and prevent the normal healing processes from occurring.
Etiology
Possible causes of rotator cuff pathology include the following:
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Outlet impingement
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Subacromial spurs
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Type 2 and type 3 acromions
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Osteoarthritic spurs of the acromioclavicular joint (including subacromial spurs)
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Thickened or calcified coracoacromial ligament
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Nonoutlet impingement
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Loss of rotator cuff causing superior migration of the humerus (ie, tear, loss of strength)
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Secondary impingement from an unstable shoulder
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Acromial defects (os acromiale)
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Anterior or posterior capsular contractures (eg, adhesive capsulitis)
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Thick subacromial bursa
Genetic factors may play a role in the pathogenesis of rotator cuff disease. A systematic review by Longo et al found significant associations between single-nucleotide polymorphisms and rotator cuff disease was found for DEFB1, FGFR1, FGFR3, ESRRB, FGF10, MMP-1, TNC, FCRL3, SASH1, SAP30BP, and rs71404070 located next to cadherin8; results reported for MMP-3 were contradictory. [10]
Epidemiology
Shoulder pain is the third most common cause of MSDs, after low back pain and cervical pain. Estimates of the cumulative annual incidence of shoulder disorders have ranged from 7% to 25% in the Western general population. The annual incidence has been estimated at 10 cases per 1000 population, peaking at 25 cases per 1000 population in persons aged 42-46 years.
In persons aged 70 years or older, 21% of persons have shoulder symptoms, most of which can be attributed to the rotator cuff. In cadaver studies, the rate of full-thickness tears has ranged from 18% to 26%. The rate of partial-thickness tears ranges from 32% to 37% after age 40 years. Before age 40 years, tears are rare. In magnetic resonance imaging (MRI) studies, tears have been observed in 34% of asymptomatic individuals of any age. After age 60 years, 26% of patients have partial-thickness tears, and 28% demonstrate full-thickness tears.
No known racial variation associated with rotator cuff disease is cited in the literature. In one study, a predominance of male patients (66%) seeking consultation for rotator disease was reported, but in other studies, the male-to-female ratio was 1:1. Rotator cuff disease is more common after age 40 years. The average age of onset has been estimated at 55 years.
Prognosis
An estimated 4% of cuff ruptures develop a cuff arthropathy. Various authors report the success rate of conservative treatment to be 33-90%, with longer recovery time required in older patients. Surgery results in better function regardless of the patient's age.
Piasecki et al found that arthroscopic revision rotator cuff repair may be a reasonable option even after previous open repair, providing improved pain relief and shoulder function. [11] In the 54 patients studied, the American Shoulder and Elbow Surgeons scores improved from 43.8 ± 5.7 to 68.1 ± 7.2, and the Simple Shoulder Test improved from 3.56 ± 0.8 to 7.5 ± 1.1. Visual Analog Scale (VAS) scores for pain improved from 5.17 ± 0.8 to 2.75 ± 0.8, and forward elevation increased from 121.0º ± 12.3º to 136º ± 11.8º. Female patients and those who had undergone more than one ipsilateral shoulder surgery had poorer results.
In a systematic review of the published literature, Nho et al compared single-row (SR) with double-row (DR) suture anchor fixation in arthroscopic rotator cuff repair. [12] They found no clinical differences between the two approaches. They concluded that the data in the published literature do not support the use of DR suture anchor fixation to improve clinical outcome, though they noted that there are some studies reporting that DR suture anchor fixation may improve tendon healing.
A meta-analysis including three randomized controlled studies and two controlled clinical cohort studies compared outcomes between SR and DR rotator cuff repair. [13] Whereas the DR technique was found to increase operating time significantly, it provided greater external rotation, improved tendon healing, and a decreased recurrence rate. However, there were no significant differences between the two techniques with regard to shoulder function, muscle strength, forward flexion, internal rotation, patient satisfaction, or return to work.
One study analyzed the structural and functional outcomes after arthroscopic rotator cuff repair between SR, DR, and combined DR/suture-bridge techniques. [14] After an average follow-up of 38.5 months, repair with the combined DR/suture-bridge technique resulted in an overall decreased retear rate, especially for large and massive tears. This combined technique proved to be an effective option for arthroscopic rotator cuff repair.
A prospective randomized controlled study by Schofer et al compared high-energy extracorporeal shock-wave therapy (ESWT) with low-energy ESWT for treatment of rotator cuff tendinopathy. [15] Patients in the high-energy group received 6000 impulses of ED+ 0.78 mJ/mm2 in three sessions, and those in the low-energy group received 6000 impulses of ED+ 0.33 mJ/mm2. Increased function and reduced pain were found in both groups. Although the improvement in Constant score was greater in the high-energy group, there was no statistically significant difference between the two groups with respect to Constant score, pain reduction, and subjective improvement after 12 weeks and after 1-year follow-up.
Drake et al, in a study reviewing the use of reverse total shoulder arthroplasty (RTSA) in patients with rotator cuff disease, [16] found that modern RTSA designs restored deltoid tension and a functional fulcrum to the rotator cuff-deficient shoulder, allowing recovery of active shoulder elevation and restoring function. Contraindications for RTSA included the following:
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Severely impaired deltoid function
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Isolated supraspinatus tear
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Presence of full active shoulder elevation with a massive rotator cuff tear and arthritis
Drake et al concluded that for properly selected patients with symptomatic and disabling rotator cuff deficiency, RTSA can yield life-changing improvements in pain, motion, function, and patient satisfaction. [16]
Wellmann et al concluded that for patients with symptomatic and disabling rotator cuff deficiency, RTSA can result in a significant reduction in pain and improvements in motion and function. [17]
Using propensity-matching methods, Oh et al compared the outcomes of patients with pseudoparalytic large-to-massive tears with those of patients with nonpseudoparalytic tears after rotator cuff repair with the aim of determining whether the presence of pseudoparalysis had a negative effect. [18] Evidence of recovery from pseudoparalysis was noted in a large portion of the study group; similar outcomes were noted in postoperative function and cuff healing, whether pseudoparalysis was present or not. Considering the possible complications from treatment with RTSA, the authors suggested that rotator cuff repair should be the first-line treatment option for large-to-massive tears.
Data from a study by Chung et al showed that the failure rate after arthroscopic rotator cuff repair was significantly higher in patients with lower bone mineral density, a higher grade of fatty infiltration of the infraspinatus, and greater amount of retraction. [19]
The T-scale, a measure of the anterolateral translation of the humeral head, has been suggested as a prognostic factor for rotator cuff repair. In a study of 120 consecutive patients with full-thickness rotator cuff tears, Taniguchi et al found that patients who had large-to-massive tears in conjunction with negative values on this scale had poorer clinical outcomes and were at greater risk for repeat tearing. [20] They concluded that a negative T-scale value is a useful prognostic factor for considering reverse shoulder arthroplasty in patients with a higher risk of retear.
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Rotator cuff anatomy.
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Series of events. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Tear in supraspinatus tendon. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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In this patient's shoulder radiography, humeral head no longer matches up with glenoid, because rotator cuff is torn and strong deltoid muscle is pulling head superiorly toward acromion. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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View of large tear from posterior (behind). Socket is to right. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Visualizing torn rotator cuff from within joint. Biceps tendon is running vertically on left. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Motorized burr removing undersurface of acromion. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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View of large tear from "50-yard line." Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Side-to-side stitches begin to close large tear defect. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Arthroscopic knot-tying instrument is used to pass tie knots in suture to secure repair. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Small metallic anchors (5 mm) with sutures attached are then inserted into humerus at site desired for tendon reattachment. Anchors are recessed below surface so that only suture is visible. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Sutures are anchored with metallic anchors. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Normal double-contrast arthrography. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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This image depicts channel between articular capsule and subacromial-subdeltoid bursa in acomplete rotator cuff tear. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Even if channel cannot be always identified, presence of contrast medium in subdeltoid-subacromial bursa signals presence of complete rotator cuff tear. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Arthrography of shoulder in axial plane. Note presence of air and contrast in subacromial-subdeltoid bursa. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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CT arthrography of shoulder in axial plane. Note presence of air and contrast in subacromial-subdeltoid bursa. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Full-thickness tear of supraspinatus, seen as hyperintensity line through full thickness of tendon in flash 2-dimensional MRI sequence in coronal oblique plane. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Slight hyperintensity signal within tendon without transsectional hyperintensity throughout tendon is compatible with tendinopathy without complete tear. Additionally, note presence of hyperintensity signal in region of subdeltoid-subacromial bursa, which indicates bursitis. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Calcifications are seen as hypointense foci in flash 2-dimensional images. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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MRI arthrography can help to identify labral tears, as seen in this image. Contrast medium penetrates between labrum and articular surface. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Ultrasonography is another modality to demonstrate complete rotator cuff tear, as seen here with gap of more than 2 cm between two extremities of the torn tendon. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
