A Rotator cuff tear is a tear of one or more of the tendons of the four rotator cuff muscles of the shoulder. A rotator cuff ‘injury’ can include any type of irritation or overuse of those muscles or tendons and is among the most common conditions affecting the shoulder.
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| Rotator Cuff Injury |
Anatomy of Rotator cuff lesion :
The tendons of the rotator cuff Muscle Group , not the muscles, are most commonly involved, and of the four Muscle Tendon Are Supraspinatus,Infraspinatus, Teres Minor And Subscapularis , the supraspinatus is most frequently affected, as it passes below the acromion. The role of the supraspinatus is to resist downward motion. The supraspinatus resists downward motion while the shoulder is relaxed as well as when carrying weight.Such a tear usually occurs at its point of insertion onto the humeral head at the greater tubercle. Even though the supraspinatus is the most commonly injured muscle of the four muscles in the rotator cuff, the other three muscles that comprise the rotator cuff, the infraspinatus, teres minor, and subscapularis, may also be injured.ROTATOR CUFF TENDON GROUP MUSCLE
The Rotator cuff is responsible for stabilizing the glenohumeral joint, abducting, externally rotating, and internally rotating the humerus. When shoulder trauma occurs, these functions can be compromised. Because individuals are highly dependent on the shoulder for many activities, overuse of the muscles can lead to tears, the vast majority again occurring in the supraspinatus tendon.SHOLDER ROTATOR CUFF SYMPTOM AND SIGN
Signs :
It has been suggested that no single physical examination test distinguishes reliably between bursitis, partial-thickness, and full-thickness tears.On the contrary, a combination of tests seems to provide the most accurate diagnosis. For impingement, these tests include the Hawkins-Kennedy impingement sign in which the examiner medially rotates the patient’s flexed arm, forcing the supraspinatus tendon against the coracoacromial ligament and so producing pain if the test is positive a positive painful arc sign, and weakness in external rotation with the arm at the side. For the diagnosis of full-thickness rotator cuff tear, the best combination appears to include once more the painful arc and weakness in external rotation, and in addition, the drop arm sign.This test is also known as Codman’s test. The arm is raised to the side to 90° by the examiner. The patient then attempts to look to lower the arm back to neutral, palm down. If the arm drops suddenly or pain is experienced, the test is considered positive.Symptoms :
Symptoms may occur immediately after trauma Which is acute Injury or develop over time Gradually Which is chronic Pain.Acute injury is less frequent than chronic disease, but may follow bouts of forcefully raising the arm against resistance, as occurs in weightlifting, for example. In addition, falling forcefully on the shoulder can cause acute symptoms. These traumatic tears predominantly affect the supraspinatus tendon or the rotator interval and symptoms include severe pain that radiates through the arm, and limited range of motion, specifically during abduction of the shoulder. Chronic tears occur among individuals who constantly participate in overhead activities, such as pitching or swimming, but can also develop from shoulder tendinitis or rotator cuff disease. Symptoms arising from chronic tears include sporadic worsening of pain, debilitation, and atrophy of the muscles, noticeable pain during rest, crackling sensations (crepitus) when moving the shoulder, and inability to move or lift the arm sufficiently, especially during abduction and flexion motions.
Pain in the anterolateral aspect of the shoulder is not specific to the shoulder, and may arise from, and be referred from, the neck, heart or gut.
Patient history will often include pain or ache over the front and outer aspect of the shoulder, pain aggravated by leaning on the elbow and pushing upwards on the shoulder (such as leaning on the armrest of a reclining chair), intolerance of overhead activity, pain at night when lying directly on the affected shoulder, pain when reaching forward (e.g. unable to lift a gallon of milk from the refrigerator). Weakness may be reported, but is often masked by pain and is usually found only through examination. With longer-standing pain, the shoulder is favored and gradually loss of motion and weakness may develop, which, due to pain and guarding, are often unrecognized by the patient and only brought to attention during examination.
Primary shoulder problems may cause pain over the deltoid muscle intensified by abduction against resistance – the impingement sign. This signifies pain arising from the rotator cuff, but cannot distinguish between inflammation, strain, or tear. Patients may report that they are unable to reach upwards to brush their hair or to lift a food can from an overhead shelf.
Many rotator cuff tears are asymptomatic. They are known to increase in frequency with age and the most common cause is age-related degeneration and, less frequently, sports injuries or trauma. Both partial and full thickness tears have been found on post mortem and MRI studies in those without any history of shoulder pain or symptoms. However, the most common presentation is shoulder pain or discomfort. This may occur with activity, particularly shoulder activity above the horizontal position, but may also be present at rest in bed. Pain-restricted movement above the horizontal position may be present, as well as weakness with shoulder flexion and abduction.
Risk factors of Rotator cuff tears
Some risk factors of experiencing a rotator cuff tear cannot be changed: age, body mass index, and height. Recurrent lifting and overhead motions are at risk for rotator cuff tears. People who have jobs that involve overhead work, such as carpenters, painters, custodians and servers are at risk of also experiencing a rotator cuff tear. People who play sports that involve overhead motions, such as swimming, volleyball, baseball, tennis, and American football quarterbacks, are at a greater risk of experiencing a rotator cuff tear. Generally, the incidence of rotator cuff tears or injuries increases by age while corticosteroid injection for pain relief increases the risk of tendon tear and delays tendon healing.Mechanisms of injury :
The two main causes are injury (acute) and degeneration (chronic and cumulative), and the mechanisms involved can be either extrinsic or intrinsic or, probably most commonly, a combination of both.Acute tears :
The amount of stress needed to tear a rotator cuff tendon acutely will depend on the underlying condition of the tendon prior to the stress. In the case of a healthy tendon, the stress needed will be high, such as a fall on the outstretched arm. This stress may occur coincidentally with other injuries such as a dislocation of the shoulder, or separation of the acromioclavicular joint. In the case of a tendon with pre-existing degeneration, the force may be surprisingly modest, such as a sudden lift, particularly with the arm above the horizontal position. This is a common occurrence with rear seated passengers in a motor vehicle collision, regardless of speed.Chronic tears :
Chronic tears are indicative of extended use in conjunction with other factors such as poor biomechanics or muscular imbalance. Ultimately, most are the result of wear that occurs slowly over time as a natural part of aging. They are more common in the dominant arm, but a tear in one shoulder signals an increased risk of a tear in the opposing shoulder. Several factors contribute to degenerative, or chronic, rotator cuff tears of which repetitive stress is the most significant. This stress consists of repeating the same shoulder motions frequently, such as overhead throwing, rowing, and weightlifting. Many jobs that require frequent shoulder movement such as lifting and overhead movements also contribute.Another factor in older populations is impairment of blood supply. With age, circulation to the rotator cuff tendons decreases, impairing natural ability to repair, ultimately leading to, or contributing to, tears.
The final common factor is impingement syndrome, the most common non-sports related injury and which occurs when the tendons of the rotator cuff muscles become irritated and inflamed while passing through the subacromial space beneath the acromion. This relatively small space becomes even smaller when the arm is raised in a forward or upward position. Repetitive impingement can inflame the tendons and bursa, resulting in the syndrome.
Extrinsic factors :
Well-documented anatomical factors include the morphologic characteristics of the acromion. Hooked, curved, and laterally sloping acromia are strongly associated with cuff tears and may cause tractional damage to the tendon.Conversely, flat acromia may have an insignificant involvement in cuff disease and consequently may be best treated conservatively. The development of these different acromial shapes is likely both genetic and acquired. In the latter case, only age has been positively correlated with progression from flat to curved or hooked. The nature of mechanical activities, such as sports involving the shoulder, along with frequency and intensity of such sports, may be responsible for the adverse development. Sports such as bowling in cricket, swimming, tennis, baseball, and kayaking, are most frequently implicated. However, a progression to a hooked acromion may simply be an adaptation to an already damaged, poorly balanced rotator cuff that is creating increasing stress on the coracoacromial arch. Other anatomical factors that may have significance include os acromiale and acromial spurs. Environmental factors implicated include increasing age, shoulder overuse, smoking, and any medical condition that affects circulation or impairs the inflammatory and healing response, such as diabetes mellitus.Intrinsic factors :
Intrinsic factors refer to injury mechanisms that occur within the rotator cuff itself. The principal is a degenerative-microtrauma model, which supposes that age-related tendon damage compounded by chronic microtrauma results in partial tendon tears that then develop into full rotator cuff tears.As a result of repetitive microtrauma in the setting of a degenerative rotator cuff tendon, inflammatory mediators alter the local environment, and oxidative stress induces tenocyte apoptosis causing further rotator cuff tendon degeneration. A neural theory also exists that suggests neural overstimulation leads to the recruitment of inflammatory cells and may also contribute to tendon degeneration.Pathophysiology :
The shoulder joint is made up of three bones: the shoulder blade (scapula), the collarbone (clavicle) and the upper arm bone (humerus).Further information: Shoulder
The shoulder is a complex mechanism involving bones, ligaments, joints, muscles, and tendons.
MRI of normal shoulder intratendinous signal :
MRI of rotator cuff full-thickness tearTears of the rotator cuff tendon are described as partial or full thickness, and full thickness with complete detachment of the tendons from bone.
Partial-thickness tears often appear as fraying of an intact tendon.
Full-thickness tears are “through-and-through”. These tears can be small pinpoint, larger buttonhole, or involve the majority of the tendon where it still remains substantially attached to the humeral head and thus maintains function.
Full-thickness tears may also involve complete detachment of the tendon(s) from the humeral head and may result in significantly impaired shoulder motion and function.
Shoulder pain is variable and may not be proportional to the size of the tear.
However, for simplicity, tears are sometimes classified based on the trauma that caused the injury:
Acute, as a result of a sudden, powerful movement which might include falling onto an outstretched hand at speed, making a sudden thrust with a paddle in kayaking, or following a powerful pitch/throw
Subacute, arising in similar situations but occurring in one of the five layers of the shoulder anatomy
Chronic, developing over time, and usually occurring at or near the tendon (as a result of the tendon rubbing against the overlying bone), and usually associated with an impingement syndrome
Diagnosis :
A complete tear of the supraspinatus resulting in a shift upwards of the head of the humerusDiagnosis is based upon physical assessment and history, including description of previous activities and acute or chronic symptoms. A systematic, physical examination of the shoulder comprises inspection, palpation, range of motion, provocative tests to reproduce the symptoms, neurological examination, and strength testing. The shoulder should also be examined for tenderness and deformity. Since pain arising from the neck is frequently ‘referred’ to the shoulder, the examination should include an assessment of the cervical spine looking for evidence suggestive of a pinched nerve, osteoarthritis, or rheumatoid arthritis.
Diagnostic modalities, dependent on circumstances, include X-ray, MRI, MR arthrography, double-contrast arthrography, and ultrasound. Although MR arthrography is currently considered the gold standard, ultrasound may be most cost-effective. Usually, a tear will be undetected by X-ray, although bone spurs, which can impinge upon the rotator cuff tendons, may be visible. Such spurs suggest chronic severe rotator cuff disease. Double-contrast arthrography involves injecting contrast dye into the shoulder joint to detect leakage out of the injured rotator cuff and its value is influenced by the experience of the operator. The most common diagnostic tool is magnetic resonance imaging (MRI), which can sometimes indicate the size of the tear, as well as its location within the tendon. Furthermore, MRI enables the detection or exclusion of complete rotator cuff tears with reasonable accuracy and is also suitable to diagnose other pathologies of the shoulder joint.
The logical use of diagnostic tests is an important component of effective clinical practice.
Clinical judgement, rather than over reliance on MRI or any other modality, is strongly advised in determining the cause of shoulder pain, or planning its treatment, since rotator cuff tears are also found in some without pain or symptoms. The role of X-ray, MRI, and ultrasound, is adjunctive to clinical assessment and serves to confirm a diagnosis provisionally made by a thorough history and physical examination. Over-reliance on imaging may potentially lead to overtreatment or distraction from the true underlying problem.
MRI :
Magnetic resonance imaging (MRI) and ultrasound are comparable in efficacy and helpful in diagnosis although both have a false positive rate of 15 – 20%. MRI can reliably detect most full-thickness tears although very small pinpoint tears may be missed. In such situations, an MRI combined with an injection of contrast material, an MR-arthrogram, may help to confirm the diagnosis. It should be realized that a normal MRI cannot fully rule out a small tear (a false negative) while partial-thickness tears are not as reliably detected. While MRI is sensitive in identifying tendon degeneration (tendinopathy), it may not reliably distinguish between a degenerative tendon and a partially torn tendon. Again, magnetic resonance arthrography can improve the differentiation. An overall sensitivity of 91% (9% false negative rate) has been reported indicating that magnetic resonance arthrography is reliable in the detection of partial-thickness rotator cuff tears. However, its routine use is not advised, since it involves entering the joint with a needle with potential risk of infection. Consequently, the test is reserved for cases in which the diagnosis remains unclear.Ultrasound :
Musculoskeletal ultrasound has been advocated by experienced practitioners, avoiding the radiation of X-ray and the expense of MRI while demonstrating comparable accuracy to MRI for identifying and measuring the size of full-thickness and partial-thickness rotator cuff tears. This modality can also reveal the presence of other conditions that may mimic rotator cuff tear at clinical examination, including tendinosis, calcific tendinitis, subacromial subdeltoid bursitis, greater tuberosity fracture, and adhesive capsulitis. However, MRI provides more information about adjacent structures in the shoulder such as the capsule, glenoid labrum muscles and bone and these factors should be considered in each case when selecting the appropriate study.Projectional radiography :
High-riding humeral head in a rotator cuff tear.X-ray projectional radiography cannot directly reveal tears of the rotator cuff, a ‘soft tissue’, and consequently, normal X-rays cannot exclude a damaged cuff. However, indirect evidence of pathology may be seen in instances where one or more of the tendons have undergone degenerative calcification (calcific tendinitis). The humeral head may migrate upwards (high-riding humeral head) secondary to tears of the infraspinatus, or combined tears of the supraspinatus and infraspinatus.The migration can be measured by the distance between:
A line crossing the center of a line between the superior and inferior rims of the glenoid articular surface
The center of a “best-fit” circle positioned over the humeral articular surface
Normally, the former is positioned inferiorly to the latter, and a reversal is therefore indicating a rotator cuff tear.Prolonged contact between a high-riding humeral head and the acromion above it, may lead to X-rays findings of wear on the humeral head and acromion and secondary degenerative arthritis of the glenohumeral joint (the ball and socket joint of the shoulder), called cuff arthropathy, may follow.[32] Incidental X-ray findings of bone spurs at the adjacent acromioclavicular joint may show a bone spur growing from the outer edge of the clavicle downwards towards the rotator cuff. Spurs may also be seen on the underside of the acromion, once thought to cause direct fraying of the rotator cuff from contact friction, a concept currently regarded as controversial.
If pain is relieved, the test is considered positive for rotator-cuff impingement, of which tendinitis and bursitis are major causes. However, partial rotator-cuff tears may also demonstrate good pain relief, so a positive response cannot rule out a partial rotator-cuff tear. However, with demonstration of good, pain-free function, treatment will not change, so the test is useful in helping to avoid overtesting or unnecessary surgery.
Prevention :
Long-term overuse/abuse of the shoulder joint is generally thought to limit range of motion and productivity due to daily wear and tear of the muscles, and many public web sites offer preventive advice. (See external links) The recommendations usually include:- regular shoulder exercises to maintain strength and flexibility
- using proper form when lifting or moving heavy weights
- resting the shoulder when experiencing pain
- application of cold packs and heat pads to a painful, inflamed shoulder
- strengthening program to include the back and shoulder girdle muscles as well as the chest, shoulder and upper arm
- adequate rest periods in occupations that require repetitive lifting and reaching
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