Imaging 15:162-173 (2003)
© 2003 The British Institute of Radiology
Imaging the shoulder
S Ostlere, FRCR
Nuffield Orthopaedic Centre and Oxford Radcliffe Hospital, Oxford, UK
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Summary
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- Plain films are useful as an initial screening test with patients with shoulder pain.
- Ultrasound and MRI are most suitable techniques for diagnosing rotator cuff disease.
- Ultrasound is suitable for providing flexible access for instant access clinics.
- MR arthrography or CT arthrography is required for investigating instability.
The shoulder is the most mobile and therefore the most unstable of all the joints. To compensate for the unstable bony anatomy the shoulder is protected anteriorly, posteriorly and superiorly by a capsule and the tendons that form the rotator cuff. The musculotendinous units that make up the cuff are a responsible for the majority of shoulder movements. Repetitive active and passive forces render the tendon susceptible to degeneration leading to swelling of the tendon and a minor degree of subluxation. The space between the humeral head and the acromium is sufficiently restricted that minor swelling of the interposed supraspinatus tendon with or without minor superior subluxation of the humeral head may lead to the most common of shoulder conditions: the impingement syndrome.
Imaging plays a major role in the management of shoulder problems. Plain films are usually the only investigation required for assessing bony trauma, osteoarthritis and most other arthropathies. Plain films are often supplemented by other techniques for primarily soft tissue abnormalities, such as rotator cuff disease or masses, and for patients with instability. MRI and ultrasound (US) have replaced arthrography for evaluating the integrity of the rotator cuff and MR arthrography (MRA) or CT arthrography are used for instability. Bone scintigraphy has no specific role to play in the imaging of the shoulder.
Patients presenting for imaging fall broadly into one of the following categories: non specific pain, pain and restricted movement on abducting the arm (implying impingement), and symptoms of instability.
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Non-specific pain
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Non-specific pain may be due a range of conditions such as arthropathies, tumour and infection. Often a plain film is sufficient to make a diagnosis. If further information is required then MRI is the technique of choice.
Arthropathies
As with all synovial joints the shoulder can be affected by degenerative disease and inflammatory arthropathies. The common arthropathies are covered in the article on imaging in rheumatology. Plain films are usually sufficient to make a diagnosis and plan management. Monoarthropathy other that osteoarthritis is rare and may require additional imaging, usually MRI. As in all joints it is important to exclude infection as the cause of a monoarthropathy. Typical MRI features of infection are an effusion, periarticular bony oedema with or without bony erosion. US is a useful simple technique to guide aspiration of joint fluid. The shoulder is an unusual site for other monoarthropathies such as pigmented villonodular synovitis (PVNS) and synovial osteochromatosis.
The shoulder is a common site for amyloid deposition associated with renal dialysis or myeloma. This is a painful condition that usually involves both shoulders. On MRI amyloid deposition in the synovium and capsule has a quite specific appearance with thickening of the tissues that return low signal intensity on T2 weighted images [1]. Bony erosison is common [2] (Figure 1
). A similar appearance may be seen in PVNS, but this condition only involves a single joint.
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Figure 1. MRI coronal scans in a patient on dialysis. (a) T1 weighted and (b) T2 weighted images. There is hypertrophy of the synovium and capsule returning low signal on the T1 and particularly the T2 weighted image typical of amyloid deposition (arrows).
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Synovial disorders may involve the various bursae surrounding the shoulder. Subacromial bursitis is usually due to impingement but may be affected by inflammatory conditions such as rheumatoid arthritis. It is a typical site for multiple intrabursal fibrous loose bodies, so called rice bodies, that are usually associated with inflammatory arthropathies or tuberculosis [3] (Figure 2).
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Figure 2. Subacromial bursa rice bodies. (a) T1 weighted and (b) short tau inversion recovery axial images showing a distended subacromial bursa (arrows) containing multiple loose bodies representing conglomerates of rice bodies.
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Shoulder pain unrelated to impingement or arthropathies is unusual and if persistent requires investigation. Plain films and MRI are the techniques of choice, as these can exclude the most important causes such as tumour, bone infection and osteonecrosis. Bony tumours are dealt with in the article on evaluation of focal bone lesions. Tumours that have a predilection for the humeral head are chondroblastoma and clear cell chondrosarcoma. It may be difficult to differentiate these two entities on imaging as chondroblastomas can be quite aggressive (Figure 3). Both lesions commonly contain calcification. Other benign lesions such as osteiod osteoma or osteoblastoma may occur around the shoulder. The proximal humeral metaphysis is a favoured site for a simple bone cyst as is the clavicle for eosinophilic granuloma. Malignant tumours are uncommon. Metastases, lymphoma, chondrosarcoma and osteogenic sarcoma are the most common to affect the proximal humerus. The shoulder region is a particularly common site for large soft tissue lipomas.
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Figure 3. Chondroblastoma. There is a large destructive calcified lesion of the proximal humeral epiphysis.
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Infection is uncommon and the imaging findings are similar to other joints. Osteonecrosis and neuropathic arthropathy (usually secondary to cervical hydromyelia) are rarer causes of pain and dysfunction.
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Impingement syndrome
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The impingement syndrome is an extremely common condition that often requires imaging.
The condition primarily affects the supraspinatus tendon and overlying subacromial bursa. The initial pathology in impingement syndrome is degeneration of the tendon [4]. The tendon becomes swollen within the restricted subacromial space resulting in impingement of the tendon against the acromium and the coracoacromial ligament. Patients have pain on attempting abduction of the shoulder. In most patients the pain settles with conservative management aided by injections of steroid into the subacromial bursa. If the pathology progresses, secondary changes such as spur formation on the under surface of the acromium and thickening of the coracoacromial ligament will further reduce the dimensions of the subacromial space exacerbating the impingement. Eventually the chronic physical abrasion will result in partial thickness, and finally full thickness, tears of the supraspinatus tendon. This tear may progress to involve the infraspinatus, the subscapularis and biceps tendons. In the final stage the humeral head migrates superiorly to articulate with the acromium and secondary osteoarthritis of the glenohumeral joint develops. The symptoms of impingement appear insidiously or following an episode of direct trauma. Isolated subscapularis tears may also occur as a consequence of acute trauma [5].
The role of imaging
The place of imaging for impingement syndrome depends on local clinical practice. The treatment of impingement and particularly rotator cuff repair is controversial. It is current normal practice to offer arthroscopic subacromial decompression to patients with impingement resistant to conservative measure. Subacromial decompression consists of widening the subacromial space by shaving the underside and anterior tip of the acromium and dividing the coracoacromaial ligament.
Treatment of rotator cuff tears is more controversial. Tears are common in the asymptomatic population so their significance may be uncertain [6]. Symptoms in patients with tears may respond to conservative management or subacromial decompression. Although there is little good quality evidence that rotator cuff repair is superior to subacromial decompression alone for the relief of pain, restoration of function may be improved by repair. Repair of large and massive tears are particularly unrewarding.
The primary purpose of imaging in impingement is to demonstrate if there is a tear and to assess its size. The degree of atrophy of the rotator cuff muscle has been cited as an indicator of predicting the rate of rerupture but it is unclear whether this is an important consideration in the younger population with small or medium sized tears that make up the major of those patients who undergo surgery [7].
US and MRI are the two main tests used in impingement. US has the advantage of being a rapid and accurate method of diagnosing rotator cuff tears and is suitable for one-stop combined clinics with instant access to scanning. MRI is also an accurate technique for tears and gives a broader overview of the shoulder. MRI is expensive, often disliked by patients and not amenable to providing an instant access service. If the question to be answered is "is there a rotator cuff tear" then US is the preferred technique. Bursal abnormalities, including dynamic signs of impingement, calcific deposits, and irregularity of the greater tuberosity are other common findings that are clearly identified on US.
Rotator cuff tear
On US a tear of the rotator cuff may appear as a clear discontinuity of the tendon with an obvious gap filled with fluid. This appearance is more common in an acute traumatic tear [8] (Figure 4). However, usually the appearances of chronic tears are more subtle as there is often not a significant amount of fluid present. A reliable US sign is the loss of the normal convexity of the superior surface of the tendon with the deltoid sagging into the gap [9] (Figure 5). Full thickness tears usually occur at the anterior edge of the tendon at its insertion to the greater tuberosity. Some tears lie more posteriorly or more proximally. With time the tear may extend to involve part of or all of the infraspinatus tendon. The subscapularis may also be involved. In massive tears the tendon cannot be seen as the free end retracts under the acromium leaving a bald humeral head (Figure 5). The most reliable sign on MRI of a full thickness tear is high signal on T2 weighted images extending from the superior to the inferior borders of the tendon. The high signal should be sufficiently intense to be compatible with fluid (Figure 6). Less intense high signal is frequently seen in degenerate but intact cuffs [10] (see below). In massive tears the cuff is sbsent and the retracted end of the torn supraspinatus tendon is seen lying medially under the acromium (Figure 7).
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Figure 4. Full thickness tear of supraspinatus tendon. Ultrasound showing fluid in the gap between the distracted ends of the torn tendon (arrows). There is irregularity of the greater tuberosity indicating impingement (arrowhead).
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Figure 5. Full thickness tear of supraspinatus. Ultrasound images of small, medium and massive tears. (a) Small tear with focal loss of the normal convexity of the distal end of the tendon (arrow). (b) Medium sized tear. There is a defect in the distal end in the supraspintus tendon with the deltoid sagging into the defect. The normal convex surface of the tendon is lost. (c) Massive tear with no tendon seen between the deltoid and the humeral head.
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Figure 6. Full thickness tear of supraspinatus. (a) The tear cannot be seen on the T1 weighted image. (b) Corresponding short tau inversion recovery image showing high signal defect in the tendon (arrow). There is fluid seen in the subacromial bursa (arrowhead).
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Figure 7. Massive tear supraspinatus tendon. Short tau inversion recovery coronal image. The retracted free end of the tendon is seen to lie at the level of the glenoid (arrow).
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An advantage of MRI over US is that the state of the supraspinatus muscle can be more easily assessed by measuring the cross sectional dimensions and degree of fat infiltration. Marked atrophy of the muscle is associated with a poor outcome following cuff repair [7] (Figure 8).
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Figure 8. Massive tear supraspinatus tendon. (a) T1 weighted coronal and (b) T2 sagittal oblique image showing marked atrophy of the supraspinatus tendon and muscle (arrows) which is largely replaced by fat.
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US has been shown to be highly accurate in diagnosing full thickness tears but less reliable in diagnosing partial thickness tears [9]. Partial tears involve the articular surface more often than the bursal surface and are seen as focal areas of low reflectivity sometimes accompanied by an echogenic element [11] (Figure 9). On MRI partial tears are seen as focal high signal extending to the articular or bursal surfaces (Figure 9). The importance of identifying partial tears is questionable as they are treated conservatively in most centres.
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Figure 9. Partial thickness tear of the supraspinatus tendon. (a) T2 weighted coronal image showing a focus of high signal in the distal end of the tendon extending to the inferior articular surface only (arrow). (b) Ultrasound showing a small hypoechoic focus at the articular surface of the tendon (arrow). (SS, supraspinatus tendon.)
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Rotator cuff degeneration
Degeneration of the tendon is very common particularly in the elderly in whom it can be regarded as a normal ageing process. MRI is probably more sensitive than US in the detection of degeneration. On short tau inversion recovery (STIR) or T2 weighted fat suppression techniques diffuse or patchy high signal is seen within the substance of the tendon (Figure 10). On US a reduction in the reflectivity is seen within the tendon. There may be signs of impingement such as fluid in the subacromial bursa, irregularity or cystic change in the greater tuberosity or spurs arising from the under surface of the acromium (Figures 11 and 12). On US tendon degeneration is seen as a reduction in the echogenicity. The tendon may be swollen in the more acute phase (Figure 13). On both MRI and US it may be difficult to differentiate degeneration from partial tears. In patients with impingement dynamic imaging on US during arm abduction may demonstrate bunching up of the subacromial bursa against the coracoacromial ligament and the acromium (Figure 14). This sign is not very specific and is seen in asymptomatic individuals.
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Figure 10. Degenaration of the supraspinatus tendon. MRI shows modest, ill-defined increased signal within the tendon on both (a) T1 and (b) T2 weighted images (arrows).
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Figure 12. Acromial spur. T1 weighted image showing a degenerate tendon and prominent spur arising from the undersurface of the acromium (arrow).
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Figure 13. Degenaration of the supraspinatus tendon. (a) T1 weighted MRI and (b) ultrasound showing diffuse swelling of the tendon (arrows).
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Figure 14. Dynamic ultrasound demonstrating impingement syndrome. On arm abduction bursal tissue (arrow) is seen to bunch up against the coracoacromial ligament (arrowhead).
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Subscapularis
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Isolated tears of the subscapularis tendon are uncommon and are usually associated with acute traumatic hyperextension or external rotation [5]. Acute tears are easily diagnosed on US or MRI with fluid replacing the torn subscapularis tendon (Figure 15). Frequently tears of the supraspinatus tendon extend to involve the superior edge of subscapularis. These tears may also involve the coracohumeral ligament which is situated in the rotator cuff interval (the gap between the supraspinatus and subscapularis). This ligament acts as a stabilizing sling for the biceps tendon. A tear of this ligament may result in subluxation of the biceps tendon (see below) [12].
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Figure 15. Acute tear of subscapularis. Axial ultrasound image showing a small remnant of the subscapularis tendon attached to the lesser tuberosity (arrow).
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Biceps tendon
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The biceps tendon often becomes attenuated or torn as a result of impingement syndrome [13]. The most reliable sign of a tear on imaging is the absence of the tendon in the bicipital groove, although differentiating a complete tear from marked attenuation may be difficult on US. Retraction of the tendon and atrophy of the long head of biceps muscle may be seen (Figure 16). Medial dislocation commonly occurs as result of tears of the coracohumeral ligament which is the main stabilizer of the biceps tendon. The transverse humeral ligament that forms the roof of the bicipital groove is an extension of the coracohumeral ligament and is not thought to contribute greatly to the stability of the biceps tendon. If the subscapularis tendon is intact the biceps tendon is usually seen to lie superficial to the tendon on the lesser trochanter (Figure 17). If subscapularis is torn the tendon may then lie in a more medial position and may even be found adjacent to the anterior lip of the glenoid [12]. Fluid in the biceps sheath is a common finding and is usually due to an effusion of the communicating glenohumeral joint rather than primary pathology of the biceps tendon (Figure 18).
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Figure 16. Biceps tendon tear. Axial ultrasound showing atrophic echogenic of the long head of biceps muscle (arrow) and normal side for comparison. (H, humerus.)
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Figure 17. Dislocated biceps tendon. Axial ultrasound shows an empty bicipital groove (arrow). The biceps tendon (arrowhead) has dislocated medially.
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Figure 18. Effusion of the biceps tendon sheath. Ultrasound showing fluid within the sheath (arrow). The biceps tendon has a normal appearances.
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Post-operative shoulder
Imaging is more challenging in the post-operative shoulder on account of the altered anatomy. US has been shown to be an accurate method of assessing the post operative cuff [14]. A detailed account of the type of surgery performed is essential as operative technique varies depending on the morphology and extent of the cuff tear. Most rotator cuff tears are repaired by tacking down the cuff to a trough made near the greater tuberosity. Arthroscopic repairs use specialized anchors. On US the key is to demonstrate intact cuff extending into the notch or to an anchor (Figure 19). The integrity of the cuff is sometimes best appreciated on dynamic scanning. Similarly on MRI the best sign of a successful repair is identifying intact tendon extending to the site of surgical attachment.
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Figure 19. Rotator cuff repair. (a) Intact supraspinatus tendon. On coronal ultrasound tendon is seen in the surgical notch (arrow). (b) Rerupture of repaired supraspinatus tendon. The tendon is torn and cannot be identified in the notch (arrow).
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Frozen shoulder
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This mysterious condition results in restriction in movement of the shoulder and is due to "adhesive capsulitis", the histology being similar to Dupyron's contracture of the hand [15]. On arthroscopy the abnormality is often seen to affect predominately the region of the rotator cuff interval [16]. Most published reports indicate that standard imaging is negative although adhesions may be seen on arthrography. In some cases a hypoechoic hypervascular area representing inflammatory tissue may be seen in the rotator cuff interval on US (Figure 20).
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Figure 20. Frozen shoulder. Ultrasound showing focal soft tissue swelling in the region of the rotator cuff interval (arrows). Doppler showed some hypervascularity in this region.
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Calcific tendinitis
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This is a common painful condition of unknown aetiology characterized by calcific deposits in the rotator cuff. The supraspinatus tendon is the most common site. The calcification is usually clearly seen on plain film. Axial view is often needed to identify involvement of the infraspinatus and subscapularis tendons. US is more sensitive than MRI in the identification of calcification. On US the calcification is seen as an echogenic focus usually with an acoustic shadow [12] (Figure 21). On MRI calcification, when visible, is seen as a low signal focus in the tendon (Figure 21). The symptoms may be severe but usually resolve spontaneously. If the calcification is immature then percutaneous irrigation of the calcific area and peritendinous injection of steroid will hasten resolution in resistant cases [17].
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Figure 21. Calcific tendonitis. (a) T1 weighted MRI showing low signal lesion in the supraspinatus tendon (arrow). (b) Ultrasound shows a echogenic lesion (arrow) with acoustic enhancement (arrowheads). There is fluid in the subacromial bursa indicating bursitis (open arrows).
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Acromioclavicular joint
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Pain from the acromioclavicular joint is common. The patient will point to the joint if asked to localize the site of pain. Imaging is usually confined to the plain radiograph as most cases are due to osteoarthritis. Hypertrophy of the capsule and osteophytes are often seen on US and MRI. On dynamic US impingement of the two articular surfaces of the joint can be demonstrated by asking the patient to move their hand onto the opposite shoulder when fluid, and often gas, is seen to be expressed superiorly. Synovial cysts arising from the joint are related to full thickness rotator cuff tears [18] and are readily diagnosed on US and MRI (Figure 22). US is an excellent method of guiding intraarticular local anaesthetic and steroid injection.
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Figure 22. Short tau inversion recovery coronal image showing synovial cyst arising from the superior aspect of the acromioclavicular joint.
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Sternoclavicular joint
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Requests for imaging the sternoclavicular joint are not uncommon. Patients usually complain of a mass that may be painful. The joint is not well demonstrated on plain films so cross sectional imaging is often performed [19]. The most common cause is osteoarthritis of the joint, which will show typical features of osteophytes, sclerosis and hypertrophy of the capsule (Figure 23). Infection can often not be excluded as periarticular oedema in the bone and soft tissues is not uncommon in osteoarthritis and aspiration or biopsy of the joint may be required. Both MRI and CT are useful in assessing the joint. MRI is often the preferred technique as the degree of inflammation can be accurately assessed. CT is more accurate in identifying early bony erosion. US is useful to guide aspiration or biopsy.
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Figure 23. Osteoarthritis of the sternoclavicular joint. (a) T1 weighted image showing hypertrophy of the capsule (arrows) osteophyte and erosion. (b) Short tau inversion recovery coronal image shows a joint effusion and periarticular bony oedema. (c) Axial T1 weighted image demonstrating a prominent palpable mass due to bony and capsular hypertrophy. (C, clavicle.)
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References
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- Karakida O, Aoki J, et al. Hemodialysis-related arthropathy. A prospective MR study with SE and GRE sequences. Acta Radiol 1997;38:158–64.[Medline]
- Llauger J, Palmer J, et al. Nonseptic monoarthritis: imaging features with clinical and histopathologic correlation. Radiographics 2000;20 Spec No:S263–78.
- Chen A, Wong LY, et al. Distinguishing multiple rice body formation in chronic subacromial-subdeltoid bursitis from synovial chondromatosis. Skeletal Radiol 2002;31:119–21.[Medline]
- Hashimoto T, Nobuhara K, et al. Pathologic evidence of degeneration as a primary cause of rotator cuff tear. Clin Orthop Related Res 2003;415:111–20.
- Deutsch A, Altchek DW, et al. Traumatic tears of the subscapularis tendon. Clinical diagnosis, magnetic resonance imaging findings, and operative treatment. Am J Sports Med 1997;25:13–22.[Abstract/Free Full Text]
- Harvie P, Ostlere SJ, Teh J, McNally EG, Clipsham K, Burston BJ, et al. Genetic influences in rotator cuff tear: sibling risk of full thickness tear. JBBS (B) 2004 (In Press).
- Goutallier D, Postel JM, Gleyze P, Leguicllous P, Van Driessche S. Influence of cuff muscle fatty degeneration on anatomic and functional outcomes after simple suture of full thickness tears. J Shoulder Elbow Sury 2003;12:550–4.[Medline]
- Teefey SA, Middleton WD, et al. Sonographic differences in the appearance of acute and chronic full-thickness rotator cuff tears. J Ultrasound Med 2000;19:377–8; quiz 383.[Abstract]
- Teefey SA, Hasan SA, et al. Ultrasonography of the rotator cuff. A comparison of ultrasonographic and arthroscopic findings in one hundred consecutive cases. J Bone Joint Surg 2000;82:498–504.[Abstract/Free Full Text]
- Wright T, Yoon C, et al. Shoulder MRI refinements: differentiation of rotator cuff tear from artifacts and tendonosis, and reassessment of normal findings. Semin Ultrasound CT MR 2001;22:383–95.[Medline]
- van Holsbeeck MT, Kolowich PA, et al. US depiction of partial-thickness tear of the rotator cuff. Radiology 1995;197:443–6.[Abstract/Free Full Text]
- Martinoli C, Bianchi S, et al. US of the shoulder: non-rotator cuff disorders. Radiographics 2003;23:381–401; quiz 534.[Abstract/Free Full Text]
- Beall DP, Williamson EE, et al. Association of biceps tendon tears with rotator cuff abnormalities: degree of correlation with tears of the anterior and superior portions of the rotator cuff. AJR Am J Roentgenol 2003;180:633–9.[Abstract/Free Full Text]
- Prickett WD, Teefey SA, et al. Accuracy of ultrasound imaging of the rotator cuff in shoulders that are painful postoperatively. J Bone Joint Surg 2003;85-A:1084–9.
- Bunker TD, Anthony PP. The pathology of frozen shoulder. A Dupuytren-like disease. J Bone Joint Surg 1995;77:677–83.
- Omari A, Bunker TD. Open surgical release for frozen shoulder: surgical findings and results of the release. J Shoulder Elbow Surg 2001;10:353–7.[Medline]
- Aina R, Cardinal E, et al. Calcific shoulder tendinitis: treatment with modified US-guided fine-needle technique. Radiology 2001;221:455–61.[Abstract/Free Full Text]
- Postacchini F, Perugia D, et al. Acromioclavicular joint cyst associated with rotator cuff tear. A report of three cases. Clin Orthop Related Res 1993;294:111–3.
- Aslam M, Rajesh A, et al. Pictorial review: MRI of the sternum and sternoclavicular joints. Br J Radiol 2002;75:627–34.[Abstract/Free Full Text]
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Answers to multiple-choice questionnaire: Musculoskeletal imaging [from Imaging 15(4)]
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Summary
Non-specific pain
