An illustrated tutorial of musculoskeletal sonography: part 2, upper extremity

Introduction to Musculoskeletal Diagnostic Ultrasound

With recent advances in computer technology and equipment miniaturization, the clinical application of diagnostic ultrasonography (U/S) has spread across various medical specialties. Diagnostic U/S is attractive in terms of its noninvasiveness, lack of radiation, readiness of use, cost-effectiveness, and its ability to make dynamic examinations possible. Dynamic imaging deserves special emphasis because it is useful in differentiating full-thickness from partial-thickness tendon tears, muscle tears, and tendon and nerve subluxations or dislocations. It is also a quick and easy avenue for side-to-side comparisons. When appropriately used, diagnostic U/S can be considered as an extension of one's physical examination. However, there are limitations of U/S, which will be discussed in this review article. This is part 1 of two articles; this first part will focus on the ultrasound examination of the upper extremity, using selected examples relevant to musculoskeletal medicine. Part 2 will cover common pathologies of the lower extremity.

Ultrasound of the shoulder and elbow

Ultrasound examination of the shoulder and elbow requires careful technique, appreciation of normal anatomy, and appropriate high-end equipment. Ultrasound provides detailed diagnostic information. Its accuracy is comparable to that of MRI in the assessment of the rotator cuff. Ultrasound is cheaper than MRI and is preferred by patients.

Sonographic differentiation of digital tendon rupture from adhesive scarring after primary surgical repair

PURPOSE

After the surgical repair of finger tendons finger range of motion may be limited by tendon rupture or adhesive scarring. Differentiating tendon rupture from adhesive scarring may be difficult clinically. Digital tendon sonography allows the evaluation of tendon integrity in a dynamic setting. Our objective was to determine if sonography could differentiate tendon rupture from adhesive scarring in patients who have had primary tendon repair.

METHODS

A retrospective review was performed of the radiographic, clinical, and surgical records of patients referred for finger sonography over a 2-year period. Twenty-eight digits in 21 patients were evaluated for finger tendon disruption after primary surgical repair. The diagnosis of complete tendon rupture was made when 1 or more of the following was identified: a gap separating the proximal and distal tendon margins, visualization of only the proximal tendon margin, or visualization of only the distal tendon margin. Adhesive scarring was diagnosed if the tendon appeared intact with abnormal peritendinous soft tissue abutting or partially encasing the tendon, with synovial sheath thickening, or with restricted tendon motion during dynamic evaluation.

RESULTS

Sonography correctly identified tendon rupture or adhesive scarring in 27 of 28 digits with 1 false-positive case (sensitivity, 100%; specificity, 93%; positive-predictive value, 93%; negative-predictive value, 100%; accuracy, 96%).

CONCLUSIONS

Sonography is an accurate modality for differentiating tendon rupture from adhesive scarring in patients with prior surgical tendon repair.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic, Level I.

Rotator Cuff Tears: Clinical, Radiographic, and US Findings

Rotator cuff tears are a common cause of shoulder pain. Clinical and radiographic findings can suggest the presence of a rotator cuff tear. The most sensitive clinical findings are impingement and the "arc of pain" sign. Radiographic findings are usually normal in the acute setting, although the "active abduction" view may show decreased acromiohumeral distance. In more chronic cases, an outlet view may show decreased opacity and decreased size of the supraspinatus muscle due to atrophy. In late cases, the humeral head may become subluxated superiorly, and secondary degenerative arthritis of the glenohumeral joint may ensue. Ultrasonography (US), with over 90% sensitivity and specificity, can help confirm the diagnosis in clinically or radiographically equivocal cases. US can also reveal the presence of other abnormalities that may mimic rotator cuff tear at clinical examination, including tendinosis, calcific tendinitis, subacromial subdeltoid bursitis, greater tuberosity fracture, and adhesive capsulitis.

Sonography in wrist tendon pathology

Wrist tendons may be affected by a variety of pathologic conditions, including those caused by trauma and overuse, inflammatory and metabolic disorders, or infection. Sonography is a very sensitive means of detecting tendinous pathology because of its spatial resolution and its comparative and dynamic capabilities. Its wide availability makes it the preferred first-line imaging modality in the case of wrist pain. This article reviews the pathologic conditions that may involve the wrist and their sonographic appearances.

Ultrasound of the elbow

The elbow is an important synovial hinge joint of the upper extremity. This joint represents a common site of musculoskeletal symptomatology, affecting all age groups. The advantages of ultrasound imaging of the elbow include easy availability, multiplanar capability and the ability to assess structures dynamically. Patient symptomatology and site of maximal tenderness can be directly correlated with imaging findings. Comparison is easily made with the contralateral side. Particular strengths include the ability to assess para-articular structures, such as regional tendons and ligaments, in addition to assessment of joint effusions, loose bodies and regional bursae. With operator experience and excellent technique, ultrasound is a valuable imaging tool for assessment of disorders of the elbow joint.

High-Resolution Sonography of the Triangular Fibrocartilage:Initial Experience and Correlation with MRI and Arthroscopic Findings

OBJECTIVE

The aim of our study was to compare the findings of high-resolution sonography of the triangular fibrocartilage with those of MRI and arthroscopy. SUBJECTS AND METHODS. Thirteen patients with clinically suspected triangular fibrocartilage tears prospectively underwent sonography, followed by MRI, of their wrists. Triangular fibrocartilage tears were classified as predominantly ulnar or predominantly radial. Only the surgeon was aware of the results of both studies, and eight patients subsequently underwent arthroscopy. The findings of the different techniques were compared.

RESULTS

For the presence or absence of a tear, seven (87.5%) of eight sonographic examinations correlated with arthroscopy, and 11 (84.6%) of 13 sonographic examinations correlated with MRI. Sonography missed one small radial tear that was detected at arthroscopy and MRI, but sonography showed an ulnar tear in triangular fibrocartilage that appeared normal on MRI.

CONCLUSION

High-resolution sonography shows good correlation with MRI and arthroscopy for the evaluation of triangular fibrocartilage tears. Sonography has the potential to be a rapid and cost-effective means of diagnosing tears of the triangular fibrocartilage, particularly those involving the ulnar aspect of the cartilage.

Peritendinous lesions: the role of high-resolution ultrasonography

PURPOSE

To evaluate the peritendinous lesions over the extremities by high-resolution ultrasonography (HRUS).

MATERIALS AND METHODS

The authors retrospectively collected 328 cases, focusing on peritendinous lesions in limbs. The diagnosis was made by US findings with long-term follow-up, aspiration and biopsy proved.

RESULTS

The most common disease entity in our study is ganglion (n=270), followed by Baker's cyst (n=24). Other disease entities included tenosynovitis, bursitis, gout, hematoma, amyloidosis, thrombophlebitis, and other tumor/tumor-like lesions, such as osteogenic sarcoma (OGS), schwannoma, lymphoma, myxoid lipomsarcoma, xanthoma, intramuscular cavernous hemangioma, pigmented villonodular synovitis (PVNS), giant cell tumor of the tendon sheath (GCTTS), etc.

CONCLUSION

Because of dynamic capabilities and aid of real-time sono-guided fine needle aspiration, HRUS becomes an efficient and inexpensive tool for musculoskeletal lesions, especially in the superficial parts.

Sonography of the medial collateral ligament of the elbow: a study of cadavers and healthy adult male volunteers

OBJECTIVE

We assessed the ability of high-resolution sonography to reveal the size and echogenicity of the anterior bundle of the normal medial collateral ligament of the elbow in cadavers and uninjured male volunteers.

MATERIALS AND METHODS

The anterior bundle of the medial collateral ligament in five cadaveric elbows was imaged and injected with contrast material by experienced musculoskeletal radiologists using a 12-MHz linear array transducer. Immediate ligament dissection was performed. The bilateral ligaments in 30 healthy 21- to 34-year-old male volunteers were imaged with gravitational stress. Of these, five randomly selected subjects also received approximately 5 lb (11.3 kg) of applied stress.

RESULTS

Contrast material was injected directly into all five cadaveric ligaments. The anterior bundle of the medial collateral ligament in all 30 asymptomatic male volunteers was hyperechoic in comparison with surrounding muscle and had a fibrillar pattern and fanlike shape. Its mean dimensions were 2.6 +/- 0.31 x 2.2 +/- 0.47 x 4.0 +/- 0.88 mm on the right and 2.6 +/- 0.36 x 2.1 +/- 0.42 x 4.0 +/- 0.86 mm on the left, in longitudinal short, transverse short, and transverse long axes, respectively. Differences in ligament measurements in sidedness, stress application, and hand dominance did not approach statistical (Bonferroni corrected, p > 0.01) or clinical (all differences, <0.2 mm) significance.

CONCLUSION

Radiologists can accurately use sonography to identify and measure the size of the anterior bundle of the normal medial collateral ligament of the elbow. These baseline parameters for the normal ligament may prove useful when evaluating the injured ligament.

Ultrasound of the elbow

This article describes the use of ultrasound (US) in the evaluation of the elbow. US is able to visualize several abnormalities affecting tendons, muscles, ligaments and bursae around the elbow joint as well as to delineate the nature of soft-tissue swelling, such as a space-occupying lesion or synovial enlargement. Occult fractures, osteophytes and intra-articular loose bodies can be depicted with this technique as well. At the cubital tunnel, US allows accurate imaging of the ulnar nerve and to document changes that occur in compressive syndromes. Over other imaging modalities, US offers several key advantages, including cost effectiveness, availability and ability to perform a dynamic examination of tendon movement and joint motion. With continued experience, it is likely that the use of US will increase further with regards to evaluation of soft-tissue abnormalities of the elbow.