Soft Tissue Rheumatism





KEY POINTS




  • •

    Soft tissue rheumatism refers to nonsystemic, focal pathologic syndromes involving the periarticular tissues, including muscle, tendon, ligament, fascia, aponeurosis, retinaculum, bursa, and subcutaneous tissue.


  • •

    Ultrasound evaluation of the soft tissues is often dictated by the clinical examination.


  • •

    Ultrasound in short-axis planes is a valuable technique for demonstration of permanent subluxation and dislocation, and it is the method of choice to show intermittent subluxation through dynamic imaging.



Soft tissue rheumatism refers to nonsystemic, focal pathologic syndromes involving the periarticular tissues, including muscle, tendon, ligament, fascia, aponeurosis, retinaculum, bursa, and subcutaneous tissue. Ultrasound evaluation of the soft tissues is often dictated by the clinical examination. It focuses on the area of concern and requires a thorough understanding of the anatomy and possible ultrasound changes. Rheumatologists must continue to expand their anatomic knowledge base through literature reviews and cadaveric studies offered at various institutions.


High-resolution ultrasound is an excellent technique for statically and dynamically visualizing the periarticular structures in real time. Ultrasound can provide detail with an axial resolution of 0.1 mm and a horizontal resolution of 0.2 mm. Table 19-1 correlates gray-scale ultrasound appearances with the anatomic components of these structures. In this chapter, a tissue-based approach is utilized with examples rather than an exhaustive discussion of all of the entities affecting the periarticular structures. This gives the rheumatologist a semiotic framework to apply to the nonarticular tissues to identify pathologic changes. The images selected represent typical examples of disorders encountered in the musculoskeletal soft tissues.





Tendon


Tendons have a consistent fibrillar echotexture that results from the echogenicity of the interface of the collagen bundles and the endotendineum. This highly ordered structure accounts for the anisotropy visualized when the probe is not oriented perpendicular to the tendon fibers. Although this phenomenon can create a pathologic appearance, it may also be helpful in dynamically distinguishing tendons from other structures of different echotexture.


Tendons are divided into anchor and sliding tendons. Anchor tendons (e.g., Achilles, patellar) are typically straighter, larger, and stronger and are covered by a vascular paratenon that blends with epitendineum to form peritendineum. The sliding tendons (e.g., flexor tendons of the fingers) typically cross synovial joints in an altered path, and their epitendineum is covered by an infolded synovial sheath made of two layers. This mesotendineum, which connects the synovial sheath to the tendon, is penetrated by the vascular supply to the tendon. The vascular supply of tendons is subject to regional variations, which results in critical zones of decreased vascularity that appear to contribute to degeneration. The component tendons of the combined tendinous extension of more than one muscle may be distinguishable on ultrasound.


Dislocation and Instability


Dislocation and instability are potential problems in sliding tendons because of the spatial malalignment to which these structures are subjected. These tendons are maintained in their appropriate location by ligaments, retinacula, or pulleys, (which are specialized retinacula). Instability results from congenital factors, such as a hypoplastic fibro-osseous groove, trauma, or destruction of the restraining structures by chronic inflammatory processes. Ultrasound in short-axis planes is a valuable technique for demonstration of permanent subluxation and dislocation, and it is the method of choice to show intermittent subluxation through dynamic imaging. Instability and dislocation of the long head of the biceps tendon, the peroneal tendons, the tibialis posterior tendon, and the flexor and extensor tendons of the fingers have been demonstrated by ultrasound, and these tendons are most frequently evaluated by rheumatologists ( Fig. 19-1 ).




F igure 19-1


B iceps tendon dislocation .

Longitudinal and transverse views (14 to 5 MHz) show a biceps tendon dislocation. The biceps tendon (1) is displaced out of the groove and surrounded by an anechoic effusion (2), which can be seen below the deltoid muscle (3).

(Courtesy of Esperanza Naredo, MD, Department of Rheumatology, Hospital Severo, Madrid, Spain.) .


Tendinosis and Partial Tears


Tendinosis is degeneration of anchor and sliding tendons that can be detected by ultrasound and can lead to partial- or full-thickness tears. The ultrasound image demonstrates a focal or diffuse loss of uniform echotexture and thickening of the tendon. A Doppler signal may indicate angiogenesis and is more likely to be found in the thickened part of the tendon in symptomatic patients. Tendon heterogenicity is a reliable indicator of poor outcome and may represent a partial tendon tear. Critical zones are vulnerable areas of tendon that are the result of many factors, including compromised blood flow, biomechanical stress, microtrauma, congenital factors, systemic disorders, and age. Calcification may occur with or without tendinosis, and it often occurs in the critical zones ( Figs. 19-2 to 19-5 ).




F igure 19-2


A chilles tendinopathy .

A longitudinal extended view (14 to 5 MHz) depicts the Achilles tendon (1) showing fusiform swelling and a hypoechoic appearance (2) of the critical zone in the distal third of the tendon. The calcaneus (3) and Kager fat pad (4) can be seen.



F igure 19-3


P atellar tendinopathy and partial rupture .

A longitudinal view (14 to 5 MHz) shows loss of the normal fibrillar pattern (2) with an intact paratenon (5), normal patellar tendon (1), tibial bone (3), and Kager fat pad (4).



F igure 19-4


A chilles tendinopathy .

A longitudinal view (12 to 5 MHz) with Doppler imaging reveals a region of hypervascularity invading the intratendinous hypoechoic area. The normal Achilles tendon (1), Kager fat pad (4), and paratenon (5) can be seen.



F igure 19-5


C alcification of the supraspinatus tendon .

A longitudinal view (14 to 5 MHz) of the supraspinatus tendon (1) demonstrates a large calcification (4) of toothpaste consistency. (2), humeral head; (3), deltoid; (5), subdeltoid bursa.


Full-Thickness Tears


Ultrasound provides a reliable means of diagnosing full-thickness rotator cuff tears and plays a decisive role in the diagnosis of acute tears. Ultrasound allows accurate assessment of the severity of the lesion, including measurement of the defect (i.e., retraction of the torn ends of the tendon). Dynamic examination can be an important adjunct to demonstration of a complete tear. Ultrasound imaging may be helpful in determining the chronicity of the lesion ( Figs. 19-6 to 19-8 ).




F igure 19-6


A chilles tendon rupture .

A longitudinal extended view (12 to 5 MHz) shows the Achilles tendon (1) with complete rupture and with anechoic fluid (star) separating the torn ends. Notice the intact plantaris tendon (5) and paratenon (4), the Kager fat pad (3), and the calcaneus (2).



F igure 19-7


F ull-thickness tear of the supraspinatus tendon .

A transverse view (14 to 5 MHz) depicts an obvious communication (stars) between the articular and bursal aspects of the supraspinatus tendon (1). The defect contains tendinous fragments, which are hyperechoic in relation to the anechoic fluid. Criteria for an acute or chronic full-thicness tear of the supraspinatus tendon consist of absent cuff, cuff atrophy, echo-poor defects, and focal hyperechoic defect (major criteria) and of an abnormal fluid collection, cartilage interface sign, and deltoid herniation (minor criteria). The deltoid muscle (2) and humeral head (3) can be seen.



F igure 19-8


F ull-thickness tear of the supraspinatus tendon .

A longitudinal view of the supraspinatus tendon (1) (14 to 5 MHz) shows deltoid muscle (3) herniation, absence of the supraspinatus tendon, and an abnormal fluid collection (stars) . The humeral head (2) has irregularities.


Peritendinosis


Inflammation of the vascular paratenon surrounding anchor tendons is detected by ultrasound and primarily affects the lower extremity, specifically the patellar and Achilles tendons. This inflammatory process can be seen in different stages that represent a continuum in the progression of the peritenon lesion. Ultrasound findings range from an anechoic or hypoechoic, ringlike appearance on short-axis views (corresponding to focal or continuous fusiform thickening of the paratenon on long-axis views) and heterogenicity with an irregular paratenon profile. Isolated involvement of the paratenon is less common than a mixed pattern with tendon abnormalities. Bursitis is frequently associated with these lesions. Doppler analysis can add information regarding the activity or involvement ( Fig. 19-9 ).




F igure 19-9


P aratendinosis of the A chilles tendon .

A transverse view (14 to 5 MHz) of the Achilles tendon shows an anechoic layer surrounding an abnormal heterogeneous tendon (1), which represents a combination of paratendinosis (2) with advanced tendinosis of the Achilles. The Kager fat pad (3) can be seen.

(Courtesy of C. Moragues, MD, Department of Rheumatology, Hospital Universitari, de Bellvitge, Barcelona, spain.) .


Tenosynovitis


Inflammation of the synovial sheath of sliding tendons is similar to the ultrasound findings for anchor tendons. Acutely, the inflammation is characterized by a concentric halo around the tendon, consisting of anechoic or hypoechoic, compressible fluid. As the lesion progresses, sheath thickening becomes more evident. The later stages can manifest as chronic, focal or diffuse, noncompressible thickening of the synovial sheath, which may lead to injury and entrapment of the tendon (i.e., De Quervain’s disease). The sheaths of some tendons (e.g., long head of the biceps tendon) communicate directly with the joint space, and tendon sheath distention may be associated with underlying articular disease ( Figs. 19-10 and 19-11 ).




F igure 19-10


T enosynovitis of the biceps tendon .

A transverse view (14 to 5 MHz) reveals the biceps tendon (1) surrounded by hypoechoic fluid (4) with a fine hyperechoic connection corresponding to the mesotenon (2). The humeral shaft (3) and deltoid muscle (5) can be seen.



F igure 19-11


T enosynovitis of the flexor tendons of the finger .

A longitudinal view (14 to 5 MHz) shows an anechoic expansion of the tendon sheath surrounding normal-appearing tendon. A mild effusion is seen in the volar synovial recess. The flexor superficialis (1), flexor profundus (2), tendon sheath (3), metacarpal bone (4), and phalanx (5) can be seen on this scan. Minimal distention of the synovial recess is noted ( ∗ ).


Enthesopathy


Enthesopathy is not limited to changes at the tendon insertion into the bone; it also includes the insertion of ligament, joint capsule, and aponeurosis into bone. Ultrasound findings can include thickening and heterogenicity of the tendon, insertional calcification, hypoechoic focal areas, and irregularity or erosions of the bony profile. Osgood-Schlatter, Sinding-Larsen-Johansson, and Sever-Haglund diseases are enthesopathic disorders of, respectively, distal patellar, proximal patellar, and Achilles tendon attachments to the cartilaginous growth plate rather than bone in children ( Figs. 19-12 and 19-13 ).




F igure 19-12


E nthesopathy of the distal patellar tendon .

A longitudinal view (12 to 5 MHz) of the distal attachment of the patellar tendon (1) to the tibial tuberosity (3) shows the linear hyperechoic insertion (2) and the Hoffa fat pad (4).



F igure 19-13


E nthesopathy of the proximal insertion of the patellar tendon .

A longitudinal view (14 to 5 MHz) shows thickening of the proximal attachment of the patellar tendon (2) associated with heterogenicity in a patient with chronic jumper´s knee (star) . The patellar bone (1) can be seen in this scan.


Tumorous Conditions


The most common tumorous lesions affecting tendons are ganglia. Ganglia may arise within the tendon itself or, more commonly, may originate from the sheath. A less common tumorous condition is the giant cell tumor of the sheath. Primary tumors are rare. Ultrasound is helpful in differentiating tendon sheath ganglia from intratendinous lesions. Dynamic examination demonstrating movement of the anechoic intratendinous lesion may help in this differentiation. Long- and short-axis views are indicated; the short-axis view is most helpful in delineating the relation of the cyst to the sheath. Giant cell tumors arise from the tendon sheath, are locally aggressive, and most commonly involve the first three digits of the hand and the first two toes. Ultrasound reveals a noncompressible, well-defined, uniform hypoechoic mass surrounding the tendon ( Fig. 19-14 ).




F igure 19-14


A chilles tendon with an intratendinous ganglion .

Transverse and longitudinal views (14 to 5 MHz) of the distal heterogeneous Achilles tendon (2) show an anechoic, well-delimited ganglion (star), the calcaneal bone (1), and the Kager fat pad (3).




Ligament


Normal Anatomy


Ligaments are thinner and less regular in their intrinsic structure than tendons and are more elastic because they contain an increased amount of elastin. Ligaments may be localized enlargements of the joint capsule (intrinsic) or unassociated with the capsule (extrinsic), and they are located within or outside of the capsule (i.e., intracapsular or extracapsular). They are primarily studied in long-axis views and appear as uniform, hyperechoic, bandlike structures adjacent to bone. With technologic advances in equipment, higher resolution enables visualization of the anatomic detail of these potentially complex structures (e.g., medial collateral ligament of the knee), along with identification of ligaments, such as the plantar calcaneonavicular (spring) ligament, that play an important role in maintaining normal joint relationships. Commonly assessed ligaments include medial and collateral ligaments of the knee; the radial and ulnar collateral ligaments and the annular ligament of the elbow; the coracoacromial and coracohumeral ligaments of the shoulder; the deltoid (tibiotalar and tibiocalcaneal components), anterior tibiofibular, anterior talofibular, and calcaneofibular ligaments of the ankle; the ulnar collateral ligament of the thumb; and the scapholunate ligament of the wrist.


Rupture or Tears


Ligamentous injuries are primarily traumatic in nature and are classified as first-, second-, and third-degree lesions. Ultrasound of first-degree lesions reveals a thickened, hypoechoic, inhomogeneous appearance with continuity of the ligament; second-degree lesions reveal an irregular outline and minimal discontinuity along with the hypoechoic, inhomogeneous appearance of first-degree lesions; and third-degree lesions reveal full-thickness discontinuity with possible retraction and a gap demarcated by hemorrhage. Dynamic examination is helpful in demonstrating tendon rupture in third-degree lesions. Doppler evaluation may be positive for more acute lesions ( Fig. 19-15 ).


Tags:
Mar 1, 2019 | Posted by in RHEUMATOLOGY | Comments Off on Soft Tissue Rheumatism

Full access? Get Clinical Tree
Get Clinical Tree app for offline access