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ECR 2012 / C-1839
Elbow synovial fold syndrome
Congress: ECR 2012
Poster No.: C-1839
Type: Educational Exhibit
Keywords: Athletic injuries, Arthrography, Ultrasound, MR, Musculoskeletal joint
Authors: L. Cerezal1, A. Canga1, M. Sammartino2, M. Fernández Hernando1, J. Arnaiz1, F. Abascal1; 1Santander/ES, 2Buenos Aires/AR
DOI:10.1594/ecr2012/C-1839

Imaging findings OR Procedure details

Synovial plicae of the elbow. Embryologic Development.

Embryologically, the elbow joint is formed by mesenchymal cavitation first at the radiohumeral site, then in the ulnohumeral region, and finally in the radioulnar site, that are divided by synovial septa. Subsequently, these three cavities merge. The incomplete resorption of these septa would leave well-developed plicae. Elbow synovial plicae or synovial folds are a septal remnant of this process.

 

 

Synovial plicae of the elbow. Anatomy.

The synovial fold is a capsular tissue located on the proximal edge of the annular ligament. It is distinct from the annular ligament but contiguous with the radiocapitellar joint capsule, which blended with the common extensor tendon imperceptibly and formed a single enthesis at the lateral epicondyle.

 

Fig. 1: The radiohumeral synovial fold is fixed to the capsule, and related to the superior edge of the annular ligament. RHF, radiohumeral fold; AL, annular ligament; C, capsule.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

The synovial plicae of the elbow are located at the humeroradial joint and surrounds the periphery of the radial dome. The synovial folds are quite large, covering an average of more than one fourth of the joint surface of the radial head in the radiohumeral joint. The normal synovial folds are thin, pink, and pliable. In a smal amount of individuals (2-12%) the elbow plica surrounds the fullest extent of the radial dome that we could call on the whole the circumferential synovial fold. The radiohumeral synovial plica has four portions clearly differentiated by their location:  anterior, lateral, posterolateral, and lateral olecranean fold.

 

 

Fig. 2: Diagram shows the normal appearance of the elbow synovial plicae (circular-type fold) when the elbow joint is laterally opened. AF, anterior fold; LF, lateral fold; PF, posterolateral fold; OF, lateral olecranean fold.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

Fig. 3: Axial diagram shows the normal appearance of the elbow synovial plicae (circular-type fold). AF, anterior fold; LF, lateral fold; PF, posterolateral fold; O, olecranon; SC, sigmoid cavity; RH, radial head.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

 

Fig. 4: Cadaveric dissection image shows the normal appearance of radiohumeral synovial fold (circular-type fold). AF, anterior fold; LF, lateral fold; PF, posterolateral fold; O, olecranon; C, capitellum; RH, radial head.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 5: Cadaveric dissection image shows a normal radiohumeral synovial fold (circular-type fold). AF, anterior fold; LF, lateral fold; PF, posterolateral fold; O, olecranon; C, capitellum; RH, radial head.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

When more than 2 portions are present, the posterolateral one is usually larger than the anterior or the lateral portion. Posterolateral folds are generally longer and extend more laterally than the anterior synovial folds; they also appear wider and more deeply interposed in the humeroradial joint than the anterior folds.


- Anterior fold

The anterior fold is the thinnest part of the radiohumeral synovial fold.  The size reported of the anterior lobe averaged 3.0 mm in width, and 1.2 in thickness.

 

Fig. 6: Diagram shows the normal appearance of the posterolateral and anterior fold. The posterolateral fold is the most common and usually the thickest synovial elbow fold. AF, anterior fold; PF, posterolateral fold.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

 

Fig. 7: Sagittal proton density fat suppressed image shows the normal appearance of the posterolateral and anterior folds. AF, anterior fold; PF, posterolateral fold.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

 

- Lateral synovial fold

The lateral radiohumeral fold is a horizontal fibroadipose meniscoid fold projected into the radiohumeral joint to lie between the capitelum and the outer edge of the radial dome. It is crescentic in shape, with a free border that extended between the articular surfaces for distances ranging from 2.5 to 4 mm. The free edge tends to be irregular or jagged in appearance and is freely mobile over the articular cartilage. The size reported of the lateral lobe averaged of 22.3 mm in lenght,  3.4 in width, and 2.1 mm in thickness.

 

Fig. 8: Frontal diagram of the humeroradial joint shows the normal ‘‘pseudo-meniscoid” appearance of the lateral radiohumeral fold, placed between the capitellum and the edge of the fovea radialis, fixed to the capsule, above the superior edge of the annular ligament. LF, lateral fold; AL, annular ligament; C, capsule.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 9: Cadaveric image shows a normal lateral synovial fold. LF, lateral fold; C, capitellum; RH, radial head; SC, sigmoid cavity.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 10: Cadaveric trasillumination image shows a normal lateral synovial fold. LF, lateral fold; O, olecranon; C, capitellum; RH, radial head.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 11: Coronal proton density fat suppressed images show the normal appearance of the lateral and posterolateral folds. LF, lateral fold; PF, posterolateral fold.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES



- Posterolateral synovial fold

The posterolateral synovial fold is located at the angle between the lower sigmoid cavity of the ulna, transverse sulcus of the major sigmoid cavity, and radial dome. It has a vertical direction and goes forward with the radiohumeral fold. It is consistent from a structural point of view. It is almost always visible in asymptomatic subjects.

The median dimensions of a posterolateral fold are 17 mm in length, 8 mm  in width, and 3.2 mm in thickness.

 

Fig. 12: Cadaveric dissection image shows a normal posterolateral synovial fold. PF, posterolateral fold; O, olecranon; SC, sigmoid cavity; RH, radial head.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 13: Cadaveric dissection image illustrating the anatomic relationship between the annular ligament and the radiohumeral synovial fold. PF, posterolateral fold; AL, annular ligament, RH, radial head.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 14: Axial proton density fat suppressed image shows a normal radiohumeral fold with lateral and posterolateral components. LF, lateral fold; PF, posterolateral fold; O, olecranon; RH, radial head.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES



- Lateral olecranean synovial fold

The lateral olecranean synovial fold is smaller than the other elbow synovial folds. It is an inconstant fold (30%). It originates from posterolateral fold, runs proximally along the lateral margin of the olecranon, and, while the rounded apex was located at the peak of the lateral nonarticular portion of the trochlear notch. It is located in the posterolateral olecranon recess adjacent to the anconeus muscle.

The median dimensions of a lateral olecranean fold are 4.3 mm in length, 3.9 mm  in width, and 1.9 mm in thickness.

There is no consensus in the literature concerning the prevalence of these persistent embryonic structures in the general population. The most common synovial plica of the elbow are the posterolateral radiohumeral synovial fold, seen in 86 to 98% of asymptomatic subjets, and the lateral olecranean synovial fold in 30%. The incidence of the circular-type fold varied from 2 % to 12%.

 

Fig. 15: Cadaveric image shows a normal lateral olecranean synovial fold. OF, lateral olecranean fold; O, olecranon; SC, sigmoid cavity; C, capitellum; TH, trochlea of humerus.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 16: Cadaveric image shows a normal lateral olecranean synovial fold. OF, lateral olecranean fold; O, olecranon; SC, sigmoid cavity; C, capitellum.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

Fig. 17: Axial proton density fat suppressed image shows a normal lateral olecranean fold in the posterolateral olecranon recess, adjacent to the anconeus muscle. OF, lateral olecranean fold; O, olecranon.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES



Synovial plicae of the elbow. Histology.

The histological study showed two types of folds: a rigid structure, with oriented fibrous tissue, triangular with a peripheral capsular base, covered on its two sides and along the free edge by a synovial layer; and a pliable structure, formed of two synovial layers that surrounded a thin fatty tissue, with a villous appearance of the free edge. The normal synovial folds appear as a meniscus-like tissue (triangular shape). However, this anatomical structure cannot be called meniscus due to the absence of a fibrochondroid structure, as in a real meniscus. The synovial folds have abundant nerve endings in their periphery, inferring the possibility of pain directly associated with pathology in this structure.

The posterolateral synovial fold is a loose structure with a thick fibrous axis and adipose tissue. The lateral fold has a more rigid structure than posterolateral fold, with more dense connective tissue and less fatty component.

The synovial folds were also classified into villous, plicate, fatty plicate, meniscus-like, membranous, and thickened annular ligament types according to their shapes and textures.

 

Fig. 18: Histology of the elbow synovial fold. Loose structure with a thick fibrous axis (1) and predominance of adipose tissue (2), without fibrocartilage, and with abundant nerve endings in their periphery (3).
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 19: Photomicrograph shows the normal vascularization of the elbow synovial folds. PF, posterolateral fold; OF, lateral olecranean fold; O, olecranon; CP, coronoid process; C, capitellum; TH, trochlea of humerus.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES


Function

The elbow folds could acts as a stabilizer to prevent excessive movement. The fold could occur in the joint and fill the humeroradial space during extension of the elbow, when the fovea radialis is no longer in close contact with the capitellum. The role during pronation and supination may be considered as a protective one, but in fact the fold is not directly compressed between the capitellum and the fovea radialis. The mechanical concept of dispersion of loading forces, as in a meniscus of the knee, is not so true because the stresses are mainly transmitted from the central part of the capitellum to the center of the fovea radialis, and from the capitellotrochlear notch to the medial crest of the ulnar edge of the radial head.

The elbow synovial  plicae may play a role in nocioception, proprioception and coordination of movements.

Finally, elbow synovial  folds could help to distribute synovial fluid within the elbow joint by way of the “windshield wiper” effect.

 

Pathophysiologic Features

The pathophysiologic features of plica syndrome are not clearly defined. Plica syndrome arises from an injury such as a direct blow, repetitive microtrauma and overloading (eg, sports that require repetitive flexion-extension like throwing athletes and golfers), a twisting force that stretches the plica, or some other pathologic elbow condition that results in an inflammatory process. This repetitive injury creates an inflammatory reaction with a thickening of the synovial fold and chronic localized synovitis. The thickened fold can generate a transient interposition and compression of the folds between the articular surfaces in certain movements of the joint, generating snapping of the joint. Abrasion is the most likely responsible for the chondromalacia seen on the radial head and capitelum over which the plica snaps.

In the early stages, the inflamed plica itself may be symptomatic, whereas in the later stages the cause of symptoms is the fibrotic plica that arises from underlying cartilage or from traction on adjacent synovium.

An overlap of plica size has been found in symptomatic and asymptomatic elbows it has been shown. Most authors accept that wider plicae are more often symptomatic and more frequently demonstrate pathologic changes at histologic analysis than thinner plicae. Cut-off values for thickened elbow folds (eg, 3 mm) are suggested in the literature.

Chondromalacia appears in patients with long time suffering symptoms where the mechanical snapping of the synovial folds lead to cartilage degeneration. Chondromalacia or cartilage damage occurs on the antero-lateral aspect of the radial head or less frequently on the capitellum humeri.

 

Fig. 20: Diagram shows the typical features of elbow synovial fold syndrome, including thickened and inflamed plica (arrow), and chondral fraying of the radial head and capitellum (arrowheads).
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

 

Fig. 21: Patient with elbow synovial fold syndrome treated with open surgical procedure. Chondral defect on the lateral aspect of the radial head (arrow).
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

A syndrome of limitation of full extension caused by impingement of lateral olecranean plica in olecranon fossa has been described. Some authors have also suggested a possible relationship of the elbow synovial folds with the pathogenesis of epicondylitis.

 


Clinical Manifestations

Posterolateral impingement of the elbow is more common in athletic young adults. It is more common in sports that require repetitive flexion-extension like tennis players, golf and sports that involve throwing.

The symptoms of synovial plicae in the elbow are unspecific and require careful evaluation to make the diagnosis. Clinical findings mimic those in an epicondylitis. If we examine carefully the elbow, the location of the pain is posterolateral and not along the lateral epicondyle or extensor tendon origin. Plica can cause lateral elbow pain, even without locking or catching during the initial phase of the pathological condition.

The diagnosis of elbow synovial fold syndrome or posterolateral impingement should be considered in any patients who have painful snapping in the elbow, particularly if they have symptoms on the lateral side of the elbow. The thickened synovial folds may present clinically as a snapping pain, which was the main complaint, or locking elbow, during elbow flexion and extension. The exact arm position for reproducing symptoms with this condition has not been consistent in the literature. On physical examination, the reproduction of the symptoms during flexion-extension of the pronated forearm (flexion-pronation test) should lead to consider the possibility of a pathological synovial plica in the radiocapitellar joint. However, reproducible snapping in flexion-pronation test occurr in 25 to 50% of the patients  suffering of mechanical symptoms such as clicking or catching. It is possible that these symptoms depend upon the location of the plicae and other anatomical variations.

 

 

Synovial plicae of the elbow. Imaging.


- Ultrasound

The normal synovial fold of the elbow appear on ultrasound as a triangular-shaped hyperechoic structure bordered by hypoechoic rims between the capitellum and the radial head. In patients with synovial plica syndrome, ultrasound allows easy identification of synovial fold thickening and focal synovitis.

Dynamic ultrasound examination of the elbow, with flexo-extension movements, can be a useful non-invasive diagnostic tool of snapping elbow.

 

 

Fig. 23: Ultrasound image reveals a thickened posterolateral fold (arrow), with focal surrounding synovitis (arrowheads).
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES


- MR imaging

Normal synovial folds in the elbow recess were seen commonly on conventional MR images. At MR imaging, synovial plicae can be seen as bands of low signal intensity within the high-signal-intensity joint fluid. Gradient-echo T2-weighted MR images and proton density fat-suppressed images are the most valuable for the evaluation of plicae. Both symptomatic and asymptomatic patients may have thickened synovial folds (greater than 3 mm thickness and an irregular or nodular appearance). Although the size and morphologic features of a given plica seen at MR imaging do not in themselves indicate whether the plica is clinically significant, symptomatic plicae usually appear thickened. MR allows a more accurately assessment of the full spectrum of injuries associated with elbow synovial fold syndrome, including synovial fold thickening, focal fibrosis/synovitis, and chondromalacia of the radial head and capitellum, and to rule out other causes of lateral elbow pain. Chondral defects and bone marrow abnormalities of the radial head and capitellum are best identified on proton density fat-suppressed and T2-weighted images.

 

Fig. 24: MR image shows a thickened lateral synovial fold (arrow) in a patient with elbow synovial fold syndrome.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

- CT arthrography/MR arthrography

CT arthrography and MR arthrography have been established as a valuable imaging studies for evaluating intra-articular conditions, chondral and osteochondral lesions, loose bodies, synovial capsule, and collateral ligaments, particularly in a joint with no or minimal joint effusion.

Some symptomatic plicae could be missed on MR Imaging in patients without joint fluid. CT/MR arthrography are useful techniques when there is not enough articular fluid and a clinically significant plica is suspected. The contrast agent highlights joint surfaces and distends the capsule, thereby providing excellent visualization of the plicae. Associated chondral lesions of the radial head and capitellum are identified more accurately on CT/MR arthrography.

 

 

Fig. 25: CT arthrography images show an irregular thickening of the posterolateral synovial fold (arrows) in a patient with elbow synovial fold syndrome. Articular cartilage has a normal appearance.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

Fig. 26: MR arthrography images show a thickened posterolateral synovial fold (arrows) in a patient with elbow synovial fold syndrome.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 27: Sagittal T1-weighted MR arthrography images of a 20 years old woman hockey player with posterolateral painful snapping elbow reveal a thickened posterolateral plica and focal irregular synovitis (arrows).
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

Fig. 28: Axial T1 fat suppressed MR arthrography images of 20 years old woman hockey player with posterolateral painful snapping elbow reveals a thickened posterolateral plica and focal irregular synovitis (arrows).
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 29: Coronal T1 fat suppressed MR arthrography images of 20 years old woman hockey player with posterolateral painful snapping elbow reveals a thickened posterolateral plica and focal irregular synovitis.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES



Differential diagnosis

It is important to know that elbow synovial folds can cause lateral elbow pain, even without joint locking or catching during the initial phase of the pathologic condition. The etiology of painful syndromes of the lateral side of the elbow may be tendinous (epicondylitis), nervous (compression of the posterior interosseous nerve), or articular. The differential diagnosis includes lateral epicondylitis, compression of the posterior interosseus nerve, and different types of intraarticular pathology. The main differential diagnosis of elbow synovial fold syndrome is lateral epicondylitis or tennis elbow. Certainly, these more frequently occurring disorders should be suspected first and mainly in athletes who epicondilitys is probably the most common initial diagnosis. The diagnosis of plica syndrome should also be considered in patients who have failed procedures for lateral epicondylitis.

When a patient complains of painful locking or snapping of the elbow, several entities must be ruled out. Loose bodies, instability, a torn or loose annular ligament, and snapping of the medial head of the triceps over the epicondyle are the most common causes of this problem.

The diagnosis of elbow synovial fold syndrome may be missed clinically for three reasons:

First, with so little literature and teaching devoted to the topic of plicae in the elbow, the phenomenon does not rank high on the list of differential diagnoses.

Second, the clinical examination and list of differential diagnoses for snapping at the elbow are not familiar to many radiologist and clinicians.

Third, the lateral location of the pain, and the typical tenderness over the radial capitellar region, make it likely that this condition may be misdiagnosed as tennis elbow. This is particularly likely if the clinician focuses more on the symptom of pain than the symptom of snapping.

 

Fig. 30: Coronal and sagittal DP fat suppressed images show a grade 2 lateral epicondylitis (arrow). Note the presence of a pseudodefect of the capitellum and a normal posterolateral synovial fold. It should not be confused with a pathological fold with chondromalacia of the capitellum.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES

 

Fig. 31: Sagittal and coronal DP fat suppressed images in a patient with painful snapping elbow show an intraarticular luxation of the anterior aspect of the annular ligament (arrows) and humeral condyle chondromalacia.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
Fig. 32: Arthroscopic images of the radiocapitellar joint show an intraarticular luxation of the anterior aspect of the annular ligament and humeral condyle chondromalacia (arrow).
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES


Fig. 33: Coronal and axial DP fat suppressed images in a patient with painful snapping elbow show a complete rupture of the annular ligament (arrows) with intraarticular luxation (arrowhead).
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES


Fig. 34: Sagittal T1-w fat suppressed and arthroscopic images in a patient with painful snapping elbow show an intraarticular loose body in the olecranean fossa (arrow) and in the lateral recess.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES



Treatment

Nonsurgical treatment is preferable initially. This treatment combines rest from all strenuous physical activities, physiotherapy, and nonsteroidal anti-inflammatory agents. Failure of the patient to improve with conservative treatment leaves arthroscopic excision of the pathologic plica as the treatment of choice. Arthroscopic intervention should not be delayed by prolonged conservative treatment, as subsequent erosion of the articular cartilage can be prevented by early resection.

The arthroscopic examination of the joint that allows not only direct inspection of the hypertrophic plica, but also helps understanding the dynamic impact of the hypertrophic folds in motion. The distension of the elbow joint during arthroscopy and high inflow pressures of arthroscopy fluid must also be taken in careful consideration when evaluating the synovial folds for their mechanical impact on elbow joint dysfunction. Placing the elbow through a range of motion while decreasing distension pressure from the fluid inflow is recommended. The plica should be entirely removed by resecting it to its base throughout its length The annular ligament should not be violated, and the articular surfaces should be protected. Arthroscopic resection of the plica and associated focal fibrosis or synovitis lead to excellent outcomes at follow-up.

 

 

Fig. 35: Arthroscopic images of the radiocapitellar joint. Impingement of the joint caused by a thickened, hypertrophic plica and irregular focal synovitis. Arthroscopic debridement allows a complete recovery of symptoms.
References: Radiology, DMC, Diagnóstico Médico Cantabria - Santander/ES
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