Benha Medical Journal

: 2016  |  Volume : 33  |  Issue : 1  |  Page : 54--59

Role of ultrasonography in the evaluation of Achilles tendon disorders

Mohamed A Borg1, Saleh El-Essawy1, Roshdy M El Sallab2, Amany Ezzat1, Ahmed M Abd El-Khalek1,  
1 Department of Diagnostic Radiology, Faculty of Medicine, Mansoura University, Mansoura, Egypt
2 Department of Orthopedic Surgery, Faculty of Medicine, Mansoura University, Mansoura, Egypt

Correspondence Address:
Ahmed M Abd El-Khalek
Department of Diagnostic Radiology, Faculty of Medicine, Mansoura University, Postal/zip code (35516), Mansoura, 35516


Background This study was conducted to highlight the role of ultrasonography as an initial imaging modality for evaluation of symptomatic Achilles tendon disorders. Patient and Methods 60 patients (33 men and 27 women) had symptomatic Achilles tendons disorders and confirmed clinically as all patients were referred from orthopedic surgery department. 20 patients had history of blunt trauma followed by pain which may be associated with lost plantar flexion. 40 patients had chronic pain either associated or not associated with swelling at the site of Achilles tendon. US examination (13 MHz probe, GE logic P5 machine) using real time with color and power Doppler examination was performed while the patient in prone position. Results US depicted full-thickness tears in 11 (18.5%) tendons where tendon gaps were not significant (less than 5 mm) in 6 tendons and significant (more than 5 mm) in 5 tendons. De novo partial tears were detected in 15 (25%) tendons. Tendinopathy were seen in 18 (30%) tendons. US depicted paratenonopathy in 3 tendons (5%). 13 (21.7%) tendons appeared normal by ultrasonography. Conclusion Ultrasonography is an initial imaging of choice for evaluation of symptomatic Achilles tendon disorders. Diagnostic accuracy reaches 85%. However, Tendons that appeared normal by US should be followed by MRI for more diagnostic accuracy, detailed regional evaluation and subsequently can exclude other etiologies giving similar clinical manifestations.

How to cite this article:
Borg MA, El-Essawy S, El Sallab RM, Ezzat A, Abd El-Khalek AM. Role of ultrasonography in the evaluation of Achilles tendon disorders.Benha Med J 2016;33:54-59

How to cite this URL:
Borg MA, El-Essawy S, El Sallab RM, Ezzat A, Abd El-Khalek AM. Role of ultrasonography in the evaluation of Achilles tendon disorders. Benha Med J [serial online] 2016 [cited 2020 Jul 7 ];33:54-59
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Achilles tendon disorders are a common health problem in middle-aged active people. With increasing sport activities in the general population, the number of overuse injuries has increased [1]. Tendon disorders comprise 30–50% of all sports-related injuries [2].

Despite this high prevalence, there is still a lack of knowledge about the aetiology and pathogenesis of these injuries.

The terminology used to describe chronic tendon disorders has changed in the past few decades. For many years, this condition was persistently defined as ‘tendinitis’, denoting an inflammation of the tendon. Several researchers proposed changing this term, as there were no signs of inflammation in chronic painful tendons analysed after biopsy or with microdialysis techniques. The term ‘tendinopathy’ was introduced to describe the clinical condition of pain, swelling and impaired performance. Nowadays, this is the most accepted term for chronic Achilles tendon disorders. Histopathological studies showed that tendinopathy is frequently characterized by degeneration of the tendon tissue, also referred to as ‘tendinosis’ [3].

Unfortunately, physical examination is not always diagnostic and plain radiographs usually do not reveal any pathology. About 25% of spontaneous ruptures of the Achilles tendon are initially misdiagnosed by the primary physician [4].

There are several modalities available for imaging of the Achilles tendon. Ultrasonography (US) provides several benefits in comparison with MRI. It is readily accessible and quick, with the possibility of interaction with the patient. Moreover, the addition of power Doppler can be helpful in examining the blood flow within and around the tendon. The major US findings in chronic mid-portion Achilles tendinopathy are tendon thickening, hypoechoic areas, disorganized tendon tissue structure and increased power Doppler flow. This increased blood flow is also described as ‘neovascularization’, referring to the formation of new blood vessels. There is still discussion about the presence and significance of tendon structure disorganization and neovascularization in chronic tendinopathy and the relation with the patient's symptoms [5].

High-frequency musculoskeletal US transducers provide better spatial resolution, and thus more detailed delineation of normal and abnormal superficial soft tissues; however, they are of limited value in the assessment of deeper structures due to poor return of echoes. As a result, musculoskeletal US has been increasingly used in the evaluation of the superficial tendon, and, in particular, the Achilles tendon, in the assessment of tendinopathy and rupture [6].

 Patients and methods

Approval from the institutional review board and informed consent from participants were obtained. This study was a prospective one and included 60 patients (33 men and 27 women) who had symptomatic Achilles tendon disorders. All patients were referred from the Orthopaedic Surgery Department. Their ages ranged from 17 to 68 years, with a mean age of 38 years.

All patients underwent US examination with a 13 MHz probe (Logic 5; GE Machine; China) using real time, power Doppler, color flow map, and dynamic techniques.

Ultrasonography technique

Patient position

The patient was made to lie in the prone position with the foot hanging over the edge of the table. Mild dorsiflexion of the ankle and use of a thick transmission gel help in optimizing imaging.


A high-frequency transducer of 13 MHz is typically used, given the superficial location of the structures.

Longitudinal and transverse evaluation

The Achilles tendon can be easily seen when the transducer is placed in the sagittal plane, longitudinal to the tendon fibres. The transducer is moved proximally from the insertion site at the calcaneal tuberosity to the myotendinous junction. The transducer is then turned 90° for evaluation in the transverse plane.

Normal appearance

The Achilles tendon has fibrillar echotexture and is uniform in thickness and echogenicity in a longitudinal plane, and has a predominately flat or concave anterior margin in a transverse plane.

Dynamic evaluation

Dynamic imaging is important in the evaluation of Achilles tendon tears as haemorrhage, fluid, debris, or scar tissue may fill the gap between torn tendon ends. With passive movement of the foot or by gently squeezing the calf muscle, the gap between the torn tendon ends becomes more obvious as one tendon end moves without translation of movement to the other tendon end.

Achilles tendon abnormalities

The main disorders affecting the Achilles include injury and degenerative processes. Tears of the Achilles tendon most commonly occur 2–6 cm proximal to the calcaneal insertion site.


Tendinosis typically appears as fusiform hypoechoic swelling of the tendon without disruption of the fibres. Hyperaemia may be present due to hypervascularity, not secondary to inflammation.

Partial tear

Achilles tendon enlargement greater than 1 cm in the anterior–posterior dimension or marked intrinsic tendon abnormalities, such as a hypoechoic or anechoic cleft, indicate a partial tear.

Full-thickness tear

This disorder is characterized by complete tendon fibre disruption and tendon retraction. An intact plantaris tendon may be more obvious in the setting of a full-thickness Achilles tendon tear, and should not be mistaken for intact Achilles tendon fibres. Herniation of Kager's fat into the site of a tendon rupture can also be seen, as well as posterior acoustic shadowing from the torn tendon ends (refraction artifact). Tendon gap was measured in the longitudinal plane between torn ends.


Isoechoic soft-tissue thickening or hypoechoic fluid surrounding the Achilles tendon indicates peritendinitis.

Other structures

Plantaris tendon

This is a thin tendon at the medial aspect of the Achilles tendon, often best appreciated in the setting of an Achilles tendon tear. It may be absent in up to 20% of normal individuals.

Kager's fat pad

This structure is echogenic to heterogeneous fatty tissue deep in relation to the Achilles tendon.

Retrocalcaneal bursa

This bursa is located between the Achilles tendon and the posterosuperior calcaneus. It may normally contain up to 3 mm of fluid.

Retro-Achilles bursa

This is a potential bursa that is superficial (posterior) to the Achilles tendon at the level of Achilles tendon insertion. In normal individuals, there is no fluid in this bursa.

Gastrocnemius muscle

Injury to the medial head of the gastrocnemius, known as ‘tennis leg’, is a relative common clinical condition and can be detected easily by means of US. It is characterized by disrupted fibres at the aponeurosis with anechoic or hypoechoic fluid/haemorrhage and variable degrees of tendon retraction.


This study included 60 patients (33 men and 27 women) who had symptomatic Achilles tendon disorders ([Table 1]). Their ages ranged from 17 to 68 years, with a mean age of 38 years ([Table 1]). The patients had different types of clinical manifestations. A total of 20 (33.3%) patients had a history of blunt trauma followed by pain; 13 (21.6%) of them developed loss of plantar flexion, whereas seven (11.7%) had normal movement. A total of 40 (66.6%) patients complained of long-standing pain with preserved tendon function; 22 (36.7%) of them had additional sensation of tendon swelling, whereas 18 (30%) of them did not have the latter clinical manifestation ([Table 2]).{Table 1}{Table 2}

US depicted full-thickness tears in 11 out of 60 (18.3%) tendons. Tendon gaps were insignificant in six (10%) tendons ([Figure 1]), which measured less than 5 mm, and significant in five (8.3%) tendons ([Figure 2]), which measured more than 5 mm ([Table 3] and [Table 4]). Plantaris tendons were intact in three out of 11 tendons and could not be identified as separable structures in 15 out of 18 tendons.{Figure 1}{Figure 2}{Table 3}{Table 4}

A total of 18 (30%) tendons appeared to have tendinopathy ([Figure 3] and [Figure 4]). Partial tears were detected in 15 (25%) tendons ([Figure 5]). Paratendinopathy was noted in three (5%) tendons ([Table 4]).{Figure 3}{Figure 4}{Figure 5}

US depicted abnormally increased anteroposterior diameter of Achilles tendons in 45 (75%) tendons. The mean diameter was 9.8 ± 2.1 mm.

No abnormality was detected by means of US in 13 (21.7%) tendons. These tendons appeared to have their normal fibrillar echotexture despite the patients complaining of long-standing pain at the region of Achilles tendons ([Table 4]).

Data analysis

Statistical analysis was performed using the statistical package for the social sciences (SPSS) software (SPSS for Windows; SPSS Inc., Chicago, Illinois, USA). Patient characteristics were analysed using descriptive data. Diagnostic data were analysed on a case-by-case basis.


The Achilles tendon is the strongest and largest tendon in the body. The normal tendon is visualized by means of US as a band comprising parallel echogenic lines that is called fibrillar echotexture; it consists of multiple parallel lines in longitudinal planes and multiple dot-like echoes in transverse planes. This described echotexture is densely packed longitudinally arranged collagen fibres. The Achilles and patellar tendons are surrounded by paratenon, whereas other tendons have tendon sheath [7],[8],[9].

This study assessed the use of US in the differential diagnosis of Achilles tendon disorders associated with acute or chronic achillodynia. Most commonly encountered Achilles tendons disorders are full or partial thickness tear, tendinopathy, and paratendinopathy.

On US, tendinopathy generally manifests as alterations of tendon morphology and echogenicity [10],[11],[12]. Intrasubstance tearing and mucoid degeneration diminish tendon echogenicity. Secondary hypertrophy may increase the overall dimension of the tendon. Discrete intrasubstance cystic areas may be apparent. Areas of dystrophic calcification or ossification may be seen, with even tiny foci of calcification being readily appreciated on sonography. Focal calcific masses resulting from calcium hydroxyapatite deposition are well seen on US and may be treated under US guidance. The latter generally appear as globular echogenic collections with variable amounts of posterior acoustic shadowing. Tears generally appear as discretely marginated defects within the tendon substance [10].

In our study, the value of US was not enhanced by the addition of colour and power Doppler interrogation. Colour and power Doppler sonography can depict high-volume flow in large vessels, and they have recently been used to identify change of perfusion in low-velocity areas such as the musculoskeletal soft tissues [13],[14]. Because grey scale sonography is operator dependent, it was hoped that the addition of colour or power Doppler assessment would add objective evidence of pathology [12]. These techniques have been reported in studies imaging the patellar tendon [14],[15],[16].

In the study by Khan et al.[17], US identified abnormal morphology in 37 out of 57 (65%) symptomatic tendons. The positive predictive value was 0.65. However, US detected an abnormal echogenicity in only two out of 16 symptomatic tendons diagnosed clinically as having insertional tendinopathy. Thus, in tendons with mid-substance tendinopathy, US abnormality was present in 35 out of 45 (78%) patients, which corresponds with a positive predictive accuracy of 0.78 [17]. Our study had a near-similar positive predictive accuracy of 0.85. In this study, US identified abnormal morphology in 47 out of 60 (75%) tendons, whereas in 13 out of 60 (21.6%) tendons US did not identify abnormality. MRI examinations were carried out for those 13 normal-appearing tendons, in which insertional tendinopathy was noted in five out of 13 (38%) tendons and paratendinopathy was detected in four (24%) tendons. No abnormality was detected in four out of 13 (38%) tendons by means of MRI.

The mean diameter of the pathological tendons was 10.4 ± 2.7 mm, whereas normal tendons measured 5.2 ± 0.8 mm [18]. This study showed similar measurements (9.8 ± 2.1).

Metabolic diseases, such as hypercholesterolaemia or gout, can contribute to the mucoid degeneration of the tendon through accumulation of deposits within the tendon's fibrillar structure, and this process may be demonstrated clearly with sonography [18].

In view of its diagnostic advantages, US can and should be applied in the primary clinic, dynamically and in real time, as shown in the present and other studies. Compared with MRI, which is static, US has the capability of demonstrating physiological movement, and is simpler and more cost-effective [19],[20]. Moreover, it can be used for comparison between two sides at the same sitting [21].

In conclusion, clinicians encountering pain in the Achilles area should not adhere to conventional radiography and clinical examination alone, and are encouraged to include sonographic examinations in the primary diagnostic protocol. US is an initial imaging of choice for the evaluation of symptomatic Achilles tendon disorders. Diagnostic accuracy reaches 85%. However, tendons that appeared normal on US should be followed up with MRI for greater diagnostic accuracy and detailed regional evaluation, and, subsequently, can exclude other etiologies giving similar clinical manifestations.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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