Comparison of high resolution ultrasonography with clinical findings in patients with ankle pain

The ankle joint is the articulation between the dome of the talus and the distal tibia and fibula⁽¹⁾. The most common clinical presentation of patients with ankle pathology is pain and swelling, followed by pain alone⁽²⁾. The differential diagnosis includes trauma, inflammation, infection, and degeneration. Detailed history and careful clinical assessment are very important. Restriction in certain movements may serve as an indirect clue to the anatomical structure involved⁽³⁾.

Various clinical tests can be used to evaluate the integrity of ligaments and tendons⁽³⁾ (Tab. 1). Different diagnoses unfortunately tend to have overlapping clinical signs and symptoms. For this reason, referring clinicians tend to rely on imaging^(3).

Plain radiographs are the first-line tool in imaging technology, but visualizing soft tissue pathologies is not very clear and may require ultrasound or magnetic resonance imaging⁽⁴⁾.

Ultrasonography (US) has many benefits for evaluating ankle pain, especially the superficial structures including tendons, ligaments, and nerves. Stress US helps to differentiate partial from complete ligament tears^(3,5).

Magnetic resonance imaging (MRI) has emerged as a good modality for the diagnosis of musculoskeletal diseases of the ankle and foot, especially the deeper structures. However, it is relatively more time-consuming and less cost-effective, compared with US^(6,7).

Appearance of common ankle pathologies on US

Ligament pathology

Ultrasound of an acute ligament sprain may show thickening of the ligament with diffuse hypoechogenicity and surrounding fluid. A tear may appear as a hypoechoic or anechoic area interrupting the ligament fibers, and extends across the ligament in a full-thickness complete tear (Fig. 1, Fig. 2). As the ligament heals, the fluid disappears but the ligament may remain thickened and laxity may be demonstrated on dynamic imaging^(8,9).

Fig. 1.

Fig. 2.

Tendon pathologies

Tendinosis

Ultrasound of tendinosis typically shows loss of the normal fibrillar structure with increased spacing of the hyperechoic fibrillar lines. The tendon appears thick and hypoechoic. Calcific tendinosis presents as a thickened tendon with diffuse or scattered echogenic foci showing distal acoustic shadowing (Fig. 3).

Fig. 3.

Tenosynovitis

Acute tenosynovitis appears as anechoic fluid in the tendon sheath and can occur with or without tendinitis (Fig. 4).

Fig. 4.

Tendon tears

Full-thickness tears are diagnosed as a gap in a tendon that is filled with hematoma in the acute setting and with scar or granulation tissue in chronic cases. Retraction of the proximal and distal ends can be visualized in a complete tear. Partial tears appear as an incomplete disruption of the fibrillar echotexture of the tendon (Fig. 5, Fig. 6).

Fig. 5.

Fig. 6.

Joint effusion

A small amount of fluid may accumulate at the talar neck, without any significant effusion in the anterior joint recess. However mild to moderate joint fluid may displace the hyperechoic anterior fat pad in the anterior joint recess. (Fig. 7).

Fig. 7.

Included in the study were 136 patients with a history of ankle pain. All were subjected to detailed clinical history and local examination.

All the patients were evaluated for age, sex distribution, and clinical presentation. Two hundred and eighteen pathologies were diagnosed. Of these, 178 pathologies were clinically suspected, but 206 were diagnosed with ultrasonography.

Most of the patients were in the age group of 16–30 years (42.64%) with the range from 15–70 years. With regard to pathology, tenosynovitis and joint effusion were more common in female patients than in male patients, and there was a male preponderance for Achilles tendon and ligamentous pathologies (Tab. 3). Right ankle involvement was more common than the left side in both sexes. Approximately 55% of patients presented with an acute history, followed by chronic symptoms in 29%, and subacute symptoms in the remaining patients. With regard to clinical features, all patients presented with pain, followed by swelling (55% of patients) and movement restriction (34% of patients). Point tenderness could be elicited in 70% of patients, with trauma being the cause of symptoms in 48% of patients.

Cases of Achilles tendon tear were clinically suspected in all patients with a US diagnosis of a full-thickness tear. However, out of 18 patients for whom US revealed a partial-thickness tear, only 14 were clinically suspected. For cases of Achilles tendon calcification, joint effusion, and miscellaneous pathologies of the ankle joint, US diagnosed more pathologies as compared with the clinical examination (Tab. 4).

Thirty-eight patients with clinical suspicion of tenosynovitis were diagnosed with US. However, it was not possible to diagnose tenosynovitis on US in 2 patients who were clinically suspected.

Thirty-eight patients were clinically suspected of having a lateral ligament injury. US detected injury in all these patients, and also diagnosed 6 more patients for whom a clinical suspicion was absent. In cases of anterior talofibular ligament (ATFL) injury, 4 patients were clinically diagnosed with grade II injury. However, by conducting the ultrasound anterior drawer test, the injury was upgraded to grade III. Eight patients with positive posterior drawer test results were sent for US. However, posterior talofibular ligament (PTFL) pathology could not be found in these patients.

In our study, 64.9% of patients were in the young age group. Similar results were reported in studies by Rubin et al. and Pugia et al. in which most patients were in the young age group, with the mean age varying from 30 to 40 years^(10,11).

Male patients outnumbered female patients in our study. A male predominance was similarly reported in studies by Pugia et al. ⁽¹¹⁾.

No time interval was specified for the inclusion of the participants in our study. Most (62.8%) patients underwent a radiological workup within 3 months of the onset of symptoms (40.0% within 1 month and 22.8% within 1–3 months), whereas 37.2% of patients presented with chronic ankle pain (>3 months). All patients in our study presented with ankle pain. The most common associated symptom was ankle swelling, which was observed in 65.8% of the patients. This finding is in close agreement with the study conducted by Carretta et al. in which 56.7% of their patients underwent imaging because of acute pain and swelling, and 43.3% due to chronic symptoms⁽¹²⁾.

In our study, the patients with tendon abnormalities as the cause of ankle pain outnumbered the patients with other abnormalities, and similar incidence was described in a study by Artul et al. ⁽¹³⁾.

In our study, we found that Achilles tendon tear was the most common tendon injury, and similar findings were described by Ibrahim et al. ⁽¹⁴⁾.

In our study, clinical tests were positive in approximately 92% of the cases with Achilles tendon tear. Kauwe et al. also stated that physical examination has high sensitivity and specificity for Achilles tendon tear⁽¹⁵⁾.

Ultrasonography was also able to detect 2 additional patients with Achilles tendon tear for whom clinical suspicion was absent. Moreover, differentiating a full-thickness tear from a partial-thickness tear was possible with ultrasound. Kayser et al. in his study was also able to use ultrasonography for differentiating full-thickness tears from partial-thickness tears or tendinosis of the Achilles tendon with 92% accuracy⁽¹⁶⁾.

Of 12 patients with partial-thickness tear of the Achilles tendon, US was possible to detect 4 of these patients by taking advantage of the dynamic nature of US. In these patients, dorsiflexion of the foot demonstrated a partial-thickness tear, which was initially mistaken for tendinosis of the Achilles tendon clinically. Kayser et al. demonstrated a partial break in the tendon continuity by using forced dynamic ultrasound assessment⁽¹⁶⁾.

Ultrasonography in our study was also able to characterize the type of Achilles tendon tear according to the clinical classification, which is a guide for deriving a graded and differentiated therapy from a broad spectrum of treatments⁽¹⁷⁾.

In our study, 14 patients had calcification in the Achilles tendon, based on US findings. Taki et al. also suggested that US could perform well in depicting calcifications⁽¹⁸⁾.

Tenosynovitis was more common in female individuals than in male individuals in our study. These findings were similar to those of El-Liethy and Kamal⁽¹⁹⁾. In 2 patients who were not suspected of having tenosynovitis it was possible to detect it on US. Similar results were shown by Pereira et al. They found high concordance between the clinical and US findings in almost all patients with ankle tenosynovitis⁽²⁰⁾. In addition, color Doppler demonstrated increased vascularity in patients that had been diagnosed with tenosynovitis on US, which was stated by Park et al. ⁽²¹⁾.

El-Liethy and Kamaland Grassi et al. also concluded that, compared with MRI, US has 100% sensitivity for tendon pathologies and no further investigation is required^(19,22).

In our study, ATFL injuries outnumbered other ligamentous injuries. Rosenberg et al. also mentioned that ATFL is the most commonly injured ligament in the ankle because it is the weakest ankle ligament⁽²³⁾. Ultrasonography also made it possible to diagnose 8 additional patients with an ATFL injury in whom clinical suspicion was absent. Croy et al. indicated that clinical examination has low reliability and diagnostic accuracy in determining ligament injuries of the ankle, especially partial-thickness tears⁽²⁴⁾.

In our study, differentiating between grades of injury was also possible with US, with similar results shown by Cheng et al. and Radwan et al. ^(25,26).

In our study, the ATFL injury grade was changed from II to III in 4 patients by performing the US anterior drawer test. Sconfienza et al. stated that dynamic maneuvers may be used to increase the diagnostic accuracy of detecting tears and to differentiate a partial tear from a complete tear⁽²⁷⁾.

In our study, US was not helpful in detecting the clinically suspected PTFL pathology in any patient. Park et al. have mentioned that PTFL is difficult to visualize on US⁽²¹⁾.

There was no patient with syndesmotic injury or medial ligament injury in our study. This finding may be attributed to the small sample size and also to the fact that these are far less common than lateral ligament injuries⁽²⁸⁾.

Chiang et al. demonstrated that the use of ultrasound is limited in detecting bony pathologies⁽²⁹⁾. For these cases, MRI remains the gold standard⁽³⁾.

In our study, US was able to detect tendo-ligamentous pathologies, as well as miscellaneous pathologies, such as hemangiomas, foreign body abscesses, granulomatous lesions, and soft tissue masses (Fig. 8).

Fig. 8.

Ultrasonography is an excellent tool for evaluating patients with ankle pain, especially in cases of lateral ligament pathologies, tendinous pathologies, joint effusion, and miscellaneous pathologies. It can be used as the primary imaging investigation because it allows a rapid, dynamic, and cost-effective examination of the ankle joint. However, ultrasonography has limitations when using it to evaluate a suspected PTFL injury, marrow abnormalities, and deep seated pathologies, for which MRI should be incorporated for a diagnosis.