**7.2 Ultrasound examination technique**


achieved, the patient may lie supine with the foot slightly laterally rotated. Placing the transducer in short-axis/transverse position behind the medial malleolus, evaluate the posterior tibial tendon following it from its myotendinous junction into its insertion [36].

3.Achilles tendon: Evaluated with the patient in prone position and the foot hanging from the examination table. With the transducer, follow the tendon from its myotendinous junction downward to its calcaneal insertion in both the short and long planes. The size of the tendon should only be obtained in the transverse plane [36].

### **7.3 Peroneal tendon**

The peroneal tendons are the third most commonly injured tendons of the ankle. Acute and chronic tears occur in young, athletic patients due to overuse or in older patients with multifactorial degenerative wear and tear. Due to their course and location, calcaneal fractures predispose to partial tears, entrapment and dislocation of the peroneal tendons. Tendinopathy more commonly affects the peroneus brevis tendon. Split peroneus brevis syndrome represents a longitudinal tear of the tendon and the term arises from the fact that the peroneus brevis tendon is usually located anteriorly, is embedded between the peroneus longus and fibula [33, 34, 38].

### **7.4 Tibialis posterior tendon**

The tibialis posterior tendon is the second most commonly injured of the ankle tendons [37]. It should never have more than twice the cross-sectional area of the flexor digitorum longus tendon. Posterior tibial tendinopathy occurs because of delayed stretching of the tendon due to chronic micro-tears, and usually occurs in older women with progressively painful flat-foot. Systemic diseases like rheumatoid arthritis and diabetes predispose this condition, as for other tendinopathies. On MR and ultrasound imaging it will appear as tendon thickening with loss of normal echogenicity and tendon sheath fluid, with increased T2 signal intensity. Imaging pitfalls include: normal tendon widening at its insertion onto the navicular bone; fluid within the tendon sheath, mimicking enlargement on T1W sequences; and magic angle phenomenon [33, 37, 39]. Due to its course and insertion, abnormalities of the navicular bone may predispose to tibialis posterior tendinopathy; like the type II accessory navicular bone or *os naviculare,* which is typically large and closely positioned at the medial pole of the navicular bone by a synchondrosis, rendering insertion of the posterior tibial tendon only on this ossicle and not extending into the cuneiforms and metatarsals [36].

### **7.5 Achilles tendon**

The Achilles tendon is the most commonly injured tendon of the ankle (**Figure 7**) [37]. It is usually hypointense on all MR sequences, although due to its fascicular anatomy, a single line may be visible (not on T2WI), mimicking an interstitial tear. Punctate foci of increased signal intensity may be noted in axial images of the distal Achilles tendon, which simply are interfascicular membranes. Normal average thickness is 6–8 mm, which may increase in male, tall and elderly patients. On axial images its margins are concave for the majority of its course, being more convex proximally to and at the soleus insertion. Normally, there should be subcutaneous fat between the Achilles tendon and the skin. Branches of the posterior tibial artery supply the Achilles tendon, but blood supply diminishes at approximately 2–6 cm proximal to its insertion site, making this region of decreased vascularity particularly susceptible to ruptures [35, 37].

**31**

**8. Conclusion**

**Figure 7.**

**Acknowledgements**

*Imaging of Tendons*

*DOI: http://dx.doi.org/10.5772/intechopen.84521*

Achilles tendinosis is common in runners and jumpers. In Achilles tendinosis and peritendinosis, the tendon may enlarge. Acute Achilles ruptures more commonly occur in patients with chronic tendinopathy; runners, middle-aged women who engage in sporadic exercise or patients with systemic diseases or chronic steroid use, resulting in a weakened tendon. Most common site of Achilles tendon rupture is 2–6 cm proximal to its insertion site, avascular zone, as detailed above. Acute ruptures show a tendon gap with intermediate signal intensity on T1WI and increased signal intensity on T2WI, consistent with edema and hemorrhage. In chronic ruptures the gap is replaced by fat and scar tissue [33, 35, 37]. An accessory soleus muscle may be mistaken with a thickened Achilles tendon, which differ by their signal intensity on MRI. Achilles tendon thickening may occur after surgical procedures. There is thickening also with of xanthomas (familial hyperlipidemia) that appear as marked tendon enlargement with heterogeneous signal masses and linear areas of low signal intensity. Haglund's disease results most commonly from ill-fitting shoes that compress the distal Achilles tendon, leading to peritendinous edema, retrocalcaneal bursitis and tendon thickening [37].

*T2 fat saturated sagittal image shows disruption of the distal Achilles tendon with a fluid-filled gap.*

MRI and US are useful imaging modalities that allow anatomic evaluation of

Thanks to the University of Puerto Rico School of Medicine Diagnostic Radiology Department for allowing us to use images from its teaching file.

tendons as well as identification of tendon pathology.

**7.3 Peroneal tendon**

**7.4 Tibialis posterior tendon**

**7.5 Achilles tendon**

achieved, the patient may lie supine with the foot slightly laterally rotated. Placing the transducer in short-axis/transverse position behind the medial malleolus, evaluate the posterior tibial tendon following it from its myotendi-

3.Achilles tendon: Evaluated with the patient in prone position and the foot hanging from the examination table. With the transducer, follow the tendon from its myotendinous junction downward to its calcaneal insertion in both the short and long planes. The size of the tendon should only

The peroneal tendons are the third most commonly injured tendons of the ankle. Acute and chronic tears occur in young, athletic patients due to overuse or in older patients with multifactorial degenerative wear and tear. Due to their course and location, calcaneal fractures predispose to partial tears, entrapment and dislocation of the peroneal tendons. Tendinopathy more commonly affects the peroneus brevis tendon. Split peroneus brevis syndrome represents a longitudinal tear of the tendon and the term arises from the fact that the peroneus brevis tendon is usually located anteriorly, is embedded between the peroneus longus and fibula [33, 34, 38].

The tibialis posterior tendon is the second most commonly injured of the ankle tendons [37]. It should never have more than twice the cross-sectional area of the flexor digitorum longus tendon. Posterior tibial tendinopathy occurs because of delayed stretching of the tendon due to chronic micro-tears, and usually occurs in older women with progressively painful flat-foot. Systemic diseases like rheumatoid arthritis and diabetes predispose this condition, as for other tendinopathies. On MR and ultrasound imaging it will appear as tendon thickening with loss of normal echogenicity and tendon sheath fluid, with increased T2 signal intensity. Imaging pitfalls include: normal tendon widening at its insertion onto the navicular bone; fluid within the tendon sheath, mimicking enlargement on T1W sequences; and magic angle phenomenon [33, 37, 39]. Due to its course and insertion, abnormalities of the navicular bone may predispose to tibialis posterior tendinopathy; like the type II accessory navicular bone or *os naviculare,* which is typically large and closely positioned at the medial pole of the navicular bone by a synchondrosis, rendering insertion of the posterior tibial tendon only on this ossicle and not extending into the cuneiforms and metatarsals [36].

The Achilles tendon is the most commonly injured tendon of the ankle (**Figure 7**)

[37]. It is usually hypointense on all MR sequences, although due to its fascicular anatomy, a single line may be visible (not on T2WI), mimicking an interstitial tear. Punctate foci of increased signal intensity may be noted in axial images of the distal Achilles tendon, which simply are interfascicular membranes. Normal average thickness is 6–8 mm, which may increase in male, tall and elderly patients. On axial images its margins are concave for the majority of its course, being more convex proximally to and at the soleus insertion. Normally, there should be subcutaneous fat between the Achilles tendon and the skin. Branches of the posterior tibial artery supply the Achilles tendon, but blood supply diminishes at approximately 2–6 cm proximal to its insertion site, making this region of decreased vascularity particularly susceptible to ruptures [35, 37].

nous junction into its insertion [36].

be obtained in the transverse plane [36].

**30**

Achilles tendinosis is common in runners and jumpers. In Achilles tendinosis and peritendinosis, the tendon may enlarge. Acute Achilles ruptures more commonly occur in patients with chronic tendinopathy; runners, middle-aged women who engage in sporadic exercise or patients with systemic diseases or chronic steroid use, resulting in a weakened tendon. Most common site of Achilles tendon rupture is 2–6 cm proximal to its insertion site, avascular zone, as detailed above. Acute ruptures show a tendon gap with intermediate signal intensity on T1WI and increased signal intensity on T2WI, consistent with edema and hemorrhage. In chronic ruptures the gap is replaced by fat and scar tissue [33, 35, 37]. An accessory soleus muscle may be mistaken with a thickened Achilles tendon, which differ by their signal intensity on MRI. Achilles tendon thickening may occur after surgical procedures. There is thickening also with of xanthomas (familial hyperlipidemia) that appear as marked tendon enlargement with heterogeneous signal masses and linear areas of low signal intensity. Haglund's disease results most commonly from ill-fitting shoes that compress the distal Achilles tendon, leading to peritendinous edema, retrocalcaneal bursitis and tendon thickening [37].
