CASE 48

By: Dr. Mai Mattar, MD and Dr. Nizar Al-Nakshabandi MD, FRCPC

HISTORY: Young male with sudden onset of posterior ankle pain while playing football.

What are your findings?

What is the differential diagnosis?

What are the causes?

FINDINGS:

Lateral ankle radiograph demonstrates thickening within the region of the Achilles tendon extending into Kager’s fat pad.

Ultrasound of the Achilles tendon demonstrates a full thickness tear with a gap measuring 2 cm, reduced to 1.7 cm on plantar flexion. The tear is 7.5 cm proximal to the calcaneal insertion.

DIFFERENTIAL DIAGNOSIS:

• Achilles tendon rupture.

• Muscle tear/hematoma.

• Chronic tendinopathy.

DIAGNOSIS:

Achilles tendon rupture.

PEARLS AND DISCUSSION:

Achilles tendon tear are likely primary related to sports injury. However, they could be induced secondary by steroid injections into the tendon, rheumatoid arthritis, gouty arthritis, diabetics, and hyperparathyroidism.

Patients present with sudden onset of pain and swelling in the Achilles region often accompanied by a snap during forced dorsiflexion of the foot. On physical examination, minimal plantar flexion against resistance is seen.

They occur often at the critical zone approximately 2-6 cm above the os calcis where it is believed to be a watershed hypovascular region.

On radiographs obliteration of Kager’s fat pad could be seen.

Ultrasound demonstrates an enlargement of the tendon with hypoechoic or anechoic areas corresponding to tears. Valuable information can be obtained from ultrasound, e.g:

• Is the tear partial or complete?

• Distance of tear to insertion.

• Tear gap and amount of reduction with plantar flexion.

MRI will demonstrate anatomic gap in the tendon filled with edema, or high signal in partial thickness tears on T2-weighted images.

Partial-thickness tears are treated conservatively. Full-thickness tears are treated with surgical repair particularly in athletes.

FURTHER READING:

1. Kleinman M, Gross AE. Achilles tendon rupture following steroid injection. Report of three cases. J Bone Joint Surg Am. 1983;65 (9): 1345-7. 

2. Hartgerink P, Fessell DP, Jacobson JA et-al. Full- versus partial-thickness Achilles tendon tears: sonographic accuracy and characterization in 26 cases with surgical correlation. Radiology. 2001;220 (2): 406-12. 

3. Schweitzer ME, Karasick D. MR imaging of disorders of the Achilles tendon. AJR Am J Roentgenol. 2000;175 (3): 613-25