Age / Sex : 15 / F

Chief complaint : Right leg pain (while doing ballet),  3 weeks ago

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy : Chung Hye Won, Asan Medical center

Discussion

Answer:  hamstring tendon tear

Findings:

A large sized cystic lesion at the intermuscular space of right posterior thigh contributing hemorrahge

Complete rupture of right hamstring tendons

 - semimembranosus tendon tear seems more severe than semitendinosus and biceps femoris common tendons

- distal retraction of tendon to the proximal thigh level, 4.0 - 7.0 cm longitudinally, seen on coronal image

Subtle edema-like signal changes in the hamstring muscles (more severe at semimembranosus muscle than biceps femoris and semimtendinosus muscles)

Differential Diagnosis:

Enthesopathy with tendon enlargement

Musculotendinous junction injury with hematoma

Soft tissue tumor with cystic degeneration or hemorrhage

Discussion:

Hamstring tendon: semimembranosus(SM), biceps femoris-semitendinosus(BF-ST) tendon

Common musculotendinous junction injury at biceps femoris > ST > SM

The amount of tendon retraction and the tendon edge morphology are important features for preoperative assessment. Coronal oblique imaging is useful for assessing the degree of retraction.

On MR, muscle injury is manifest by high signal on T2-weighted imaging (T2WI) secondary to edema, although hemorrhage may contribute to the abnormal signal. MR imaging may show focal areas of myofibril disruption

References:

1. Brandser EA, El-Khoury GY, Kathol MH, Callaghan JJ, Tearse DS. Hamstring injuries: radiographic, conventional tomographic, CT and MR imaging characteristics. Radiology 1995;197:257–262


2. Speer KP, Lohnes J, Garrett WE. Radiographic imaging of muscle strain injury. Am J Sp Med 1993;1:89–95


3. Koulouris G, Connell D. Evaluation of the hamstringmuscle complex following acute injury. Skeletal Radiol. 2003;32:582-589


4. Bierry G, Simeone FJ, Borg-Stein JP, Clavert P, Palmer WE. Sacrotuberous ligament: relationship to normal, torn, and retracted hamstring tendonson MR Radiology. 2014;271:162-171