Rectus femoris muscle injury with "Bull's eye" sign

Case contributed by Ammar Haouimi
Diagnosis almost certain

Presentation

Sport injury.

Patient Data

Age: 20 years
Gender: Male

At the right mid-thigh, there is edematous infiltration of the inner bipennate portion around the indirect tendon of the right rectus femoris muscle with minimal surrounding fluid "bull's eye sign" separating the outer unipennate portion of the rectus femoris muscle which shows as well extensive edema well-demonstrated on the axial T2 sequence.

The inner portion of the rectus femoris muscle is moderately proximally retracted with minimal fluid separating it from the outer portion muscle well-demonstrated on the sagittal T2 and STIR sequences.

subcutaneous edema with perifascial fluid along the rectus femoris muscle.

Case Discussion

MRI features of a rectus femoris muscle injury.

The rectus femoris has two heads with separate origins:

  • direct/straight head: originates from the anteroinferior iliac spine (AIIS)

  • indirect/reflected head: originates from the superior acetabular ridge

Both these heads unite to form the deep musculotendinous junction.

Rectus femoris muscle injuries are a common injury in athletes, especially in football/soccer players. The rectus femoris muscle is most frequently affected in a quadriceps injury and the most common pattern are muscle strains.

The bull’s eye sign is seen on axial MRI sequences indicating a deep intramuscular degloving injury of the muscle fibers from the indirect head, while the peripheral direct head fibers remain intact. 

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