Fig 5.

Ultrasound images of a 20-year-old football player (the same patient as the one shown in Fig. 4) taken at the same time as Fig. 4a–c. a A newly developed haematoma (arrow) measuring 2 cm × 0.8 cm is noted in the proximal mid-portion of the rectus femoris muscle. b More proximally, a known pre-existing fluid collection (2.5 cm × 0.5 cm, arrow) from the previous injury 3 weeks prior is observed. It is difficult to differentiate (a) as a new and (b) as an older lesion on the basis of ultrasound alone. c In between these two lesions, a notable echo inhomogeneity is noted, suggestive of a partial tear of the proximal rectus femoris muscle