A 20-year-old male presents with right posterior thigh pain and difficulty walking after he felt a “pop” while sprinting in a race. An ultrasound of the right posterior thigh is performed and the above image is seen on the transverse view without compression (Image 1. ST- semitendinosus; BF – bicep femoris; H – hematoma.Courtesy of Matthew Negaard, MD).
The patient has sustained an acute hamstring strain of the biceps femoris muscle and involvement of the semitendinosus muscles as evident by the muscle edema in addition to the hypoechoic area representing an acute hematoma.
Pearl: The biceps femoris is the most common hamstring muscle injury in athletes .
The use of ultrasound (US) over MRI should be performed to evaluate for hamstring injuries in the Emergency Department. Although MRI is traditionally the imaging modality of choice to diagnose and classify hamstring injuries, US is being used more and more to diagnose and classify these injuries [2,3].
Image 2. Extended longitudinal view of the biceps femoris. Note the disruption of fiber organization (<<) indicating a biceps femoris muscle injury. Case courtesy of Dr. Maulik S Patel, Radiopaedia.org, rID: 45598.
Pearl: Although US evaluation in the ED is preferred, muscle and tendon injuries may be best visualized 48 hours after the initial injury as it takes time for hematoma or muscle edema to develop . Be wary of a negative US in a patient who presents with history and exam concerning for a partial rupture.
Patients can be discharged with Sports Medicine follow up within 2 weeks. If diagnostic ultrasound imaging can be arranged, this would ideally take place 48 hours after the injury. Some patients may require a brief period of limited weight-bearing using crutches. Compression with an ACE bandage or thigh sleeve may be beneficial.
Pearl: Appropriate diagnostic imaging is essential as the classification and location of the injury can drastically change the recovery time and rehabilitation treatment protocols .
Resources & References:
Looking for more ways to incorporate ultrasound into your daily practice? Check out ALiEM’s Ultrasound for the Win series.
De Smet AA, Best TM. MR imaging of the distribution and location of acute hamstring injuries in athletes. AJR Am J Roentgenol. 2000;174(2):393-399. PMID: 10658712
Hall MM. Return to play after thigh muscle injury: Utility of serial ultrasound in guiding clinical progression. Curr Sports Med Rep. 2018;17(9): 296-301. PMID: 30204633
Macdonald B, McAleer S, Kelly S, et al. Hamstring rehabilitation in elite track and field athletes: Applying the British Athletics Muscle Injury Classification in clinical practice. Br J Sports Med. 2019;53(23):1464-1473. PMID: 31300391