A hamstrings injury is an injury to the hamstrings muscles or tendons in the thigh or knee.

Complex injuries
Hamstrings injuries are one of the most common sporting injuries, but their exact nature can be complex because the origin and the insertion of the muscles within the group - biceps femoris, semimembranosus and semitendinosus - are themselves complex, and new injuries may further complicate old injuries. In most people rest with suffice but in athletes it may be challenging to plan treatment protocols.
CLINICAL PUBLICATIONS
The natural history and management of hamstring injuries. Carlson C. Curr Rev Musculoskelet Med. 2008 Jun; 1(2): 120–123.
Distal tears of the hamstring muscles: review of the literature and our results of surgical treatment. Lempainen L, Sarimo J, Mattila K, Heikkilä J and Orava S. CBr J Sports Med. 2007 Feb; 41(2): 80–83.
Hamstring injuries: update article. Ernlund L and de Almeida Vieira L. Rev Bras Ortop. 2017 Jun-Jul; 52(4): 373–382.
MR imaging of the distribution and location of acute hamstring injuries in athletes. De Smet AA and Best TM. AJR Am J Roentgenol. 2000 Feb;174(2):393-9.