Hamstring spasm in anterior cruciate ligament injuries

The accurate diagnosis of an anterior cruciate ligament (ACL) injury continues to be a challenge to clinicians, and often requires magnetic resonance imaging or arthroscopy for confirmation. We present a literature review of the currently known physical signs of ACL injury, followed by three case reports that describe a sign we believe may be helpful in the diagnosis of acute/semi-acute ACL injury: involuntary hamstring spasm.