The hamstring is made up of three separate muscles called the semitendinosus, semimembranosus, and biceps femoris. The hamstring muscles run down the back of the thigh and help you flex your knee and extend the leg at the hip.
Hamstring injuries can commonly occur in sports such as track, soccer, and basketball which involve running. They can also occur from high flexibility sports that require 'the splits' such as gymnastics and martial arts.
Injuries to the hamstring can be minor, requiring only a few days to resolve, to complete tears which take weeks to months to heal. If the muscle tears fully off the bone this is referred to as an avulsion injury. When an avulsion injury occurs many patients describe hearing and feeling a popping sensation in the buttocks with sudden severe pain. In adolescents, the growth plate where the hamstrings attach has not fully turned to bone, and can be at risk of breaking off. This special type of bone avulsion injury is referred to as an "ischial tuberosity avulsion fracture".
Risk factors for hamstring injuries include muscle tightness, fatigue, insufficient warm-up prior to exercise and poor technique in running or sprinting.
When the muscle or tendon tears, patients may experience and even hear a popping sensation in the back of the thigh or buttock. Swelling and bruising can be visible on the back of the thigh and have difficulty extending the leg or walking. Crutches may be needed to offload the leg while the injury heals.
Hamstring avulsion injuries can require surgery to reattach the tendon back to its origin on the base of the pelvic bone (ischium). Depending on the size, type, and chronicity of tear, it may be done through an incision in the crease of the buttock, or endoscopically through small key hole incisions. During the procedure the tendon is reattached back to the bone using anchors and stitches.
After surgery, you will need to use crutches and a brace to protect the newly repaired tendon and keep the muscle in a relaxed position. Physical therapy will be required to restore normal function, and rehabilitation will take 3 to 6 months to return to athletics and activities.
