The hamstring muscles are a group of muscles in the back of the thigh.  These muscles start as a tendon at the bottom of the pelvis (sit bone) and travel down the back of the thigh and attach as a group of tendons just beyond the back of the knee joint.  Hamstring muscle tears are frequently seen in sprinters, football players, soccer players, and a variety of other athletes who run or jump.  Tears commonly occur in the muscle fibers in the middle of the muscle and do not require surgery.  Occasionally, tears occur at the site where the tendon is attached to the pelvic bone (ischium).  Unlike muscle tears, these tears generally do not occur during sprinting, but instead occur when a person’s leg is straight (knee locked out) and the torso bends excessively (hyper-flexes) causing significant tension on the hamstring tendon.  This type of tear is called a proximal hamstring tendon tear, and it commonly occurs during water skiing, tennis, or a slip and fall.  Unlike hamstring muscle tears, proximal hamstring tendon tears frequently require surgery, as the tendon is unable to heal back to the bone on its own.  Partial (incomplete) and full (complete) tears can occur, with the complete tears commonly pulling back away from the bone (retracting).  Both incomplete and complete tears have demonstrated better long-term results with surgical fixation