Hamstring injuries are common in athletes who participate in sports activities such as track, soccer, and basketball that involves sprinting and running.  The three hamstring muscles – semimembranosus, semitendinosus, and biceps femoris are located at the back of the thigh and help you bend (flex) the knee and extend your hip. 

Injuries to the hamstring group of muscles can range from minor sprain/strain to a complete tear with tendon retraction.  Avulsion injuries occur when the hamstring muscle tendon completely tears away from the bone.  Sometimes, the tendon or ligament may even pull off a piece of bone along with it.

Cause of Hamstring tendon avulsions:

Hamstring tendon avulsions are caused by a sudden forceful contraction of the hamstring muscle during strenuous exercise.  A sudden jump, overstretch, or large sudden load to the muscle can increase your risk of hamstring tendon avulsion injury.

Symptoms

Symptoms of hamstring tendon avulsions include extreme pain, weakness, cramps while walking and running, and poor leg control particularly while walking down a slope.  Patients will often report pain in their buttock while sitting on the affect side.

Diagnosis

Hamstring tendon avulsions are rare and are often difficult to differentiate from simple strains.  Diagnosis is made through detailed medical history and physical examination.  During the physical examination, your thigh will be examined for tenderness and bruising as well as to evaluate for pain, swelling, and weakness in the back of your thigh.  You may need X-rays to determine if the avulsion has a piece of bone or an MRI to determine the severity of the hamstring tendon tear. 

Treatment

Initial treatment for hamstring tendon injuries includes RICE protocol to assist in pain and swelling:

• Rest
• Ice
• Compression
• Elevation

Hamstring avulsions are serious injuries that may require surgery.  During the tendon avulsion repair, hamstring muscles are pulled back to its normal attachment.

Endoscopic Hamstring Repair

If there is a partial tear or small amount of retraction, the hamstring tendon tear may be repaired endoscopically using a “minimally-invasive” approached requiring two or three “poke-hole” incisions and repairing the tendon with anchors into the bone and sutures passed through the retracted tendon.  The tendon is then brought down to the bone at its anatomical location.

Open Hamstring Repair

If there is a large avulsion with retraction of the hamstring tendon, an open approach is used.  This incision is made in the buttock crease for cosmetic purposes and is several centimeters in diameter.  The hamstring tendon avulsion is identified and a repair is performed by placing anchors into the bone and passing sutures through the retracted tendon.  The tendon is then brought down to the bone at its anatomical location.

Postoperative Rehabilitation

Postoperatively, the patient is placed in a brace to protect the underlying hamstring tendon repair by keeping your hamstring muscle in a relaxed position.  Physical therapy will begin after the tendon is healed to the bone and involves gentle stretching exercises in order to restore normal function.  The rehabilitation period may last at least 3 to 6 months before returning to athletic activity.