Introduction

Hamstring is the common name for the big group of muscles and tendons in the back of your thigh. These powerful muscles are often injured, especially by athletes. Though hamstring injuries can be very painful, they will usually heal on their own. But for the hamstring to return to full function, these injuries need special attention and a specially designed rehabilitation program.

Anatomy

The hamstrings are a group of three muscles that run from the pelvis to the knee. They form the back of the thigh. Their function is to pull the leg backward and propel the body forward while walking or running. This is called hip extension. The hamstrings also bend the knees, called knee flexion.

Most hamstring injuries occur in the area where the muscles and tendons connect (musculotendinous complex). The hamstring has an extensive musculotendinous complex. 
 

When injured, the fibers of the hamstring muscles are actually torn. The body responds to the damage by producing enzymes and other body chemicals at the site of the injury. These chemicals produce swelling and pain.

In a severe injury, the small blood vessels in the muscle can be torn as well. This results in bleeding into the muscle tissue. Until these small blood vessels can repair themselves, less blood can flow to the area. With reduced blood flow, the muscles cannot begin to heal.

The chemicals produced and the blood clotting are your body's way of healing itself. Your body heals the muscle by rebuilding the muscle tissue and by forming scar tissue.

In rare cases, an injury can cause the muscle and tendons to tear away from the bone. This happens most often where the hamstrings attach to the pelvis just under the buttock. These tears, called avulsions, sometimes require surgery.

Causes

Hamstring injuries happen when the muscles are stretched too far. Sprinting and other fast or twisting motions with the legs are the major cause of hamstring injuries. Hamstring injuries most often occur in running, jumping, and kicking sports. Water skiing, dancing, weight lifting, and ice-skating also cause frequent hamstring injuries. These sports are more likely to cause avulsions.

The major factors in hamstring injuries are low levels of fitness and poor flexibility. Children very seldom suffer hamstring injuries, probably because they are so flexible. Muscle fatigue and not warming up properly can contribute to hamstring injuries.

Imbalances in the strength of different leg muscles can lead to hamstring injuries. The hamstring muscles of one leg may be much stronger than the other leg, or the quadriceps muscles on the front of the thigh may overpower the hamstrings.

Symptoms

Hamstring injuries usually occur during heavy exercise. In especially bad cases, the person will suddenly become lame, or even fall to the ground. They may also hear a popping sound. The person may be able to walk with only mild pain even in a severe injury. But taking part in strenuous exercise will be impossible, and the pain will continue.

In less severe cases, a tight feeling or a pulling in their hamstring may be felt. This type of hamstring injury often turns into a long-lasting problem. The hamstring may be pulled or torn.

In the rare case of a complete tear, the pain is excruciating. The torn tissues may form a hard bunch in the back of the thigh when the leg is bent. The skin may also bruise, turning purple due to bleeding under the skin.

Diagnosis

The doctor will take a detailed medical history that includes questions about your exercise schedule, activities, and the way you warm up. The doctor will also ask for a description of your symptoms.

The doctor will examine the back of your thigh. The physical exam will involve flexing and extending your leg. The probing and the movement may hurt, but it is important to identify exactly where and when there is pain.

Radiological Tests

Your doctor may want to schedule imaging tests. X-rays usually don't show hamstring injuries, but they may rule out other problems such as a bone injury. Magnetic resonance imaging (MRI) can be useful in showing the details of muscle injuries. These tests may not be required to diagnose your condition.

Doctors group hamstring injuries into three categories:

• Grade One - mild. Grade one injuries are muscle pulls that do not result in much damage to the structure of the tissues.

• Grade Two - moderate. Grade two injuries are partial tears.

• Grade Three - severe. Grade three injuries are complete tears. 

Grade one injuries are muscle pulls that do not result in much damage to the structure of the tissues. Grade two injuries are partial tears. Grade three injuries are complete tears.  

Treatment

It is very important to treat and rehabilitate a hamstring injury correctly. Incomplete or improper healing makes re-injury much more likely.

For the first three to five days after the injury, the main goal of treatment is to control the swelling, pain, and bleeding. Hamstring injuries are initially treated using the RICE method. RICE stands for rest, ice, compression, and elevation.

Rest

The doctor may recommend a short period of immobilization (up to one week). Severe tears may require a longer period of rest. You may be required to spend most of your time lying down and use crutches to get around. If too much weight is put on your hamstring after an injury, more damage may occur and more scar tissue may form.

Ice

Ice applied to the injured hamstring controls swelling and pain but doesn't stop it completely. This is important because the body's inflammatory response actually helps muscles heal. Cold treatments slow the metabolism and blood flow in the area. Cold also reduces sensations of pain by numbing the nerves. Experiencing less pain helps you relax, reducing muscle spasms.

Cold gel packs, chemical mixtures, or cold sprays can also be used. A plastic bag full of ice cubes or crushed ice, held on with an elastic bandage, is the most effective type of cold treatment. The ice should be kept on the injury for twenty to thirty minutes. Cold treatments should be repeated at least four times a day for the first two to three days. They can be done as often as every two hours if needed.

Compression

Compression can help reduce the bleeding in the muscle to limit swelling and scarring. To apply compression, the doctor may suggest wrapping the hamstring firmly in an elastic bandage.

Elevation

Elevation can help reduce swelling. The idea behind elevation is to raise the injured body part above the level of the heart. In the case of a hamstring injury, this requires lying down and supporting the leg up on pillows.

Medication

The doctor may also prescribe a short course of nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, to help relieve the swelling and pain. For muscle injuries, pain relief may be the major benefit of NSAIDs.
 
Surgery

Surgery will be required to reconnect the hamstring if there is a complete rupture. An orthopaedic surgeon will perform this surgery and will give advice on post-surgical care.

After surgery, there will be a period of rest, which may involve using crutches. Most likely a physical therapist will work with you to learn exercises for rehabilitation after surgery.

Rehabilitation

A physical therapist or athletic trainer may oversee your rehabilitation program. For minor muscle pulls, four to six weeks may be needed to safely get back to your activities. For more severe muscle tears, rehabilitation for up to three months may be needed, with complete healing occurring by four to six months.

At first, the therapist may use the RICE method. After three days, treatments may include contrast applications where heat and ice are alternated over twenty to thirty minutes. Ultrasound treatments may also be applied to improve blood flow and healing in the injured tissues.

As the hamstring begins to heal, it is critical that you follow an exercise program to regain strength and mobility. Specially designed exercises encourage your body to rebuild muscle instead of scar tissue. The exercises also help prevent reinjury. Rehabilitation can be slow, so it is important to be patient and not push yourself too hard or too fast.

Early in rehabilitation, exercises may be done in a swimming pool or on a stationary bike set to low resistance. These exercises allow the hamstring to go through its range of motion without having to hold up your weight. When you can walk without a limp and feel very little tenderness, you can start a walking program. Eventually you can work up to jogging.

Stretching will be a key feature of a rehabilitation program. You will be shown how to stretch. Plan to continue these stretches even after healing, because a re-injury of the same hamstring muscle is common. Increasing flexibility may help you avoid another hamstring injury in the future. It is important to maintain good flexibility to keep your hamstring muscles healthy.

Strengthening exercises usually begin with isometric exercises. These exercises involve contracting the muscles without moving the leg joints. As the hamstring gets stronger, light weights are used. It is important that you feel no pain during these exercises.

You should maintain your general level of fitness throughout rehabilitation. A therapist can suggest workouts that don't stress the hamstring muscles. 

Most hamstring injuries get better with treatment and rehabilitation. Even world-class athletes with severe hamstring injuries are usually able to return to competition. By keeping the muscle flexible and giving the body time to heal, you should be able to return to the activities you enjoy.