Pulled Hamstring (Hamstring Injury)

Strains are initially treated with rest, ice, compression, and elevation (known as RICE). A pulled hamstring is also treated this way.

The hamstrings are a collection of three muscles located in the back of the thigh that are responsible for bending, or flexing, the knee. These are the semitendinosus, the semimembranosus, and the biceps femoris muscles that begin as a tendon that inserts in the ischium, one of the pelvic bones, and run the length of the femur (the thighbone), crossing the back of the knee to attach to the tibia and fibula. A small portion of the hamstring muscle also spans across the hip joint and is involved in hip extension. The hamstring muscle fibers gradually become tendon fibers near the knee to attach to the bone. The thick tendon bands can be noticed when feeling behind the knee joint.

The hamstring muscle is balanced by the quadriceps muscles on the front of the thigh which causes the knee to extend. Together the hamstrings and the quadriceps help control the power and stability of the knee joint, allowing activities like walking, running, jumping, and squatting.

A pulled hamstring is a strain of one or more of the hamstring muscles. Muscle fibers of the hamstring can become strained or torn during running, kicking, or even walking down steps. When a hamstring muscle is pulled, the muscle fibers are abruptly stretched. Depending on the severity of the strain injury, the muscle can actually tear and many people can hear and feel an audible "pop" when the muscle is damaged.

The hamstring pull may occur anywhere along the muscle tendon, however it most commonly occurs in the middle of the hamstring muscle.

As people age, the tendon can be injured when it inserts into the ischial tuberosity in the pelvis and cause groin or hip symptoms. On occasion, the tendon injury can pull a small part of bone away from the pelvic bone where the tendon inserts.

Avulsion injuries often occur with a quick muscle contraction during a burst of speed. This occurs in activities like ice skating, weightlifting, or skiing.

There are a variety of potential risk factors for hamstring injuries:

• Inadequate warming up and poor stretching
• Muscle weakness or an imbalance in the muscle strength within the hamstring muscles
• Muscle weakness or an imbalance between the hamstrings and quadriceps
• Poor footwear
• Recurrent injury when the muscle hasn't completely healed from the previous damage

The symptoms of a pulled hamstring depend upon the severity of the injury. Strains are described by how much damage occurs to the muscle and tendon fibers.

• Grade 1 strain describes fibers that are stretched but not torn.
• Grade 2 strain occurs if there is a partial tear of some of the muscle or tendon fibers.
• Grade 3 strain describes the rare situation where there is a complete tear or rupture of the muscle or tendon.

Muscle strains may occur over time as a result of overuse injury, or they may occur acutely with an abrupt specific injury. Moreover, there can be a worsening in the severity of a hamstring pull if strenuous activity is attempted before the muscle has fully healed.

Muscle or tendon strains cause inflammation surrounding the injury site and symptoms include tenderness, pain, and swelling. Muscle spasms may also occur. Since muscles have an excellent blood supply, a hamstring injury may cause bruising at the site of injury. After the injury, blood can ooze downward, pulled by gravity by gravity, so that bruising may be noted in the back of the knee or in the calf.

• Grade 1: A grade 1 strain of the hamstring may be felt as a slight pull or ache in the back of the thigh. The exact injury may not be remembered or recognized, and the onset of the pain may be gradual. There may be minimal swelling and nonspecific pain when the knee is extended. A limp may or may not be present, but the pain is usually worsened with aggressive activity like running or walking up or downstairs.
• Grade 2: Grade 2 strains often occur with an acute event, and an immediate sharp pain is felt in the back of the thigh or higher up toward the buttock. Walking may be difficult because extending the knee stretches the injured muscle, and a limp is often present. Swelling and tenderness can be appreciated in the area of injury.
• Grade 3: Symptoms of a grade 3 strain are a progression of a grade 2 strain with symptoms of pain and swelling being more pronounced. Many times in athletic injuries, the muscle can be so aggressively stretched that it tears with a popping sound so loud that it can be heard by other players on the field. If there is a significant tear, a divot can sometimes be felt in the belly of the muscle at the site of injury.

A pulled hamstring is diagnosed by history and physical examination. The circumstances of the injury will give a clue as to the type of injury, while the physical examination will be used to grade the amount of damage to the muscle or tendon.

The healthcare professional may ask a question about the circumstances of the injury to analyze the mechanism of injury and review what home treatments were attempted. A past medical history may also be important since previous injury or arthritis of the back, hip, or knee can decrease the range of motion and flexibility of the muscles, causing the hamstring to become more prone to injury.

Physical examination often consists of touching (palpation) the muscle to assess swelling and tenderness. Grade 2 or 3 tears may have a defect or divot that can be felt along the course of the muscle, confirming the diagnosis. A range of motion of the back, hip, and knee may be tested with and without resistance, trying to unmask pain that is not necessarily appreciated by palpation.

Often the doctor will lay the patient prone (flat on their stomach) and bend the knee to 90 degrees. This relaxes the hamstring muscles and may minimize muscle spasms. The hamstring muscles can then be felt and a potential defect appreciated.

Other potential sources of pain may be considered, and the physical examination will help to differentiate a pulled hamstring from bone or joint pain. Sciatica, a pain that originates in the nerves as they leave the spinal canal in the low back, can also mimic hamstring injury.

Most patients do not need further testing. If there is concern that the pain is due to an avulsion fracture or another injury to the pelvis, femur, or knee, X-rays may be suggested. Magnetic resonance imaging (MRI) is able to evaluate the extent of muscle and tendon injury but is not necessary for most patients. In elite athletes, MRI scanning can be used to help plan rehabilitation, time to recovery, and return to competition.

Strains are initially treated with rest, ice, compression, and elevation (known as RICE). A pulled hamstring is also treated this way. Alternating ice and heat may also be recommended.

• Rest: Since the hamstring is stretched with each step as the knee extends or straightens, walking may be difficult. It may be necessary to rest and even avoid weight-bearing activities for a period of time. Crutches may be used temporarily to help get around.
• Ice: Icing should be done frequently for 15-20 minutes at a time. The ice is placed on the area of injury and pain. It is important that the skin is protected from direct contact with the ice to prevent frostbite.
• Compression: An Ace wrap may be used for compression. Often one or two 6-inch wraps are applied beginning at the knee and circling the thigh until the wrap ends at the hip and groin. The compression should feel firm but not too tight to cause pain. Athletes are often taped to provide the same compression and support to allow them to return to practice and competition more quickly.
• Elevation: Elevating the leg is helpful to decrease swelling. Fluid caused by inflammation can drain back toward the center of the body if the leg is elevated above the level of the heart.

Medications to reduce inflammation, such as ibuprofen (Advil, Motrin, Nuprin), may be helpful in controlling the pain of inflammation. While these are over-the-counter medications, there may be interactions with prescription medications, or there may be underlying medical conditions that may prohibit the use of anti-inflammatory medications. It is wise to check with a healthcare professional or pharmacist before taking any medications.

Grade 1 or 2 injuries may require no further therapy and over a few weeks, the pulled hamstring should gradually improve and return to normal function. It may take a few weeks to recover from a hamstring strain, but if symptoms persist, physical therapy may be recommended.

In rare cases, surgery may be required to repair grade 3 strains that have damaged significant amounts of muscle and tendon. If a large, bony avulsion fragment is present, it may require reattachment.

The recovery of strains goes through three phases. The first phase decreases the inflammation of the pulled muscle, the second returns normal blood supply, and the third begins remodeling and repair of the muscle to allow it to return to full function.

Anytime a muscle is torn, the body repairs itself by forming scar tissue. It may take four to six weeks for the area to completely heal. Aside from return to activity, it will be important to consider rehabilitation at home or with a therapist to return full range of motion and power to the hamstring muscles. If the hamstrings do not return to full function, they are at risk for recurrent injury and developing chronic pain and weakness.

After RICE treatment lasting five to seven days, physical therapy may be considered to increase range of motion and begin gentle stretching and return to activity of the pulled muscle. Electrical stimulation therapy and muscle ultrasound may be used to increase blood circulation and begin the healing phase. This may take two to three weeks and may be followed by muscle strengthening and further stretching.

Every patient progresses at a different speed, and the transition from one phase to the next will depend upon the severity of the injury and the response to treatment.

One way of estimating how long it will take to recover from a hamstring injury is to know if the patient could walk without pain within a day. If this is not the case, recovery will likely take more than 3 weeks.

While all injuries cannot be prevented, pulled hamstrings are often due to tight muscles and poor flexibility. Routine stretching to promote flexibility should be a daily consideration to minimize muscle injuries. Whether it is a home fitness program, neighborhood yoga classes, or Pilates at the gym, increasing flexibility, balance, and muscle tone will help prevent not only pulled hamstrings but also much other bone, joint, and muscles injuries.

Eccentric (away from the center) muscle-strengthening exercise may be helpful in decreasing the risk of a hamstring pull. Exercises that allow the muscle to strengthen as it is stretched include walking down steps, running slowly downhill, and the downward motion of squatting.

Muscles that are warm and stretched are less inclined to tear. Prior to exercise or manual labor, which can include gardening, shoveling snow, and other household chores, it is important that the leg and back muscles be stretched and flexible to prevent pulled hamstrings. Since the hamstring muscles span the hip and knee, they can be damaged if the back muscles are too tight to allow controlled proper movement.