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Sprains and Strains

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Sprains and strains facts

  • A sprain is abnormal stretching or tearing of a ligament that supports a joint.
  • A strain is abnormal stretching or tearing of a muscle or tendon.
  • Sprains and strains may be caused by repetitive activities or by a single injury.
  • The diagnosis of a sprain or strain usually can be made after the health-care professional takes a history of the injury and performs a physical examination. Depending upon the situation, X-rays, a CT scan, or an MRI may be needed to help make or confirm the diagnosis.
  • RICE (rest, ice, compression, and elevation) are the keys to initial treatment.
  • Most sprains and strains resolve with time, but occasionally other treatments, including physical therapy and surgery, may be required.
  • Anti-inflammatory medications may be helpful in decreasing the pain and inflammation of the injury.

What is the difference between a sprain and a strain?

A sprain is an injury to a ligament, while a strain is an injury to muscle or tendon tissue.

How muscles work

The purpose of muscles is to allow the body to move. A muscle attaches to bone on each side of a joint, either directly or by way of a tendon. When the muscle contracts, the joint moves through its range of motion. The muscle that you can feel moving underneath your skin is really made up of many smaller bundles of muscle fibers called fascicles. These, in turn, are made up of individual muscle fibers that are crosslinked to allow them to slide back and forth within the fascicle. Sliding together causes the muscle fibers to shorten and the muscle to contract and move the joint. When the muscle relaxes, the muscle fibers return to their resting position and as the fibers elongate, the joint may return to its previous position.

The transition of muscle to tendon happens gradually as muscle fibers give way to tendon fibers before the bony attachment occurs. The anatomy of each tendon is different and depending upon their location in the body, the tendon portion may be very short or very long. A strain is damage caused by an overstretched muscle or tendon, causing their fibers to be pulled apart, losing the ability to adequately contract. The severity of injury depends upon the amount of tissue that is damaged. The muscle fiber may be just stretched, partially torn, or completely torn apart.

The most common cause of a muscle or tendon strain is overuse, which weakens the tissue fibers. Muscles and joints may also be forced to perform movements for which they are not prepared or designed, stretching and potentially damaging the surrounding muscle or tendon. An injury can occur from a single stressful incident, or it may gradually arise after many repetitions of a motion. The damage can occur in three areas: the muscle itself, the muscle tendon intersection where the muscle fibers transition to tendon fibers, or the tendon itself.

Strains are described by the severity of damage in three grades:

  • Grade 1 strain usually causes stretching of a few of the muscle fibers.
  • Grade 2 strain has more significant damage, and some muscle fibers are damaged or torn.
  • Grade 3 strain is a complete rupture of the muscle.

How joints work

Joints are stabilized by thick bands of tissue called ligaments that allow the joint to move only in specific directions. Some joints move in multiple planes. Therefore, they need more than one group of ligaments to hold the joint in proper alignment. The ligaments are anchored to bone on each side of the joint. If a ligament is stretched or torn, the injury is called a sprain.

The grading system for sprain injury is similar to that of strains.

  • Grade 1 sprains occur when fibers of the ligament are stretched but not torn.
  • Grade 2 sprains are injuries where the ligament is partially torn.
  • Grade 3 sprains occur when the ligament is completely torn or ruptured.


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