Muscle Injury

Risk: Skeletal muscle injuries, including contusions, strains, and avulsion, occur most often in work or athletic settings. Athletes are at a particularly high-risk for muscle injuries caused by over stretching, sudden muscle contraction (weight lifting), or rapid changes in speed or direction (sprinting, tennis). Young people in periods of rapid growth or older individuals with osteoporosis or other chronic conditions resulting in loss of bone integrity are most at risk for avulsion injury.

Incidence and Prevalence: Stretch-induced injury or muscle strains represent up to 30% of all injuries seen by clinicians specializing in occupational or sports medicine (DeBernardino).

History: Symptoms of a muscle strain include swelling, constant pain or pain with muscle use, and muscle weakness or loss of muscle function. Muscle contusion symptoms include pain, swelling, and local skin discoloration. A muscle avulsion usually causes severe pain, swelling, and loss of function in the affected limb. An exercise-induced injury may result in swelling, joint stiffness, pain, and usually a decrease or loss of muscle function 1 to 2 days after exercising. Delayed-onset soreness refers to muscle pain, weakness, and a decreased range of motion occurring 1 to 3 days following the performance of a new exercise. Headaches or dizziness (vertigo) may also be present if neck muscles are injured. The individual may report recent trauma experienced during physical activity such as “pulling” of a muscle, a fall, a direct blow, or other impact of some kind; sometimes no source of injury may be recalled.

Physical exam: The exam may reveal swelling, muscle tenderness, ecchymosis, and hard areas in the affected muscle. Specific "trigger points" of pain may be present. A disproportionately high level of pain for the degree of injury may suggest compartment syndrome. Movement may be decreased with the individual guarding the affected muscle. Gait abnormalities may be observed with quadriceps or Achilles injuries. The individual will be examined for the presence of other injuries.

Tests: Plain x-rays, CT, MRI, nerve conduction tests, or electromyography (EMG) may be done to determine the extent of the injury and rule out bone fractures. Ultrasound imaging also has high sensitivity and specificity for evaluating muscle tears. Compartment pressure measurements may be taken if compartment syndrome of a limb is suspected.

The various types of muscle injuries are categorized as strains, bruises (contusions), detached injuries (avulsions), and exercise-induced injury or delayed onset soreness.

Rehabilitation of a muscle injury depends on the type, location, and extent of the injury. For example, muscles can be strained by excessive stretching or forced contracture. They can also be torn and need surgical repair. Each muscle performs a different function and responds differently to injury as well as treatment. Consequently, the degree of the strain will determine the rate of rehabilitation.

Muscle injuries often result in the formation of a hematoma. The immediate goal of the rehabilitation of all muscle injuries is to decrease pain and swelling. The best way is to follow the PRICE principle (protection, rest, ice, compression, elevation) (Braddom). Physical activities should be terminated immediately after the injury to avoid further damage. Application of a compression bandage and ice can reduce the formation of a hematoma. Elevation of the injured extremity decreases blood flow to the injury site and increases venous return, thus further limiting the size of the hematoma. The immobilization should be kept as short as possible. It has been shown that short immobilization is beneficial in the early phase of muscle regeneration and prolonged immobilization results in the atrophy of healthy fibers around the injury. Usually 1 to 5 days after injury gentle exercise can be started, depending on the severity of the injury, with the intensity increased as tolerated. Early stretching exercises as tolerated help to minimize the negative effects of scar formation. Modalities such as local heat can be used for pain management once the edema is controlled.

If pain and functional limitations persist, the injury needs to be re-evaluated. Besides clinical evaluation, sonography or an MRI may help to detect the extent of the injury (Noonan). Depending on the severity of the muscle injury a surgical intervention might be necessary.

Additional information may provide insight into the rehabilitation needs of these individuals (Kirkendall).