A blow, a tear or a sharp cutting object all cause a similar type of muscle injury.
Muscle tissue has a good healing capability.
Acute care is based on the application of cold, elevated position, compression and rest of the injured part.
After a short immobilization, an early mobilization is gradually started (1-6 days after the injury).
Classification of muscle injuries
Degree I: A few muscle fibres are ruptured, the fascia is intact, muscle strength is preserved; symptoms include pain and muscle spasm.
Degree II: A moderate amount of muscle fibres are ruptured, the fascia is intact, there is intramuscular haematoma, muscle strength is decreased.
Degree III: 25-50% of the muscle is ruptured, the fascia is torn, there is intermuscular haematoma, muscle strength is decreased.
Degree IV: Most or all of the muscle is ruptured, the fascia is torn, there is no function in the muscle.
Diagnosis
Patient history is essential. In combination with clinical examination, it is usually sufficient to establish a diagnosis.
The patient history should include a description of the injury mechanism, the start and localization of pain, as well as whether a snap or pop was heard from the injured area at the time of injury.
In clinical examination, swelling and bruising may be seen in the injured area (compare to the unaffected side). In more severe injuries, and sometimes also in milder ones, a hollow may be felt by palpation as a sign of retraction of the ruptured muscle ends.
The function of the injured muscles is tested both without resistance and, subsequently, carefully against external force. The decrease in the muscle strength and function correlates with the severity degree of the injury.
The severity of the injury may sometimes be underestimated in the initial phase because the injured patient may be able to use the extremity almost normally despite the pain and damage.
Muscle cramp poses a differential diagnostic problem particularly when the patient is clinically examined immediately after the injury or the onset of pain in the muscle.
In more severe injuries, ultrasonography may be used in adjunct to clinical examination to assess the degree of the injury (partial/total rupture) and the nature of the haematoma (intramuscular/intermuscular, solid/liquid) in more detail. MRI, however, is the most exact examination and is the easiest to interpret.
Treatment
First aid: application of cold, elevated position, compression and rest of the injured part. NSAID for pain relief for a few days, as necessary.
Further treatment: short immobilisation and then gradual start of mobilisation 1 (degree I) to 6 days (degrees II to III) after the injury. The training is first started without load and then continued with load.
The extremity is supported with an elastic bandage during kinesiotherapy and training.
Stretching, the pain allowing, is first started with passive and then continued with active stretching (after one day in degree I injuries and after 3 to 6 days in degree II to III injuries).
Activities that require strong muscular efforts should not be started before the muscle strength and distensibility are restored to normal (takes about 3 to 6 weeks).
The antagonist muscle should also be trained so as to avoid imbalance between the function of the muscles.
If there is no progress during the rehabilitation, a more severe muscle injury should be suspected.
Only extensive ruptures and intramuscular haematomas that cause strong symptoms may require operative treatment.
Complications
Mobilisation that is too rough and starts too early may cause a rerupture of the muscle because the tissue has not yet reached sufficient tensile strength.
Permanent scar tissue and adhesions that form inside the muscle may lead to decreased elasticity of the entire muscle-tendon unit.
A haematoma may be encapsulated inside the muscle.
Heterotopic bone formation (myositis ossificans) may sometimes be encountered in the injured area. It may be detected both by ultrasonography and by plain x-ray imaging. Symptoms include recurrence of pain and limitation of movement in the injured area.