A muscle contusion (a.k.a. muscle bruising or bruise) is a form of muscle injury usually due to direct impact and associated with intramuscular hemorrhage.
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Epidemiology
Muscle contusions are common injuries and are more frequently seen in males 1,2. In athletes, muscle contusions are the most frequent injury next to strains 1. They are also common in non-athletes and if not severe they will probably often not even be seen by a doctor.
Risk factors
Any form of behavior potentially leading to a fall to the ground, collision, fight or any other blunt injury can be considered as a risk factor for a muscle contusion.
Additionally, muscle contusions happen with increased frequency in the following sports and activities 1,2:
- football (soccer)
- rugby / American football
- ice hockey
- martial arts
- skating or similar activities
Additional factors that increase the likelihood of developing a muscle contusion include:
- insufficient or no protective equipment
- a relaxed state of the muscle during impact
Clinical presentation
History will usually be positive for a definitive mechanism for the contusion or impact like a blow, fall or collision.
Typical symptoms:
- skin discolouration
- swelling
- tenderness
- localized pain
- limited range of motion
If the lower extremity is involved there might be difficulties in weight-bearing.
Muscle contusions can be graded clinically based on pain, and associated functional limitations 1-3.
Complications
If very severe muscle contusions can lead to the following 1-3:
- myositis ossificans
- compartment syndrome (rare)
- rhabdomyolysis (rare)
Pathology
A muscle contusion is characterized by damage and/or rupture of muscle fibers confined to the location at and immediately adjacent to the area of impact or compression and is often associated with hemorrhage and hematoma formation 1-3. The injury can result from the direct impact or the compression of the muscle between the object and underlying bone 2,3.
Etiology
The typical cause of a muscle contusion is a direct impact to the muscle by a blunt object, collision or fall.
Location
Muscle contusions often affect larger muscles. In athletes, the anterior and posterior thigh, as well as the anterolateral upper arm, are often affected. Within the thigh, the quadriceps muscle and the vastus intermedius muscle are commonly affected muscles. In non-athletes, the distribution of muscle contusions can be quite diverse 3.
Radiographic features
The diagnosis of muscle contusions can be usually made clinically with a thorough history and physical examination and diagnostic imaging is rarely needed 1. However, imaging and in particular ultrasound and MRI can provide information regarding the extent and can help in the differentiation to other forms of muscle injury, if the history is not quite clear, or in the work-up of alternative differential diagnosis 1.
Plain radiograph
Plain radiographs might show soft tissue swelling and can show bony involvement if a fracture is suspected or in case of heterotopic ossification.
Ultrasound
Ultrasound might show ill-defined hyperechoic or hypoechoic lesions with or without fibrillar discontinuity and might show associated muscle hematoma. Also, ultrasound can be used for imaging-guided needle aspiration 1,2.
CT
CT can detect and depict large intramuscular hemorrhage with or without active bleeding or muscular enlargement and can reveal fractures or help in the workup of vascular injuries in the context of more severe muscular contusions.
MRI
Typical features of muscle contusions include fluid signal intensity tracking and surrounding the muscle fibers and/or discontinuities of the respective muscle components often associated with intramuscular hematoma. A muscle contusion will display a similar picture to a muscle strain except that the contusion will be not confined to the myotendinous or myofascial units, but rather the location and adjacent area of impact and might cross the fascial planes. It is more commonly associated with intramuscular hematoma.
Radiology report
The radiological report should include a description of the following:
- the extent of muscle contusion
- affected muscles
- associated hematoma
- associated injuries – especially vascular injuries
- signs of complications e.g. compartment syndrome/necrosis
Treatment and prognosis
Muscle contusions are managed conservatively similar to other types of muscle injury with rest, cryotherapy, compression and limb elevation (RICE) as well as non-steroidal anti-inflammatory drugs (NSAIDs) to decrease pain for a short period (usually 24 hours) 1,2. Compression is important to limit hematoma formation. In case of a quadriceps muscle contusion, the injured leg should be placed in a flexed position 1,2. Immediately thereafter, patients can gradually commence movement, stretching, strengthening and range of motion exercises. Function rehabilitation can begin once the range of motion is pain-free 1.
Recovery is usually fast compared to other muscular injuries but can take up to 2-3 weeks in more severe contusions. If pain aggravates after 2-3 weeks and soft tissue swelling continues to be present myositis ossificans should be suspected 1,2.
To return to sports or activity patients should be pain-free and range of motion should be able to perform the desired activities without limitations 1,2.
Differential diagnosis
Conditions that can mimic the presentation and/or the appearance of muscle contusions include:
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