Laboratory Studies
In most cases of contusions, extensive workup is unnecessary and unwarranted. An adequate history and physical examination usually provide enough information for diagnosis and treatment.
In the event that massive bleeding occurs or if the patient has a bleeding disorder, coagulation studies and a complete blood cell (CBC) count may be beneficial to track the sequelae of the disease.
If the patient has extensive bruising and rhabdomyolysis is a consideration, a serum creatine kinase level, serum myoglobin level, and urinalysis may be warranted.
Imaging Studies
Imaging studies in patients with contusions may be helpful to rule out other significant disease processes.
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Radiographs
If the initial history and physical examination merit further evaluation, radiographs of the traumatized region may help rule out a fracture.
If treatment fails or symptoms worsen, roentgenogram evaluation helps rule out a missed fracture or the development of myositis ossificans. If myositis ossificans is considered, it may show up radiographically approximately 6 weeks after the injury, although the process actually begins very early after the initial injury. If imaging studies are obtained before this time period, this disease process may not have matured and may not show up on radiographic examination. See the image below.
Lateral view of the neck showing calcification in the paraspinal muscles. Image contributed by Ajay K. Singh, MD, William Beaumont Hospital, Royal Oak, Mich.
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MRI is rapidly becoming the imaging modality of choice for soft-tissue injuries. However, use of this imaging tool tends to be limited to the professional athlete, to those patients in whom the diagnosis is in doubt, and in those whose symptoms are not responding to therapy.
In an MRI study, contusions evidenced a diffuse focus of increased signal intensity within the injured muscle with T2-weighted and short-tau inversion recovery (STIR) sequences. A focus of abnormality is noted within the muscle belly (hematoma and edema), with generally minimal disruption of the muscle architecture. The contusion tends to demonstrate a variable signal intensity, presumably reflecting the differences in age and microscopic environment of the collection, although it can appear heterogeneously or homogeneously bright.
Muscle strain appears as diffuse or patchy bright signals on T2-weighted images, with preservation of the muscle architecture. These high-signal regions represent a combination of edema and hemorrhage.
Complete muscle tear is a clinical diagnosis. Partial muscle tears range from slight tears to almost complete tears. MRI imaging of a muscle tear reveals a strain pattern, with an area of intense focus or brightness where the muscle architecture has been altered.
Other Tests
Physicians must maintain a high index of suspicion for compartment syndrome, a limb-threatening and life-threatening condition that is seen when tissue pressure in a closed anatomic space exceeds perfusion pressure. Contused tissue within a confined compartment can rapidly reach elevated or critical pressure levels. Clinicians should have a low threshold for testing compartments for increased pressure if compartment syndrome is suspected. See the images below.
Picture of compartment pressure measuring device for use when commercial devices are unavailable.
Stryker STIC Monitor. Image courtesy of Stryker Corporation, used with permission.
An illustration that depicts measurement of compartment pressures in the forearm.
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Athlete with a quadriceps strain. Place knee passively in 120º of flexion and immobilize with a double elastic wrap in a figure-8 fashion. This should occur within minutes of the injury. Used with permission courtesy of John Aronen, MD.
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Modified treatment of quadriceps contusion. Used with permission courtesy of John Aronen, MD.
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Rotator cuff injury.
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In this patient's shoulder radiography, the humeral head no longer matches up with the glenoid because the rotator cuff is torn and the strong deltoid muscle is pulling the head superiorly toward the acromion. Courtesy of Dr Thomas Murray, Orthopaedic Associates of Portland.
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Lateral view of the neck showing calcification in the paraspinal muscles. Image contributed by Ajay K. Singh, MD, William Beaumont Hospital, Royal Oak, Mich.
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A 6-year-old girl who presents a few days after being disciplined on the buttocks with a wooden spoon by her mother. This pattern of bruises is of suspicious shape, number, and location.
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Picture of compartment pressure measuring device for use when commercial devices are unavailable.
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Stryker STIC Monitor. Image courtesy of Stryker Corporation, used with permission.
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An illustration that depicts measurement of compartment pressures in the forearm.
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Anteroposterior radiograph of the right hip in a 16-year-old boy who had suffered trauma to the hip 2 years previously (same patient in Images 10-11). The patient is currently experiencing hip pain. Mature heterotopic ossification (arrowheads) projects over and lateral to the femoral head.
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Corresponding lateral view of the right hip (same patient in Images 10-11). Distal to the mature heterotopic ossification (HO) seen on the anteroposterior view (arrowheads) is a subtle area of early mineralization (arrows) consistent with early HO.
