![]() In the acute setting, the muscle appears swollen and may be isoechoic with respect to the unaffected adjacent muscle. On ultrasound, contusions are described by discontinuity of the normal musculature with indistinct hyperechogenicity that may cross fascial boundaries. These changes tend to occur deep in the muscle and are often less symptomatic than strains. Muscle contusions result from direct trauma that causes a series of events that include microscopic rupture and damage to muscle cells, macroscopic defects in the body of the muscle, infiltrative bleeding, and inflammation. Posterior constriction of the Achilles tendon can occur from direct compression often aggravated by ill-fitting shoes. Particular attention should also be paid to the insertion site where pain and anterior constriction of the Achilles tendon from a Haglund’s deformity can result in tendinopathy. The most common location of Achilles tendon injury is the middle to distal portion and is usually attributed to underlying tendinopathy. A complete tear will show fiber disruption with a visual gap between the two edges of the retracted tendon. The clinician should carefully evaluate any muscle atrophy, underlying tendinosis, and the distance between torn edges of the tendon as each factor will play a role in determining management options. A tear is more likely if there are findings of edema/hemorrhage surrounding the site of increased signal intensity. In a partial tear, fluid signal intensity will be seen within the tendon but can be difficult to distinguish from tendinosis. MRI or ultrasound can be used to characterize Achilles tendon pathology and diagnosis Achilles tendon tears that are not obvious on physical exam. The plantaris tendon (present in 90 % of people) runs medial to the Achilles tendon prior to its insertion on the calcaneus and should not be mistaken for an Achilles tendon tear, or in the case of a complete tear, not be mistaken for residual intact fibers of the Achilles. In tendonitis, the tendon volume increases and becomes oval or round in cross section. ![]() A healthy Achilles tendon appears flat or concave anteriorly except for the focal convexities at the proximal and distal tendon where it is joined with the calf muscles and the calcaneus, respectively. Īthletes, particularly runners, have a high incidence of Achilles tendon overuse injuries that range from paratendonitis to complete tears. Contrast is rarely used in evaluation of routine muscle injury but should be included if infection, tumor, or myositis is in the differential. A marker can be used on the patient’s skin to allow the clinician to correlate clinical symptoms with imaging abnormalities. Sagittal and axial images are especially helpful for distinguishing the anterior and posterior aspects of the leg, as the presence of bony structures aid in anatomic reference. It is important to include both short- and long-axis imaging of the leg with a fat- and water-sensitive sequence for each imaging plane. Since T2-weighted images are generally fluid sensitive, they are more sensitive to the accumulation of edema in muscle strain injuries and especially useful in a setting of known trauma. T1-weighted images highlight fatty structures (fat planes, lipomas, and muscle atrophy), mature myositis ossificans, degenerative tendon conditions, and aid in the characterization of hemorrhagic lesions (hematomas, contusions, hemorrhagic tumors, etc.). (From ©Springer)Ī typical MRI protocol uses a combination of T1- and T2-weighted sequences to emphasize the anatomy and any pathologic edema (Fig. A 7-month follow-up MRI showed complete recovery (not shown). Color Doppler imaging was normal (not shown). d On ultrasound, a persistent hypoechogenic area was noted that appeared to have increased in extent (arrow). b Axial and c coronal FS T2-w TSE images reveal areas of hyperintensity with feathery appearance, consistent with a partial tear of the medial head of the gastrocnemius muscle with intramuscular edema (arrow). b–d Follow-up imaging 2 months after initial presentation. Magnetic resonance imaging (MRI) was not performed on this patient at this time. No evidence of hematoma or other abnormality was observed. ![]() a On ultrasound at initial presentation, a hypoechoic area measuring 1.0 × 0.4 cm was noted (arrow), corresponding with a partial tear of the medial head of the gastrocnemius (GM). A 27-year-old football player presenting with left calf pain, clinically diagnosed as grade II injury.
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