Laboratory Studies
The ruptured medial gastrocnemius can usually be diagnosed clinically. Although laboratory and imaging studies can also be used to evaluate some of the other diagnostic possibilities (see Differentials and Other Problems to Be Considered), they are not necessary.
Laboratory studies are usually not necessary in the workup of gastrocnemius strains. They may, however, aid in the evaluation of a potential DVT, if clinical suspicion is present.
Complete blood cell (CBC) count: If a DVT is present, the platelet count may be abnormal, but in gastrocnemius strains, the CBC count is normal.
Coagulopathy panel: Before initiating treatment for DVT, prothrombin time (PTT), activated partial thromboplastin time (aPTT), protein C, protein S, and D-dimer levels should be measured. Of course, these results all are within the normal reference range in a medial gastrocnemius strain.
Imaging Studies
Radiographs
In the face of a classic history and presentation for a medial gastrocnemius strain, radiographs are usually normal and do not offer additional information for treatment.
X-ray films may be ordered to rule out an avulsion fracture, especially when the patient describes an audible pop or any history of impact or trauma to the calf region. (See also the Medscape Reference article Tibial Tubercle Avulsion.)
Plain films of the leg and tibia/fibula are usually normal, except for the finding of soft-tissue swelling.
MRI
Studies have shown that magnetic resonance imaging (MRI) and ultrasound studies can be useful in the diagnosis and/or follow-up of injuries to the lower leg. MRI is the most sensitive and specific imaging method, and this technique is able to show the area of disrupted soft tissue better than other imaging modalities (eg, computed tomography [CT] scanning, ultrasonography). [10, 11]
Koulouris et al retrospectively reviewed 59 MRIs from patients who had sustained calf muscle injuries. [12] The authors reported that of the 39 isolated strains, gastrocnemius injuries were the most common (48.7%), in which the majority of these (94.7%) involved the medial head, followed by soleus muscle injuries (46.2%), including 2 cases of distal avulsions of the plantaris. In cases in which there were dual injuries, the most common finding (60%) was a combined gastrocnemius and soleus muscle injury. Koulouris et al concluded that dual injuries to the calf region may be more common than has been reported and such injuries may have a prognostic significance. The authors also noted that in the literature, soleus muscle injury is a rarely reported finding with ultrasonography.
In a retrospective review by Dai et al of 58 patients who had a clinical diagnosis of tennis leg, MRI showed that 90.2% of the patients had edema or disruption of the gastrocnemius, 36.1% had edema or disruption of the soleus, and 11.5% had plantaris tendon disruption. Reparative tissue at the distal myotendinous junction of the medial head of the gastrocnemius was noted on follow-up MRI in four patients. [13]
Ultrasonography
In areas where ultrasound experience is good, this modality may also demonstrate the medial gastrocnemius injury and usually costs less than MRI. However, limited MRI protocols, in which a few images of the suspected region of pathology are performed, can have competitive pricing and demonstrate superior images than ultrasonography. However, in emergency department settings, rapid diagnostic ultrasonography can be used to evaluate the structure of the medial gastrocnemius and to rule out some of the diagnostic possibilities, such as DVT (see Differentials and Other Problems to Be Considered). [14]
In a Korean study, 22 patients with clinically suspected ruptures of the medial head of the gastrocnemius under went ultrasound examination of both the affected and unaffected limbs. [15] The authors reported that 7 of the 22 patients were diagnosed with a partial rupture, and the remaining 15 patients were diagnosed with complete ruptures of the head of the gastrocnemius. In addition, the authors noted fluid collection between the head of the gastrocnemius and the soleus muscle in 20 patients, and they reported the thickness of the fluid collection was significantly greater in those patients with complete gastrocnemius medial head ruptures (mean: 9.7 mm) compared with those of the individuals with partial tears (6.8 mm). The authors concluded that ultrasound is a useful imaging modality for the diagnosis and follow-up of patients with ruptures of the medial head of the gastrocnemius.
Other Tests
Other tests are not necessary for the diagnosis of an uncomplicated medial gastrocnemius strain. If the suspicion of DVT persists, then further evaluation with Doppler ultrasonography is indicated.
