Kyle Peters, MS4
The Article: Bianchi, S. , Martinoli, C. , Abdelwahab, I. F., Derchi, L. E. and Damiani, S. (1998), Sonographic evaluation of tears of the gastrocnemius medial head ("tennis leg"). Journal of Ultrasound in Medicine, 17: 157-162. doi:10.7863/jum.1998.17.3.157
The Idea: Tennis leg is rupture of the medial head of the gastrocnemius muscle, and it is a fairly common lesion that most often affects middle aged people. It is important to have an imaging modality in order to rule out other disease processes and assess the severity of tears. Radiographs and CT scans are clearly not useful in the setting of acute muscle traumas, and MRI is both costly and somewhat limited in availability, so this study looked at ultrasound. Ultrasonography is low cost, non-invasive, and well tolerated, and this study assessed the usefulness of using ultrasound to assess suspected tennis leg.
The Study:
65 patients clinically suspected to have tennis leg injury were evaluated.
Primary Endpoints: evidence of partial or complete tear
- normal = muscle fibers of the medial head and fibroadipose septa as regularly organized parallel hypoechoic and hyperechoic lines ending in the muscle aponeurosis
- partial tear = localized disruption of the regular arrangement of a portion of the MTJ
- complete tear = involvement of the entire medial head of the gastrocnemius muscle
Secondary Endpoints: evidence of reparative/healing process on followup ultrasound
Results: Of the 65 patients examined, 51 partial and 14 complete tears were diagnosed by ultrasound. Twenty-four patients that had partial tears had small lesions (less than 2 cm), and 41 patients had larger partial lesions or complete tears. Small tears were difficult to detect if examined within a few hours after the trauma. There typically was an absence of a definite hypoechoic or anechoic blood collection, which made it difficult to detect. It was crucial to evaluate the distal portion of the medial head, which showed that the muscle fibers and septa did not reach the aponeurosis. Larger lesions and complete tears showed a hematoma appearing as a fusiform heterogeneous area between the disrupted medial head and the aponeurosis of the soleus. In terms of the reparative process, follow-up examination showed a hypoechoic area starting from the periphery of the hematoma and gradually working its way towards the center, causing the amount of central fluid to decrease in size. Compression through the probe demonstrated partial collapse of only the central anechoic fluid portion. Nine patients were evaluated more than one year after the injury, and ultrasound showed a hyperechoic area interposed between the medial head and the soleus muscle, probably corresponding to fibrous tissue.
The Takeaway: Ultrasound examination of TL was easy to perform, was painless and could be done in 10 to 15 minutes in patients with suspected tennis leg injury, and the findings on ultrasound were quite characteristic. Even though this study did not obtain any confirmatory imaging (MRI) or surgery, sonography showed the extent of the disruption of the medial head of the gastrocnemius as well as the extension of the uninvolved muscle, which maintained its normal organized pattern of hypo- and hyperechoic structures. Ultrasound distinguished between partial and complete tears. Importantly, TL needs to be differentiated from a ruptured Baker cyst, DVT, and even Achilles rupture, and all of these conditions can be diagnosed accurately with ultrasound.