Teaching Case

The patient presented to the outpatient department complaining of a sudden pain in the posterior aspect of the right calf he had felt three days before during a sprint while playing football. He mentioned a “snapping” sensation inside his calf. The pain persisted and this prompted him to visit the hospital.

The patient was referred for calf ultrasound, which revealed the presence of a flattened fluid collection situated between the medial head of gastrocnemius and soleus muscle. The collection’s dimensions were 90x7.8x69 mm. The whole length of the collection was visualized using the extended field-of-view (EFOV) technique. (Fig. 1a, b, c) While examining the nearby veins with colour Doppler technique, thrombosis of a venous branch was identified. (Fig. 1d) The patient received conservative treatment.
Follow-up of the patient one week later revealed an increase of the collection, which now measured 10.1x97.3 mm. A small layer of reparative tissue appeared at the periphery of the collection. (Fig. 2a, b, c) The venous thrombosis persisted. (Fig. 2d, e)
Five weeks later, the patient underwent follow-up ultrasound, which demonstrated almost complete healing of the injury. There was evidence of a layer of hypoechoic reparative tissue between the medial head of the gastrocnemius and soleus muscle. (Fig. 3a, b) Colour Doppler technique showed normal flow within the previously thrombosed vein. (Fig. 3c, d)

The term “tennis leg” (TL) refers to the plantaris tendon rupture or more commonly the distal part of the medial head of the gastrocnemius muscle (MHG) at the point of the myotendinous junction. [1, 2] TL affects middle-aged people who suffer from acute pain in the middle part of the calf during sport activities associated with a snapping sensation. The pain worsens with ankle dorsiflexion and knee extension. [1, 2] The mechanism causing TL is considered to combine both active contraction and passive stretching of the gastrocnemius during movements involving plantar flexion of the foot and extension of the knee. [2]
Ultrasound represents the primary modality to initially evaluate and follow-up patients with calf pain. Normal anatomy demonstrates the tapering of the MHG to the soleus muscle (SM), forming the Achilles tendon. The plantaris tendon can be seen between these two muscles. Rupture of the MHG appears on ultrasound as disruption, discontinuity and indistinctness of the parallel hyper- and hypoechoic linear echostructure of the fibroadipose septa, muscle bundles and tendon at the myotendinous junction. [2, 3] A gap may be evident between the torn ends. [3] Axial images are useful to characterize MHG ruptures as partial or complete. [2, 4] Sagittal images demonstrate the proximal retraction of muscle bundles. [4] A fluid collection of heterogeneous mixed echogenicity and sometimes fusiform shape representing haematoma between MHG and SM is found in 90% of patients with TL. The fluid collection is more common and significantly larger in cases of complete rupture. [2, 4, 5] It is reported that the amount of fluid indicates the prognosis and duration of healing. [3] During recovery, the fluid may occasionally expand but is normally gradually absorbed and replaced by reparative tissue. The latter appears hypoechoic and gradually fills the collection in a centripetal pattern, from the periphery to its centre. US may also identify a torn and proximally retracted plantaris tendon. The healing process of TL may last for three to 16 weeks. [2] After complete healing of TL, a hyperechoic area between the MHG and SM representing fibrous tissue is present for years. [4]
TL is usually treated conservatively with lower extremity elevation, supportive elastic dressings, ice and anti-inflammatory medications. [1, 2] Complete recovery and return to painless activity may require several months. Fasciotomy should be performed in cases where compartment syndrome complicates TL. [2, 6] Deep vein thrombosis (DVT) is another possible complication of TL. [7, 8] According to some authors, DVT is seen associated with other conditions in 5% of patients with suspected TL. [9]