Ultrasound of Tennis Leg

In this radiology lecture, we review the ultrasound appearance of tennis leg, including medial gastrocnemius and plantaris injury!

Key teaching points include:

Tennis leg = Injury to muscles of the calf. Tear of myotendinous junction of medial head of gastrocnemius, rupture of plantaris tendon (less common), in isolation or together
Classically described in tennis players, but can occur in various athletic activities (running, skiing) with extension of knee and forced dorsiflexion of ankle. Typically seen in middle-aged, active individuals
Clinical: Sudden sharp calf pain with associated popping/snapping sensation followed by tenderness and swelling
Gastrocnemius & soleus are pennate muscles. Fascicles attach obliquely to a tendon = Aponeuroses with long length of musculotendinous junction. Feathers converging on a single point
Triceps surae muscle = Two headed gastrocnemius, soleus and plantaris. Distal continuation of the gastrocnemius and soleus forms the Achilles tendon
Distal medial head of gastrocnemius where tapers over soleus = One of most commonly injured calf structures
Medial gastrocnemius tear appears as disrupted tendon fibers at aponeurosis with anechoic/hypoechoic fluid or hemorrhage +/- muscle retraction
May see retracted muscle fascicles. Hematoma can dissect between and extends into medial gastrocnemius and soleus muscles
Tx: Conservative (self-limiting). Surgical fasciotomy if compartment syndrome
Plantaris muscle arises from the posterosuperior aspect of lateral femoral condyle near lateral head origin of gastrocnemius muscle. Medially crosses posterior knee joint in oblique fashion
Plantaris continues into calf as a long, thin tendon traveling between medial head of gastrocnemius and soleus muscles. Courses distally at medial aspect of Achilles tendon, usually inserts onto calcaneus. Plantaris is absent in up to 20%
Plantaris injury/rupture less common than medial head gastrocnemius tear and typically more proximal in calf (at myotendinous junction)