Plantaris Tendon / Muscle Rupture

Plantaris Tendon Rupture has become known as “Tennis Leg” although this term is also used for tears to the Gastroc or Soleus and / or any combination of the three muscles.
The Plantaris muscle can become strained or suffer a complete tear.


If you look at the tendon which is blue in the diagram you can see that it stretches from just below the knee to the heel.
In the diagram both the lateral and medial Gastrocnemius muscles have been cut away to show the Plantaris and Soleus muscles below.

True “Tennis Leg” or Plantaris Tendon Rupture tends to occur when a stress is applied to the muscle when the knee is straight.
This can be associated with jumping or pushing off quickly.
Both of these actions are common in tennis and this is why it has become known as “Tennis Leg.”

Plantaris Muscle

The Plantaris muscle is small and thin. In fact it is so small that it is missing in 7-15% of the population.
It is known as a vestigial muscle – this suggests that we have somehow evolved and that we don’t really need the muscle any more.
The same label applies to the Appendix in your intestine.


The muscle belly is small – ranging between 1 to 3 cm wide and from 7 to 13cm long – it is coloured purple in the diagram.
The Plantaris muscle is attached just above the lateral head of the Gastrocnemius Muscle on the lateral supracondylar line of the Femur.

Plantaris Tendon

The Plantaris tendon (blue in the diagram above) runs obliquely across the calf between the Gastroc and Soleus muscles.
It then runs parallel to the Achilles Tendon and attaches to the medial side of the Calcaneum.


The Plantaris muscle and tendon act similarly to the Gastrocs in that they flex the knee and plantarflex the ankle.
However they do this so weakly that their contribution is negligible.
The muscle is well populated by muscle spindles.
These provide feedback to the central nervous system about the length of the muscle – this is known as proprioception.
It may well be that the Plantaris Muscle provides proprioception for the bigger stronger Gastrocs.

Plantaris Tendon Harvesting

Because this tendon is long and easily accessible it is quite often used by surgeons as a donor site for tendon repairs elsewhere in the body.
There is no apparent loss of function by surgically removing the tendon.

Plantaris Tendon Rupture / Torn Calf Muscle Symptoms

There is a sharp stabbing pain at the back of the calf or occasionally knee.
It may be difficult to put the heel down properly.
Victims can describe being struck by an object from behind and often feel a “pop”.
There can be a significantly swollen calf muscle and bruising.

There can be Plantaris muscle rupture co-existing with other muscles tears – especially the Gastroc.
It is not uncommon to find Plantaris muscle rupture with Anterior Cruciate Ligament injuries.

For treatment of a Plantaris muscle rupture see