Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

Anatomy

• Plantaris muscle arises from the lateral supracondylar ridge of the femur.
• Origin is located above the lateral head of the gastrocnemius muscle.
• The tendon passes between the gastrocnemius and soleus muscles.
• It inserts on the medial side of the calcaneus.
• It lies in the superficial posterior compartment of the leg.

Function

• Assists in plantarflexion of the ankle.
• Assists in flexion of the knee.
• Contains a high density of proprioceptive receptors providing position feedback to the CNS.

Innervation

• Innervated by the tibial nerve.

Clinical Importance

• Often used as a tendon graft in reconstructive procedures.
• Commonly used to augment Achilles tendon repair.

Association with Achilles Tendon Rupture

• Plantaris tendon may rupture together with the Achilles tendon.
• If plantaris remains intact with Achilles rupture, the Thompson test may appear falsely negative.
• Plantarflexion may still occur due to the intact plantaris tendon.

Plantaris Tendon Rupture (Tennis Leg)

• Patients feel sudden sharp pain in the posterior calf.
• Often described as feeling like being struck from behind.
• Associated with swelling and bruising of the calf.
• Commonly called ‘Tennis leg’.

Mechanism of Injury

• Injury usually occurs due to eccentric loading of the ankle with the knee extended.

Management

• Conservative treatment.
• Crutches for ambulation if needed.
• Pain control.