Plantaris Tendon Insertion Variant

Background: The plantaris muscle is thought to be a vestigial muscle and its tendon lies between the gastrocnemius and soleus muscles. It is most common for the plantaris tendon to insert onto the medial calcaneal tuberosity or onto the calcaneal tendon. The plantaris muscle and tendon insertion are thought to possibly play a role in calcaneal tendinopathy. Although it does not play a significant role in foot plantarflexion, it could possibly play a role in proprioception for the muscles that surround it. Case Information: Dissection of the posterior compartment of the left leg of a - year old embalmed female revealed a rare variation in muscular anatomy. The plantaris tendon inserted into the transverse inter-muscular septum between the tibia and the calcaneal tendon. The literature review revealed that this insertion point occurs approximately 3% of the time. Conclusion: While this variation in insertion is documented, it is the least common of the 5 types of plantaris tendon insertions. This case report attempts to further the understanding of the variance of plantaris tendon insertion points and how they can impact diagnosis and treatment of calcaneal tendinopathy.