Inconstant high bifurcation of tibial nerve found in posterior ankle arthroscopy

A case report

Abstract

Endoscopy for the posterior region of the ankle is becoming more widespread for the treatment of a large number of conditions which used to be treated with open surgery years ago including posterior impingement syndromes, like sintomatic Os trigonum and posterior prominent talar process. This case report describes the finding of a duplicated nerve during a posterior arthroscopic procedure for the treatment of a sintomatic Os Trigonum. A 32-year-old male professional soccer player was evaluated due to pain in the posterior area of his left ankle. He started with pain in the posterior area of the ankle when he kicked the ball. He presented a negative Tinel´s sign and numbless in his foot and ankle. The MRI showed two compatible nerve structures of the posterior tibial nerve considering most of all the usual diameter of the mentioned. During posterior arthroscopy exploration of the medial side and after removing the Os trigonum we could recognize two anatomical structures compatible with two nerves. An important variation of the terminal branches of the tibial nerve is observed, both in the level of their bifurcation and in the number and origins of the medial and lower calcaneal branches, with some differences in their prevalence. Based on the arthroscopic image, it´s difficult to conclude whether the nerve was indeed a high bifurcation of the tibial nerve or a calcaneal branch. In relation to this and due to the size of the nerve found added to the high percentage of high bifurcation we determine that in fact is a “second” tibial nerve. Adequate knowledge of the anatomy of the joint to be treated should cover not only the most common anatomic configurations (extra-articular and intra-articular) in statistical terms but also the possible anatomic variations to avoid confusion and serious technical errors.