The tarsal tunnel syndrome is one of the nerve constriction nerve compression syndromes. A distinction is made between anterior and posterior tarsal tunnel syndrome. The anterior tarsal tunnel syndrome affects the N. fibularis profundus.
In the posterior tarsal tunnel syndrome, the tibial nerve is compressed in the so-called tarsal tunnel. Both originate from the sciatic nerve (“sciatic nerve”). The posterior tarsal tunnel syndrome occurs more frequently.
The tibial nerve runs along the rear lower leg to the lateral foot up to the sole of the foot. It supplies motor muscles of the calf and foot and is thus responsible, among other things, for the tiptoe walk. It supplies a sensitive part of the calf and the sole of the foot. It can be narrowed in its course behind the inner ankle. This is where the so-called tarsal tunnel is located, which is bounded by bones from the inside and spanned by a band from the outside, the Retinaculum flexorum or Ligamentum laciniatum.
Anterior tarsal tunnel syndrome
The anterior tarsal tunnel syndrome is a nerve constriction syndrome affecting the N. fibularis profundus (sometimes obsolete also called N. peroneus profundus). A synonym is therefore also “fibularis syndrome”. The N. fibularis profundus is a nerve branch of the N. fibularis communis, which in turn is a nerve part (fibularis part) of the N. ischiadicus.
This is divided into 2 nerves above the popliteal fossa: N. fibularis communis and N. tibialis. In addition to the N. fibularis profundus, the fibularis part also gives rise to the N. fibularis superficialis. The two nerve branches separate in the region of the fibula head, more precisely in the M. fibularis longus.
However, the main symptomatic branch of the fibular nerve is the N. fibularis profundus. The cause of anterior tarsal tunnel syndrome is considered to be nerve compression in the area of the ankle joint, since the nerve runs along below a ligament structure, the Retinaculum extensorum inferius (in the literature also called the Ligamentum cruciforme). In addition to the retinaculum, a muscular structure, the M. extensor hallucis brevis, can also lead to nerve compression.
The constriction can be provoked by the frequent wearing of high shoes. Ski boots and mountaineering shoes can also aggravate the symptoms. As with many other nerve constriction syndromes, a frequent reason is the presence of a tendosynovitis, since the affected region swells at the expense of the N. fibularis profundus.
But also after injuries, the presence of a ganglion (=overleg, tumorous tissue changes in joint capsules or tendon sheaths) or diabetes mellitus can increase the risk of anterior tarsal tunnel syndrome enormously. Finally, the state of pregnancy or a chronic circulatory disorder can also compress the N. fibularis profundus. Anterior tarsal tunnel syndrome can be treated conservatively with lymphatic drainage, local infiltration of steroids and local anesthetics, ointments and insoles. If the patient does not respond to conservative treatment, surgery is usually performed.
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