Tarsal tunnel syndrome is a painful condition of foot due to compression of the posterior tibial nerve in the tarsal tunnel. The flexor retinaculum covers the nerve. It is similar to the carpal tunnel syndrome where the median nerve is compressed. It causes a burning pain in the foot along with pins and needles and pain radiating in the arch of the foot.
Hyperpronation of foot while walking or running can contribute to compression of the nerve. Since hyperpronation is the key contributing factor, it is common for the problem to occur in both feet at the same time.
The term “anterior tarsal tunnel syndrome” is used for a rare entrapment of the deep peroneal nerve at the front of the ankle. This is different to tarsal tunnel syndrome as symptoms appear on the top of the foot and radiate towards the 1st and 2nd toes.
Tarsal tunnel syndrome can be either idiopathic (occurs spontaneously for apparently no reason) or it can be associated with a traumatic injury. Causes include:
- Arthritis at the ankle joint, osteoarthritis – possibly as a result of an old injury
- Talonavicular coalition – fusing of two of the tarsal bones
- ganglion in the tarsal tunnel
- Accessory muscles
- Soft tissue mass
If the condition occurs spontaneously in running based sports athletes then hyperpronation is the most frequent cause.
Differential diagnosis may include:
- Herniated disc- the symptoms mimics a herniated disc but can be easily differentiated. Normally the sensation of pins and needle runs down the complete limb in cases of herniated disc and Straight leg raise worsens the condition while not affect with hyperpronation in neutral leg position. Nerve conduction studies can be done to confirm the diagnosis and indicate the location of the entrapment.
- Stress fracture- stress fractures around the medial malleolus can be ruled out with an x-ray.
- Plantar fasciitis- Sometimes it is initially mistaken for plantar fasciitis which also causes pain from the inside heel and throughout the arch of the foot. Neural symptoms (such as tingling or numbness) as well as the location of tenderness can help to easily distinguish between the conditions.
- Pain on the medial aspect of the foot.
- Pain worsens with dorsiflexion and eversion due to tension on the nerve.
- Parasthesia and numbness of the foot.
- Positive tinnel’s sign behind the medial malleolus.
- EMG usually not helpful.
Rest: In the early phase, the best is to avoid all activities that induce pain.
Ice is a simple and effective modality to reduce pain and swelling. Apply ice for 10-15 minutes every 2 to 4 hours during the initial phase.
Protection: the physiotherapist may normally apply supportive taping or ankle binder to help relieve pain and commence realignment phase. Taping is normally immediately effective in providing pain relief.
Anti-inflammatory medication and creams may help reduce pain and swelling.
Iontophoresis with cortisone ointments can be recommended. Iontophoresis is a treatment that uses electric current to deliver medically active ions through the skin.
Once the initial pain and inflammation subsides the next aim as a physiotherapist should be maintain the mobility and strength around the ankle and foot.
Stretching exercises may include stretching for the calf muscles (gastronomies and soleus) as well as the plantar fascia under the foot. Gentle nerve stretching can be done to prevent double cross syndrome and maintain the nerve mobility and elasticity.
Strengthening exercises of overall complete limb muscles particularly invertors strengthening. Gradually the physiotherapist should put the patient through more challenging activities to Restore Speed, Power, Proprioception and Agility.
Consult a physiotherapist who can assess and correct the biomechanical faults of the foot.
If conservative treatment fails then a corticosteroid injection may be administered.
Surgery is indicated when X-ray or MRI indicates the presence of any other structures such as cysts, ganglia or a tarsal coalition or when the athlete doesn’t responded to the conservative treatment. For stubborn and persistent cases surgery may be required to decompress the nerve. The operation is undertaken to decompress the nerve by freeing the soft tissue structures in the area, creating more space for the nerve.