TARSAL TUNNEL SYNDROME

Dr.PRASHANTH KUMARJunior resident of orthopaedics

• A compressive neuropathy caused by compression of the tibial nerve

•may be subdivided into anterior  or posterior tarsal tunnel syndrome 

• Tarsal tunnel syndrome is analogous to carpal tunnel syndrome,

• but instead of median nerve entrapment beneath the transverse carpal ligament, the tibial nerve is constricted beneath the flexor retinaculum (laciniate ligament).

• Release of the flexor retinaculum is not as effective in tarsal tunnel syndrome as release of the transverse carpal ligament in carpal tunnel syndrome.

Anatomy

• Posterior tarsal tunnel an anatomic structure defined by – flexor retinaculum (laciniate ligament)– calcaneus (medial)– talus (medial)– abductor hallucis (inferior)

• contents include• tibial nerve• posterior tibial artery• FHL tendon• FDL tendon• tibialis posterior tendon

• Tibial nerve has 3 distal branches – medial plantar– lateral plantar– medial calcaneal– the medial and lateral plantar nerves can be

compressed in their own sheath distal to tarsal tunnel

– bifurcation of nerves occurs proximal to tarsal tunnel in 5% of cases

Mechanism

• types of impingment• intrinsic

– ganglion cyst – tendonopathy– tenosynovitis– lipoma/tumor– peri-neural fibrosis– osteophytes

• Extrinsic• shoes• trauma• anatomic deformity (tarsal coalition, valgus hindfoot)• post-surgical scaring• systemic inflammatory disease• edema of the lower extremity• cause of impingement able to be identified in 80% of

cases

• Prognosis results vary between 50-90% success

• worse results with 'double crush' injuries and post-operative scarring

• revision surgery less successful than index operation

Presentation

• History may have previous trauma or surgery• Symptoms

– pain with prolonged standing or walking– often vague and misleading medial foot pain

– sharp, burning pains in the foot

• numbness – intermittent paresthesias and numbness in the plantar

foot

• Physical exam tenderness of tibial nerve (tinel's sign)• sensory exam equivocal• pes planus• muscle wasting of foot intrinsics

– abductor digiti quinti or abductor hallucis• pain with dorsiflexion and eversion of the ankle• compression test

– plantar flexion and inversion of ankle– digital pressure over tarsal tunnel

• highly senstitive and specific

• Imaging  Radiographs – weight-bearing radiographs provide osseous

structure• MRI

– may be helpful to rule out accessory muscle or soft-tissue tumor

• Studies EMG – positive finding include

• distal motor latencies of 7.0 msec or more• prolonged SENSORY latencies of more than 2.3 msec

– sensory (SAP) more likely to be abnormal than motor• decreased amplitude of motor action potentials of

– abductor hallucis– or abductor digiti minimi

• Diagnosis – history is often most useful diagnostic aid

• It is important to attempt to determine the source of the problem.

• Trauma• Space occupying lesion: ganglion cyst, benign

tumors, swollen tendon, varicose veins• Ankle deformities: pes planus (flat foot)• Peripheral neuropathy: diabetes (if pain follows

"stocking distribution")• .

• Herniated lumbar disk: back pain in L4, L5, S1 regions, leg/thigh pain, "double crush"–one nerve pinch in the lower back, and the second in the tarsal tunnel.

• Complex regional pain syndrome: if regional discoloration, swelling, temperature changes, allodynia, hyperesthesia

• Neurofibromatosis: formation of pigmented, cutaneous neurofibromas can invade tarsal tunnel and create pressure

Red flags

• It is important to rule out nerve compression in the low back area.

• There is a fairly high correlation between nerve compression in the spine region (ex from a disk or spinal stenosis) and tarsal tunnel-type symptoms.

• If this is the case, then local treatments may not be effective if the real problem is at the level of the low back.

Non-operative treatment

• The vast majority of patients with tarsal tunnel syndrome can (and should) be treated nonoperatively.

• The primary approach to treating this condition is to attempt to decrease the repetitive traction injury across the nerve and the other structures in this area of the foot.

• In this regard, treatment is quite similar to that for acquired adult flatfoot deformity and plantar fasciitis.

• In fact, these three conditions (tarsal tunnel, acquired adult flatfoot, and plantar fasciitis) together have been labeled as the terrible triad and it is not uncommon to see them all together in one patient.

• This patient is typically someone with a flattened arch of the foot who is overweight.

• Comfort shoes designed to disperse the force more evenly across the foot can be very helpful.

• A prefabricated orthotic with a supportive arch will help to disperse the force more evenly across the foot may also be helpful.

• Stretching exercises designed to stretch the calf muscle and thereby indirectly decrease the load through this area of the foot may also be helpful.

• Weight loss will often end up being a critically important component of non-operative treatment, as this will serve to decrease the repetitive forces through this area of the foot.

• Activity modification to limit the amount of standing and walking and thereby the amount of repetitive injury to this area is also an important component of nonoperative management.

• .

• Physical therapy to establish exercise program characterized by appropriate fitness and stretching exercises, as well as some localized massage to help desensitize the area and perhaps breakdown scar may be of some benefit.

• Corticosteroid injections may help to decrease the swelling around the nerve in the short and intermediate term.

• However, it is unclear what effect they have in the long term.

• In addition it is possible to injure the nerve during the injection process

•medications –anti-inflammatory medications

–SSRIs have been used

Operative

• surgical release of tarsal tunnel – indications

• after 3-6 months of failed conservative management and

–compressive mass (ganglion cyst) identified–positive EMG–reproducible physical findings

–outcomes

• best results following surgery are in cases where a compressing anatomic structure (ganglion cyst) is identified and removed

• traction neuritis does not respond as well to surgery

TARSAL TUNNEL RELEASE

• Extend the incision from 1 cm plantar to the navicular tuberosity in a proximal direction, bisecting the area between the medial malleolus and the medial aspect of the tuberosity of the calcaneus, ending 1 cm anterior to the Achilles tendon.

• With the foot in gravity equinus, this is almost a straight line .

• Do not undermine the incision.

• Coagulate or tie the superficial veins connecting the plantar and saphenous systems, and deepen the incision through the investing fascia of the calf proximally and the medial side of the foot distally.

• This allows identification of the proximal and distal (posterior and anterior)borders of the flexor retinaculum and the neurovascular bundle before the bundle disappears beneath the retinaculum

• Occasionally, the nerve is enlarged at the upper border of the retinaculum. Release the retinaculum from a proximal to a distal direction until the muscle fibers of the abductor hallucis are reached.

• ■ Sometimes a medial calcaneal branch penetrates the retinaculum,and care must be taken to avoid severing one or more branches of this nerve (medial calcaneal) to avoid a painful neuroma

• The tibial nerve divides beneath the flexor retinaculum into the medial and lateral plantar branches.

• The medial calcaneal branch may arise from the main tibial nerve or its lateral plantar branch .

• An anatomical study by Havel et al. showed the tibial nerve to bifurcate into its medial and lateral components beneath the laciniate ligament in 93% of 68 foot dissections.

• When the medial and lateral plantar nerves reach the medial border of the abductor hallucis, they turn plantarward and lateral deep to this muscle

• Trace each nerve well distal to the inferior edge of the flexor retinaculum until it is certain that no tethering by the fascial origin of the abductor hallucis exists.

• This is made easier by releasing part of the origin of the abductor hallucis.

• ■ If the epineurium appears unequally thickened, it should be incised.

• ■ Remove a section of the flexor retinaculum over the neurovascular bundle .

• Remove the tourniquet and secure hemostasis before closing the wound (skin and subcutaneous tissue only).

• Apply a sterile compression dressing.• ■ Apply a short-leg posterior splint to “rest”

the wound while the incision is in the initial stages of healing (10-14 days).

POSTOPERATIVE CARE

• A bulky compression dressing and a short-leg plaster splint with the foot in mild equinovarus are applied and are worn for 7 to 10 days.

• The sutures are removed, and adhesive strips are applied.

• The foot is brought to a neutral position, and a fiberglass prefabricated short-leg cast-brace is worn for an additional 10 to 14 days while the wound matures

• Ankle edema persisting for many weeks is common if the dissection has been extensive, and complete recovery may require 6 to 12 months.

Risk factors and prevention

• Tarsal tunnel syndrome is known to affect both athletes and individuals that stand a lot.

• Strenuous activities involved in athletic activities put extra strain on the ankle and therefore can lead to the compression of the tibial nerve.

• Activities that especially involve sprinting and jumping have a greater risk of developing TTS.

• This is due to the ankle being put in eversion, inversion, and plantarflexion at high velocities.

• Examples of sports that can lead to TTS include basketball, track, soccer, lacrosse, and volleyball.

• Neuropathy can occur in the lower limb through many modalities, some of which include obesity and inflammation around the joints. By association, this includes risk factors such as RA, compressed shoes, pregnancy, diabetes and thyroid diseases

• Complications • Recurrence

– usually caused by inadequate release– repeat tarsal tunnel release not recommended

ANTERIOR TARSAL TUNNELSYNDROME (DEEP PERONEAL

NERVE ENTRAPMENT)

• The anterior tarsal tunnel syndrome, denoting entrapment of the deep peroneal nerve beneath the inferior extensor retinaculum

Anatomy

• Anterior Tarsal Tunnel – borders

• superficial – inferior extensor retinaculum

• deep – capsule of talonavicular joint

• lateral – lateral malleolus

• medial – medial malleolus

contents of anterior tarsal tunnel

• EDL• EHL• Tibialis anterior• peroneus tertius• Deep peroneal nerve

– within tunnel division of nerve between mixed (lateral) and sensory only (medial) occurs

• dorsalis pedis artery and vein

• Epidemiology incidence – rare

• demographics – adults of all ages and genders

• risk factors – high heel use– compressive show wear– previous fracture

• Pathophysiology site of compression – anterior leg/ankle/foot from 1 cm proximal to

ankle joint proximally to talonavicular joint distally• position of compression

– ankle inversion and plantar flexion (when traumatic)

pathoanatomy

-intrinsic impingement • dorsal osteophytes over tibiotalar or talonavicular

joints• other bony deformity (pes cavus, post-fracture)• ganglion cyst• tumor• tendinitis or hypertrophic muscle belly of EHL, EDL or

TA• peripheral edema

–extrinsic impingement • tight laces or ski boots• high heels (induces plantar flexion)• trauma (including recurrent ankle instability)

• Associated conditions pes cavus• fracture

– navicular nonunion• talonavicular arthritis• systemic conditions causing peripheral edema• Prognosis recalcitrant cases may require

surgery, which may yield 80% good to excellent results

Presentation

• Symptoms – dysesthesia and paresthesias on dorsal foot

• lateral hallux, medial second toe and first web space are most common locations

– vague pain on dorsum of foot

• Physical exam – motor

• weakness or atrophy of EDB– sensory

• decreased two-point discrimination

– provocative tests • Tinel sign over course of DPN with possible radiation to

first web space• exacerbation with plantar flexion and inversion (puts

nerve on stretch)• relief of symptoms with injection of lidocaine (DPN

nerve block)

• Imaging Radiographs – recommended views

• lateral view of foot and ankle– findings

• dorsal osteophytes• sequelae of prior fracture

• CT – to define bony anatomy of canal

• MRI – best for evaluation of mass lesions

Treatment

• Nonoperative – shoe modifications

• indications – first line of treatment

• techniques – well padded tongue on shoe– alternative lacing configurations – full length rocker-sole steel shank– night splint (to prevent natural tendency for ankle to assume

plantar flexion)

–NSAIDs–PT (if ankle instability contributing)–injection

--diuretic if chronic peripheral edema is implicated

Operative

• surgical release of DPN by releasing inferior extensor retinaculum and osteophyte / ganglion resection – indications

• failure of nonoperative treatment• symptoms of RSD are a contraindication to release

– outcomes • 80% satisfactory

ANTERIOR TARSAL TUNNEL RELEASE

• Before surgery, locate the area of compression at the anterior ankle joint or the dorsal talonavicular joint.

• ■ Make a longitudinal incision 5 to 7 cm long over the dorsum of the foot from the talonavicular joint to the first intermetatarsal space.

• ■ Identify the deep peroneal nerve and dorsalis pedis artery.

• .

• Identify the deep peroneal nerve as it courses beneath the extensor hallucis brevis, and release the constricting portion of the inferior extensor retinaculum.

• ■ Mann and Baxter recommend releasing only the portion of the retinaculum that seems to be constricting the nerve.

• ■ Remove any underlying lesion, such as a ganglion cyst or osteophyte

POSTOPERATIVE CARE

• The patient is placed in a cast or removable walking boot and begins weight bearing to tolerance.

• The sutures are removed at 2 weeks, and immobilization is discontinued unless tenderness persists.

• If the patient is an athlete, training can resume 4 to 6 weeks after surgery

• Complications Persistent symptoms following decompression – warn patient that recovery is prolonged