DEFINITION

Morton neuroma was first described in 1845 by Lewis Durlacher, a chiropodist to the Queen of England.

A primary interdigital (Morton) neuroma is in fact not a neuroma, as it does not involve the haphazard proliferation of axons seen in a traumatic nerve injury.

Instead, this condition is best described as an interdigital perineural fibrosis.

Recurrent neuromas are true histopathologic (haphazard proliferation of axons) amputation stump neuromas.

Eighty-five percent to 90% of nontraumatic neuromas are found in the third web space. The rest are found in the second web space.

 

 

ANATOMY

 

The medial plantar nerve supplies sensation to the first to third digits and the medial aspect of the fourth digit. It emerges plantar and medial to the flexor digitorum brevis, coursing obliquely across the plantar surface of the muscle.

 

The lateral plantar nerve supplies sensation to the lateral half of the fourth and the fifth digits.

 

Both are branches of the tibial nerve and terminate with digital branches that course plantarly deep to the transverse metatarsal ligament (FIG 1).

 

The lumbrical tendon appears lateral and superficial to the digital nerve, as it attaches to the medial aspect of the extensor expansion of the digit and may be mistaken for nerve.

 

In a cadaveric study, Levitsky et al5 found that 27% of specimens had a communicating branch connecting the medial and lateral plantar nerves. They also noted that the second and third interspaces were significantly narrower than the first and fourth.

 

Changes in the nerve itself involve perineural fibrosis, demyelinization and degeneration of nerve fibers, endoneural edema, and the absence of inflammatory changes.

 

 

Plantar-directed nerve branches may tether the common digital nerve to the plantar skin. These nerve branches are present up to 4 cm proximal to the transverse metatarsal ligament.

PATHOGENESIS

 

All histologic changes in a primary interdigital neuroma occur distal to the transverse metatarsal ligament, as shown in studies by Lassmann4 and Graham et al.3

 

The cause is unclear but is thought to evolve as an entrapment neuropathy.

 

The second and third intermetatarsal spaces are narrower than the first and fourth.

 

Mobility between the medial three rays and the lateral two rays may contribute to the high number of primary neuromas in the third interspace.

 

In a limited number of patients (about 27%), the common digital nerve to the third interspace consists of branches from the medial and lateral plantar nerves, which perhaps increases the size of the nerve and predisposes it to entrapment (see FIG 1).

 

A “recurrent interdigital neuroma” may be due to several factors, including failure to make the correct diagnosis originally.

 

Neurogenic pain may be due to causes other than perineural fibrosis, such as neuropathy and radiculopathy. Also, neuroma-like symptoms may be due to nerve irritation from local synovitis or bursitis.

 

Beskin and Baxter2 found that in patients with recurrent symptoms of interdigital neuroma, about two-thirds presented within 12 months and one-third had recurrence 1 to 4 years after primary surgery.

 

 

 

 

FIG 1 • Course of medial and lateral plantar nerves. A communicating branch of the lateral plantar nerve

occurs in about 27% of patients.

 

 

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FIG 2 • A. Standing palpation of the web space. B. MTP joint plantarflexion stress test. C. Mulder test: The examiner places the thumb on the dorsal surface and the index finger on the plantar surface in the affected web space and applies gentle pressure. D. With the opposite hand, the examiner applies a gentle squeeze to the forefoot in a mediolateral direction. A clicking sensation that reproduces the patient's pain will often be appreciated.

 

 

Those with “recurrence” within the first 12 months probably represent patients who were originally misdiagnosed.

 

Those presenting after 12 months probably represent patients with a true bulb neuroma at the cut end of the common digital nerve. It probably requires at least this length of time for a neuroma to grow big enough to cause symptoms.

 

Formation of a recurrent neuroma after primary surgery is usually due to inadequate resection.

 

Plantar-directed nerve branches may tether the common digital nerve to the plantar skin and not allow for retraction of the nerve after it is cut. These nerve branches may occur up to 4 cm proximal to the transverse metatarsal ligament.

 

NATURAL HISTORY

 

Interdigital neuromas occur more commonly in females.

 

 

The primary symptom of an interdigital neuroma is pain, most often described as burning, aching, or cramping. The pain often radiates to the toes or proximally along the plantar aspect of the foot.

 

Relief usually occurs with removing narrow toe box shoes.

 

Walking barefoot on soft surfaces often produces no symptoms.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

In patients with an interdigital neuroma, the most common complaint is plantar pain, which is often increased by walking.

 

Pain is often relieved by resting and removing shoes.

 

 

Often, there are no symptoms with barefoot walking on a soft surface. About half of patients describe pain radiating to the toes.

 

The duration of pain varies from a few weeks to many years.

 

Plantar tenderness in the web space is the most common physical examination finding.

 

The examiner should inspect for deviation or subluxation of the toes or fullness of the web space. This is best done with the patient standing (FIG 2A).

 

Palpating the web space proximal to the metatarsal heads and proceeding distally will usually reproduce the patient's symptoms.

 

It is often difficult to differentiate adjacent metatarsophalangeal (MTP) joint synovitis from a neuroma.

 

 

Plantarflexion of the corresponding MTP joint may help with the diagnosis (FIG 2B). This maneuver often causes little increased pain in those with an interdigital neuroma but is quite painful in those with MTP joint synovitis.

 

Difficulty in making a diagnosis may arise when primary synovitis causes secondary neuritic symptoms.

 

The Mulder test is also useful.

 

 

Pain may be present on the asymptomatic contralateral side but is usually not as painful and the “click” not as striking.

 

This test is best performed with the patient lying prone and the knee flexed 90 degrees. The examiner places the thumb on the dorsal surface and the index finger on the plantar surface in the affected web space and applies gentle pressure (FIG 2C). With the opposite hand, the examiner applies a gentle squeeze to the forefoot in a mediolateral direction (FIG 2D). A clicking sensation that reproduces the patient's pain will often be appreciated.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

The diagnosis of an interdigital neuroma is most often made solely on the basis of the history and physical examination.

 

Standing anteroposterior (AP), lateral, and oblique radiographs are necessary to exclude osseous pathology and to assess the MTP joint.

 

 

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FIG 3 • A. Soft inserts and metatarsal support should be the first line of treatment. B. Steroid injection may improve symptoms and help with diagnosis.

 

 

The use of nerve conduction testing has not been shown to be beneficial, as findings often are abnormal in patients without symptoms of an interdigital neuroma.

 

Studies differ as to the benefit of ultrasonography or magnetic resonance imaging (MRI). If necessary, ultrasonography appears to be more useful than MRI in cases with a questionable diagnosis.

 

A diagnostic injection may be helpful, although other pathology in the area may improve with this local anesthetic.

 

 

Two milliliters of lidocaine is placed in the symptomatic web space through a dorsal approach.

 

The needle must be plantar to the transverse metatarsal ligament.

DIFFERENTIAL DIAGNOSIS

Adjacent web space neuroma MTP joint synovitis

Freiberg osteochondrosis

Stress fracture of the metatarsal neck Tarsal tunnel syndrome

Peripheral neuropathy Lumbar radiculopathy

Unrelated soft tissue tumor (eg, ganglion, synovial cyst, lipoma)

 

 

NONOPERATIVE MANAGEMENT

 

Although reported results of conservative treatment vary, it is still worthwhile to try, as 30% to 40% of patients may avoid surgery.

 

The patient should be fitted with a wide, soft, laced shoe with a low heel.

 

A soft metatarsal support should be added just proximal to the metatarsal heads (FIG 3A).

 

An injection of steroids with anesthetic may be both diagnostic and therapeutic. For there to be diagnostic value, however, the anesthetic must be directed to the common digital nerve in the affected web space and not into the MTP joint. A combination of 40 mg Depo-Medrol and 1 mL 0.25% Marcaine is used for the injection (FIG 3B).

 

 

Thirty percent of patients may have relief for 2 years or longer. Steroids should be used with caution as fat pad atrophy, skin discoloration, or MTP joint capsule laxity may result and create a new problem for the patient.

 

SURGICAL MANAGEMENT

 

The indication for excision surgery is failure of conservative treatment in a patient who is healthy enough to undergo forefoot surgery and who has appropriate vascular status.

 

For endoscopic decompression, the advantage of dividing the transverse intermetatarsal ligament (TIML) without excising the interdigital neuroma is that there is no loss of sensation or possible formation of a stump neuroma, which may produce symptoms worse than those with which the patient originally presented. Barrett

and Pignetti1 introduced endoscopic decompression of the intermetatarsal nerve, a procedure that offers several advantages over an open procedure, including a smaller incision, faster postoperative recovery, and a reduced incidence of hematoma and infection.

 

 

Although these authors reported good and excellent results in 88% of patients, the original technique was difficult, with a steep learning curve.

 

They have since modified their technique, changing from two portals to a single portal.

 

Preoperative Planning

Excision

 

A forefoot or ankle block may be used. Twenty to 30 mL of a 50% mixture of a short- and long-acting anesthetic (eg, lidocaine and Marcaine) without epinephrine is recommended.

 

An examination under anesthesia allows for better appreciation of an interspace mass and often will produce a more striking Mulder click.

 

Instruments needed include a Weitlaner or neuroma retractor (FIG 4), small tenotomy scissors, a Senn retractor, and a Freer elevator.

 

An ankle tourniquet is used with cast padding and an Esmarch bandage.

 

If a plantar approach is being used (recurrent neuroma), the surgeon should palpate and outline with a sterile marker the metatarsal heads corresponding to the web space being explored.

 

Endoscopic Decompression

 

All patients should have plain films preoperatively to rule out other diagnoses, in particular stress fracture or Freiberg infraction.

 

 

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FIG 4 • A neuroma retractor may help with exposure during surgery.

 

 

In our experience, preoperative ultrasound is valuable in confirming the diagnosis.

 

Without ultrasound, simple palpation of the web space is typically accurate in determining which web space is most tender.

 

Diagnostic lidocaine injection may also pinpoint the appropriate web space. However, if both the second and third web spaces are symptomatic, the surgeon should consider endoscopy on both spaces.

 

Positioning

Excision

 

The patient is placed supine with a 3-inch bump under the distal leg just proximal to the heel. The heel should be floating just off the bed.

 

Endoscopic Decompression

 

The patient is positioned supine on the operating table with a bump under the ipsilateral buttock and thigh if the leg tends to externally rotate.

 

 

The toes should extend just beyond the end of the table, with the heel firmly resting on the table.

 

Anesthesia may be general or regional (popliteal or ankle block).

 

Local anesthesia should be avoided, as it may distort the endoscopic anatomy.

 

 

 

FIG 5 • Left to right: elevator, cannula and obturator, disposable knife.

 

 

 

 

FIG 6 • A. Surgeon position for primary neuroma excision. Magnifying loupes are beneficial. B. Surgeon position for revision neuroma excision.

 

 

Prophylactic intravenous antibiotics are given when the patient comes to the operating room. We routinely use an ankle tourniquet inflated to 250 mm Hg.

 

Equipment required includes the AM Surgical set and a 30-degree 4-mm scope. The AM Surgical system includes an elevator, slotted cannula and obturator, locking device, and disposable knife blade.

 

Presented here is a technique originally designed by Dr. Ather Mirza for endoscopic carpal tunnel release. The instrumentation has been adapted for uniportal endoscopic decompression of the intermetatarsal nerve

(FIG 5).6

 

Approach

Excision

 

A dorsal approach is used for primary neuromas. The surgeon should sit proximal to the foot with the assistant positioned at the end of the table to assist with retraction (FIG 6A).

 

For recurrent neuroma excision, either a plantar longitudinal incision or a plantar transverse incision is used. The surgeon sits at the end of the table facing the plantar aspect of the foot (FIG 6B).

 

 

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TECHNIQUES

• Primary Interdigital Neuroma Excision Incision and Exposure

A dorsal incision is made 3 cm proximal to the web, extending distally to the edge of the web space (TECH FIG 1).

The incision is slightly oblique and medial to the extensor tendons. It is important not to follow the tendons themselves, as they will take a more lateral direction.

The dissection is deepened and the dorsal sensory nerves are retracted to the side of least resistance. The lumbrical tendon is lateral to the dissection.

The surgeon should proximally identify the dorsal interosseous fascia and muscle belly and follow it distally to the bursa overlying the transverse metatarsal ligament.

The surgeon should place a Weitlaner or neuroma retractor between the metatarsals and spread them apart.

The bursa is opened to identify the transverse metatarsal ligament.

Web space fat is retracted using a Senn retractor and the distal aspect of the intermetatarsal ligament is identified.

A Freer elevator is placed beneath the transverse metatarsal ligament from distal to proximal, protecting the underlying structures.

The transverse metatarsal ligament is incised with a no. 15 blade knife, staying on top of the Freer elevator.

The lumbrical tendon is in the lateral aspect of the dissection just plantar to the intermetatarsal ligament. The neurovascular bundle is identified medial and plantar to the lumbrical.

Excision

Once the approach has been completed, the nerve should be identified in the wound. It is usually easier

to identify the nerve proximally and dissect distally (TECH FIG 2A).

 

 

 

TECH FIG 1 • For a primary interdigital neuroma, a 3-cm incision is made in the affected web space just medial to the extensor tendons.

 

 

Manually palpate the wound to be sure the transverse metatarsal ligament has been completely transected, as this is essential to a successful outcome.

 

Despite the size of the nerve or the obvious presence of a neuroma, the nerve should be resected as planned.

 

Structures that may be mistaken for the nerve include the lumbrical tendon, which passes to the medial portion of the adjacent proximal phalanx (extensor expansion) and therefore is lateral to the nerve. The common digital artery usually crosses proximalmedial to distal-lateral lying dorsally over the nerve. The artery often emerges from under the metatarsal neck and if identified needs to be dissected away from the nerve and preserved.

 

Using gentle traction (TECH FIG 2B), transect the nerve about 4 cm proximal to the transverse metatarsal ligament.

 

The transverse head of the adductor hallucis may need to be retracted dorsally to identify the plantar-directed branches of the common digital nerve. Divide these branches to allow the proximal aspect of the nerve to retract at least 1 to 2 cm proximal to the weight-bearing pad of the forefoot (TECH FIG 2C).

 

Use a hemostat to place the remaining nerve stump well proximal and dorsal into the interosseous muscles.

 

 

Circumferentially dissect the nerve distally to the bifurcation of the proper digital branches. Divide the proper digital nerve just distal to the bifurcation.

 

Send the specimen (TECH FIG 2D) for pathologic examination.

Completion and Closure

 

With the Weitlaner or neuroma retractor still in place, release the ankle tourniquet. Use cautery to obtain hemostasis.

 

Irrigate the wound with sterile saline.

 

Close the wound with 4-0 nylon suture in a running locking fashion.

 

If subcutaneous suture is desired, use a 3-0 Monocryl, taking care not to include the dorsal sensory nerves.

 

Place a mildly compressive dressing over a Xeroform gauze covering the wound (TECH FIG 3A,B).

 

 

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TECH FIG 2 • A. The transverse intermetatarsal ligament must be divided. B. The neuroma is visualized and the common digital nerve transected 4 cm proximal to the transverse intermetatarsal ligament and allowed to retract proximal to the weight-bearing pad of the forefoot. C. After transection of the intermetatarsal ligament, the nerve is transected proximally (the transverse head of the adductor hallucis muscle often must be retracted) and dissected distally past the bifurcation. D. The specimen is sent for pathologic examination.

 

 

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TECH FIG 3 • A,B. For a primary neuroma excision, a mildly compressive dressing is placed and the patient is allowed to bear weight as tolerated in a postoperative shoe.

• Revision Interdigital Neuroma Excision Plantar Longitudinal Incision Approach

 

A longitudinal plantar incision is made 4 cm proximal to the web, extending distally to within 1 cm of the web space.

 

The incision is made between the metatarsal heads (which have been identified and marked before making an incision) and proceeds just distal to this area (TECH FIG 4).

 

 

A small Weitlaner retractor is placed to retract the fat overlying the plantar aponeurosis. Using a no. 15 blade knife, the aponeurosis is incised in line with the skin incision.

 

 

A tenotomy scissors is used to bluntly spread until the common digital nerve is identified proximally. The surgeon dissects distally to identify the stump neuroma.

 

 

 

TECH FIG 4 • For recurrent interdigital neuromas, a 4-cm longitudinal plantar incision is made proximal to the web extending distally to within 1 cm of the web space.

Plantar Transverse Incision Approach

 

Alternatively, 3- to 4-cm transverse plantar incision is made over the affected interspace just proximal to the weight-bearing pad and parallel to the natural crease (TECH FIG 5).

 

The metatarsal heads are continually palpated to provide a reference point to the appropriate interspace to be explored.

 

 

The dissection is carefully deepened with scissors to expose the septa of the plantar fascia. The interval between the longitudinal limbs of the plantar fascia septa is opened with scissors.

 

The bands of the plantar fascia are retracted medially and laterally with a Senn retractor and the interspace is carefully explored with blunt dissection to identify the common digital nerve and vessel.

 

The nerve (neuroma) will lie superficial (plantar) to the flexor digitorum brevis muscle or tendon and immediately deep (dorsal) to the plantar fascia.

 

The surgeon dissects distally to identify the stump neuroma.

 

 

 

TECH FIG 5 • Alternatively, one may use a 3- to 4-cm transverse plantar incision. The incision is placed over the affected interspace just proximal to the weight-bearing pad and parallel to the natural crease.

 

 

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Excision

 

The neuroma is identified just deep to the distal extensions of the plantar fascia that fan out to attach to the plantar aspects of the MTP joints and just superficial (plantar) to the flexor digitorum brevis.

 

The intermetatarsal ligament is often scarred in but does not need to be transected, as it is distal and dorsal to the neuroma.

 

Place gentle traction on the common digital nerve (TECH FIG 6A). Identify and excise the neuroma (TECH FIG 6B).

 

 

 

TECH FIG 6 • A. The plantar longitudinal incision is shown with gentle traction placed on the common digital nerve. B. Excision of the recurrent neuroma through a plantar longitudinal incision.

 

 

 

Allow the common digital nerve to retract proximally as far as possible. Release the ankle tourniquet and obtain hemostasis.

 

Irrigate the wound with sterile saline.

 

 

Close the wound with interrupted 3-0 nylon suture in a vertical mattress fashion. Place a mildly compressive dressing over a Xeroform gauze on the wound.

 

Place the patient in a short-leg posterior splint.

• Uniportal Endoscopic Decompression of the Interdigital Nerve Port Creation

 

Make a 1-cm vertical incision in the appropriate web space and spread the subcutaneous tissue gently with blunt Stevens scissors.

 

 

 

TECH FIG 7 • A. Surgical technique for uniportal endoscopic decompression of the intermetatarsal nerve. Cannula is in the interspace just plantar to the TIML and dorsal to the intermetatarsal (interdigital) nerve. The TIML is being transected from distal to proximal. B. Intraoperative view of insertion of cannula and obturator into second web space, notch at 12 o'clock, positioned to view the TIML. (continued)

 

 

Use the AM Surgical elevator to palpate and separate the TIML from the surrounding soft tissues. Scrape the elevator both dorsal and plantar to the TIML.

 

Place the slotted cannula and obturator through the same path, just plantar to and scraping against the TIML. The slot should face dorsally at the 12 o'clock position (TECH FIG 7A,B).

 

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TECH FIG 7 • (continued) C. Endoscopic view of TIML. D. Normal interdigital nerve. E. Thickened interdigital nerve (neuroma). (A: Courtesy of AM Surgical.)

 

 

Remove the obturator from the cannula, and remove any fat or fluid from the cannula with absorbent cotton-tipped applicators.

 

Insert a short, 4-mm 30-degree scope into the cannula.

 

Visualize the entire TIML by advancing the scope. The ligament is dense and white. The lumbrical tendon can often be seen just lateral to the TIML.

 

The intermetatarsal nerve can be visualized by rotating the cannula 180 degrees so that the slot is facing plantar at 6 o'clock position. The nerve can often be seen unless obscured by fat. It is often thickened distally, tapers, and becomes normal proximally (TECH FIG 7C-E).

 

Return the cannula to the 12 o'clock position and remove the scope from the cannula.

 

 

 

TECH FIG 8 • A. Intraoperative view of knife mounted to scope in position in cannula ready to enter second web space and transect the TIML. Endoscopic views of TIML (B), knife blade transecting the TIML (C,D), and after release of TIML (E).

Transverse Intermetatarsal Ligament Transection

 

Slide the disposable endoscopic knife onto the locking device with the lever in the open position.

 

Insert the knife and locking device assembly into the scope and advance the knife blade until it nearly touches the lens. The blade should also be parallel to the lens. Push the lever of the locking device forward until finger tight (TECH FIG 8A).

 

Advance the scope and knife assembly through the cannula. Visualize the knife blade transecting the TIML from distal to proximal (TECH FIG 8B-E).

 

While cutting the TIML, maintain the cannula tight against the ligament. Place more tension on the TIML by placing a finger of the nondominant hand between the adjacent metatarsal necks.

 

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Withdraw the scope and knife assembly and remove the knife from the scope. Reinsert the scope to confirm complete transection of the TIML. The divided edge of the ligament can be observed to further separate by applying manual digital pressure between the adjacent metatarsal heads.

 

Irrigate the wound through the cannula.

 

Remove the cannula, insert the elevator into the wound, and palpate the interspace. The taut TIML should no longer be palpable.

Completion and Closure

 

 

Deflate the tourniquet; irrigate and close the wound with one or two interrupted mattress sutures. Apply a soft compression dressing and postoperative shoe.

 

If the surgeon chooses to perform a neurectomy in cases in which the nerve is very large and bulbous,

the incision can be extended proximally 1 to 2 cm and neurectomy can be performed in routine fashion.

 

 

Always perform a thorough history and physical

examination. This is the primary basis of diagnosis and treatment.

• Perform standing, sitting, and prone

examination of the foot and ankle.

Attempt conservative treatment before surgery.

• Discuss with the patient possible

complications of surgery, especially incomplete relief and recurrence.

Transect the common digital nerve at least 3-4

cm proximal to the transverse metatarsal ligament.

• Grasp the nerve and with gentle traction,

pull it distally. Transect and allow the nerve to retract.

Release the tourniquet and obtain hemostasis

before closure.

• Hematoma formation increases the risk of

slow wound healing and infection.

The key to the endoscopic procedure is isolating

and separating the TIML from the soft tissues.

• Developing these tissue planes with the

  elevator is the critical step; everything else follows.

• Hugging the TIML with the cannula while cutting is very important.

• If unable to visualize the TIML, abort the procedure and perform the procedure open.

 

PEARLS AND PITFALLS

 

 

POSTOPERATIVE CARE

Excision

 

For 24 hours, the operative extremity is maximally elevated and the patient ambulates only for bathroom privileges.

 

For a primary excision (dorsal approach), the patient is then allowed to ambulate with weight bearing as tolerated in a hard-soled postoperative shoe for 4 weeks.

 

For a revision excision (plantar approach), the patient is kept non-weight bearing on crutches for 2 weeks and then transitioned into a stiff-soled postoperative shoe for another 2 weeks with weight bearing as tolerated.

 

Sutures are removed at 2 weeks and Steri-Strips are placed on the wound.

 

At 4 weeks after surgery, the patient is allowed into a wide toe box, soft-vamp comfortable shoe and progressed as tolerated.

 

Endoscopic Decompression

 

Ice and elevation are recommended for the first 48 to 72 hours.

 

Weight bearing as tolerated is permitted in a surgical shoe. Crutches or a walker should be provided as needed.

 

 

Sutures are removed in 12 to 14 days. A comfortable shoe or sandal may then be worn. Vigorous activities such as running or racquet sports should be avoided for 4 to 6 weeks.

Patients should be advised that complete resolution of symptoms may take up to 4 months.

OUTCOMES

Surgical excision of a primary neuroma has a reported success rate of 51% to 90%, although results tend

to diminish with time. A recent study by Womack et al7 suggests longterm pain relief is not as significant as once thought.

These results seem to be similar for both second and third web space neuroma excisions.

After reexploration for a recurrent neuroma, less than complete satisfaction can be expected in 20% to 40% of individuals.

 

 

COMPLICATIONS

Recurrence of symptoms may be due to incorrect diagnosis, incomplete resection, or true recurrence.

Recurrence of symptoms due to incorrect diagnosis and incomplete resection usually occurs within the first 12 months.

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Recurrence after 1 year is more likely related to the formation of a stump neuroma.

Significant wound complications are rare, but slow wound healing and superficial cellulitis are more common.

Incisional tenderness after a plantar approach is less common than one may suppose but may occur if placed under a weight-bearing portion of the forefoot.

 

 

REFERENCES

1. Barrett SL, Pignetti TT. Endoscopic decompression for intermetatarsal nerve entrapment—the EDIN technique: preliminary study with cadaveric specimens; early clinical results. J Foot Ankle Surg 1994;33: 503-508.

    

    

2. Beskin JL, Baxter DE. Recurrent pain following interdigital neurectomy —a plantar approach. Foot Ankle 1988;9:34-39.

    

    

3. Graham CE, Johnson KA, Ilstrup DM. The intermetatarsal nerve: a microscopic evaluation. Foot Ankle 1981;2:150-152.

    

    

4. Lassmann G. Morton's toe: clinical, light and electron microscopic investigations in 133 cases. Clin Orthop Relat Res 1979;(142): 73-84.

    

    

5. Levitsky KA, Alman BA, Jevsevar DS, et al. Digital nerves of the foot: anatomic variations and implications regarding the pathogenesis of interdigital neuroma. Foot Ankle 1993;14(4):208-214.

    

    

6. Shapiro SL. Endoscopic decompression of the intermetatarsal nerve for Morton's neuroma. Foot Ankle Clin 2004;9:297-304.

    

    

7. Womack JW, Richardson DR, Murphy GA, et al. Long-term evaluation of interdigital neuroma treated by surgical excision. Foot Ankle Int 2008;29:574-577.