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Mortons Neuroma

Discussion in 'Biomechanics, Sports and Foot orthoses' started by podomania, Feb 11, 2007.

  1. podomania

    podomania Active Member

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    Dear all
    Is it possible that a neuorma can occur simultaneously between the 2nd-3r, 3rd-4th and 4rth-5th cleft? I got a positive mortons click test in all the above mentioned intermetatarsal head spaces. I provided the patient with a prefab orthoses pair with a metatarsal bar and the symptoms seemed to improve within the fisrt day of wearing them. Unfortunately i wasnt sure about the diagnosis and i dont feel comfortable with that. I would appreciate some advice.
    Many thanks
  2. David Smith

    David Smith Well-Known Member


    This is an article from eMedicine that I had on file.

    Interdigital neuritis, or the more commonly known Morton neuroma, is a condition that is a result of entrapment of the plantar interdigital nerve as it passes under the transverse metatarsal ligament. This condition was named after Thomas Morton, who reported “A peculiar and painful affection of the fourth metatarso-phalangeal articulation” in 1876. This condition has since been defined as a perineural fibrosis of the involved interdigital nerves, and true neuromatous involvement is not seen.

    Other terms used for this condition include interdigital neuroma, Morton metatarsalgia, interdigital nerve compression, and interdigital neuritis.

    This condition is most common in the second or the third interspace, but occurrences in the first and fourth have been reported. Double neuromas occurring in the second and third interspace are not uncommon. Interdigital neuromas are more common in women than men; they can occur in persons of all ages, but they are most common in middle-aged persons.


    The common digital nerves originate from the medial and lateral plantar nerves. The medial plantar nerve divides into 3 common digital nerves, which in turn bifurcate, supplying cutaneous branches to the medial 3.5 digits. The lateral plantar nerve gives rise to 2 common digital nerves, supplying cutaneous branches to the lateral one and a half digits. As the common digital nerves travel distally, they pass plantar to the transverse intermetatarsal ligament.

    Substantial variability has been noted in the cutaneous innervation of both the web space and the plantar aspect of the foot adjacent to the web space.


    The most direct cause of entrapment of the interdigital nerve is compression of the nerve as it passes under the transverse intermetatarsal ligament. As weight is transferred to the ball of foot when the toes are dorsiflexed during the last phase of stance, the interdigital nerve is compressed between the plantar foot and the distal edge of the intermetatarsal ligament. Many theories exist about the pathophysiology of this compression. These theories include ischemia, inflammation, soft tissue trauma, tumor, muscle imbalance, and fibrous ingrowth.

    Edema of the endoneurium, fibrosis beneath the perineurium, axonal degeneration, and necrosis are often seen and suggest that nerve damage occurs secondary to mechanical impingement. Using electron microscopy, Ha'Eri et al saw lesions consisting of a progressive fibrosis that enveloped and disrupted nerves and arteries. They did not see nerve-tissue proliferation or inflammation. They concluded that repeated trauma leads to reactive overgrowth and scarring that disrupts the nerves and the arteries. Typically, these changes are evident proximal to bifurcation of the common digital nerve, immediately distal to the transverse intermetatarsal ligament. In more chronic cases, degeneration of the axons and proliferation of blood vessels may occur about the site of an enlarged nerve. Shereff and Grande describe the presence of Renaut bodies, which are densely packed whorls of collagen, in the supraneural space. These bodies are characteristically present only in peripheral neural entrapment.

    Morscher et al, however, in a histomorphologic study, found only a diameter difference between biopsy results from patients with typical symptoms of Morton metatarsalgia and nerves examined from autopsies of persons without forefoot problems. In addition, some have implicated the inter-MTP bursa as the main cause of Morton metatarsalgia.

    Forefoot deformities such as hammertoes can further aggravate the nerve due to dorsal subluxation of the proximal phalanx, which stretches the interdigital nerve over the intermetatarsal ligament. In addition, there are a number of external conditions that have been noted to contribute to the development and aggravation of this compression. High-heeled shoes put the feet in chronic dorsiflexion and result in forcing one's weight onto the forefoot; tight shoes, which compress the foot further, limit the intermetatarsal space.

    Multiple investigations have looked into the underlying reason for the common locations in the second and third web space. Levitsky et al demonstrated in their study that the relative space in the metatarsal head/transverse metatarsal ligament is smaller in second and third web spaces than the others, where the condition is more common and thus supports the mechanical factors as the underlying pathophysiology. They also refused the common theory that the cause is the lateral and medial plantar combination and anatomical thickness of the nerve. They reported neuromas in third web spaces whose plantar nerves were not from both medial and lateral plantar nerves. The intermetatarsal head distances in the second and third interspace have been noted to be significantly less than those at the first and fourth intermetatarsal spaces.


    Many patients with Morton metatarsalgia present with an intermittent dull ache or cramping sensation on the plantar aspect of either the second or third interspace. Many patients present with a vague discomfort in the involved toes and some may feel numbness or burning, with occasional shooting pain. Some patients notice spreading of the involved toes, and others may notice symptoms only with certain shoes. Symptoms usually worsen with walking, particularly with bare feet on hard surfaces, and sudden sharp pain may be felt with activities such as such as sprinting, jumping, squatting, or repeated hopping, and with wearing high-heeled or tight shoes. They improve with rest, and night pain is rare. With progression of the condition, pain may radiate proximally. In chronic cases, patients may sense a mass or a stone bruise in the ball of the foot.

    Near equal involvement of the second and third interspace is reported in the literature. Involvement of the first and fourth spaces has been reported, rarely.

    Simultaneous tenderness in the second and third interspace is not rare. Bilateral cases have been reported but are uncommon. Coexistence of other pathologies of the forefoot, such as instability of the second MTP joint, is not uncommon. Coughlin et al reported that 20% of their patients originally had concomitant instability of an adjacent MTP joint.

    Clinically, dorsoplantar compression of the second or third intermetatarsal space reproduces pain that may radiate to the toes or proximally along the course of the affected nerve. The patient may display relative paresthesia of the web space supplied by the injured nerve, although this is often difficult to ascertain.

    The Mulder click is a useful diagnostic test. The forefoot is held in one hand, and the metatarsal heads are squeezed while the other hand places direct pressure on the plantar aspect of the interspace. As the metatarsal heads are compressed, the enlarged nerve is pushed plantar and away from the metatarsal heads, and a click is palpated with the digit in the plantar web space just distal to the transverse intermetatarsal ligament. This is often uncomfortable for the patients but does not usually reproduce their symptoms. This palpated mass can be again pushed up in the interspace with manual pressure, while partial compression is maintained on the metatarsal heads. Many times one digit is noted to move suddenly.

    A range of conditions may mimic Morton neuroma, including metatarsal stress fracture, MTP joint synovitis, intermetatarsal bursitis, extensor tendon tenosynovitis, tumor, and nerve injury more proximally. Metatarsal stress fracture will present with bony tenderness and pain upon palpation of the metatarsal shaft, rather than the common digital nerve. MTP joint synovitis will often prove painful during active or passive joint motion.

    The diagnosis of interdigital neuroma is primarily based on clinical findings. Careful clinical examination will usually reveal other conditions that can mimic or coexist with intermetatarsal neuritis. In complex cases, immediate temporary resolution in response to a local anesthetic block proximal to the involved area below the intermetatarsal ligament can confirm the diagnosis.

    Ultrasonography and MRI are helpful in rare complex situations. The accuracy of these studies, however, varies significantly and depends on multiple factors including the MRI machine, the technician and the technique, and the interpreting radiologist or orthopedic surgeon.

    Ultrasonography reveals a hypoechoic ovoid mass, parallel to the long axis of the metatarsal. Ultrasonography can also be used to diagnose other pathologic conditions in forefoot, such as bursitis and MTP joint effusion. Reed et al have reported this study to be 95% sensitive in detection of web space abnormality, but Morton neuroma could not be clearly distinguished from an associated mass such as mucoid degeneration in the adjacent loose connective tissue.

    Quinn et al found that sonography revealed the diagnosis in 85% of cases in which it was suspected. They reported limitation in detecting neuromas shorter than 5 mm. Terk et al reported MRI with T1- and T2-weighted sequences and a combination of fat suppression and the administration of gadopentetate dimeglumine. Williams et al have shown that T1-weighted axial and coronal images obtained with an axial fast spin-echo (FSE) T2-weighted sequence depict neuromata more consistently than other methods.

    Zanetti et al studied 54 feet in which Morton neuroma was suspected to determine the effect of MRI results on diagnostic thinking and therapeutic decisions by orthopedic surgeons. They noted considerable change in the diagnosis, location, and number of neuromas and also in treatment plans after MRI.

    In a second report, Zanetti et al suggested that the diagnosis of Morton metatarsalgia based on MRI results are relevant only when the transverse diameter of the fluid collection in the bursa is 5 mm or more and when it was correlated with the clinical findings. Fluid collections in the first 3 metatarsal bursa with a transverse diameter of 3 mm or less are likely physiologic.

    In a histomorphologic study of patients and autopsies, Morscher concluded that diagnostic MRI or ultrasonography is unnecessary for making decisions about operative treatment. In addition, Resch et al found that MRI modalities had little or no value in the diagnosis of Morton neuroma because of the high rate of false-negative results.


    If a Morton neuroma is detected early, conservative measures may be reasonably successful. About 20-30% of patients achieve adequate relief with nonoperative management. This may be accomplished by eliminating or minimizing the external sources of compression or stretch on the interdigital nerve.

    Extra-wide shoes and low heels, as well as placement of a small metatarsal pad just proximal to the heads of the central 3 metatarsals, may reduce symptoms by increasing the intermetatarsal space, elevating the metatarsals and the intermetatarsal ligament and reducing the likelihood of neural irritation. Accommodative orthotic devices with built in metatarsal pads may at times be helpful, especially in patients with alignment abnormalities.

    NSAIDs may relieve acute pain and inflammation. If NSAIDs provide insufficient relief, a local anesthetic injection can also relieve pain and may help confirm the diagnosis of Morton neuroma.

    Corticosteroid injections have not been shown to result in predictable or lasting relief, as reported by Mann et al. Rasmussen et al reported initial pain relief in 80% of patients who received a single corticosteroid injection. However, 47% ultimately required surgical excision, and 53% continued to have residual symptoms. In addition, corticosteroid injection for intermetatarsal neuroma has been associated with a number of complications, including plantar fat-pad atrophy depigmentation, hyperpigmentation, and telangiectasias. Fat-pad atrophy can result in metatarsalgia and gait impairment.

    A number of different surgical procedures have been used. Excision of the interdigital nerve and release of the intermetatarsal ligament is the most commonly performed procedure. A variable degree of subjective numbness occurs in the 2 toes served by that nerve, which symptomatic in fewer than 10% of cases. Dorsal or plantar incisions have been reported in the literature.

    Most surgeons in the United States perform a primary surgery through a dorsal approach. The incision is approximately 3 cm in length and is centered in the respective interspace starting from the metatarsal head level and extending distally into the respective web space. Blunt dissection into the web space and placement of a lamina-style spreader reveals the intermetatarsal ligament. The proximal and distal aspect of the ligament is identified and released sharply. An enlarged nerve may be readily identified beyond the ligament. Smaller nerves are more difficult to identify. Most times, intertwining vessels require careful dissection and protection. The digital branches are identified and sharply amputated distally. The nerve is then followed proximally, gently pulled distally, and sharply amputated as far proximally as visible and allowed to retract into the deep soft tissues.

    Mann and Reynolds reported retrospectively on a surgical excision of 76 interdigital neuromas. Although 65% of patients still noted some local plantar tenderness to touch, 80% were subjectively improved. Coughlin and Pinsonneault noted residual pain in either the involved or adjacent interspace, which is not uncommon. They also reported 85% good or excellent results. They noted mild or major footwear restrictions by 70% of patients.

    Dereymaeker et al reported on 32 feet that were treated with excision of the interdigital neuroma by using a dorsal incision. Twenty-five of 32 patients had a macroscopically visible neuroma, and 2 had no evidence of a neuroma on histological examination. After resection, 81% had a good or excellent result, and 6.5% had no improvement after their operation. Dereymaeker et al note that 60% of their patients benefited from wearing adapted shoes or inner soles for a considerable time after the operation. At final follow-up, only 30% had no restrictions in the choice of their shoes.

    Some authors advocate the plantar approach for primary resection of the intermetatarsal neuroma, as it provides more direct access to the nerve and is technically simpler. However, painful plantar scars, intractable plantar keratosis beneath an adjacent lesser metatarsal head, and wound drainage have been reported. Because of these potential complications, most surgeons reserve the plantar approach in revision cases. Karges reported on 57 plantar surgeries performed using a plantar incision. He reported 23% indurated plantar keratosis (IPK) after surgery, and only 7% had poor results.

    Potential complications of interdigital nerve excision, including development of a stump neuroma and digital numbness, have led some authors to recommend release of the transverse metatarsal ligament with or without epineurolysis. Gauthier has reported on releasing 304 intermetatarsal ligaments and epineural neurolysis. He reports 83% had rapid and stable improvement, and 15% were improved but with some persistent pain. Others, such as Weinfeld and Myerson, have advocated this procedure without neurolysis and report good preliminary results. Mann and Reynolds cautioned against this procedure except for interdigital neuritis, as they noted reconstitution of the ligament in revision cases.

    Adjacent neuromas in the second and third interspace should be investigated. Reports of double neuromas in the literature are sparse. Benedetti reported simultaneous excision of 2 primary interdigital neuromas in adjacent web spaces and noted significant pain relief in 84%, but substantial numbness involving the third toe resulted. Thompson and Deland described 89 adjacent neurectomies and reported similar results to those achieved with single neurectomies.

    More recently, Hort and DeOrio reported on 23 patients with adjacent intermetatarsal nerve irritation who underwent excision of the more enlarged nerve in one space and release of the intermetatarsal ligament in the other. This allowed preservation of protective sensation. They reported 95% complete satisfaction with no or only minimal activity limitation. Approximately 11% had persistent pain with compression of the interspace where the nerve was released. None had pain in the interspace where the nerve was excised. The investigators performed this procedure through 1 incision centered over the third metatarsal.

    Interdigital neuritis is the result of chronic compression of the interdigital nerve as it passes under the transverse intermetatarsal ligament. It is most commonly seen in the second and third intermetatarsal space, and it causes pain that may radiate to the toes or proximally along the course of the affected nerve. Pain with compression of the intermetatarsal space and the presence of a Mulder click confirms the diagnosis.

    Nonoperative management is successful in about 20-30% of all cases. Nonoperative management includes the avoidance of high-heeled and tight shoes, as well as the use of a small metatarsal pad and stiffer rocker-soled shoes. Surgical excision of the nerve and release of the intermetatarsal ligament with a dorsal or plantar approach results in a high percentage of successful results. The dorsal approach is recommended because of fewer potential complications and as it allows early weight bearing. Patients should be counseled preoperatively that postoperative numbness of a varying degree is commonly associated with resection of an interdigital neuroma. Other surgical options include isolated intermetatarsal ligament release.

    Adjacent neuromas in the second and third interspaces are not uncommon. Excision of the most involved nerve and release of the intermetatarsal ligament in the less involved nerve leads to good relief of symptoms without significant neurologic deficit.

    Hope that is of some use Cheers dave Smith
  3. It is possible to have neuromas in the 2nd, 3rd and 4th intermetatarsal spaces simultaneously, however, this is exceedingly rare. Just because a patient has a positive Mulder's sign does not also mean that they have a neuroma. It may simply mean their metatarsal pain is being caused by another structure, not a neuroma, and they also have some other soft tissue structure that is mimicking the "palpable click" of a Mulder's sign when the maneuver is performed.

    If the symptoms are neurologic in nature (i.e. burning, cramping, partial anesthesia in plantar interdigital nerve distribution), then also consider that they have a plantar capsulitis or plantar plate tear that, because of its local edema, is irritating the intermetatarsal nerve enough to cause "neuroma-like" symptoms. These patients will have more tenderness on the plantar metatarsal heads, generally at the base of the proximal phalanx of the digit, than they will have within the intermetatarsal space, where neuromas live. Careful history and physical examination by the experienced podiatrist should allow one to differentiate between these common forms of plantar forefoot pain.
  4. podomania

    podomania Active Member

    Many thanks.
    Excuse the mistake...my return to my native counrty..greece the past 2 years sometimes leads me to confusion...Mulder's click..i found it a rediculous method of diagnosing something anyway when i was in uni..
    Thanks again both Prof Kirby and dave Smith
  5. mazzoncini

    mazzoncini Member

    Excuse my ignorance, but I always thought that the neuroma was distal to the intermetatarsal ligament and therefore in the digital webspace and not in the intermetatarsal space?? Compressing the metatarsal heads together can irritate the intermetatarsal bursa which can be inflammed and a differential diagnosis when trying to establish whether you are dealing with a Morton's neuroma or intermetatarsal bursitis (especially between the 4th and 5th metatarsals). The click one feels on lateral compression is usually the movement of the neuroma when it moves plantar-dorsally.

  6. NewsBot

    NewsBot The Admin that posts the news.

    An Anatomical Study of Morton's Interdigital Neuroma: The Relationship Between the Occurring Site and the Deep Transverse Metatarsal Ligament (DTML).
    Kim JY, Choi JH, Park J, Wang J, Lee I.
    Foot Ankle Int. 2007 Sep;28(9):1007-10.
  7. Stanley

    Stanley Well-Known Member

    Yes, I have seen it once. When I started my residency, I had the privilege of watching Ray Suppan do surgery. He was noted for his speed, so the first time I watched him, I decided to time him. It turned out that his first patient that day had 3 neuromas. By the way, it took him 13 minutes to do all three skin to skin. :eek:
    An important point about neuroma surgery, is that there will be vasospasms after surgery that may last for several hours. Most podiatrists will not operate on adjacent neuromas for this very reason.
    For a third interspace neuroma, look for a subluxation of the 4th metataral cuneiform joint. Manipulate it and make an orthosis with a metatarsal pad and an extension under the fifth metatarsal.


  8. Craig Payne

    Craig Payne Moderator

    Who reckons that a mortons/interdigital neuroma could be due to low gear vs high gear propulsion?

    In the gym I get neuroma pain on the step machine and cross trainer - if I make a conscious effort to move the foot to a high gear position, the pain goes away ??
  9. Admin2

    Admin2 Administrator Staff Member


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