Morton’s neuroma, Morton’s foot

Morton’s neuroma causes burning pain, tenderness, and paresthesias in the forefoot due to interdigital nerve enlargement from compression, often between the third and fourth toes.

Synonym: Morton’s metatarsalgia, Morton’s disease interdigital neuritis, Morton’s pinch, interdigital neuralgia, interdigital neuroma, interdigital nerve compression syndrome and intermetatarsal neuroma.

Introduction

Morton’s neuroma, known by various synonyms such as Morton’s metatarsalgia, Morton’s disease interdigital neuritis, Morton’s pinch, interdigital neuralgia, interdigital neuroma, interdigital nerve compression syndrome and intermetatarsal neuroma, is a painful condition affecting the feet, especially the region between the third and fourth toes. This condition results from thickening of the interdigital nerve , causing various unpleasant symptoms, and although generally benign, it can significantly impair the quality of life of affected individuals.

The causes of Morton’s neuroma are usually related to compression or irritation of the plantar interdigital nerve. Factors such as tight shoes, activities involving excessive pressure on the feet, structural abnormalities of the foot, or overuse can contribute to its development. Women are more commonly affected than men, probably due to the frequent use of high-heeled and narrow shoes.

Symptoms of Morton’s neuroma include pain, numbness, and sometimes a burning sensation in the affected area. The pain may be described as throbbing or like a feeling like a stone in the shoe. Symptoms may worsen when walking or doing activities that put pressure on the feet.

The diagnosis of Morton’s neuroma is based on clinical examination, the patient’s history and sometimes imaging tests such as x-rays or MRIs. Treatment options vary depending on the severity of symptoms. Conservative measures such as wearing wider shoes, using orthotic insoles, reducing high-impact activities, and applying ice may relieve symptoms in less severe cases.

If symptoms persist, corticosteroid injections may be considered to reduce inflammation. Physiotherapeutic treatments, such as stretching and strengthening exercises, may also be beneficial. In more severe cases or cases resistant to conservative treatment, surgery to remove the neuroma may be considered.

It is essential to emphasize that Morton neuroma is a manageable condition, and appropriate treatment depends on the severity of symptoms and the patient’s response to non-invasive approaches. Prevention also plays a crucial role, emphasizing wearing appropriate footwear, avoiding narrow or high-heeled shoes, and practicing regular foot care.

Thomas George Morton 1835-1903

Thomas George Morton (1835–1903) was a 19th-century Scottish surgeon and anatomist. He is best known for his description of Morton’s neuroma. This is also sometimes called “Morton’s disease” in his honor. Morton published his first description of this condition in 1876. He emphasized the importance of nerve compression between the metatarsal heads of the foot in the development of symptoms.

Morton’s contribution to the understanding of Morton’s neuroma was crucial in the advancement of medical knowledge of the time. Its name remains closely associated with this condition, and the term “Morton’s neuroma” is commonly used in medical practice to describe this specific condition. However, it is important to emphasize that although Morton made a significant contribution to the study of this condition, Morton’s neuroma itself probably existed long before its first description.

It should be noted that other researchers and practitioners have also contributed to the exploration and understanding of Morton’s neuroma over the years. The collaboration between these enlightened minds has made it possible to develop more comprehensive diagnostic and therapeutic approaches for this condition. Subsequent advances in neurology and orthopedic surgery have also enriched our understanding of Morton neuroma and led to more varied treatment options to relieve patients’ symptoms.

Summary

The interdigital nerves navigate through the space between the metatarsal heads, close to the bottom of the foot, passing under the ligaments that join the adjacent metatarsal heads. These nerves are responsible for carrying sensation to the medial and lateral sides of the adjacent toes.

Morton’s neuroma represents an alteration of these nerves in the anterior region of the foot. The most common symptom is pain felt directly between the metatarsal heads. Typically, only one nerve is affected, although cases involving multiple nerves can occur. The most common location of an interdigital neuroma is between the third and fourth toes, but it is not uncommon to see neuromas between the second and third toes.

Morton’s Foot

Morton’s foot, or the toe is shorter, is often the cause of Morton’s neuroma. Instead of receiving the force of pushing from the foot on the first metatarsal, this load will be transferred laterally, that is to say on the other metatarsals. So, this increased pressure on the other metatarsals would be a reason for the development of Morton’s neuroma.

Lateral weight transfer mechanism with Morton’s foot

When the foot makes contact with the ground, it initiates a complex weight transfer process which plays an essential role in the biomechanics of the foot. This process begins at the heel and then naturally moves toward the first metatarsal, particularly the big toe.

The anatomical design of the foot reflects this sequence, as the big toe is designed to effectively receive the load of weight transfer when walking or running.

However, anatomical variations can influence this pattern of weight transfer, leading to adjustments in how the foot absorbs pressure. One of these variations concerns the length of the first metatarsal. If the first metatarsal is shorter than normal (Morton’s foot), the foot must compensate by performing a supination movement. Supination is a movement of the foot that occurs as it rolls outward, directing weight toward the lateral side of the foot.

In this situation, the natural path of weight transfer towards the big toe is modified. Instead, the weight is directed to the second and third metatarsals, which are not necessarily adapted to support such a load. This redistribution of forces can lead to problems, including the formation of corns in the area of ​​the metatarsal heads of the second and third metatarsals.

Morton’s neuroma, a painful condition, is often seen in this setting, particularly between the third and fourth metatarsal heads. Morton’s neuroma is a condition resulting from compression of the interdigital plantar nerve, usually between these two metatarsals. This compression can be accentuated by the change in the weight transfer pattern caused by supination of the foot.

Symptoms of Morton’s neuroma include shooting pain, tingling, or burning sensation between the toes, usually between the third and fourth toes. These symptoms may worsen while walking, running, or wearing tight shoes. The specific location of the symptoms is linked to the compression of the nerve in the region of the metatarsal heads, accentuated by the supination of the foot due to the reduced length of the first metatarsal.

Risk factors

1. Foot Anatomy: Some individuals have foot anatomy that predisposes to the development of a Morton neuroma, such as mechanical instability of the foot or variation in bone structure.
2. Wearing Inappropriate Shoes: Wearing shoes that are narrow, pointed, high heels, or pointed toes can put excessive pressure on the nerves in the foot, leading to the development of a neuroma.
3. Repeated-impact activities: Certain activities that involve repeated impact on the feet, such as running or other high-impact sports, may increase the risk of developing Morton neuroma.
4. Foot deformities: People with foot deformities, such as hammertoes or bunions, may be more likely to develop Morton neuroma.
5. Trauma: Repeated injuries or trauma to the foot can contribute to the development of a neuroma.
6. Biomechanical Disorders: Biomechanical disorders of the foot, such as excessive pronation (inward rotation) or excessive supination (outward rotation), can influence neuroma development.
7. Age and sex: Morton neuroma is more common in women, and its incidence increases with age.

Symptoms

Morton’s neuroma is a condition that usually causes symptoms in the front of the foot, between the third and fourth toes. The most common symptoms include:

1. Pain: Pain is the most common symptom associated with Morton’s neuroma. It is often described as a burning, tingling or electric shock sensation. The pain may radiate towards the toes.
2. Numbness: Some individuals may experience numbness or loss of sensation in the affected toes.
3. Foreign body sensation: Some patients describe the sensation of having a foreign object, such as a rock, inside their shoe or the ball of their foot.
4. Worsen with activity: Morton neuroma symptoms tend to get worse with physical activity, especially walking, running, or wearing uncomfortable shoes.
5. Relief at rest: Symptoms may improve or partially disappear upon rest or after removing shoes.
6. Palpation of a mass: In some cases, a doctor may detect a small mass or thickened area between the metatarsal heads during physical examination.

Morton’s neuroma refers to symptoms caused by painful damage to the branches of the common digital nerves, most commonly in the interdigital spaces of the foot, primarily in the second or third space. The term “interdigital neuropathy” (IDN) was introduced to replace Morton’s neuroma, because the condition appears to result more from inflammatory changes than from true neuroma tumor formation.

The pathogenesis of IDN is linked to a traction phenomenon, where the edge of the intermetatarsal ligament compresses the nerve during the normal gait cycle. This compression makes the nerve susceptible to irritation or direct trauma, as shown in Figure 29-1. Most patients with symptoms are middle-aged women with a history of wearing narrow-toed or high-heeled shoes, both of which contribute to increased plantar pressure in the forefoot.

IDN most commonly manifests in the second or third interdigital space, resulting in a chief complaint of localized pain or tingling that worsens with wearing shoes. Fortunately, symptoms are often relieved by removing shoes and massaging the toes. Although a patient may report decreased sensation, it is rare to observe widespread pain, pain on the sole of the foot, or the patient limping when walking. The unique characteristics of IDN highlight the importance of considering not only symptoms, but also contributing factors such as shoe choice in the diagnosis and management of this condition.

Recommendations to avoid Morton’s neuroma

1. Wearing appropriate shoes: Choose comfortable shoes that provide good support and do not excessively compress the toes. Avoid high-heeled or pointy shoes which can increase pressure on the neuroma area.
2. Using orthotic insoles: Orthopedic insoles or metatarsal pads can help reduce pressure on the nerves between the toes.
3. Avoid shoes that are too tight: Shoes that are too tight can contribute to nerve irritation. Opt for shoes that allow your feet to move comfortably.
4. Avoid shoes with pointed toes: Shoes with pointed toes can compress the toes and increase pressure on the nerves. Choose shoes with wider toes.
5. Frequent shoe changes: Avoid wearing the same shoes every day. Alternate between different pairs to reduce pressure on the same areas.
6. Maintain a healthy weight: Maintaining a healthy weight helps reduce pressure on the feet, which can help prevent Morton’s neuroma.
7. Avoid walking barefoot on hard surfaces: Walking barefoot on hard surfaces can increase pressure on the nerves between the toes. Wear appropriate shoes or slippers.
8. Avoid high-impact activities: Reduce participation in high-impact activities, especially if you experience pain or irritation between your toes.
9. Foot Stretching: Practice stretching exercises for your feet regularly, especially if you tend to feel tension or pain in that area.

Conclusion

In conclusion, Morton’s neuroma represents a challenge for those who suffer from it, significantly impacting their daily lives. A thorough understanding of this condition, its underlying causes and possible interventions is essential for effective management. Whether through conservative approaches such as wearing appropriate shoes, using orthotics, or more advanced options like corticosteroid injections or, in severe cases, surgery, treatment for Morton’s neuroma can be adapted according to the severity of the symptoms. It is recommended to consult a healthcare professional for an accurate diagnosis and personalized treatment plan, allowing individuals to regain optimal quality of life while minimizing the effects of this painful condition.

References

1. Ruiz Santiago F, Prados Olleta N, Tomás Muñoz P, Guzmán Álvarez L, Martínez Martínez A. Short term comparison between blind and ultrasound guided injection in morton neuroma. Eur Radiol. 2019 Feb;29(2):620-627. [ PubMed ]
2. Ganguly A, Warner J, Aniq H. Central Metatarsalgia and Walking on Pebbles: Beyond Morton Neuroma. AJR Am J Roentgenol. 2018 Apr;210(4):821-833. [ PubMed ]
3. Lorenzon P, Rettore C. Mechanical Metatarsalgia as a Risk Factor for Relapse of Morton’s Neuroma After Ultrasound-Guided Alcohol Injection. J Foot Ankle Surg. 2018 Sep – Oct;57(5):870-875. [ PubMed ]
4. Di Caprio F, Meringolo R, Shehab Eddine M, Ponziani L. Morton’s interdigital neuroma of the foot: A literature review. Foot Ankle Surg. 2018 Apr;24(2):92-98. [ PubMed ]
5. Edenfield KM, Michaudet C, Nicolette GW, Carek PJ. Foot and Ankle Conditions: Midfoot and Forefoot Conditions. FP Essent. 2018 Feb;465:30-34. [ PubMed ]
6. Santiago FR, Muñoz PT, Pryest P, Martínez AM, Olleta NP. Role of imaging methods in diagnosis and treatment of Morton’s neuroma. World J Radiol. 2018 Sep 28;10(9):91-99. [ PMC free article ] [ PubMed ]
7. LiMarzi GM, Scherer KF, Richardson ML, Warden DR, Wasyliw CW, Porrino JA, Pettis CR, Lewis G, Mason CC, Bancroft LW. CT and MR Imaging of the Postoperative Ankle and Foot. Radiographics. 2016 Oct;36(6):1828-1848. [ PubMed ]
8. Naraghi R, Bremner A, Slack-Smith L, Bryant A. The relationship between foot posture index, ankle equinus, body mass index and intermetatarsal neuroma. J Foot Ankle Res. 2016;9:46. [ PMC free article ] [ PubMed ]
9. Naraghi R, Bremner A, Slack-Smith L, Bryant A. Radiographic Analysis of Feet With and Without Morton’s Neuroma. Foot Ankle Int. 2017 Mar;38(3):310-317. [ PubMed ]
10. Masala S, Cuzzolino A, Morini M, Raguso M, Fiori R. Ultrasound-Guided Percutaneous Radiofrequency for the Treatment of Morton’s Neuroma. Cardiovasc Intervent Radiol. 2018 Jan;41(1):137-144. [ PubMed ]
11. Lizano-Díez : A Prospective, Double-Blinded, Randomized, Placebo-Controlled Trial. Foot Ankle Int. 2017 Sep;38(9):944-951. [ PubMed ]
12. Lee J, Kim J, Lee M, Chu I, Lee S, Gwak H. Morton’s Neuroma (Interdigital Neuralgia) Treated with Metatarsal Sliding Osteotomy. Indian J Orthop. 2017 Nov-Dec;51(6):692-696. [ PMC free article ] [ PubMed ]
13. Credit in part: Usama Munir; Dawood Tafti; Samer Morgan.