Morton’s Neuroma: Is Excision Superior?

Yes.

The authors contend that surgical removal of Morton’s neuroma is preferred due to long-term positive clinical outcomes and patient satisfaction. Here they present evidence from the literature, and a discussion of pros and cons for several surgical approaches.

By Marc Jones, DPM, DABFAS, FASPS, and Jean V. Archer DPM, FACPM, CWS, FACCWS, FASPS, FAPWHc

In 1876, Thomas Morton first described Morton’s neuroma, characterizing it as digital nerve impingement between the metatarsal heads.¹ Cirvinini reported the first recorded case in 1835,² and Durlacher provided details on cause and treatment in 1845.³ Over the past 140 years with continued research, the choice is clear to these authors: surgical excision is better than conservative treatment for pedal neuromas.

Impacting Outcomes Through the Diagnostic Process

Morton’s neuromas are found in the third pedal interspace, the most common location of pedal neuromas.¹ The history and clinical exam are the most effective diagnostic tools. A positive Mulder’s click is 94–98% sensitive, although a negative test does not rule out the diagnosis.¹ For successful and comprehensive diagnosis, one must rule out other differential diagnoses, including potentially using diagnostic blocks when indicated. Advanced imaging such as magnetic resonance imaging (MRI) or ultrasound are unnecessary and generally complicate the picture. A positive finding on MRI has not been shown to correlate with the size of the lesion or clinical and histopathological exams.² However, history and clinical examination offers greater specificity and sensitivity than ultrasound and MRI.⁴ Foot X-rays can help to exclude other causes of forefoot pain.^5,6

Why Conservative Treatment Is Not Always the Answer

In the authors’ experience, conservative treatment options for Morton’s neuroma carry their own list of complications to consider. The literature on alcohol sclerosing injections includes reports of bone marrow edema, burning, worsening of symptoms, digital ischemia, osteonecrosis of the metatarsal heads and skin depigmentation.⁷ In a 5-year follow-up study, only 29% of patients receiving alcohol sclerosing injections had pain relief, with up to 80% of patients going on to surgery.⁸ Studies also note that these injections may only reduce the size of the neuroma from 30–50%.^8,9  

In a large meta-analysis by Lu and colleagues, corticosteroid injections only provided relief for 1 week to 3 months, with a satisfaction rate of 35%, and only 43% of patients related complete pain relief immediately after the injection.¹⁰ Eventually, 95% of patients receiving corticosteroid injection had recurring pain and symptoms. One must also consider the risk of metatarsophalangeal joint capsule or plantar plate rupture when undertaking corticosteroid injection therapy in this anatomic region.

When Is Surgery the Best Option?

The literature strongly supports surgical excision for Morton’s neuroma. Patients report 80–89% good-to-excellent results^10-12 with complications as low as 1%, as reported in a large meta-analysis.¹⁰ One may argue that conservative treatment can be done initially with the goal of periodic relief and/or delaying surgery. However, the literature suggests that the best results for treating neuromas occur when a single neuroma resection take place within 12 months of onset of symptoms.¹³ Therefore, delaying surgical treatment may decrease the chance of a successful surgical outcome.

Examining Various Surgical Approaches

Multiple types of surgical treatment have been discussed in the literature: neurectomy with dorsal incision, neurectomy with plantar incision (transverse or longitudinal), and release of the dorsal intermetatarsal ligament without neurectomy. The decision on which approach to use is typically based on the surgeon’s preference.¹³ Some authors advocate for the dorsal approach, allowing for immediate weight-bearing and decreasing the risk of a painful plantar scar. The literature does report increased scar complications with a plantar approach, up to 32% in one study.¹² Zhang and colleagues published equal outcomes between the dorsal and plantar approaches, 89% versus 88%.¹² Although non-weight-bearing after plantar incision surgery is generally an accepted practice, Soldait and team showed only a 7% incision complication rate with weight-bearing immediately postop.¹⁴ Other complications seen more commonly with the plantar approach as compared to dorsal are wound dehiscence and hematoma.⁸ The dorsal surgical approach takes more dissection, which may increase surgery time and risk for sensory loss.⁸

Amis and team¹⁵ suggest that the plantar branches of the digital nerve can cause tethering of the transected nerve, resulting in recurrent neuromas under the weight-bearing portion of the foot, rather than retracting into the intrinsic musculature. Some experts recommend cutting the digital nerve 1-3 cm proximal to the bifurcation to prevent this.¹⁵ However, this can be challenging to achieve through a dorsal approach, as it may result in inadequate resection of the digital nerve and damage to cutaneous nerves in the web space, which can become painful.

The plantar approach is more traditionally used for recurrent Morton’s neuromas or amputation/stump neuromas. This approach is more direct than the dorsal approach because the nerve lies superficial to the intermetatarsal ligament. Betts first described the plantar approach in 1940¹⁶, and Nissen reinforced the description in 1948.¹⁷ Incision placement is crucial, as dissection performed medially or laterally can create scarring of the fatty tissue. This may result in the scar becoming inverted, or the fat pad beneath a metatarsal head may become atrophic. The most frequent complications of the plantar excisional approach include localized scar tenderness, wound drainage, and plantar keratosis.

Neurolysis, the release of the deep intermetatarsal ligament without neurectomy, is another surgical option. The theory is that once the neuroma is decompressed, the pain will resolve. Research reveals that results are not ideal when compared to neurectomy. Complete pain relief with neurolysis is reported in 68% of patients, with a satisfaction rate of 63%.¹⁰ Minimally invasive neurolysis revealed a success rate of 50%, and 41% of the patients eventually proceeded to a traditional open neurectomy.¹⁸

Concluding Thoughts

Surgical excision has been proven effective in treating neuromas through various studies. However, it is important to note that long-term follow-up studies are rare. However, in a retrospective analysis of 111 excised neuromas conducted by Kasparek in 2013, the clinical outcome was followed for 15.3 years.¹³ The author revealed that 76.5% of participants reported good or excellent results and experienced pain relief.¹³ Coughlin in 2001 reported that 85% of patients had good clinical results after neuroma excision through a dorsal approach.¹⁹ The study also found that patients who underwent excision of neuromas in adjacent interspaces or bilaterally had slightly lower satisfaction levels. The Kasparek study similarly found that the incidence of multiple neuromas correlated with inferior outcomes.¹³ In Kasparek’s study, the loss of sensation was expected but did not affect the patient’s overall satisfaction. The rate of complications and recurrence was very low. The study demonstrated that excision resulted in a high rate of good and excellent results.¹³

Neuromas are a common pathology that presents to our offices. There are many different types of conservative treatment options that have been proposed including pads and injections but often they only offer temporarily relief and many patients end up pursuing surgical treatment. Surgery has a high rate of success and a very low complication rate, especially when properly managing patient expectations on numbness, intervening early, and when the excision involves a single, unilateral neuroma. Neurolysis is less than favorable due to higher failure rate than neurectomy, supporting that excision is indeed superior.

Dr. Jones is a Fellow of the American Society of Podiatric Surgeons and an attending with the DVA Puget Sound HCS residency program. He practices in Spokane, WA.

Dr. Archer is affiliated with Noyes Health/University of Rochester Medical Center Geneseo Regional Orthopedics & Podiatry in Dansville, NY.  

References

1.     Morton D. A peculiar and painful affection of the fourth metatarsal-phalangeal articulation. Am J Med Sci. 1876; 7:37-45.
2.     Civinini F. Su d’un nervosa gangliare rigonfiamento alla pianta del piede. Lettera anatomica l Dr. Salomone Lampronti, Pistoia, Tip Bracali. 1835.
3.    Durlacher L. Treatise on Corns, Bunions, the Disease of the Nails and the General Management of the Feet. Simpkin-Marshall, London. 1845.
4.     Torres-Claramount R, Gines A, Pidemunt G, Puig Ll de Zabala S. MRI and ultrasonography in Morton’s neuroma: Diagnostic accuracy and correlation. Indian J Orthop. May 2012; 46(3):321–5.
5.     Read JW, Noakes JB, Kerr D, Crichton KJ. Morton’s metatarsalgia: sonographic findings and correlated histopathology. Foot Ankle Int. 1999;20:153–161. doi: 10.1177/107110079902000303
6.     Sharp RJ, Wade CM, Hennessy MS, Saxby TS. The role of MRI and ultrasound imaging in Morton’s neuroma and the effect of size of lesions on symptoms. J Bone Joint Surg Br. 2003;85:999–1005. doi: 10.1302/0301-620X.85B7.12633.
7.    BIiz C, Bonvicini B, Sciarrretta G, Pendin M, Cecchetto G, Ruggieri P.  Digital Ischemia after ultrasound guided alcohol injection for Morton’s sundrome: case report and review of the literature. J Clin Med. 2022; 11:6263
8.    Caprio FD, Meringolo R, Eddine MS, Ponziani L. Morton’s interdigital neuroma of the foot a literature review. Foot Ankle Surg. 2018; 24:92-98
9.    Gurdezi S, White, T Ramesh P. Alcohol injection for Morton’s neuroma: a five-year follow-up. Foot Ankle Int. 2013; 34(8): 1064-1067
10.    Lu VM, Puffer RC, Everson MC, Gilder HE, Burks SS, Spinner RJ. Treating Morton’s neuroma by injection, neurolysis or neurectomy; a systematic review and meta-analysis of pain and satisfaction outcomes. Acta Neurochirurgica. 2021; 163:531-543.
11.    Akermark C, Crone H, Skoog A, Weidenhielm L. A prospective randomized controlled trial of plantar versus dorsal incisions for operative treatment of primary Morton’s neuroma. Foot Ankle Int. 2013; 34(9):1198-1204.
12.    Zhang J, Li J, Cai W, Zheng K, Huang X, Rong X, Li Q. Effect of surgical approach on the treatment of Morton’s neuroma: a systematic review and meta-analysis. J Foot Ankle Res. 2023; 16(1):57
13.     Kasparek M, Wolfgang, S Surgical Treatment of Morton’s Neuroma: clinical results after open excision. Int Orthoped. 2013;37:1857-1861 doi:10.1007/s00264-013-2002-6
14.    Soldati F, Klaue K. Longitudinal plantar approach for excision of Morton’s neuroma: long term results. J Foot Ankle Surg. 2022; 61(6):1145-1151.
15.    Amis JA, Siverhus SW, Liwnicz BH. An anatomic basis for recurrence after Morton’s neuroma excision. Foot Ankle. 1992 Mar-Apr;13(3):153-156.
16.     Betts LO. Morton’s metatarsalgia: neuritis of the fourth digital nerve. Med J Aust. 1940;1:514-515.
17.    Nissen KI. Plantar digital neuritis: Morton’s metatarsalgia. J Bone Joint Surg Br. 1948 Feb;30B(1):84-94.
18.    Archuleta AF, Darbinian J, West T, Ritterman Weintraub ML, Pollard JD. Minimally invasive intermetataral nerve decompression for Moton’s neuroma: A review of 27 cases. J Foot Ankle Surg. 2020; 59(6):1186-1191.
19.    Coughlin MJ, Pinsonneault T. Operative treatment of interdigital neuroma. A long-term follow-up study. J Bone Joint Surg Am. 2001;83(9):1321–1328.

No.

These authors argue that one should use surgery as a last resort for Morton’s neuroma, citing the encouraging effects of orthotics and shoe gear adaptations, steroid injections, radiofrequency ablation, and deep transverse metatarsal ligament release.

By Nicholas Butler, DPM, and Isaac Adu-Gyamfi, MS

Morton’s neuroma pertains to a neuropathy involving the third common plantar digital nerve. In the third intermetatarsal space, the common digital nerve receives the communicating nerve, culminating in increased nerve thickness and rendering it susceptible to potential trauma and compression. The principal location of Morton’s neuroma is conventionally in the third webspace, situated between the third and fourth metatarsals.

It is essential to clarify that Morton’s neuroma is not a “true” neuroma, and various etiological hypotheses have been debated within the field of podiatry. The precise etiology of Morton’s neuroma remains elusive, yet several theories have gained prominence. These theories are the mechanical theory, entrapment theory, ischemic theory, and bursa theory:¹

• The mechanical theory posits that the repetitive mechanical stresses incurred during walking cause chronic micro-traumas to the common plantar digital nerve.
• The entrapment theory suggests that compression of the nerve transpires against a thickened deep transverse intermetatarsal ligament and the surrounding plantar soft tissue structures, thereby causing neuritis.
• The ischemic theory contends that degenerative changes in the common plantar digital artery precede the fibrous thickening of the nerve, offering insights into the potential ischemic underpinnings.
• The bursa theory suggests that bursitis within the intermetatarsal region provokes compression, inflammation, and consequent fibrosis of the affected common plantar digital nerve.

Primary Neurectomy: Is It the Better Treatment Option?

Primary neurectomy has long held its position as a conventional treatment modality for addressing Morton’s neuroma. While it is undeniable that many surgeons report positive outcomes associated with neurectomy, it is paramount to recognize that a significant subset of patients may contend with persistent complications subsequent to the surgical procedure. In light of these considerations, embracing an infiltrative management approach, with surgical intervention as a final resort, emerges as a more encompassing and pragmatic therapeutic strategy.

As exemplified in the study conducted by Johnson and colleagues, about 25% of individuals who received neurectomy had no discernible improvement after surgery.² This outcome raises pertinent questions regarding the universal benefit of primary neurectomy in Morton’s neuroma cases. It is worth noting, as mentioned by Coughlin, that on occasion, surgical excision and nerve resection can inadvertently lead to the formation of a genuine neuroma, particularly if it is located in weight-bearing regions.³ In certain investigations, the documented recurrence rate of neuromas was approximately 1 in 10 cases.³ Moreover, the occurrence of paresthesia, often challenging to prevent, remains a notable complication.

As elucidated in the study by Coughlin and colleagues, subjectively reported numbness (paresthesia) was identified in 36% of feet, albeit with considerable variability among patients.³ However, an objective assessment revealed paresthesia between the digits in 72% of feet, in the plantar web space in 65%, and in the terminal aspect of the digits in 41%. Several patients experienced paresthesia in multiple areas. This issue of paresthesia is corroborated by additional studies, such as those conducted by Akermark and Valente, which demonstrated that patients in both studies endured paresthesia.^4,5

Are Non-Surgical Treatments Superior?

Orthotics and shoe gear. Orthotic interventions and adaptations to footwear are integral components of the non-surgical management of forefoot pathologies. Tailored footwear can optimize a patient’s gait and enhance their mobility. Conversely, inadequate footwear selections can exacerbate symptoms and potentially serve as a contributing factor to the development of these conditions.⁶ The utilization of a metatarsal pad can significantly alleviate neuroma-related pain by evenly distributing force across all metatarsal bones.⁷ Bennett and colleagues’ research highlights the efficacy of conservative treatments, with a noteworthy 41% of patients experiencing improvements when their footwear was either altered or customized.⁸ This underscores the positive impact of noninvasive interventions in the realm of forefoot pathology management.

Steroid injections. In cases where orthotic interventions prove insufficient, corticosteroid administration presents a viable alternative for patients. Steroid injections have demonstrated favorable results, as indicated by Johnson satisfaction scores.⁹ Nevertheless, it’s essential to note that the efficacy of steroid injections might be limited to several months, with an annual usage cap recommended. An alternative approach involves the utilization of a 4% alcohol sclerosing solution, boasting a remarkable 89% success rate, with 82 out of 89 patients experiencing complete resolution of their symptoms.¹⁰ This promising outcome suggests a robust treatment option for those who do not respond favorably to conventional orthotic interventions or corticosteroid injections.

Radiofrequency ablation. Radiofrequency ablation is a medical procedure employing high-frequency radio waves to elevate the temperature of the affected sensory nerve in Morton’s neuroma to approximately 90ºC. This controlled heat application effectively disintegrates proteins, thereby impeding the transmission of pain signals along the nerve fibers. Chuter and colleagues conducted a study that reported the use of ultrasound-guided radiofrequency ablation had proven to be highly successful in alleviating the symptoms associated with Morton’s neuroma, achieving this outcome in over 85% of patients. Moreover, this approach demonstrated a reduction in the necessity for surgical excision, highlighting its potential as a promising non-surgical treatment option for this condition.¹¹

Deep transverse metatarsal ligament release. The concept of entrapment prompted Gautier to pioneer the documentation of outcomes resulting from two specific procedures: the deep transverse metatarsal ligament release and epineural neurolysis.¹² In his study, encompassing treatment of 304 nerves, it was observed that symptoms were successfully resolved in 83% of the patients.¹² This method, unlike neurectomy, exhibits a distinct advantage by averting any loss of sensation or recurrent neuroma-related issues. Furthermore, the use of endoscopic instruments, advocated by Shapiro, ensures a rapid recovery period, accompanied by a notably low risk of complications such as hematoma or infection.¹³ This underscores the safety and effectiveness of these procedures in managing Morton’s neuroma.

Final Words

Morton’s neuroma is a complex condition involving the third common plantar digital nerve, commonly located in the third intermetatarsal space. While its precise etiology remains elusive, several theories, including the mechanical, entrapment, ischemic, and bursa theories, provide insight into its potential origins. Contributory factors such as footwear choices, high-impact activities, joint pathology, and trauma play significant roles in Morton’s neuroma’s development. Primary neurectomy has traditionally been a conventional treatment option, but its universal benefit is now being questioned due to persistent complications and the potential for neuroma recurrence and paresthesia. Alternative treatment modalities, such as orthotics and shoe gear adaptations, steroid injections, radiofrequency ablation, and deep transverse metatarsal ligament release, offer promising non-surgical options. These approaches provide relief for patients without the risks associated with surgery, making them valuable considerations in the management of Morton’s neuroma.

In light of the evolving understanding of this condition and the availability of effective non-surgical interventions, the choice of treatment for Morton’s neuroma should be carefully tailored to the individual patient’s needs and preferences, with surgery being reserved as a last resort. This comprehensive approach acknowledges the multifaceted nature of Morton’s neuroma and strives to provide patients with the most effective and least invasive treatment options available.

Dr. Butler is an Assistant Professor in the Division of Clinical Medicine and Surgery at Kent State University College of Podiatric Medicine.

Isaac Adu-Gyamfi, MS, is a podiatric medical student at Kent State University College of Podiatric Medicine.

References

1. Munir U, Tafti D, Morgan S. Morton Neuroma. [Updated 2023 May 22]. In: StatPearls[Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.https://www.ncbi.nlm.nih.gov/books/NBK470249/
2. Johnson JE, Johnson KA, Unni KK. Persistent pain after excision of an interdigital neuroma. Results of reoperation. J Bone Joint Surg Am. 1988 Jun;70(5):651-7.
3. Coughlin MJ, Pinsonneault T. Operative treatment of interdigital neuroma. A long-term follow-up study. J Bone Joint Surg Am. 2001 Sep;83(9):1321-8.
4. Akermark C, Crone H, Skoog A, Weidenhielm L. A prospective randomized controlled trial of plantar versus dorsal incisions for operative treatment of primary Morton’s neuroma. Foot Ankle Int. 2013; 34(9):1198-1204
5. Valente M, Crucil M, Alecci V. Operative treatment of interdigital Morton’s neuroma. Chir Organi Mov. 2008 May;92(1):39-43.
6. Colò G, Rava A, Samaila EM, et al. The effectiveness of shoe modifications and orthotics in the conservative treatment of Civinini-Morton syndrome: state of art. Acta Biomed. 2020 May 30;91(4-S):60-68.
7. Hinz A. Nerve disorders. In: DiGiovanni CW, Greisberg J, editors. Foot and Ankle: Core Knowledge in Orthopaedics. Philadelphia: Elsevier Mosby; 2007, pp. 171–6.
8. Bennett GL, Graham CE, Mauldin DM. Morton’s interdigital neuroma: a comprehensive treatment protocol. Foot Ankle Int. 1995 Dec;16(12):760–3.
9. Choi JY, Lee HI, Hong WH, Suh JS, Hur JW. Corticosteroid injection for Morton’s interdigital neuroma: a systematic review. Clin Orthop Surg. 2021 Jun;13(2):266-277.
10. Dockery GL. The treatment of intermetatarsal neuromas with 4% alcohol sclerosing injections. J Foot Ankle Surg. 1999 Nov-Dec;38(6):403-8. Doi: 10.1016/s1067-2516(99)80040-4. PMID: 10614611.
11. Chuter GS, Chua YP, Connell DA, Blackney MC. Ultrasound-guided radiofrequency ablation in the management of interdigital (Morton’s) neuroma. Skeletal Radiol. 2013 Jan;42(1):107-11.
12. Gauthier G. Thomas Morton’s disease: A nerve entrapment syndrome. Clin Orthop Relat Res. 1979;142:90–92.
13. Shapiro SL. Endoscopic decompression of the intermetatarsal nerve for Morton’s neuroma. Foot Ankle Clin. 2004 Jun;9(2):297-304.

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