Morton's Neuroma

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | References

Definition

Morton's neuroma is a painful condition affecting one of the nerves between the toes, typically the nerve between the third and fourth metatarsals. It is characterised by the thickening of the tissue around one of the nerves leading to the toes, causing sharp, burning pain in the ball of the foot.

Aetiology

Morton's neuroma is primarily caused by:

• Repetitive irritation or pressure on the plantar nerve, often due to wearing tight or ill-fitting shoes
• Foot abnormalities such as flat feet, high arches, or bunions that increase pressure on the nerve
• Occupational or athletic activities that involve repetitive stress to the foot, such as running or dancing
• Previous foot injuries that may alter the structure of the foot or cause scarring around the nerve

Pathophysiology

The pathophysiology of Morton's neuroma involves:

• Chronic compression and irritation of the interdigital nerve, leading to nerve inflammation and thickening of the surrounding tissue
• Formation of a benign growth or neuroma around the affected nerve, exacerbating symptoms
• Nerve compression causes altered nerve signalling, resulting in pain, numbness, or tingling in the toes

Risk Factors

• Wearing high-heeled or narrow-toed shoes
• Participation in high-impact sports, especially running or racquet sports
• Foot deformities, such as bunions, hammertoes, or flat feet
• Previous foot injuries
• Female gender, as women are more likely to wear tight shoes and are more commonly affected

Signs and Symptoms

The signs and symptoms of Morton's neuroma include:

• Sharp, burning pain in the ball of the foot that may radiate into the toes
• Feeling like there is a pebble in the shoe or a fold in the sock
• Numbness or tingling in the toes, especially the third and fourth toes
• Worsening of pain with activities such as walking, standing, or wearing tight shoes
• Relief of symptoms when removing shoes or massaging the foot

Investigations

Specific investigations to diagnose Morton's neuroma include:

• Clinical examination: Palpation of the affected area may reproduce symptoms, and a Mulder’s click test may indicate the presence of a neuroma.
• Imaging studies:
  • Ultrasound: Commonly used to detect thickening of the nerve and surrounding tissue.
  • MRI: Provides detailed images of soft tissues and can confirm the diagnosis of Morton's neuroma.
  • X-rays: Typically used to rule out other causes of foot pain, such as fractures or arthritis.

Management

Primary Care Management

• Footwear modification: Wearing shoes with a wide toe box, low heels, and adequate cushioning to reduce pressure on the neuroma.
• Orthotic devices: Custom or over-the-counter orthotics to offload pressure from the affected area.
• Pain management: Analgesics such as paracetamol or NSAIDs to relieve pain and inflammation.
• Activity modification: Avoiding activities that exacerbate symptoms, such as high-impact sports or prolonged standing.
• Padding and taping: Using metatarsal pads or taping the foot to help redistribute pressure away from the neuroma.

Specialist Management

• Corticosteroid injections: Administered to reduce inflammation and pain around the affected nerve.
• Alcohol sclerosing injections: Occasionally used to shrink the neuroma by injecting alcohol into the nerve.
• Surgical intervention: Considered for persistent or severe cases where conservative treatment fails. Surgery may involve removing the neuroma or releasing the surrounding ligament.
• Postoperative care: Includes physiotherapy and rehabilitation to restore function and prevent recurrence.

References

1. NHS (2024) Morton's Neuroma. Available at: https://www.nhs.uk/conditions/mortons-neuroma/ (Accessed: 24 June 2024).
2. National Institute for Health and Care Excellence (2024) Morton's Neuroma. Available at: https://cks.nice.org.uk/topics/mortons-neuroma/ (Accessed: 24 June 2024).
3. British Medical Journal (2024) Morton's Neuroma: Clinical Features, Diagnosis, and Management. Available at: https://www.bmj.com/content/350/bmj.h2921 (Accessed: 24 June 2024).
4. American Academy of Orthopaedic Surgeons (2024) Morton's Neuroma. Available at: https://orthoinfo.aaos.org/en/diseases--conditions/mortons-neuroma/ (Accessed: 24 June 2024).

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