Description

• Painful condition of the webbed spaces of the toes
• Features perineural fibrosis of the common digital nerve as it passes between metatarsals
  • The interspace between the 3rd and 4th metatarsals is most commonly affected.
  • The interspace between the 2nd and 3rd metatarsals is the next most common site.
• Systems affected: musculoskeletal, nervous
• Synonyms: plantar digital neuritis; Morton metatarsalgia; intermetatarsal neuroma

Epidemiology

Prevalence

• Unknown
• Mean age: 45 to 50 years
• Predominant sex: female > male (8:1)

Etiology and Pathophysiology

• Lateral plantar nerve joins a portion of medial plantar nerve, creating a nerve with a larger diameter than those going to other digits.
• Etiology not fully understood; four main theories:
  • Chronic traction damage
  • Inflammatory environment due to intermetatarsal bursitis
  • Compression by the deep transverse intermetatarsal ligament
  • Ischemia of vasa nervorum
• Nerve lies in SC tissue, deep to the fat pad of foot, just superficial to the digital artery and vein.
• Superficial to the nerve is the strong, deep transverse metatarsal ligament that holds the metatarsal bones together.
• With each step the patient takes, the inflamed nerve becomes compressed between the ground and the deep transverse metatarsal ligament. This can generate perineural fibrotic reaction with subsequent neuroma formation.

Risk Factors

• High-heeled shoes
  • Transfer more weight to the forefoot.
• Shoes with tight toe boxes
  • Cause lateral compression
• Pes planus (flat feet)
  • Pulls nerve medially, increasing irritation
• Obesity
• Female gender
• Ballet dancing, particularly associated with the demi-pointe position
• Basketball, aerobics, tennis, running, and similar activities
• Hyperpronation

General Prevention

• Wear properly fitting shoes.
• Avoid high heels and shoes with narrow toe boxes.