Definition
- Compressive neuropathy of the interdigital nerve
Epidemiology
- Women > Men – likely shoewear related
Aetiology
- Shoewear – narrow toe box and high heels (squeezes spaces together)
- Bursal Hypertrophy causes compression
- Position:
- Most common in 3rd space (between 3rd and 4th toes)
- Then 2nd space, followed by 4th space
- 4th space uncommon, 1st space virtually unheard of
- Think again if these areas are affected
Symptoms
- Pain – well-localised to area
- Worse on weight-bearing, especially in high heels
- Burning or numb sensation around toes
Signs
- Pain on palpation between plantar MT spaces
- Mulder’s Click
- Click felt while palpating on volar aspect and squeezing MTs
- Painful click felt
Imaging
XR
- Screening for other causes of metatarsalgia-type pain
USS & MRI
- Both potentially useful, but diagnosis is clinical
- MRI has a high false-positive rate
- USS is user-dependent – may not change management
Management
Non-Operative
- Works for the majority
- Activity modification
- Shoewear alteration – avoid heels or narrow toe boxes
- Metatarsal bar to offload forefoot
- Steroid Injection
- Can work permanently
- Probably most accurate under USS guidance
- Diagnostic and therapeutic value
Surgical
- Commonly through a longitudinal incision in IM space
- Nerve lies deep to Transverse Metatarsal Ligament (TMTL)
- Surgical Steps:
- Divide TMTL
- Dissect nerve
- Key: Excise nerve and all its fibres just proximal to the bifurcation and a few centimetres proximal to web space
- Send for histology to confirm you have excised the original neuroma
- Minimises risk of neuroma formation
Results
- 80-85% cure rate
- Improved by correct patient selection
Complications
- Primary complication is recurrence – neuroma formation
- Usually due to insufficiently proximal nerve resection
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