Morton's Neuroma & Metatarsalgia

History: forefoot pain described as burning, shooting, or electrical - localised to the intermetatarsal space (most commonly the 3rd). The neuropathic character is the key distinguishing feature. Numbness or tingling radiates into the adjacent sides of the two affected toes. Symptoms worsen with tight or narrow shoes and with weight-bearing, improving on rest and shoe removal. Patients often describe a sensation of walking on a pebble or a lump in the shoe. Symptoms are usually unilateral; widespread or bilateral symptoms should prompt consideration of proximal neuropathic causes (lumbar radiculopathy, peripheral neuropathy).

Examination:

• •Tenderness in the intermetatarsal space - palpate between the metatarsal heads from plantar and dorsal simultaneously. The tenderness is between the heads (interdigital), NOT directly under a metatarsal head
• •Mulder click (Mulder test): squeeze the metatarsal heads together transversely with one hand while applying plantar-to-dorsal pressure in the affected space with the other; a palpable or audible click as the neuroma subluxes is positive. Supports the diagnosis when present but is often absent and is not pathognomonic
• •Sullivan sign: visible splaying of the toes adjacent to the neuroma when weight-bearing, from the mass effect of the thickened nerve and bursa
• •Sensory alteration in the web space and adjacent sides of the affected toes
• •Assess the forefoot (hallux valgus, hammer or claw toes, callosities, metatarsal head prominence) and footwear (narrow toe box, high heels)

The critical clinical differentiation: Morton pain is interdigital and neuropathic; mechanical metatarsalgia pain is directly plantar to a metatarsal head, usually with overlying callosities. Plantar plate tear (usually 2nd MTP) shows direct plantar MTP tenderness with instability on the vertical stress test (modified Lachman of the MTP) and progressive crossover toe.

Red flags: a hot, swollen, erythematous MTP joint requires exclusion of septic arthritis and crystal arthropathy; bilateral symmetrical forefoot pain with prolonged morning stiffness suggests inflammatory arthritis (MTP synovitis is often the earliest sign of RA); focal metatarsal bone tenderness raises stress fracture; night pain and weight loss raise bone tumour or infection.

Morton neuroma is often diagnosed clinically. Investigations are used when the diagnosis is uncertain, another cause is possible, or before injection or specialist referral.

Ultrasound is the most commonly used imaging modality in UK MSK practice. It demonstrates the neuroma as a hypoechoic mass; neuromas larger than 3 mm are generally considered clinically significant, and those larger than 5 mm are less likely to respond to conservative measures. USS also differentiates from bursitis (identifying the neuroma-bursal complex), allows dynamic Mulder manoeuvre, and guides injection. It is operator-dependent.

MRI is more detailed and less operator-dependent, used when USS is inconclusive or for surgical planning. Incidental interdigital neuromas can be seen on MRI in asymptomatic individuals - imaging must always be interpreted in clinical context.

Weight-bearing plain radiographs do not visualise the neuroma but assess metatarsal alignment, stress fractures, Freiberg disease, MTP osteoarthritis or erosions, and hallux valgus.

Bloods are not routine. Consider RF, anti-CCP, ESR and CRP if inflammatory arthritis is suspected; serum urate for gout; HbA1c if peripheral neuropathy is in the differential.

Management depends on the underlying cause. For Morton neuroma, conservative management is first-line per NICE CKS.

Morton neuroma - conservative:

• •Footwear modification (the standard first step per NICE CKS): wide toe box, avoid narrow pointed or tight shoes, heels no higher than 2 cm, good forefoot cushioning, lace-up shoes that can be loosened
• •Metatarsal pad (dome pad): placed just PROXIMAL to the metatarsal heads (NOT directly under them) to splay the heads and offload the intermetatarsal space. Correct positioning is critical - placed too distally it worsens symptoms
• •Orthoses: prefabricated or custom insoles with metatarsal pad and forefoot cushioning
• •Activity modification: reduce high-impact forefoot loading temporarily
• •Short-course oral NSAIDs or paracetamol; topical NSAIDs may be tried
• •Corticosteroid injection: a reasonable second-line intervention when footwear and padding are insufficient, often USS-guided. Including a local anaesthetic alongside provides immediate diagnostic confirmation if pain resolves. Response is variable and may not be sustained; risks include fat pad atrophy, skin depigmentation, and plantar plate weakening - repeat injections should be limited

Morton neuroma - surgical:

• •Indicated after failure of adequate conservative management
• •Neurectomy (the standard procedure): excision of the affected nerve segment, typically via a dorsal approach in UK practice. Results in permanent numbness in the adjacent sides of the affected toes (expected - must be counselled). Stump neuroma formation is a recognised complication
• •Nerve decompression (DTIML release): an alternative preserving sensation; evidence is less extensive

Mechanical metatarsalgia: address the biomechanical cause, supportive or rocker-bottom footwear, metatarsal pad proximal to the heads, custom orthoses, calf stretching (tight gastrocnemius or Achilles shifts load to the forefoot - one of the most important interventions), podiatric callus management.

Plantar plate tear: taping the toe in plantarflexion, stiff-soled shoes, metatarsal pad, orthoses; surgical plantar plate repair for persistent symptoms with progressive deformity.

Refer to podiatry for footwear assessment, orthoses, and callus management. Refer to a foot and ankle service if conservative measures fail, diagnosis is uncertain, progressive toe deformity (plantar plate), or suspected Freiberg disease; refer to rheumatology if inflammatory arthritis is suspected.

Rehabilitation for Morton neuroma is primarily conservative management (footwear, padding, orthoses) rather than a progressive loading protocol.

• •Phase 1 (symptom modification, 0 to 6 weeks): footwear modification (wide toe box, low heel - the priority), metatarsal pad correctly positioned proximal to the metatarsal heads, activity modification, trial of prefabricated insole, short-course analgesia, calf stretching if gastrocnemius tightness contributes
• •Phase 2 (optimisation, 6 to 12 weeks): review response to footwear and padding; if insufficient, consider corticosteroid injection (with local anaesthetic for diagnostic confirmation) and custom orthoses; intrinsic foot strengthening (short-foot exercise, toe curls)
• •Phase 3 (return to activity, 12+ weeks): gradual return to higher-impact activity if symptoms allow, maintain footwear modifications permanently, ongoing metatarsal pad or orthoses, specialist referral if symptoms persist

Mechanical metatarsalgia rehabilitation centres on calf stretching (gastrocnemius and soleus), intrinsic foot strengthening, and supportive or rigid-soled footwear with podiatric callus management.

Post-neurectomy: supportive footwear, progressive weight-bearing, graduated return to walking over 4 to 6 weeks. Expect permanent web space numbness; monitor for stump neuroma symptoms.

• •NICE CKS: Morton neuroma - footwear modification is the standard first step; corticosteroid injection is reasonable second-line; refer if conservative care fails.
• •NICE CKS: Metatarsalgia - structured framework for the broader differential and biomechanical management.
• •Bencardino et al. (Radiology 2000) - established USS criteria for clinically significant neuroma (greater than 3 mm) and the operator-dependent nature of the technique.
• •Thomson et al. (Cochrane review) - inconclusive evidence base for individual interventions; symptom-led stepwise care remains the UK norm.
• •BOFAS UK consensus - conservative measures are first-line; neurectomy is reserved for failed conservative management with appropriate counselling about expected permanent web space numbness.

• •Morton neuroma is NOT a true neuroma - perineural fibrosis and compressive neuropathy. The 3rd space is most commonly affected because the nerve there is thicker (dual supply) and the space is narrower.
• •Pain is INTERDIGITAL (between the metatarsal heads) and neuropathic - mechanical metatarsalgia pain is directly UNDER the heads. This location distinction is the most important clinical differentiation.
• •The metatarsal pad is placed PROXIMAL to the metatarsal heads (not under them) - commonly tested.
• •Mulder click supports the diagnosis when positive but is often absent and is not pathognomonic.
• •USS is the most commonly used imaging modality; neuromas larger than 3 mm are clinically significant. Incidental neuromas can be seen on MRI in asymptomatic feet.
• •Neurectomy is the standard surgery - permanent web space numbness is expected and must be counselled; stump neuroma is a recognised complication.