mortons neuroma

Mortons neuroma definition

Benign enlargement or thickening of the interdigital nerve due to chronic irritation, compression or trauma of the nerve causing fibrotic changes in the nerve tissue

Clinical signs and symptoms

sharp burning tingling plantar pain between 3/4th met during weight bearing activities

slight swelling and palpable lump

mortons neuroma anatomy

commonly between 3/4 th met heads

common medial branch of medial/lateral plantar nerve

Mortons neruoma pathophysiology

Common plantar digital nerve

Compressed between met heads and deep transverse inter-metatarsal ligament

mechanical irritation/direct trauma

axonal degeneration (damage to myelin sheath)

chornic irritation triggers inflammatory response

Proliferation of Perineural connective tissue

Deposition of collagen fibers (perineural fibrosis)

Enlargement and thickening of nerve

Vascular insufficiency (localised ischemia/Subsequent axonopathy)

central sensitisation/ectopic firing

mortons neruoma aetiology

4x more common in women

rhematoid arthirtis

mortons neuroma risks

pes cavus (arch) ^forefoot pressure

pes planus (flat)

excessive pronation - abnormal pressure on forefoot

hypermobile forefoot stretch nerve

narrow intermetatarsal space

footwear (narrow toe box/heels- shifts weight on forefoot)

arthritis (joint inflammation/nerve irritation)

mortons neuroma muscles

gastrocnemius/soleus overworked (rely on ankle for propulsion)

FHL/FDL overused

lumbricals/interossei disused (reduced weight bearing on toes)

mortons neuroma ligaments

plantar plates tear - compensatory gait

mortons neuorma secondary consequences

forefoot instability (reduced neuromusclular control, weakens support provided by intrinic muscles of foot)

altered gait (knee/hip/lower back pain)

joint alignment (hammer toe/bunion formation)

functional testing

Mulders click test: Place thumb and fingers around forefoot, Squeezing lateral side of the foot, Use other thumb to push into the webspace +Positive mulder's click hear a click/pop sensation felt under the thumb

lateral squeeze test: Clasp forefoot with one hand, squeeze metatarsal bones together, Compress intermetatarsal web spaces, Pain is indicative of pathology

palpation: pain

MRI Imaging

RESULTS:

Well defined teardrop shaped mass (can detect in early stages, rules out differential diagnosis - stress fractures/arthritis/tumors)

Bright hyperintensive (increased fluid from swelling)

Focal enlargement (swollen portion of nerve)

Ultrasound imaging

RESULTS: Hypoechoic mass (dark) seen within interdigital space (swelling increased fluid in affected nerve)

Thickened/widened nerve

Absence of vascularity - not inflamed lesion

Management exercise

Avoid high impact activities

management footwear/orthotics

Insoles with metatarsal pad or dome to spread metatarsals)

Wide toe box

Carbon fiber insole

Rocker bottom shoe

Management NSAID’s

Anti-inflammatory effect reduces inflammation in surrounding tissue due to nerve irritation or degeneration from mechanical stress/compression

Management Corticosteriod injections

Intermetatarsal space under ultrasound guidance

Management surgery

Neurectomy (removal of affectednerve)(incission in top of the foot)(most invasive)

Neurolysis (Decompression surgery structures compressing nerve are released)

Radiofrequency ablation (heat and destroy nerve tissue)(less intensive)

limitations: infection, nerve damage, stump neuroma, reoccurance, scaring,foot deformity

physical therapy, orthotics during recovery to offload (adherence issues)