Morton’s neuroma

Dr.Rajiv Shah‘Foot & Ankle Orthopaedics’Foot & Ankle SurgeonPresident, Indian Foot & Ankle Society

Anatomy of Plantar Nerves

Nomenclature Traditionally referred to as “Morton’s

Neuroma” Other terms

Interdigital Neuroma▪ Though histological analysis shows its

not a true nerve tumor ▪ Intraneural fibrosis, increased elastic

fibers in stroma, degeneration of fibers

Interdigital Neuritis▪ “itis” implies inflammation though

this is also a misnomer

Interdigital Neuralgia Preferred term Implies pain and lack of inflammation

Metatarsal head spacing

Intermetatarsal ligament thickness

Mobility of surrounding joints

Trauma

Pathogenesis: theories

MPN and LPN share a communicating branch between the 3rd and 4th toe in ~ 28% of feet

Significantly narrower space between 2nd and 3rd webspace compared to the 1st and 4th (Levitsky, FAI 1993)

Mobility of 1/2/3 MT small secondary to cuneiform complex

4/5 are more mobile which could lead to traction and trauma

However, incidence of 2nd webspace neuromas negate this as a primary cause

Direct insult Overuse with tight shoe Aberrant anatomical bands, fat pad atrophy, and thickening of MTP joint capsuleMultifactorial

Diagnosis

Women > Men (4-15 times more common)

Average age: 40 – 60 years old (avg 55)

Symptoms: Sharp, stabbing, tingling with radiation to the toes, feeling of “waddling up of their sock”

Mulder’s click Compression of the forefoot and

the nerve is pushed plantar by the 3rd and 4th metatarsal heads

Neuroma should be diagnosis of exclusion Doubt if not in 3rd webspace Very rare in 1st and 4th

Radiographs – Evaluate for osseous abnormalities, arthritis, subluxations

Reliance on MRI or ultrasound would have led to inaccurate diagnosis in 18 of 19 cases (Sharp, JBSJ Br 2003)

33%, 57 MRIs, of asymptomatic feet were reported to have a neuroma (Bencardino AJR 2000)

Electrodiagnostic studies are not recommended

Diagnostic injections had a 24% failure rate after resection of nerve and 43% failure after revision resection (Younger Can J 1998)

Ultrasound Mahadevan et al4

assessed the diagnostic accuracy of 7 clinical tests for Morton's neuroma compared with ultrasonography

Morton’s neuroma was confirmed on US at the site of clinical diagnosis in 98% feet

Conservative care

Metatarsal Pads and a wide toe box can improve symptoms in 41% of patients

Corticosteroid injections show 60-80% relief with injection, but only 30% maintain benefit at 2 years

Neuroma Alcohol-Sclerosing Therapy (NAST) report overall success of 61% , best with greater than 5 injections (Mozenza et al, J Am Pod ’07)

Phenol injection: An electrode-guided injection of phenol proved

to be effective in 80.3% of cases7

~70% of patients eventually elect to have surgical intervention

Operative care

Long term outcomes with 85% satisfaction 5.8 years after resection (Coughlin JBJS 2001)

Poor results in 40% and worse outcomes in 2nd webspace neuromas (Womack FAI 2008)

Must be sure to resect off WB surface of foot

Long term failure rates range from 15-50% after surgery

Dorsal approach usually advocated secondary to low rate of wound complications and ability to immediately weight bear

Dorsal: Avoids plantar scar Further from nerve (nerve always plantar to vessel)

Plantar: Close to nerve Can produce painful scar Better for revisions

Plantar transverse incision with neuroma resection without disruption of deep transverse ligament

Five percent complained of scar-related symptoms

Plantar neurectomy allows complete resection of nerve without taking perineural fat or bursa by mistake

Operative care: Plantar approach

Endoscopic decompression w/o excision 40 patients No hematomas, infections 3 returned for neurectomy

Operative care

Post-operative care

Mildly compressive dressing Elevation of operative extremity

for 24 hrs WBAT in a hard-soled post-

operative shoe for 4 weeks 2 weeks of NWB for revision cases

Suture removal 2 weeks post-op 4 weeks after surgery may

progress as tolerated in wide toe-box shoes

Return to sports in 4-6 weeks

Position

Magnification is a must!

Tourniquet & Bipolar coagulation

Marking

Incision

Lamina spreader

Deep dissection

Frayer supported dissection

Release

Nerve identification

Nerve excised

Final picture

10 days post-op

End result -6 months follow up

Complications

Recurrence of symptoms is the most common complication May be due to incorrect diagnosis,

incomplete resection or true recurrence Counsel patients pre-operatively

Wound complications (slow healing, superficial cellulitis)

Incisional tenderness after a plantar approach

Residual numbness 2% to 14% of

patients will have persistent pain after surgery

60% to 75% of patients still limited in choice of shoe wear and certain activities

That’s all…Thank you all..