Morton's Neuroma

Question 1

What is Morton’s Neuroma?

Answer 1

• Compression neuropathy of INTERDIGITAL NERVE

Question 2

Describe its epiemiology?

Answer 2

• More common in females 9:1
• Most Frequent between 3rd/4th Metatarsals
• 2nd most common between 2/3rd Metatarsals

Question 3

What is the pathology of Morton’s Neuroma?

Answer 3

• Poorly understood
  
  • COMPRESSION/ Tension around TRANSVERSE INTERDIGITAL LIGAMENT
  • Repeptitive microtrauma
  • Endoneural oedema
  • Excessive bursal tissue
  • All of the above can -> fibrosis

Question 4

What is the anatomy of the plantar nerves to the foot?

Answer 4

• From the tibial nerve
• Lateral plantar nerve supplies sole of little, 4th toes and 4/5 and 3/4 webspaces
• Medial plantar nerve supplies sole of great toe, 1st websapace and 2/3 web space
• Note the 3rd interspace recieves branches from noth medial and lateral plantar nerves

Question 5

What webspace has dual nerve supply?

Answer 5

• Between 3rd/4th Metatarsals- the third webspace

Question 6

What does a patient with Morton’s Neuroma present with?

Answer 6

Symptoms

• Pain- 60% -RADATION TO TOE DISTALLY
• Pain often DURING PUSH OFF
• Feelig like a stone on ball of foot
• PARATHESIA- 40% numbness/ dysesthesia plantar web space

Signs

• Plantar tenderness with palpation just DISTAL to METATARSAL heads
• A Mulder’s click ( bursa click) may be elicited when squeeze Metatarsals together
• Metatarsalgia, MTP synovitis or instability must be ruled out

Question 7

What investigations are helpful in DDX Morton’s neuroma?

Answer 7

• Xrays
  
  • 3 weight bearing views of feet to rule out bony deformity
• MRI
  
  • Rule out other pathology
  • not required for diagnosis
• USS
  
  • maybe helpful to evaluate nerve
  • Dependent on size
  • not necessary for diagnosis

Question 8

What is the DDx of Morton’s Neuroma?

Answer 8

• MT synovItis
  
  • can mimic interdigital neuroma
  • Tx of neuroma by steriod injection can exacerbate pathologic ocndition of MTP joint
• MT instability

Question 9

Describe tx of Morton’s Neuroma?

Answer 9

• Non operative
  
  • WIDE SHOE BOX, w FIRM SOLE, MT PAD
    
    • first line of TX
  • CORTICOSTERIOD INJECTION
    
    • ​Usually dorsal
    • Nerve is below transverse mt ligament
    • Avoid injecting MTPJ due to risk of iatrogenic instability
• Operative
  
  • NEUROMA EXCISION
  • ​when non op fails
  • ​NEUROMA DECOMPRESSION
    
    • ​alternative to resection, esp in adjacent neuroma as excision would -> complete numb toe

Question 10

Describe surgical tx of Morton’s Neuroma?

Answer 10

NEUROMA EXCISION

• dorsal longitudinal incision in central web space incise fascia in line
• Incise TRANSVERSE METATARSAL LIG to reveal NEUROMA BENEATH
• EXCISE NEUROMA 2-3CM PROXIMAL to Transverse metatarsal ligament
• BURY STUMP IN INTRINSICS

Question 11

What are the surgical complications?

Answer 11

• STUMP NEUROMA
  
  • most common from INADEQUATE RETRACTION (traction neuritis)
  • tethering of plantar neural branches that prevent retraction following resection
  • INADEQUATE RESECTION ( not proximal enough)
• PAINFUL PLANTAR SCAR- 5% increased risk cf dorsal