Interdigital Neuroma 355.6

• Likely due to repetitive trauma from transverse intermetatarsal ligament especially in shoes that cause MTP joint extension

Interdigital Neuroma Anatomy

• common digital nerve to 3rd web space is enlarged.  It is formed from merger of medial branch of lateral planter nerve and lateral branch of medial planter nerve just prox to deep transverse ligament.  Clinical symptoms of IDN occur in 3rh webspace 80% of the time.

Interdigital Neuroma Clinical Evaluation

• Plantar pain that is relieved by rest is the most consistent finding in approximately 90% of patients with Morton's neuroma.  Swelling is not normally associated with Morton's neuroma.  Numbness into the toes is reported in approximately 40% of patients.  Mulder's click is a frequent finding, but is not consistently associated with the presence of a neuroma.  Approximately 3% of patients with a neuroma show widening of the toe interspace
• most commonly female 8/1
• patestehsia, dysesthesia usally 3rd & 4th toes, often vague, diffuse discomfort in forefoot, midfoot and lower leg.  Pts often describe pain as dorsal

Interdigital Neuroma Xray / Diagnostic Tests

Interdigital Neuroma Treatment

• Nonop=wide toe box shoe with a firm sole, metatarsal pad inside shoe or bar on sole of shoe, steroid injection
• Operative=resection of neuroma 2-3cm proximal to deep transverse intermetatarsal ligament through a dorsal incision. 85% good to excellent results
• CPT 28080 excision interdigital neuroma (Morton's neuroma)
• 15% surgical failure rate may be due to incorrect diagnosis, improper web space selection, or stump neuroma formation.

Interdigital Neuroma Technique

• Calf tourniquet.
• Dorsal longitudinal incision from the web space extending proximally 2-3cm.
• Fascia released over the intermetatarsal ligament
• Intermetatarsal ligament transected with a freer elevator placed underneath the ligament to protect the underyling structures
• Dorsally directed pressure under the area aids exposure of the neuroma
• Fine right angle hemostat was utilized to free the nerve and expose the bifucation.
• Proper digital nerves were then transected.
• gentle pressure was placed on the proper nerve and the nerve was then transected proximally
• Specimen was sent for histologic examination.
• Area was copiously irrigated.
• Tourniquet released, hemostasis obtained
• Closure

Interdigital Neuroma Follow-up Care

Interdigital Neuroma Review References

1. Beskin, JAAOS 5:261;1997
2. Bennett GL, Graham CE, Mauldin DM: Morton's interdigital neuroma: A comprehensive treatment protocol.  Foot Ankle Int 1995;16:760-763
3. Weinfeld SB, Myerson MS: Interdigital neuritis: Diagnosis and treatment.  J Am Acad Orthop Surg 1996;4:330-335