Review Question - QID 211638

The patient in the above scenario presents with symptoms consistent with an interdigital neuroma. The most effective treatment is excision of the interdigital nerve and the most common complication is a neuroma secondary to inadequate nerve resection.

Interdigital neuroma (Morton's neuroma) most commonly involves the 3rd and 4th interdigital nerves at the 3rd webspace. Patients typically present with pain, plantar paresthesias, and may have a palpable neuroma or a Mulder click. Treatment usually begins with a wide toe box shoe and metatarsal pads. Corticosteroid injections have shown limited efficacy. The most efficacious and long-lasting treatment is interdigital nerve excision. The most common complication is a neuroma secondary to inadequate nerve resection. Other complications include inadequate nerve retraction as it remains tethered leading to continued symptoms, painful plantar scar, intermetatarsal instability if the intermetatarsal ligament is not repaired, and inappropriate resection of the neurovascular bundle or lumbrical.

Pomeroy et al. reviewed the different entrapment neuropathies of the lower extremity. They discussed the anatomy, diagnosis, and treatment of tarsal tunnel, proximal tarsal tunnel, jogger's foot, Baxter Neuropathy, Soleal sling syndrome, Morton neuroma, Superficial peroneal nerve entrapment, anterior tarsal tunnel syndrome, and entrapment neuropathies of the sural and saphenous nerves. In regards to Morton's neuroma, the most common complication is a recurrence secondary to inadequate nerve resection and excellent outcomes have been reported with adequate resection in 78-96%.

Johnson et al looked at 34 patients for a total of 37 feet that had reoperations for pain that persisted following Morton neuroma excision. They found on reoperation that 67% of people suffered from a neuroma secondary to inadequate initial resection and only one patient had a painful plantar scar. They concluded that inadequate resection is the most common reason for persistent symptoms following nerve resection.

Incorrect Answers:
Answer 1: Most commonly these are approached dorsally and as such a painful plantar scar is not as common.
Answer 2: Intermetatarsal instability is possible if the intermetatarsal ligament is violated and not repaired, but is not the most common complication of nerve excision.
Answer 4: Inappropriate resection of the neurovascular bundle or lumbrical is a possible complication, but is not the most common.
Answer 5: The nerve can become tethered on local tissue, which prevents retraction but this is not the most common cause of a neuroma.