Review Question - QID 211649

The patient has a Morton's (interdigital) neuroma and has failed nonoperative treatment. The best next step in treatment is, therefore, dorsal neurectomy.

Morton's neuroma is a compressive neuropathy of the interdigital nerve of the foot that most commonly involves the 2nd and 3rd interdigital nerves. Nonsurgical management involves shoewear modifications using flat shoes with a wide toe box shoe and metatarsal pad and/or corticosteroid injections. Serial corticosteroid injections cause local tissue atrophy and are therefore discouraged. Surgical management via excision of the offending interdigital nerve provides more reliable results than the release of the transverse metatarsal ligament. The most common complication of surgical excision is persistence or recurrence of pain related to inadequate excision of nerve tissue and resultant stump neuroma formation or pain resulting from inadvertent excision of the digital artery or lumbrical tendon instead of the interdigital nerve.

Pomeroy et al. published a review on entrapment neuropathies of the foot and ankle. They reported that surgical treatment of Morton's neuroma is indicated when nonsurgical management fails to provide relief. Excision of the neuroma may produce excellent results but are not guaranteed, with studies demonstrating good outcomes in 51% to 93% of patients. They state that the most common complication is a recurrence of pain as a result of inadequate nerve resection or removal of the incorrect tissue (ie, commonly the lumbrical tendon or digital artery).

Johnson et al. performed a study to assess the outcomes of reoperation for patients with persistent pain after excision of an interdigital neuroma. They found that the recurrent pain in these patients had probably resulted from an incomplete initial excision. Of the 24 patients included in the study, 22 (67%) had complete relief from or marked improvement in pain after reoperation.

Figure A is an MRI demonstrating a neuroma in the 2nd webspace. Illustration A is the same MRI with the neuroma indicated by the yellow arrow.

Incorrect Answers:
Answer 1: Repeat corticosteroid injections is not the best next step in treatment due to the risk of local tissue atrophy.
Answer 3: Transverse metatarsal ligament release may be performed for patients with Morton's neuroma; however, it has shown to be less effective than a dorsal neurectomy.
Answer 4: Distal oblique shortening metatarsal osteotomy can be performed for patients with MTP synovitis and a long 2nd metatarsal but is not an appropriate intervention for a Morton's neuroma.
Answer 5: MTP capsular release with extensor tendon lengthening can be performed for patients with MTP synovitis and without a long 2nd metatarsal but is not an appropriate intervention for a Morton's neuroma.