summary Interdigital Neuromas, also known as Morton's neuroma, is a compressive neuropathy of the interdigital nerve that often leads to plantar forefoot pain. Diagnosis is made clinically with tenderness over the plantar aspect of the involved webspace with a palpable neuroma and a positive Mulder's click on examination. Treatment is a trial of nonoperative management with a wide shoe box with metatarsal pads. Operative management is indicated for patients with persistent symptoms who fail nonoperative management. Epidemiology demographics middle-aged females (9:1) body location most commonly involves the 3rd and 4th interdigital nerves between the metatarsal heads (3rd webspace) Etiology Pathophysiology mechanism of injury not fully understood compression/tension of the interdigital nerve around the transverse intermetatarsal ligament repetitive microtrauma pathoanatomy perineural fibrosis and entrapment of the interdigital nerve Anatomy Interdigital nerve location lies plantar to the transverse intermetatarsal ligament between the metatarsal heads components confluence branches of the lateral and medial plantar nerves Presentation Symptoms pain worse with weight-bearing or wearing narrow toe box shoes (e.g. high heels) relief of symptoms by removing shoes and massaging foot paresthesia most commonly on the plantar aspect of web space Physical exam palpation neuroma may be palpable positive web-space compression test provocative tests Mulder's click bursal click may be elicited by squeezing metatarsals together Drawer test at metatarsal phalangeal joint (MTPJ) assess for MTPJ instability Imaging Radiographs recommended views weight bearing AP/lateral/oblique views findings usually normal may see bony deformity Ultrasound indication non-palpable neuroma with clear clinical presentation findings oval, hypoechoic mass oriented parallel to the metatarsal bones outcomes highly operator dependent MRI indication not usually required for diagnosis may be used to rule out other pathologies Studies Common digital nerve block indication confirmatory for accurate diagnosis of interdigital neuroma findings numbness over lateral surface of toe with relief of patient reported pain Differential MTP synovitis consider if there is no relief of pain after well positioned digit nerve block Metatarsalgia Stress fracture MTPJ arthritis Metatarsal head osteonecrosis Neoplasm Lumbar radiculopathy Treatment Nonoperative wide shoe box with firm sole and metatarsal pad indications first line of treatment outcomes results are unpredictable approximately 20% of patients will have complete resolution of symptoms adding anti-inflammatory medications rarely provide any benefit corticosteroid injection indications symptomatic benefit modality usually approached dorsal after isolating the neuroma with palpation or ultrasound outcomes evidence for its effectiveness is weak suggested to provide symptomatic benefit in short term randomized control studies Operative neurectomy indications failure of nonoperative management techniques dorsal or plantar approach (dorsal most common) neurectomy with nerve burial (bury proximal stump within intrinsic muscles) transverse intermetatarsal ligament release Technique Dorsal neurectomy approach 3 to 4 cm incision just proximal to the involved webspace blunt dissection to avoid injury to branches of superficial peroneal nerve technique spread the metatarsal bones to visualize the webspace, as well as tension the transverse intermetatarsal ligament protecting the neurovacular bundle, transect the transverse intermetatarsal ligament identify the interdigital nerve proximal and distal to the nerve bifurcation resect the nerve at least 3 cm proximal to intermetatarsal ligament reapproximate and repair the transverse intermetatarsal ligament to avoid intermetatarsal head instability Complications Stump neuroma causes include inadequate retraction (traction neuritis) caused by tethering of plantar neural branches that prevent retraction following resection inadequate resection (not proximal enough) most common nerve should be resected at least 3 cm proximal to intermetatarsal ligament resect through plantar or dorsal incision Painful plantar scar increased risk (5%) with plantar incision