Revision Surgery for Recurrent Morton Neuroma with Use of a Collagen Conduit
Authors: Scheinberg Mila , Underwood Meghan , Sankey Matthew , Sanchez Thomas , Shah Ashish 
Published: November 2023

Background:
Painful neuromas of the foot and ankle frequently pose a treatment dilemma because of persistent pain or recurrence after resection. Primary surgical treatment of painful neuromas includes simple excision with retraction of the residual nerve ending to a less vulnerable location
1–4
. The use of a collagen conduit for recurrent neuromas is advantageous, particularly in areas with minimal soft-tissue coverage options, and is a technique that has shown 85% patient satisfaction regarding surgical outcomes
7
. Additionally, the use of a collagen conduit limits the need for deep soft-tissue dissection and reduces the morbidity typically associated with nerve burial.

Description:
Specific steps include appropriate physical examination, preoperative planning, and supine patient positioning. The patient is placed supine with a lower-extremity bolster under the ipsilateral extremity in order to allow improved visualization of the plantar surface of the foot. A nonsterile tourniquet is placed on the thigh. The incision site is marked out, and a longitudinal plantar incision is made until proximal healthy nerve is identified—typically approximately 1 to 2 cm, but the incision can be extended up to 6 cm. The incision is made between the metatarsals, with blunt dissection carried down to the neuroma. The neuroma is sharply excised distally through healthy nerve, and a whip stitch is placed to facilitate the collagen conduit placement. The collagen conduit is passed dorsally into the intermetatarsal space and secured to the dorsal fascia of the foot. The wound is closed with 3-0 nylon horizontal mattress sutures. Postoperatively, a soft dressing is applied to the operative extremity, and patients are advised to be non-weight-bearing for two weeks. At two weeks, patients begin partial weight-bearing with use of a boot, and physical therapy is initiated. No antibiotics are necessary, and 300 mg of gabapentin is prescribed and tapered off by the six-week follow-up visit. Follow-ups are conducted at 2, 6, 12, 24, and fifty-two weeks. It is necessary to monitor for signs and symptoms of infection, surgical complications, and neuroma recurrence during follow-up appointments.

Alternatives:
Simple excision of the neuroma with proximal burial into muscle or bone is a common surgical technique. However, inadequate resection of the nerve or poor surgical technique can lead to recurrent neuromas. For neuromas not responding to simple excision, other techniques have been utilized, including cauterization, chemical agents, nerve capping, and muscle or bone burial
5,6
. The results of these techniques have varied, and none has gained clinical superiority over the other
6
.

Rationale:
A study analyzing the use of collagen conduits for painful neuromas of the foot and ankle has shown this technique to be a safe and successful alternative to the previously discussed methods of resection
7
. That study by Gould et al. found that 85% of patients had a substantial reduction in pain, with mean visual analog scale (VAS) pain scores reducing from 8 to 10 preoperatively to 0 to 4 postoperatively
7
. Moreover, alternative biological conduits, such as the greater saphenous vein, have proven to be costly in time and resources, as this structure is often utilized in cardiovascular bypass surgery and its harvest conveys a risk of iatrogenic nerve injury to the patient
7
.Numerous studies focusing on excision of recurrent Morton neuromas via a plantar approach have found variable success rates. Of the patients surveyed in those studies, 75% reported substantial pain improvement. However, <50% of these queried patients reported complete pain relief
8,9
. Studies analyzing the dorsal approach for revision Morton neuroma excision found similar success rates. Approximately 78% of patients reported good or excellent postoperative outcomes, and significant improvements were observed in patient postoperative Patient-Reported Outcomes Measurement Information System (PROMIS) scores for pain interference, intensity, and global physical health
10,11
. One study comparing outcomes following plantar versus dorsal approaches for recurrent Morton neuroma found no significant difference in postoperative patient outcomes. That study suggested that surgeons utilize the approach with which they are most comfortable
12
. Gould et al. reported an 85% success rate with collagen conduit, which was similar to if not slightly improved compared with the other prior studies. The utilization of a collagen conduit technique thus offers comparable patient outcomes for patients with difficult neuromas
7
.

Expected Outcomes:
Recurrent neuroma resection with the use of a collagen conduit has proven to provide satisfactory patient outcomes regarding pain and neuritis symptoms
7
. The goal of any neuroma resection is to greatly diminish or entirely eliminate nerve pain. Based on the available evidence, there has been no proven clinical superiority of any particular technique over the others
6
. However, in the present example case, the location of the patient’s neuroma in this video makes it 85% likely that the patient will report satisfactory outcomes and 50% likely that the patient will be entirely symptom-free
7
. At two weeks postoperatively, the patient reported well controlled pain, absence of burning or tingling sensation, full range of movement in the foot, and intact sensation throughout all major nerve distributions, including the saphenous; superficial peroneal nerve; deep peroneal nerve; and sural, medial, and lateral plantar nerves. However, sensation is absent distal to the site of a neuroma resection.

Important Tips:

Careful preoperative planting is of utmost importance.Ruling out other potential pathologies is necessary to ensure proper outcomes.Meticulous dissection should be carried out, with delicate handling of the proximal nerve ending.Excision of the nerve should be done sharply through the healthy portion of the nerve.Appropriate sizing of the nerve conduit (with a commercially available industry sizer) should be performed.The nerve conduit should be passed dorsally and secured to the dorsal fascia without any tension.

Acronyms and Abbreviations:

MRI = magnetic resonance imagingUS = ultrasoundVAS = visual analog scale