Long-term results of dorsal neuroma/nerve transposition in the surgical management of Morton’s neuroma and correlation with intraoperative anatomical variations

Background Morton's neuroma (MN) is a common cause of forefoot pain. After failure of conservative management, surgical procedures include neurectomy or neuroma preserving procedures; resection of deep transverse intermetatarsal ligament only (DTIML), dorsal neurolysis, dorsal nerve transposition (DNT). Objectives This retrospective study evaluates the long-term results of open DNT, and it also reports anatomical variants in the plantar interdigital nerve. Material and methods The study included 39 patients (30 females and 9 males) who were treated for MN between 2002 and 2016. Results The mean pre-operative Giannini score of 13 (0–30) improved to 61 (20–80) (p < .0001), with only 6 patients scoring less than 50 (poor). Using Coughlin’s criterion for overall satisfaction, 9 patients (23%) reported excellent, 18 patients (46%) good, 6 patients (15%) fair and 6 patients (15%) reported poor results. In the long term, 25 patients (64%) had no pain, 8 patients (20%) had mild pain, and 6 patients (16%) had severe pain. Ten patients (26%) reported normal sensitivity in their toes, 26 patients (66%) had numbness, and 3 patients (8%) reported dysesthesia in their toes. Twenty-two patients (56%) could wear fashionable shoes, 11 patients (28%) comfortable shoes, and 6 patients (16%) modified shoes. Regarding walking distance, 30 patients (77%) had no limitation, and 9 patients (23%) reported some limitation. Nineteen per cent regretted having surgery. Around 40% (17 out of 43 web spaces) showed anatomical variations in either the nerve or in the web space and we could not identify any specific risk factors in relation to the outcome. Conclusion Dividing the DTIML or dorsal neurolysis should be considered as the primary surgical treatment and, if this fails, neurectomy would be an option. DNT can be considered if one is concerned about stump neuroma, but this may be technically demanding and in some patients it may not be possible. Level of Evidence: Level IV - Case Control Retrospective study.

“The Feasibility of Targeted Muscle Reinnervation for the Management of Morton’s Neuroma”

Background Despite multiple surgical modalities available for the management of Morton’s neuroma, complications remain common. Targeted muscle reinnervation (TMR) has yet to be explored as an option for the prevention of recurrence of Morton’s neuroma. The purpose of the present investigation was to determine the consistency of the relevant foot neurovascular and muscle anatomy and to demonstrate the feasibility of TMR as an option for Morton’s neuroma. Methods The anatomy of 5 fresh-tissue donor cadaver feet was studied, including the course and location of the medial and lateral plantar nerves (MPNs and LPNs), motor branches to abductor hallucis (AH) and flexor digitorum brevis (FDB), as well as the course of sensory plantar digital nerves. Measurements for the locations of the muscular and sensory branches were taken relative to landmarks including the navicular tuberosity (NT), AH, FDB, and the third metatarsophalangeal joint (third MTPJ). Results The mean number of nerve branches to FDB identified was 2. These branch points occurred at an average of 8.6 cm down the MPN or LPN, 9.0 cm from the third MTPJ, 3.0 cm distal to AH distal edge, and 4.8 cm from the NT. The mean number of nerves to AH was 2.2. These branch points occurred at an average of 6.3 cm down the MPN, 11.9 cm from the third MTPJ, 0.8 cm from the AH distal edge, and 3.8 cm from the NT. Conclusions Recurrent interdigital neuroma, painful scar, and neuropathic pain are common complications of operative management for Morton’s neuroma. Targeted muscle reinnervation is a technique that has demonstrated efficacy for the prevention and treatment of neuroma, neuropathic pain, and phantom limb pain in amputees. Herein, we have described the neuromuscular anatomy for the application of TMR for the management of Morton’s neuroma. Target muscles, including the AH and FDB, have consistent innervation patterns in the foot, and consequently, TMR represents a viable option to consider for the management of recalcitrant Morton’s neuroma. Levels of Evidence: V

The interphalangeal angle as a novel radiological measurement tool for Morton’s neuroma – a matched case-control study

Background The aim of this retrospective study was to examine if a correlation between Morton’s Neuroma (MN) and an increased interphalangeal angle (IPA) or intermetatarsal angle (IMA) can be found in preoperative weightbearing dorsal-plantar X-rays of the foot. Methods Forty-five patients with forty-nine MN in the interspaces 2/3 or 3/4 and 49 controls were recruited for this study. Every MN was matched with an asymptomatic control without history of metatarsalgia. The diagnosis was made by clinical examination, magnetic resonance imaging (MRI) and positive histopathology after operative resection. IMA 1/5, 2/3, 2/4, 2/5, 3/4 and IPA 2/3, 3/4 were measured for both groups. Results The IPA 3/4 was significantly enlarged by 2.8 degrees (p < 0.001) with Area under the curve (AUC) 0.75 (p < 0.001), sensitivity of 73% and specificity of 67% in feet with MN compared to controls. The IMA 3/4 was significantly enlarged by 1 degree (p < 0.048) with AUC 0.64 (p < 0.031), sensitivity of 71% and specificity of 43% in feet with MN compared to controls. No difference between IMA 2/4, 2/5, 1/5 or correlation between IPA or IMA and the size of the MN in the MRI was found. Conclusion The results confirm the clinical observation of an increased IPA in patients with MN. An increased IPA should therefore be considered in the diagnosis of MN.

Depression and Anxiety as Important Aggravating Factors of Pain in Morton’s Neuroma

This report represents a case of Morton’s Neuroma with episodic severe sharp pain. Initially, the patient was prescribed Naproxen 500 mg twice per day, anti-inflammatory topical cream, as well as massage. In a follow up visit, the patient was still experiencing frequent episodic sharp pain. In detailed patient interview, it was revealed that she has depression and anxiety and suffers from social isolation, which was concurrent with episodes of severe pain. Therefore, she was referred to a psychologist and a community support group and started practicing body relaxation techniques such as guided imagery and breathing exercises. The new treatment strategy had a major impact on improving her symptoms. This report aims to illustrate that depression and anxiety can be one of the main aggravating factors in episodic pain in Morton’s neuroma and removing psychosocial contributors of pain has the potential to decrease the need for more invasive interventions.

The Vulcan salute sign: a non-sensitive but specific sign for Morton’s neuroma on radiographs

Objectives To assess the value of the divergence of toes on conventional radiographs of the foot for diagnosing Morton’s neuroma. Methods This retrospective case–control study was approved by the local ethics committee. In 100 patients with MRI-proven Morton’s neuroma 2/3 or 3/4 (study group) and 100 patients without (control group), conventional weight-bearing dorso-plantar view radiographs were evaluated for the subjective presence of interphalangeal divergence, called the Vulcan salute sign or V-sign, by two blinded, independent musculoskeletal radiologists. Interphalangeal angles (2/3 and 3/4) and intermetatarsal angle I/V were measured. The t test and chi-squared test were used to compare the groups. Diagnostic performance was calculated. Interobserver reliability was assessed using κ statistics and intraclass correlation coefficient (ICC). Results The difference between the groups was significant (P < 0.05) regarding the presence of the V-sign, which was found in 30 of 100 patients with Morton neuroma and in 3 of 100 control patients, with a sensitivity of 30% and a specificity of 97%. The differences between interphalangeal angles were significant (P < 0.05) between the groups. The interphalangeal angle 2/3 mean values were 7.9° (± 4.8) for the study group vs 5.4° (± 2.6) for the controls; the 3/4 angle values were 6.5° (± 3.8) and 3.4° (± 2.5), respectively. There was no significant difference between the groups in the intermetatarsal angle I/V. Interobserver agreement was substantial for the V-sign, with a κ value of 0.78. The ICC was excellent concerning angle measurements, with all values ≥ 0.94. Conclusion The Vulcan salute sign on conventional radiographs is specific for Morton’s neuroma.

Efficacy of a Single Corticosteroid Injection for Morton's Neuroma in Adults: A Systematic Review

Background Morton's neuroma is a common condition that routinely presents in podiatric practice. The aim of this study was to systematically synthesize the evidence relating to the effectiveness of a corticosteroid injection for Morton's neuroma. Methods Studies with a publication date of 1960 or later were eligible, and searches were performed within the Turning Research Into Practice database; the Cochrane Central Register of Controlled Trials; the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register; MEDLINE (Ovid); PubMed; Embase; Cumulative Index to Nursing and Allied Health Literature; and the gray literature. Study selection criteria included randomized and nonrandomized controlled trials where a single corticosteroid injection for Morton's neuroma pain was investigated. The primary outcome was Morton's neuroma pain as measured by any standard validated pain scale. Results Ten studies involving 695 participants were included. The quality of the studies was considered low and subject to bias. Of the included studies, five compared corticosteroid injection to usual care, one compared corticosteroid injection to local anesthetic alone, one compared ultrasound-guided to non–ultrasound-guided injections, three compared corticosteroid injections to surgery, one compared small to large neuromas, six assessed patient satisfaction, four measured adverse events, one studied return to work, and one examined failure of the corticosteroid injection to improve pain. Overall, these studies identified a moderate short- to medium-term benefit of corticosteroid injections on the primary outcome of pain and a low adverse event rate. Conclusions A single corticosteroid injection appears to have a beneficial short- to medium-term effect on Morton's neuroma pain. It appears superior to usual care, but its superiority to local anaesthetic alone is questionable, and it is inferior to surgical excision. A very low adverse event rate was noted throughout the studies, indicating the intervention is safe when used for Morton's neuroma. However, the quality of the evidence is low, and these findings may change with further research.