Non-surgical treatments for Morton's neuroma: A systematic review

Treatments for Morton's neuroma

BACKGROUND

Morton's neuroma (MN) is a painful neuropathy resulting from a benign enlargement of the common plantar digital nerve that occurs commonly in the third webspace and, less often, in the second webspace of the foot. Symptoms include burning or shooting pain in the webspace that extends to the toes, or the sensation of walking on a pebble. These impact on weight-bearing activities and quality of life.

OBJECTIVES

To assess the benefits and harms of interventions for MN.

SEARCH METHODS

On 11 July 2022, we searched CENTRAL, CINAHL Plus EBSCOhost, ClinicalTrials.gov, Cochrane Neuromuscular Specialised Register, Embase Ovid, MEDLINE Ovid, and WHO ICTRP. We checked the bibliographies of identified randomised trials and systematic reviews and contacted trial authors as needed.

SELECTION CRITERIA

We included all randomised, parallel-group trials (RCTs) of any intervention compared with placebo, control, or another intervention for MN. We included trials where allocation occurred at the level of the individual or the foot (clustered data). We included trials that confirmed MN through symptoms, a clinical test, and an ultrasound scan (USS) or magnetic resonance imaging (MRI).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodological procedures. We assessed bias using Cochrane's risk of bias 2 tool (RoB 2) and assessed the certainty of the evidence using the GRADE framework.

MAIN RESULTS

We included six RCTs involving 373 participants with MN. We judged risk of bias as having 'some concerns' across most outcomes. No studies had a low risk of bias across all domains. Post-intervention time points reported were: three months to less than 12 months from baseline (nonsurgical outcomes), and 12 months or longer from baseline (surgical outcomes). The primary outcome was pain, and secondary outcomes were function, satisfaction or health-related quality of life (HRQoL), and adverse events (AE). Nonsurgical treatments Corticosteroid and local anaesthetic injection (CS+LA) versus local anaesthetic injection (LA) Two RCTs compared CS+LA versus LA. At three to six months: • CS+LA may result in little to no difference in pain (mean difference (MD) -6.31 mm, 95% confidence interval (CI) -14.23 to 1.61; P = 0.12, I2 = 0%; 2 studies, 157 participants; low-certainty evidence). (Assessed via a pain visual analogue scale (VAS; 0 to 100 mm); a lower score indicated less pain.) • CS+LA may result in little to no difference in function when compared with LA (standardised mean difference (SMD) -0.30, 95% CI -0.61 to 0.02; P = 0.06, I2 = 0%; 2 studies, 157 participants; low-certainty evidence). (Function was measured using: the American Orthopaedic Foot and Ankle Society Lesser Toe Metatarsophalangeal-lnterphalangeal Scale (AOFAS; 0 to 100 points) - we transformed the scale so that a lower score indicated improved function - and the Manchester Foot Pain and Disability Schedule (MFPDS; 0 to 100 points), where a lower score indicated improved function.) • CS+LA probably results in little to no difference in HRQoL when compared to LA (MD 0.07, 95% CI -0.03 to 0.17; P = 0.19; 1 study, 122 participants; moderate-certainty evidence), and CS+LA may not increase satisfaction (risk ratio (RR) 1.08, 95% CI 0.63 to 1.85; P = 0.78; 1 study, 35 participants; low-certainty evidence). (Assessed using the EuroQol five dimension instrument (EQ-5D; 0-1 point); a higher score indicated improved HRQoL.) • The evidence is very uncertain about the effects of CS+LA on AE when compared with LA (RR 9.84, 95% CI 1.28 to 75.56; P = 0.03, I2 = 0%; 2 studies, 157 participants; very low-certainty evidence). Adverse events for CS+LA included mild skin atrophy (3.9%), hypopigmentation of the skin (3.9%) and plantar fat pad atrophy (2.6%); no adverse events were observed with LA. Ultrasound-guided (UG) CS+LA versus non-ultrasound-guided (NUG) CS+LA Two RCTs compared UG CS+LA versus NUG CS+LA. At six months: • UG CS+LA probably reduces pain when compared with NUG CS+LA (MD -15.01 mm, 95% CI -27.88 to -2.14; P = 0.02, I2 = 0%; 2 studies, 116 feet; moderate-certainty evidence). (Assessed with a pain VAS.) • UG CS+LA probably increases function when compared with NUG CS+LA (SMD -0.47, 95% CI -0.84 to -0.10; P = 0.01, I2 = 0%; 2 studies, 116 feet; moderate-certainty evidence). We do not know of any established minimum clinical important difference (MCID) for the scales that assessed function, specifically, the MFPDS and the Manchester-Oxford Foot Questionnaire (MOXFQ; 0 to 100 points; a lower score indicated improved function.) • UG CS+LA may increase satisfaction compared with NUG CS+LA (risk ratio (RR) 1.71, 95% CI 1.19 to 2.44; P = 0.003, I2 = 15%; 2 studies, 114 feet; low-certainty evidence). • HRQoL was not measured. • UG CS+LA may result in little to no difference in AE when compared with NUG CS+LA (RR 0.42, 95% CI 0.12 to 1.39; P = 0.15, I2 = 0%; 2 studies, 116 feet; low-certainty evidence). AE included depigmentation or fat atrophy for UG CS+LA (4.9%) and NUG CS+LA (12.7%). Surgical treatments Plantar incision neurectomy (PN) versus dorsal incision neurectomy (DN) One study compared PN versus DN. At 34 months (mean; range 28 to 42 months), PN may result in little to no difference for satisfaction (RR 1.06, 95% CI 0.87 to 1.28; P = 0.58; 1 study, 73 participants; low-certainty evidence), or for AE (RR 0.95, 95% CI 0.32 to 2.85; P = 0.93; 1 study, 75 participants; low-certainty evidence) compared with DN. AE for PN included hypertrophic scaring (11.4%), foreign body reaction (2.9%); AE for DN included missed nerve (2.5%), artery resected (2.5%), wound infection (2.5%), postoperative dehiscence (2.5%), deep vein thrombosis (2.5%) and reoperation with plantar incision due to intolerable pain (5%). The data reported for pain and function were not suitable for analysis. HRQoL was not measured.

AUTHORS' CONCLUSIONS

Although there are many interventions for MN, few have been assessed in RCTs. There is low-certainty evidence that CS+LA may result in little to no difference in pain or function, and moderate-certainty evidence that UG CS+LA probably reduces pain and increases function for people with MN. Future trials should improve methodology to increase certainty of the evidence, and use optimal sample sizes to decrease imprecision.

The Ageing Foot

Feet suffer significant stress throughout a lifetime and undergo ageing-associated problems due to gradual tissue degeneration affecting the skin, connective tissue, and nerves. Oxygen supply to the tissues may be diminished. The skin gets dry and calluses, ulcers and fungal infections of the skin and nails are not uncommon. Ligaments and tendons degenerate and, without proper prevention, deformities including claw toes, hammer toes, tendonitis, and bursitis may occur. Skeletal toe deformities such as bunions, bony spurs, and hallux valgus may increase discomfort, while stress fractures may have an adverse impact on the patients' quality of life. The ageing foot pathology may add up to common age-related problems, such as crystal deposition arthropathies, diabetes mellitus, peripheral circulatory disorders, and peripheral edema, increasing morbidity. This review summarizes ageing-related feet problems, focusing on prevention and treatment. Foot health has a paramount role in overall wellbeing, therefore prevention, proper foot care, and prompt diagnosis and management of ageing-related changes are vital for maintaining a healthy, active status.

Infiltrative Type I Collagen in the Treatment of Morton's Neuroma: A Mini-Series

Morton's neuroma (MN) is a compressive neuropathy of the common plantar digital nerve, most commonly affecting the third inter-digital space. The conservative approach is the first recommended treatment option. However, other different approaches have been proposed, offering several options of treatments, where, several degrees of efficacy and safety have been reported. We treated five consecutive patients affected by MN through three indirect ultrasound-guided injections of type I porcine collagen at weekly intervals. All patients were assessed before the treatment, after the treatment and up to 6 months after the last injection via AOFAS and VNS scores for pain, in which the function and pain were evaluated, respectively. In all patients, both analyzed variables progressively ameliorated, with benefits lasting until the last follow-up. The trend of the scores during the follow-up showed significant statistical differences. No side effects occurred. To our knowledge, this is the first study on injections of type I porcine collagen for the treatment of Morton's neuroma. Future research is needed to confirm the positive trend achieved in this MN mini-series.

Rheumatoid nodule presenting as a Morton's neuroma in the foot: An important differential diagnosis to consider

A 51-year-old lady with a background of rheumatoid arthritis presented to the foot and ankle clinic with pain and a typical history of Morton's neuroma. Examination revealed a palpable swelling over the right foot in the third intermetatarsal space. Following failed conservative management, the patient underwent excision of the neuroma. Histology revealed of necrotizing granulomas with peripheral palisading and no evidence of features specific to a neuroma. This has rarely been described previously and supports the concept of rheumatoid synovitis and nodules producing symptoms mimicking Morton's neuroma/metatarsalgia. Level of clinical evidence: 4.

Clinical and electrophysiological efficacy of extracorporeal shock-wave therapy in carpal tunnel syndrome: a placebo-controlled, double-blind clinical trial

OBJECTIVE

The aim of this study was to evaluate the efficacy of radial extracorporeal shock wave therapy on pain, functionality, and electrophysiological measurements in carpal tunnel syndrome.

METHODS

Between June 2021 and January 2022, a total of 66 wrists in 45 participants with mild-to-moderate carpal tunnel syndrome were included in this double-blind, prospective, randomized, placebo-controlled study. Patients were randomized into two groups, namely, the radial extracorporeal shock wave therapy (group 1, n=33) and the sham radial extracorporeal shock wave therapy (group 2, n=33). Night splints and tendon nerve gliding exercises were given to all participants. The participants were evaluated at baseline and the first month after treatment. Participants were evaluated using a visual analog scale, the Boston Carpal Tunnel Questionnaire, Leeds Neuropathic Symptom and Symptom Assessment, and electrophysiological examinations.

RESULTS

A total of 37 participants (a total of 55 wrists, radial extracorporeal shock wave therapy n=27, and sham radial extracorporeal shock wave therapy n=28) completed the study. After the intervention, there was a significant decrease in visual analog scale values (p<0.001) and a significant increase in Boston Carpal Tunnel Questionnaire scores (p<0.001) and Leeds Neuropathic Symptom and Symptom Assessment scores (p<0.001). In electrophysiological measurements, there was a significant decrease in median nerve sensory (p=0.002) and motor (p=0.003) distal latency, and a significant increase in median nerve sensory conduction velocity (p=0.026) was found in the radial extracorporeal shock wave therapy group.

CONCLUSION

This study shows that radial extracorporeal shock wave therapy has positive effects on pain, functionality, and electrophysiological measurements for mild-to-moderate carpal tunnel syndrome 1 month after application.

Ultrasound-guided continuous radiofrequency ablation of the suprascapular nerve for chronic shoulder pain secondary to osteoarthritis: a retrospective cohort study

OBJECTIVES

The objective of this study is to retrospectively evaluate the use of ultrasound-guided continuous radiofrequency (CRF) lesioning of the suprascapular nerve for treating chronic shoulder pain, due to osteoarthritis. We describe a modified distal and selective ablation technique in the spinoglenoid notch, with motor and sensory stimulation, which protects the motor branch of the nerve from ablation.

METHODS

A retrospective analysis was performed of patients, who underwent ultrasound-guided CRF lesioning of the suprascapular nerve from October 2013 to January 2020. During the procedure, the CRF electrode is placed in the spinoglenoid notch, at the distal suprascapular nerve capsular branch. Motor and sensory stimulations are used to confirm the position. CRF lesioning is applied up to three times, at 3 different points, for 1 min each time, at 80^° C.

RESULTS

In total, 127 first CRF suprascapular nerve lesioning procedures were performed on 101 patients with chronic shoulder pain secondary to osteoarthritis. One hundred nineteen diagnostic ultrasound-guided suprascapular nerve corticosteroid injections were performed prior to ablation. Mean pre-injection Visual Analogue Scale pain score (VAS) was 8.3, with post-injection VAS score of 4.4 at 24 h and 4.5 at 2 weeks. Mean pre-CRF lesioning VAS pain score was 7.7 with post-CRF lesioning VAS score of 4.4 at 24 h and 4.5 at 2 weeks.

CONCLUSIONS

Ultrasound-guided CRF lesioning of the suprascapular nerve in the spinoglenoid notch is a safe treatment for chronic osteoarthritic shoulder pain, with repeat treatments infrequently required. It is associated with significant improvement in VAS pain scores.

KEY POINTS

• Ultrasound-guided continuous radiofrequency lesioning of the suprascapular nerve in the spinoglenoid notch is a safe treatment for chronic shoulder pain in degenerative disease, with repeat treatments infrequently required. • The procedure is performed under ultrasound guidance, without the use of ionising radiation.

"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 Management of Multiple Morton's Neuromas in the Same Foot: A Systematic Review

The optimal treatment strategy for the presentation of multiple Morton's neuromas in adjacent intermetatarsal spaces of the same foot is yet to be determined. We aimed to summarize and assess the efficacy of current treatment strategies. A systematic review, adhering to PRIMSA guidelines was performed. A computer base search was completed in PubMed, Embase, Cinahl, ISI Web of Science, Scopus and Emcare, for articles reporting the treatment of multiple neuromas in the same foot. The review is registered in the international prospective register of systematic reviews (CRD42020213631). A total of 253 articles were identified, with 7 articles being included in the review. The most common treatment strategy reported was simultaneous neuroma excision using a single incision, while 2 studies each describe simultaneous excision with 2 separate incisions and delayed excision respectively. There is no strong evidence favoring use of delayed excision or multiple incisions. Further high-quality research is required to make more definitive conclusions and future research should investigate other strategies such as non-operative treatment.

Fascial Manipulation Technique in the Conservative Management of Morton's Syndrome: A Pilot Study

Background and Objective: Morton’s syndrome (MS) is a common cause of neuropathic chronic forefoot pain, characterised by the development of a swelling of the common digital plantar nerve, whose aetiology is not fully known. There is currently no gold standard of treatment; nonoperative management commonly involves manual therapies, orthoses therapy and infiltrative techniques, while surgery is indicated after failure of conservative measures. The present preliminary study prospectively evaluates patients affected by MS treated by Fascial Manipulation technique (FM), a noninvasive manual therapy, focused on the release of the deep fascia, reducing its stiffness. Materials and Methods: Patients with clinical and sonographic diagnosis of MS with at least a 4-month history of neuropathic symptoms underwent a cycle of three weekly FM sessions. Clinical follow-up, including VAS and AOFAS scores, was performed 21 days (T1) and 3 months (T2) after treatment. Results: Nine patients, among 28 recruited initially, completed the manual therapy sessions and relative follow-up points. This noninvasive pain treatment led to significant improvement of VAS (p = 0.0034) and AOFAS scores (p = 0.0240) at the first follow-up (T1). At 3-month follow-up (T2), both scores decreased slightly, remaining however superior to the pre-treatment values. Only VAS was still significant (p = 0.0184). Conclusions: Despite the small size of the case series, this pilot study is unique in supporting Fascial Manipulation in the nonoperative treatment of MS. Further studies are needed with a large cohort of gender balanced patients to confirm the encouraging results obtained.

Ultrasound-guided treatment of Morton's neuroma

Morton’s neuroma is a painful lesion of the interdigital nerve, usually at the third intermetatarsal space, associated with fibrotic changes in the nerve, microvascular degeneration, and deregulation of sympathetic innervation. Patients usually present with burning or sharp metatarsalgia at the dorsal or plantar aspect of the foot. The management of Morton’s neuroma starts with conservative measures, usually with limited efficacy, including orthotics and anti-inflammatory medication. When conservative treatment fails, a series of minimally invasive ultrasound-guided procedures can be employed as second-line treatments prior to surgery. Such procedures include infiltration of the area with a corticosteroid and local anesthetic, chemical neurolysis with alcohol or radiofrequency thermal neurolysis. Ultrasound aids in the accurate diagnosis of Morton’s neuroma and guides the aforementioned treatment, so that significant and potentially long-lasting pain reduction can be achieved. In cases of initial treatment failure, the procedure can be repeated, usually leading to the complete remission of symptoms. Current data shows that minimally invasive treatments can significantly reduce the need for subsequent surgery in patients with persistent Morton’s neuroma unresponsive to conservative measures. The purpose of this review is to present current data on the application of ultrasound for the diagnosis and treatment of Morton’s neuroma, with emphasis on the outcomes of ultrasound-guided treatments.

Corticosteroid Injection for Morton's Interdigital Neuroma: A Systematic Review

Backgroud

This review aimed to evaluate the effects of corticosteroid injections on Morton's neuroma using an algorithmic approach to assess the methodological quality of reported studies using a structured critical framework.

Methods

Several electronic databases were searched for articles published until April 2020 that evaluated the outcomes of corticosteroid injections in patients diagnosed with Morton's neuroma. Data search, extraction, analysis, and quality assessments were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). guidelines, and clinical outcomes were evaluated using various outcome measures.

Results

With 3–12 months of follow-up, corticosteroid injections provided satisfactory outcomes according to Johnson satisfaction scores except in two studies. Visual analog scale scores showed maximal pain reduction between 1 week and 3 months after injection. We found that 140 subjects out of 469 (29.85%) eventually underwent surgery after receiving corticosteroid injections due to persistent pain.

Conclusions

Corticosteroid injections showed a satisfactory clinical outcome in patients with Morton's interdigital neuroma although almost 30% of the included subjects eventually underwent operative treatment. Our recommendation for future research includes using more objective outcome parameters, such as foot and ankle outcome scores or foot and ankle ability measures. Moreover, studies on the safety and effectiveness of multiple injections at the same site are highly necessary.

Medium-Term Results of Corticosteroid Injections for Morton's Neuroma

BACKGROUND

The objective of this study was to evaluate the medium-term results of corticosteroid injections for Morton's neuroma.

METHODS

This was a prospective follow-up study of a previous randomized controlled trial (RCT). Forty-five neuromas in 36 patients were injected with a single corticosteroid injection either with or without ultrasound guidance. As the results of the RCT showed no difference in outcomes between techniques, the data were pooled for the purpose of this study. Questionnaires were sent out and responses were collected via mail or telephone interview. Results were available in 42 out of 45 neuromas. There was a sex split of 68% female/32% male with a mean age of 62.6 years (SD, 12 years).

RESULTS

At mean follow-up of 4.8 years (SD, 0.91 years), the original corticosteroid injection remained effective in 36% (n = 16) of the patients. In these cases, the visual analog scale (VAS) pain score (P < .001) and Manchester-Oxford Foot Questionnaire Index (MOxFQ Index) (P = .001) remained significantly better than preintervention scores. The remaining cases underwent either a further injection or surgery. Fifty-five percent of the 11 neuromas that received a second injection continued to be asymptomatic in the medium term. Overall, 44% (n = 20) of the initial cohort underwent surgical excision by the medium-term follow-up. The VAS score, MOxFQ Index, and satisfaction scale score across all groups were not significantly different.

CONCLUSION

Corticosteroid injections for Morton's neuroma remained effective in over a third of cases for up to almost 5 years. A positive outcome at 1 year following a corticosteroid injection was reasonably predictive of a prolonged effect from the injection.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Morton's neuroma - Current concepts review

Morton's neuroma is a common pathology affecting the forefoot. It is not a true neuroma but is fibrosis of the nerve. This is caused secondary to pressure or repetitive irritation leading to thickness of the digital nerve, located in the third or second intermetatarsal space. The treatment options are: orthotics, steroid injections and surgical excision usually performed through dorsal approach. Careful clinical examination, patient selection, pre-operative counselling and surgical technique are the key to success in the management of this condition.