The operational characteristics of ultrasonography for the diagnosis of plantar intermetatarsal neuroma

Minimally invasive neurectomy for Morton's neuroma with interdigital approach. Long term results

BACKGROUND

"Morton's Neuroma" is a frequent cause of chronic forefoot pain. It can affect general population, including athletes, and can lead to progressive foot pain and discomfort for daily life activities and sports.

HYPOTHESIS/PURPOSE

Our objective is to evaluate the long-term results in a series of 85 feet, operatively treated with minimally invasive interdigital approach for neurectomy.

STUDY DESIGN

Case series.

METHOD

83 patients (85 feet) were treated between January 2003 and December 2019. The AOFAS score and VAS scale were used to evaluate the patients pre and postoperatively. Results were analyzed using the JASP software.

RESULTS

Mean age was 50.58 years (range 23-77). Eleven (11) were men, and seventy-four (74) women, with two bilateral cases. Mean follow up was 49 months. Our series was evaluated with AOFAS and VAS scores, both showing statistically significant improvement posterior to the operative procedure.

CONCLUSIONS

A series of 85 feet operatively treated for Morton's neuroma with minimally invasive interdigital approach for neurectomy is presented. Long term results were similar to other published series with different approaches, with the advantage of minimal incision, minimum soft tissue dissection and no need to release intermetatarsal ligament, immediate weightbearing and quick return to daily activities and sports. It is concluded that minimally invasive neurectomy with interdigital approach is a safe procedure for Morton's neuroma treatment with similar results that other operative procedures.

LEVEL EVIDENCE

Level IV.

Relationship Between Sensory Symptoms, Mulder's Sign, and Dynamic Ultrasonographic Findings in Morton's Neuroma

BACKGROUND

Morton's neuroma (MN) is often a diagnostic dilemma lacking a gold standard set of diagnostic criteria. Advanced imaging of MN is evolving including ultrasonography. The current study aimed to analyze the relationship between ultrasonographic findings and symptoms, clinical data, and operative findings in a subgroup of patients.

METHODS

We evaluated physical examination, ultrasonographic findings, symptoms, and in a subgroup, the operative findings for Morton's neuroma. We analyzed the symptoms, the findings on physical examination, and ultrasonography data and performed a statistical correlation between them. A total of 175 patients were seen for suspected Morton's neuroma during the last 7 years.

RESULTS

Neuropathic pain of the toes was reported in 63% of patients. Presence of ultrasonographic findings suggesting Morton's neuroma was observed in 77% of cases. A mild significant relationship between neuropathic pain and positive ultrasonographic findings was observed. We found a strong correlation between ultrasonographic and clinical evaluation, but more than half with clinical negative Morton's neuroma had positive findings at ultrasonography. In the subgroup of operatively treated patients (n = 44) surgery confirmed Morton's neuroma in all patients who had positive ultrasonography findings.

CONCLUSIONS

The current study suggests that the association of ultrasonographic evaluation and clinical evaluation can be very useful for the management of Morton's neuroma. Our study could help with the development of a multiperspective approach in the diagnosis of Morton's neuroma.

LEVEL OF EVIDENCE

Level II, prospective cohort survey study.

Sex Correlation to the Prevalence of Pedal Neuromas in Various Interspaces: A Retrospective Study

BACKGROUND

Morton's neuromas are abnormalities of the common digital nerve branch located between the lesser metatarsal heads. Historically, interdigital (Morton's) neuromas have been characterized as being most common in the third interspace and in females. The principal investigator observed Morton's neuromas commonly in the second and third interspaces in both sexes. To our knowledge, no literature exists to evaluate Morton's neuroma location with a focus on each sex independently. The present study evaluates Morton's neuroma interspace location and whether there is a variation by sex.

METHODS

In this retrospective study, 582 deidentified magnetic resonance imaging reports with a diagnosis code for Morton's neuroma were evaluated for patients scanned from January 2, 2015, through April 19, 2016. Incomplete records and those with radiologist findings inconsistent with Morton's neuroma were eliminated. For the remaining 379 patients, data were collected on sex, laterality, history of trauma, plantar plate tear, age, and interspace location. Special focus was given to second and third interspace Morton's neuromas. Data were evaluated using the Pearson χ2 and independent-samples Mann-Whitney U tests, with P < .05 indicating statistical significance.

RESULTS

No statistically significant distribution between sex and second and third interspace Morton's neuromas was noted. Right vs left foot, age, and history of trauma did not vary statistically significantly between sexes. There was a statistically significant difference between the presence of plantar plate tears between sexes. Male patients with Morton's neuromas were found to have a higher rate of plantar plate tears (P = .01).

CONCLUSIONS

This study found that there were no statistically significant differences between sexes and Morton's neuromas location, laterality, or age.

Intra- and Interobserver Reliability of Size Measurement of Morton Neuromas on Sonography

OBJECTIVES

Sonography is often used for analysis of Morton neuromas, but the measurement reliability is unknown. The aim of this study was to determine the intra- and interobserver reliability and precision of sonographic measurement of Morton neuromas.

METHODS

Three observers with different levels of sonography experience (observer A, expert; observer B, intermediate; observer C, beginner) performed repeated measurements of the size of Morton's neuroma in 20 patients. Intraclass correlation coefficient and limit of agreement were used to evaluate reliability and measurement precision.

RESULTS

The intraclass correlation coefficient for intraobserver reliability was 0.80, 0.71, and 0.43 (limit of agreement, 20%, 18%, and 47%) in observers A, B, and C, respectively. The intraclass correlation coefficient for interobserver reliability was 0.72, 0.38, and 0.38 (limit of agreement, 25%, 36%, and 35%) between observers A/B, A/C, and B/C, respectively.

CONCLUSIONS

The intra- and interobserver reliability values for sonographic measurement of Morton neuroma size were dependent on observer experience. Experienced observers had higher reliability, while observers who were less familiar with sonography showed moderate to low reliability.

Mechanical Metatarsalgia as a Risk Factor for Relapse of Morton's Neuroma After Ultrasound-Guided Alcohol Injection

Although many treatment modalities are available for Morton's neuroma, the injection of the neuroma with alcohol has gained popularity. However, recently, some investigators have observed a progressive deterioration in pain scores for patients initially pain free after the treatment. The purpose of the present retrospective comparative study was to determine whether mechanical metatarsalgia is related to symptom recurrence. We included 104 consecutive cases of ultrasound-guided alcohol injection for Morton's neuroma in 92 patients. Of these 104 cases, 51 were in group A (49%; Morton's neuroma) and 53 in group B (51%; Morton's neuroma associated with mechanical metatarsalgia). We evaluated each patient using a visual analog scale and American Orthopaedic Foot and Ankle Society forefoot scale, and Johnson satisfaction scale, with a mean follow-up period of 24 (range 12 to 39) months. Concomitant functional and mechanical disorders have been identified and treated with orthopedic inserts. The present study compared the clinical results and recurrence of symptoms in patients with isolated Morton's disease or Morton's disease associated with mechanical metatarsalgia. Of the 104 cases, the patients for 93 cases (89%) were completely satisfied or satisfied with minor reservations. No major complications developed. Symptoms recurred in 6 patients (6%), in whom neuroma was associated with mechanical disorders (p = .0269). Ultrasound-guided alcohol injection of Morton's neuroma is a relatively safe and well-tolerated treatment. Symptom recurrence is often associated with mechanical metatarsalgia. The treatment of the concomitant anatomical and functional disorders that target the genesis of the neuroma has an important role in the prevention of recurrence of this pathology.

Diagnostic Value of Elastography in the Diagnosis of Intermetatarsal Neuroma

The objective of the present study was to characterize the ultrasound and elastographic properties of intermetatarsal neuroma (interdigital neuroma) and their contribution to diagnosis. Eighteen patients with metatarsalgia, who had presented to an orthopedic clinic from April 2013 to February 2015, were diagnosed with 25 intermetatarsal neuromas (11 unilateral [61.11%], 7 bilateral [38.89%]). These patients underwent evaluation with ultrasonography and simultaneous ultrasound strain elastography to assess the elastographic properties of the tissues in the intermetatarsal space. The intermetatarsal neuroma diagnosis was confirmed by histopathologic inspection. The lesion contours, localization, dimensions, and vascularization were evaluated before surgical excision. The elasticity and strain ratio values were compared between the neuroma and adjacent healthy intermetatarsal space. Of the 25 intermetatarsal neuromas, 1 (4%) was not detected by ultrasonography (incidence of detection of 96%). The mean neuroma width was 6.35 (range 3.7 to 13) mm in the coronal plane, and the mean elasticity and strain ratio values were 3.44 (range 1.1 to 5.1) and 9.47 (range 2.3 to 19.3), respectively. The elasticity and strain ratio values were significantly greater in the presence of an interdigital neuroma than in the adjacent healthy intermetatarsal spaces (Z = -3.964, p = .0001 and Z = -3.927, p = .0001, respectively). The diagnostic cutoff values were calculated as 2.52 for elasticity and 6.1 for the strain ratio. Four neuromas (16%) were not demarcated, and the elasticity and strain ratio values for these were lower than those for neuromas with demarcated contours but were greater than those for healthy intermetatarsal spaces (p < .006 and p < .005, respectively). Patients with clinically suspected intermetatarsal neuromas that do not show demarcation and with smaller lesions might benefit from the use of ultrasound elastography for diagnosis.

The accuracy of diagnostic ultrasound imaging for musculoskeletal soft tissue pathology of the extremities: a comprehensive review of the literature

Musculoskeletal diagnostic ultrasound imaging (MSK-DUSI) has been growing outside the traditional radiology speciality. Increased use of this technology has been reported in several healthcare settings, however an apparent gap in the knowledge of the accuracy of this diagnostic technology indicated a review was warranted. We undertook a structured review of the literature to assess the accuracy of MSK-DUSI for the diagnosis of musculoskeletal soft tissue pathology of the extremities. An electronic search of the National Library of Medicine’s PubMed database (1972 to mid-2014) was conducted. All relevant systematic reviews of diagnostic studies, all diagnostic studies published after the date of the latest systematic reviews and relevant diagnostic studies outside the scope the systematic reviews that directly compared the accuracy of MSK-DUSI (the index test) to an appropriate reference standard for the target condition were included. A fundamental appraisal of the methodological quality of studies was completed. The individual sensitivity, specificity and likelihood ratio data were extracted and entered into diagnostic accuracy tables. A total of 207 individual studies were included. The results show that MSK-DUSI has acceptable diagnostic accuracy for a wide spectrum of musculoskeletal conditions of the extremities. However, there is a lack of high quality prospective experimental studies in this area and as such clinicians should interpret the results with some caution due to the potential for overestimation of diagnostic accuracy.

Ultrasound versus magnetic resonance imaging for Morton neuroma: systematic review and meta-analysis

OBJECTIVES

To compare ultrasound (US) and magnetic resonance imaging (MRI) in the diagnosis of Morton's neuroma.

METHODS

Studies that assessed the diagnostic accuracy of US and MRI for Morton's neuroma were retrieved from major medical libraries independently by two reviewers up to 1 April 2014. Predefined inclusion and exclusion criteria were adopted.

RESULTS

277 studies were initially found, and the meta-analysis was conducted on 14 studies. US sensitivity was studied in five studies, MRI sensitivity in three studies, and bothin six studies. All studies used surgery as the reference standard. A high sensitivity (SE) of diagnostic testing was observed for both US (SE (95 % CI) = 0.91 (0.83-0.96)) and MRI (SE (95 % CI) = 0.90 (0.82-0.96)) with no significant differences between the two modalities in diagnosis (Q test p = 0.88). For MRI, specificity of test was 1.00 with a pooled estimation of 1.00 (0.73-1.00), while the pooled specificity was 0.854 (95 % CI: 0.41-1.00) for US. No differences were observed between US and MRI in study design (p = 0.76).

CONCLUSION

This meta-analysis shows that the SE of US (0.91) is equal to (p = 0.88) that of MRI (0.90) for identification of Morton's neuroma.

KEY POINTS

• For Morton's neuroma, US sensitivity is equal to MRI. • US is as accurate as MRI in diagnosing Morton's neuroma. • US may be the most cost-effective imaging method for Morton's neuroma.

The accuracy of ultrasonography and magnetic resonance imaging for the diagnosis of Morton's neuroma: a systematic review

AIM

To determine the accuracy of MRI versus ultrasound for Morton's neuroma.

MATERIALS AND METHODS

A search was undertaken for clinical studies published in any language in PubMed up to the date of December 2013. Studies assessing the accuracy of the ultrasound or MRI for the diagnosis of Morton's neuroma were included. Data were pooled for meta-analysis. Study selection, data collection, and extraction were performed independently by two authors. Meta-disc 1.4 and Revman 5.2 software were applied for statistical analysis.

RESULTS

The study included 12 studies; 217 patients underwent MRI and 241 underwent ultrasound examinations. There appeared greater diagnostic accuracy for ultrasound than MRI for the diagnosis of Morton's neuroma (ultrasound sensitivity 90%, specificity 88%, positive likelihood ratio 2.77, negative likelihood ratio 0.16 versus MRI sensitivity 93%, specificity 68%, positive likelihood ratio 1.89, negative likelihood ratio 0.19).

CONCLUSIONS

The available evidence suggests that ultrasound can provide better accuracy for the diagnosis of Morton's neuroma than MRI.

Contribution of a new electrophysiologic test to Morton's neuroma diagnosis

BACKGROUND

Morton's neuroma causes metatarsalgia due to the interdigital neuropathy. The small nerve diameter compromises their evaluation in image studies. To overcome this problem we propose a new electrophysiological test.

METHODS

We conducted a prospective case-control study performing a orthodromic electroneurography using subdermal electrodes in controls and patients to assess the validity. Additionally all patients were tested with magnetic resonance. Some patients required surgery and subsequent histological evaluation.

RESULTS

The new ENG procedure showed higher sensitivity and specificity. Methodological standardization was easy and the test was well tolerated by the subjects.

CONCLUSIONS

Our test demonstrated remarkable diagnostic efficiency, and also was able to identify symptomatic patients undetected by magnetic resonance, which underlines the lack of correlation between the size and intensity of the lesion. This new electrophysiological method appears to be a highly sensitivity, well-tolerated, simple and low-cost for Morton's neuroma diagnosis.

Magnetic resonance imaging versus musculoskeletal ultrasound for identification and localization of plantar plate tears

PURPOSE

Plantar plate injuries have been identified as a cause of forefoot pain and deformity. Magnetic resonance imaging (MRI) and musculoskeletal ultrasound (US) have been suggested as appropriate imaging modalities for this pathology. A comparison of these two modalities utilizing intra-operatively pathology as the reference standard has not been published.

METHODOLOGY

51 feet of 42 consecutive patients presenting to clinic with forefoot pain and a suspected unilateral plantar plate tear at the 2nd metatarsophalangeal (MTP) joint were identified. A two plane (longitudinal and transverse) US was performed on the painful second MTP joint. Longitudinal ultrasound images were graded as 'torn' or 'intact'. Transverse ultrasound images were used to localize pathology. All ultrasound exams were performed by the same reconstructive foot & ankle fellow. A pre-operative MRI was performed on these patients and read by a Fellowship Trained Musculoskeletal Radiologist. The physicians reading US and the MRI were blinded to each other's findings.

RESULTS

All 51 feet were examined intra-operatively. 46 plantar plate tears were identified. The sensitivity, specificity, positive predictive value and negative value of MRI were 73.9%, 100%, 100%, 29.4% respectively while the same values for US were 91.5%, 25%, 91.5%, 25% respectively. MRI identified 4 collateral ligaments tears not identified on ultrasound. Discussion &

CONCLUSIONS

Both MRI and US are appropriate modalities for imaging of the plantar plate. While US is a highly sensitive exam, MRI is a more specific exam. Overall these results do not suggest that MR should be replaced by US in all cases.

LEVEL OF EVIDENCE

Diagnostic, Level I.

Prevalence of interdigital nerve enlargements in an asymptomatic population

BACKGROUND

Morton's neuroma is a common primary diagnosis for referral to foot and ankle surgeons. On presentation, many patients have had an ultrasound reporting the presence of Morton's neuroma, which may not correlate with the clinical examination findings. The prevalence of such sonographic findings in the general population remains unknown.

METHODS

In this observational prospective study, patients with asymptomatic forefeet who were seen by two foot and ankle surgeons for unrelated mid- or hind foot pathology were examined clinically and sonographically for the presence of interdigital nerve thickening. Forty-eight volunteers participated in the study (96 feet). For the purpose of this study, asymptomatic thickenings greater than 5 mm in diameter were termed sonographic neuromas. Ultrasound examination was performed by two specialist musculoskeletal radiologists.

RESULTS

Fifty-four percent of the volunteers (26 of 48) had sonographic nerve thickening and in 17 cases (35.4%) enlarged nerves were found bilaterally. Differences for gender, original diagnosis or side of original pathology were not significant. Older subjects were more likely to have a sonographic neuroma (p = 0.018). Feet with a positive Mulder's click were more likely to have a sonographic neuroma (p = 0.015).

CONCLUSION

Ultrasound, even in highly skilled hands, has a high rate of incidental finding of an asymptomatic interdigital nerve enlargement, which can lead to a false diagnosis of a Morton's neuroma. Sonographic evidence of Morton's neuroma per se is unreliable unless it is correlated with an equivocal clinical examination. Clinical examination is still the gold standard for the diagnosis of a Morton's neuroma.

MRI and ultrasonography in Morton's neuroma: Diagnostic accuracy and correlation

BACKGROUND

The diagnosis of Morton's neuroma is based primarily on clinical findings. Ultrasonography (US) and magnetic resonance image (MRI) studies are considered complementary diagnostic techniques. The aim of this study was to establish the correlation and sensitivity of both techniques used to diagnose Morton's neuroma.

MATERIALS AND METHODS

Thirty seven patients (43 intermetatarsal spaces) with Morton's neuroma operated were retrospectively reviewed. In all cases MRI or ultrasound was performed to complement clinical diagnosis of Morton's neuroma. In all cases, a histopathological examination confirmed the diagnosis. Estimates of sensitivity were made and correlation (kappa statistics) was assessed for both techniques.

RESULTS

Twenty seven women and 10 men participated with a mean age of 60 years. Double lesions presented in six patients. The second intermetatarsal space was affected in 10 patients and the third in 33 patients. An MRI was performed in 41 cases and a US in 23 cases. In 21 patients, both an MRI and a US were performed. With regard to the 41 MRIs performed, 34 were positive for Morton's neuroma and 7 were negative. MRI sensitivity was 82.9% [95% confidence interval (CI): 0.679-0.929]. Thirteen out of 23 US performed were positive and 10 US were negative. US sensitivity was 56.5% (95% CI: 0.345-0.768). Relative to the 21 patients on whom both techniques were carried out, the agreement between both techniques was poor (kappa statistics 0.31).

CONCLUSION

Although ancillary studies may be required to confirm the clinical diagnosis in some cases, they are probably not necessary for the diagnosis of Morton's neuroma. MRI had a higher sensitivity than US and should be considered the technique of choice in those cases. However, a negative result does not exclude the diagnosis (false negative 17%).

Interdigital neuralgia

Interdigital neuralgia affects a significant number of individuals, with an average age of presentation in the sixth decade and a 4- to 15-fold increased prevalence in women. Historical descriptions date back to the 19th century. Nonoperative treatment with shoe modifications, metatarsal pads, and injections provides relief for most, but long term, 60% to 70% of patients eventually elect to have surgery. Although excision can be performed through a dorsal or plantar approach, we prefer the dorsal incision to prevent scar formation on the plantar aspect of the foot. Satisfactory results are common but not certain with reports of excellent or good ranging from 51% to 93%.

Morton's neuroma

Morton neuroma is a common source of forefoot pain. This condition is more correctly termed as interdigital nerve compression and is not a true neuroma. Although Morton neuroma is a common diagnosis, debate exists as to the best surgical and nonsurgical treatments. This article discusses the pathogenesis, diagnosis, nonsurgical and surgical management, and surgical complications of this common disorder.

The Use of Ultrasound in Diagnosing Morton's Neuroma and Histological Correlation

This was a retrospective study examining 60 surgically excised Morton's neuromas from 53 patients over a period of three years at Southend University Hospital, Essex. The initial diagnosis of Morton's neuroma was based on history and examination findings. In only one-third of cases was the neuroma palpable. However, many patients had difficulty localizing the pain and had atypical presentation. We attempted to assess the reliability of ultrasound in diagnosing Morton's neuroma in the 60 histologically confirmed cases. Our second objective was to assess whether size estimate of a neuroma seen on ultrasound correlated with subsequent real specimen measurement. In our study, preoperative ultrasound reliably diagnosed Morton's neuroma in 97% of the cases. In contrast, there was poor correlation in real specimen size measurements when compared with ultrasound reports.