The effectiveness of non-surgical interventions for common plantar digital compressive neuropathy (Morton's neuroma): a systematic review and meta-analysis

Abstract

Background: Morton's neuroma (MN) is a compressive neuropathy of the common plantar digital nerve. It is a common compressive neuropathy often causing significant pain which limits footwear choices and weight bearing activities. This paper aims to review non-surgical interventions for MN, to evaluate the evidence base for the clinical management of MN.

Methods: Electronic biomedical databases (CINAHL, EMBASE, MEDLINE and Cochrane) were searched to January 2018 for studies evaluating the effectiveness of non-surgical interventions for Morton's neuroma. Outcome measures of interest were treatment success rate (SR) (binary) and pain as measured using 100-point visual analogue scale (VAS) (continuous). Studies with and without control groups were included and were evaluated for methodological quality using the Downs and Black Quality Index. Results from randomised controlled trials (RCT) were compared between-groups, and case series were compared pre- versus post-treatment. Effect estimates are presented as odds ratios (OR) for binary data or mean differences (MD) for continuous data. Random effects models were used to pool effect estimates across studies where similar treatments were used. Heterogeneity was assessed using the I ² statistic.

Results: A total of 25 studies met the inclusion criteria, seven RCTs and 18 pre/post case series. Eight different interventions were identified, with corticosteroid or sclerosing injections being the most often reported (seven studies each). Results from a meta-analysis of two RCTs found corticosteroid injection decreased pain more than control on VAS (WMD: -5.3, 95%CI: -7.5 to - 3.2). Other RCTs reported efficacy of: manipulation/mobilisation versus control (MD: -15.3, 95%CI: -29.6 to - 1.0); extracorporeal shockwave therapy versus control (MD: -5.9, 95%CI: -21.9 to 10.1). Treatment success was assessed for extracorporeal shockwave therapy versus control (OR: 0.3, 95%CI: 0.0 to 7.1); and corticosteroid injection vs footwear/padding (OR: 6.0, 95%CI: 1.9 to 19.2). Sclerosing and Botox injections, radiofrequency ablation and cryoneurolysis have been investigated by case series studies, however these were of limited methodological quality.

Conclusions: Corticosteroid injections and manipulation/mobilisation are the two interventions with the strongest evidence for pain reduction, however high-quality evidence for a gold standard intervention was not found. Although the evidence base is expanding, further high quality RCTs are needed.

Keywords: Common plantar digital nerve; Compression neuropathy; Morton’s neuroma; Non-surgical intervention.

Fig. 1

Flow diagram of study selection

Fig. 2

Clinical evidence summary: Morton’s neuroma non-surgical interventions for pain reduction. RCT Randomised controlled trial; Clinical evidence summary may be used in combination with the existing published treatment pathways for Morton’s neuroma; *No studies assessing the effect of orthoses on foot function related to Morton’s neuroma were found by the review; ^#Statistically significant reduction in pain may not be a clinically significant reduction in pain (no data on the minimal important difference for pain reduction in Morton’s neuroma was found)

Fig. 3

Meta-analysis for RCTs of corticosteroid injection on continuous outcomes (Pain VAS 0–100). VAS visual analogue scale; WMD weighted mean difference; CI confidence interval

Fig. 4

Mean difference (with 95% CI) for RCT continuous outcomes (Pain VAS 0–100). *Two or more studies required to calculate I² statistic; #UG single injection and NUG three injections outcome data combined; VAS visual analogue scale; MD mean difference; CI confidence interval; UG ultrasound guided; NUG non-ultrasound guided; ESWT extracorporeal shock wave therapy

Fig. 5

Odds ratio (with 95% CI) for RCT binary outcomes. *Three or more studies required to calculate I² statistic; OR odds ratio; CI confidence interval; UG ultrasound guided; NUG non-ultrasound guided; ESWT Extracorporeal shockwave therapy

Fig. 6

Effect of intervention on pre/post case series continuous outcomes (Pain VAS 0–100). *Two or more studies required to calculate I² statistic; VAS visual analogue scale; MD mean difference; CI confidence interval; ESWT extracorporeal shock wave therapy

Fig. 7

Effect of intervention on case series binary outcomes. *Three or more studies required to calculate I² statistic; SR success rate; CI confidence interval; ESWT Extracorporeal shockwave therapy