Corticosteroid injections for Morton's neuroma - does ultrasound guidance improve efficacy? A randomised controlled trial

D. Mahadevan, R. Bhatt, M. Bhatia

Background: The purpose of this double-blind randomised controlled trial was to assess whether ultrasound guidance improved the efficacy of steroid injections for Morton's neuroma (MN).

Methods: Following IRB approval, cases with MN confirmed on ultrasound were randomised to 2 groups: Group 1 received ultrasound-guided injections (1ml 40mg Depo-Medrone and 1ml 1% lignocaine) and Group 2 received the same injection under sham ultrasound guidance. All ultrasounds and injections were performed by a single MSK radiologist. Patients were reviewed at 3 months.
The primary outcome measure was the VAS for pain. The study was powered to detect a MCID of 15mm on a 100mm VAS scale between the groups (21 per group). Secondary outcomes included the Manchester-Oxford Foot Questionnaire (MOxFQ), Johnson's satisfaction scale and failure of treatment.

Results: 50 cases (feet) were recruited for this study. Demographics included 29 female to 21 male with a mean age of 58 years (29 - 88 yr). Five cases declined further participation and were excluded from analysis. The VAS score improved significantly in both groups (64 to 25mm in Group 1 vs. 67 to 34mm in Group 2; p< 0.005) but there was no significant difference between the groups (p=0.08). Similarly, the improvement in MOxFQ scores was also significant in both groups (38 to 18 in Group 1 vs. 38 to 23 in Group 2; p< 0.05) but did not reach statistical significance when the groups were compared (p=0.086). The Johnson's satisfaction scale was however, significantly better in Group 1 (p=0.011). Seventy-percent in Group 1 were either completely satisfied/ satisfied with minor reservation compared to only 50% in Group 2. At 3 months, 17% in Group 1 versus 36% in Group 2 failed treatment.

Conclusion: The results suggest that the use of ultrasound guidance improved the efficacy of steroid injections for symptomatic Morton's neuroma.