No Effect of Oral Mecobalamin on Skin Numbness at 3 Months After Total Knee Arthroplasty: A Randomized, Double-Blinded, Placebo-Controlled Superiority Trial

An area of skin numbness (AON) around an incision commonly occurs following total knee arthroplasty (TKA). Mecobalamin has been shown to facilitate peripheral nerve recovery in various conditions; accordingly, the present study aimed to investigate the ameliorative effect of mecobalamin on AON following TKA, as compared with a placebo. METHODS: This superiority study was a double-blinded, randomized controlled trial. All patients undergoing primary TKA were assessed for eligibility. Included patients were randomized to receive either mecobalamin (500 µg, twice daily) or placebo (corn starch powder; 500 µg, twice daily) for 3 months. The primary outcome was the change in the AON around the surgical site from 2 weeks to 3 months after TKA. Secondary outcomes included the rates of different adverse events, functional outcomes, and visual analogue scale patient satisfaction scores. RESULTS: A total of 154 patients were enrolled, with 77 patients each in the mecobalamin and placebo groups. The mean AON among patients in the mecobalamin group was 61.6 cm(2) at baseline (2 weeks) and 29.1 cm(2) at 3 months, compared with 55.9 cm(2) and 33.2 cm(2) among patients in the placebo group, respectively. Intention-to-treat analysis showed no significant difference in the change in AON around the surgical site between the 2 groups (mean difference, 7.5; 95% confidence interval, −4.2 to 25.3; p = 0.159). The rates of adverse events, functional outcomes, and visual analogue scale patient satisfaction score were also not significantly different between groups. CONCLUSIONS: Mecobalamin did not demonstrate superiority over a placebo in reducing the AON around the surgical site at 3 months after primary TKA. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.