Patients who receive prophylactic mecobalamin following foot and ankle surgery may have a lower incidence of complex regional pain syndrome type 1.
Researchers conducted the single-center trial between June 2022 and May 2025 to evaluate whether mecobalamin could prevent complex regional pain syndrome type 1 (CRPS-1) following foot and ankle surgery. A total of 440 adult patients undergoing the procedures were randomly assigned to receive either mecobalamin 500 μg or placebo three times daily for 50 days postsurgery, with 432 patients completing the 12-month follow-up. The primary outcome was the incidence of CRPS-1 diagnosed using the Budapest criteria. Secondary outcomes included pain measured with the visual analog scale (VAS), changes in activities of daily living measured with the Foot and Ankle Ability Measure (FAAM), and physical and mental health-related quality-of-life scores measured with the Short Form-36 (SF-36) health survey.
During the follow-up, 2% of patients who received mecobalamin developed CRPS-1 compared with 9% of those who received placebo, corresponding to an adjusted absolute risk reduction of about 8%. The number needed to treat to prevent one case of CRPS-1 was 14.
Patients in the mecobalamin group also experienced greater improvement in postoperative pain compared with those receiving placebo. The researchers noted improvements in FAAM and SF-36 scores with mecobalamin following adjustment for baseline differences. Improvements in sport-specific FAAM scores were greater with mecobalamin prior to but not after adjustment.
The researchers noted that the functional improvements observed in those who received mecobalamin may reflect the lower incidence of CRPS-1 in that group. Previous studies have supported mecobalamin for diabetic peripheral neuropathy and postherpetic neuralgia, whereas evidence supporting vitamin C for CRPS-1 prevention remains inconsistent.
The study had several limitations. The trial was conducted at a single center, CRPS-1 diagnoses were made by one reviewer using standardized criteria, and baseline differences in functional and mental health scores required adjusted analyses. In addition, the researchers noted that although the treatment effects were statistically significant, the magnitude of the effects was relatively modest and should be confirmed in larger multicenter studies.
"Regardless of the limitations, this study discovered that prophylactic mecobalamin significantly lowered the event rate of CRPS-1 after foot [and] ankle surgery and improved pain and functional outcomes of postoperative [...] patients," wrote lead study author Marut Arunakul, MD, of the Department of Orthopedics in the Faculty of Medicine at Thammasat University in Thailand, and colleagues.
This study was supported by Thammasat University. Full disclosures of the study authors can be found in the study.
Source: JBJS Open Access