Abstract
Background
Avulsion fractures of the base of the fifth metatarsal are some of the commonest foot injuries. The robust scientific evidence on the optimal non-operative treatment of these fractures is scant. We designed and conducted a prospective randomised non-inferiority controlled trial of symptomatic treatment versus cast immobilisation with the null hypothesis that cast immobilisation gave substantial benefit over the symptomatic treatment in terms of patient reported outcome measures(PROMs). The alternative hypothesis was that symptomatic treatment was not inferior.
Methods
The primary outcome was the validated Visual Analogue Scale Foot and Ankle (VAS FA) score ranging from 0 to 100. The non-inferiority boundary was set at −10 points. Power sizing determined a minimum of 12 patients per group. Anticipating a significant loss to follow up, 60 patients of 16 years of age or older were randomised to receive either below knee walking cast immobilisation (n = 24) or symptomatic double- elasticated bandage (n = 36) for 4 weeks. Secondary outcome measures were EuroQol-5D, and American Orthopaedic Foot and Ankle Society scores. Data was analysed at the baseline, 4 weeks, 3 months and 6 months post injury by a clinician blinded to a treatment arm.
Results
Symptomatic treatment proved to be non-inferior to cast immobilisation treatment in terms of VAS FA at baseline, 4 weeks and 6 months. Secondary outcomes showed similar comparative values between two treatment groups. Loss to follow up reached 43% at 6 months. The imputation of missing data was done and confirmed the non-inferiority of symptomatic treatment.
Conclusions. Cast immobilisation does not appear to give benefits over symptomatic treatment of these injuries in terms of validated PROMs in adults. A significant loss to follow up should be expected with these fractures in medium term.
Level of Evidence
II
Approval
NRES Yorkshire and the Humber reference: 11/YH/0297
Disclosure
This study was supported with a small research grant from a British Orthopaedic Foot and Ankle Society.
