Predictors of outcome of non-displaced fractures of the base of the fifth metatarsal

The purpose of this study was to identify those factors that influence the outcome after conservative treatment of undisplaced fractures of the fifth metatarsal. This was done with univariate analyses and, for the first time, with regression analyses of day-to-day clinical practice. Thirty-eight patients were treated with plaster and periods of no weight bearing (NWB). Their mean age was 48 years. They were evaluated using the Olerud ankle score, with analogue scales for pain and comfort, and with questions about cosmesis and wearing of shoes. Six patients sustained a Jones fracture and 32 a tuberosity avulsion fracture. The mean period of NWB was 17 days and of casting was 38 days. Three Jones fractures and all the avulsion fractures were healed at the end of treatment. After a mean of 490 days, the global ankle score was 82/100. Ten patients reported problems with shoes and nine reported cosmetic problems. The linear analogue scale for pain was 2.11/10 and for comfort 8.42/10. Gender, age, and fracture type did not affect outcome. The most significant predictor of poor functional outcome was longer NWB, which was strongly associated with worse global outcome, discomfort, and reported stiffness. NWB should be kept to a minimum for acute avulsions of the tuberosity of the fifth metatarsal.