Aims: To explore potential predictors of functional outcome after conservative treatment of acute fractures of the base of the fifth metatarsal. These fractures are the most frequent fracture of the foot. The factors that influence final clinical outcome are rarely investigated. Regression analysis regarding this problem was never performed.

Methods: The study design was observational and retrospective. Adults, conservatively treated for an acute fracture of the base of the fifth metatarsal included. All patients were given a plaster cast at the emergency department and were instructed not to bare weight (NWB) on the affected limb for at least one week. The further modalities of treatment were decided by individual surgeons according to their current clinical practice. A validated scoring system was used. Additional questions were asked about residual cosmetic and shoe problems and also about intensity of pain and the general feeling of comfort. The respective influences of factors on clinical outcome were examined using multiple linear and logistic regression modeling.

Results: 38 patients (11 men, 27 women) were analysed. The mean age was 48 years. 6 had a Jones fracture, while 32 had a tuberosity avulsion fracture. The mean non-weight bearing period was 2 weeks and 4 days (range 1 to 5 weeks) while the cast was worn for a mean of 5 weeks and 3 days (range 1 to 10 weeks). Three Jones fractures and all the avulsion fractures were healed at the end of treatment. The mean follow-up time was 298 days, ranging from 51 to 603 days. The mean result of the ankle score at follow-up was 77.5 (range 20 to 100). Thirteen of the 38 patients reported problems in wearing shoes. Only 8 patients experienced cosmetic problems. The mean linear analogue score for pain was 2.34, that for general comfort was 8.11. Overall, the most significant predictors of poor functional outcome at final follow-up evaluation were increasing duration of NWB and longer follow-up time. Longer NWB was importantly associated with worse global score, pain, comfort and reported stiffness. Neither gender nor fracture type had any significant influence on the overall clinical outcome.

Conclusions: The most important variable linked to final clinical outcome is the duration of the non-weight bearing period. Neither gender, age, length of casting nor even fracture type, had any significant influence on the overall clinical outcome. Therefore NWB should be kept to a minimum for acute avulsions.