Fractures of the tuberosity are avulsions. Traditionally these were thought to be pulled off by peroneus brevis but biomechanical studies by Richli and Rosenthal (1984) and Theodorou et al (2003) suggest the lateral band of the plantar fascia is more likely to be responsible.
Most are displaced only a small amount. Intra-articular fractures are relatively common but major intra-articular displacement is not.
Wiener et al (1997) randomised 89 patients to layered soft dressing or below-knee cast. All were weight-bearing. All fractures united, but the patients treated in soft dressings returned to activities quicker. 30% were lost to follow-up.
Clapper reported 68 fractures in naval personnel, all of which united in a mixture of casts and soft dressings.
Konkel reported 4 delayed unions and one non-union in 35 patients, although none required surgery.
Overall the non-union rate is 1/192 in these series and there is no evidence that the mode of treatment influences fracture union. These patients should be treated functionally with as little restriction as possible.
We advise the RICE regime, usually with an elastic bandage, immediate weightbearing and no follow-up. Patients are advised there is a 1% risk of symptomatic non-union and can call for a further appointment if still in pain at 2 months. Using this regime we have fixed one tuberosity fracture in 10 years.