Stress fracture of the navicular bone.

Navicular stress fractures in athletes are notoriously difficult to diagnose, resulting in an average delay in diagnosis of 4 months after the onset of symptoms. There are various reasons for this delay. Navicular stress fractures are characterised by an unspecific symptomatology combined with a paucity of physical findings. Furthermore there is difficulty in visualising stress fractures on plain radiographs, with only 33% of fractures visible on the initial films. There are several factors contributing to this: the vast majority (83%) of fractures are incomplete fractures at initial presentation and those that are complete are often non displaced and not visible because bony resorption at the fracture site requires 10 days to 3 weeks to occur. For this reason, 3-phase Tc99bone scan is the examination of choice, with almost 100% sensitivity after 72 hours. A favourable outcome can be expected with early diagnosis and proper management. Delayed diagnosis and subsequent improper management can lead to a poor outcome with adverse effects on the activities of the athlete. Treatment consists of 6-8 weeks in a non weight bearing cast for incomplete fractures and non displaced complete fractures. Surgical treatment consists of screw fixation with or without bone graft. Some authors advocate aggressive treatment of non displaced complete fractures. It is imperative to maintain a high index of suspicion when treating patients, especially sprinting athletes, who present with vague mid-foot or ankle pain associated with weight bearing.