About 15% of all stress fractures. Difficult to manage.
Usually a combination of risk factors – especially overuse; navicular is exposed to considerable compressive stress from adjacent tarsal bone, so foot biomechanics may play a significant role.
More common in athletes, especially those involved with explosive movements (eg sprinting, basketball, jumping). Potentially a serious injury.
History of insidious onset of insidious onset of vague and diffuse midfoot pain – usually dorsal, but can radiate alone medial arch area. Pain does not necessarily decrease with rest.
Tender ‘N’ spot often palpated over dorsal navicular.
Fracture line not often seen on pain x-rays (often unhelpful) need bone scan or CT scan.
Usually a linear fracture in central third of bone blood supply is limited.
Initially manage with foot orthoses immobilisation and activity modification, then if non-responsive non-weightbearing cast for 6 – 8 weeks or until tenderness on ‘N’ spot resolves progressive return to activity. Nonweightbearing on crutches + cam walker maybe used instead of cast immobilisation (depends on compliance)
Fixation + graft if non-union, acute and unstable, symptomatic dorsal ossicle present, osteoarthritis of talonavicular joint is present
Correction of any biomechanical abnormalities before return to activity is important.