Misdiagnosis of occult hip fracture is more likely in patients with poor mobility and cognitive impairment.

The diagnosis of occult hip fracture is frequently missed. We wished to investigate if patients in whom occult hip fracture was initially misdiagnosed had any distinct features, and their outcome. We reviewed 297 patients who presented with hip fractures over a two-year period. There were 24 occult hip fractures, the diagnosis was initially missed in 9 patients and correctly made in the other 15. Of the correctly identified patients, 8/15 were independently mobile and 9/15 were living in their own home compared to 0/9 independently mobile and 2/9 living in own home among those with missed diagnosis (p < 0.001). Seven of nine patients with a missed diagnosis had mental confusion but none in the other 15 (p < 0.001). Eight of the nine patients with missed diagnosis of fracture had intra-capsular fractures, of which 6 secondarily displaced. Three of those nine patients died within one year from their fracture. We suggest a low threshold of investigation for occult hip fracture in the elderly, infirm and mentally confused who present to the accident department with suspected occult hip fracture.