Subtrochanteric/femoral shaft versus hip fractures: incidences and identification of risk factors.

Subtrochanteric and femoral shaft (ST/FS) fractures are now considered to be fragility fractures in osteoporotic patients. Although rare, there is growing evidence of the burden that they constitute. Little is known about the change over time in incidence of ST/FS fractures. We assessed the incidence of ST/FS fractures and the associated risk factors from 2002 to 2009 compared with those of hip fractures. Data were obtained from the French National Database, which includes all hospital discharge codes from acute care facilities. Hospitalizations for primary surgical management of neck/trochanteric (hip) and ST/FS fractures in patients aged above 50 years were selected and described for different age groups. Incidences per million populations were calculated using the estimated French population adjusted for each year, age, and gender. We studied the change for each fracture site. The comorbidity factors related to these fractures were assessed in 2009 using multivariate logistic regression. From 2002 to 2009, the adjusted incidence of hip fractures decreased continuously from 4368 to 3662 in women (p < 0.0001), and a mild increase from 1476 to 1384 in men (p < 0.0001) after an initial decrease. In contrast, the incidence of ST/FS increased significantly in both genders (from 353 to 395 in women, from 146 to 159 in men). In 2009, the incidence of ST/FS in the general population remained low, reaching the levels of 412 in women and 168 in men, but were 2966 and 1461 in women and men aged >89 years. The adjusted risk of having a ST/FS fracture was significantly higher in a context of obesity (odds ratio [OR]: 2.26; 1.95-2.61) and dementia (OR: 1.23; 1.16-1.30), but decreased with age (OR: 0.83; 0.79-0.88) and hypertension (OR: 0.90; 0.86-0.95). In conclusion, ST/FS fractures mainly affect elderly people and incidence increased significantly from 2002 to 2009. Obesity and dementia are the risk factors associated with these rare fractures, compared with regular hip fractures.