Relationship between bone mineral density of the distal radius and ulna and fracture characteristics.

PURPOSE

This study was designed to elucidate the different decrease patterns of bone mineral density (BMD) in the distal tenth and third of the radius and ulna that influence the incidence of fractures, the fracture type, and redisplacement after closed reduction and casting.

METHODS

The BMD of 1024 healthy women and 86 women treated for distal radius and ulna fracture was measured in the distal tenth and distal third zones of the radius and ulna (termed R10, R3, U10, and U3, respectively) using dual-energy x-ray absorptiometry. The BMD in the fracture group was compared with age-matched BMD in the nonfracture group. The relationship between BMD, type of fracture, and radiographic parameters (radial length, radial inclination, and palmar tilt) determined after closed reduction and at bone union were examined.

RESULTS

The BMD of the distal radius in zones R10 and R3 in the fracture group were significantly lower than those in the nonfracture group among subjects older than 80 years, whereas the BMD in the U10 and U3 in the fracture group were lower than those in the nonfracture group among subjects aged 50 to 59 years. No significant difference in the mean BMD in any of the fracture group subjects was found, irrespective of the fracture pattern. A significant correlation was found between the BMD in the R10 and radial length measured at bone union and between radial length measured at bone union and RL measured after closed reduction. The radial length, radial inclination, and palmar tilt measured at bone union correlated significantly with each other.

CONCLUSIONS

The BMD in the R10 and R3 are potential indicators of a distal radius fracture in women over 80 years old, whereas the U10 and U3 are indicators of an ulnar styloid fracture in women in their fifties. In addition the distal radius (R10) is an important prognostic parameter of possible deformity of the radius after closed reduction and casting.