The authors prospectively reviewed 4024 distal radius fractures between June of 1988 and December of 1993. Seventy-nine percent of the fractures were in female patients and 21% were in male patients. The mean age for all patients was 59 years (range, 14 - 100 years). Early instability occurred in 10% of patients with minimally displaced fractures at presentation and occurred 10 times more frequently in patients who were more than 80 years old compared with patients who were less than 30 years old. Associated comminution resulted in early instability 6 times more frequently in fractures with any form of comminution. Original dorsal angle and ulnar variance were also associated with early instability 5 times more frequently in fractures with a dorsal angle between 5 and 10 degrees compared with fractures that maintained any degree of volar angulation and two times more frequently with greater ulnar variance. Late instability occurred in 22% of fractures that initially presented minimally displaced. The age of the patient, presence of comminution, dorsal angle and ulnar variance retained significance but age was the most important factor occurring 4 times more frequently in patients more than 80 years old compared with those less than 30 years old. Fracture comminution of any type increased the frequency of late instability by a factor of 3.
Factors that were predictive of malunion in fractures that were minimally displaced at presentation included age (six fold increase in those over 80 years), dorsal angle (those between 4 degrees and 10 degrees of dorsal angle was 3 times more frequent than those with any degree of volar angulation), comminution (3 times more common in fractures with any type of comminution), involvement of the ulnar styloid, and dependency of the patient. Of those patients that presented with displaced fractures, early instability occurred in 43% overall. Age, dorsal angle and ulnar variance were found to be significant measured at one week post presentation. In patients who presented with displaced fractures at presentation, prediction of malunion were greatest in patients over 80 years, dependent patients, ulnar variance greater than 2 mm and in comminuted fractures. Carpal malalignment was present in 31% and was found to be associated with increased age, patient dependence, dorsal comminution and original dorsal angulation. Formulas were developed by the authors based on the data to predict the probability for fracture instability.
This study confirmed a number of independent variables that have been associated with overall poor outcomes related to distal radius fractures. Most notably, the most important predictive factors were the age of the patient, the type of comminution of the fracture and the position of the fracture at presentation. Early and late instability as well as carpal malalignment increased significantly with advanced age. In the prediction of malunion, the presence or absence of comminution was important, whereas in the prediction of carpal malalignment, the location of comminution (dorsal) was important. The position of the fracture at presentation was predictive of the position at union as malunion occurred more frequently with displaced fractures and initial ulnar variance was consistently significant. Dorsal angle was of variable significance. It was important in the fractures that were minimally displaced at presentation and in the prediction of carpal malalignment.
Although not presented in this summary, this study produced a predictive formula for fracture instability and carpal malalignment. Although not validated, this study has helped produce a method to potentially prospectively quantify the risk of fracture instability. Future studies may help validate these formulas.
Distal, Radius, Fracture, Instability
J. Bone and Joint Surgery