OSTEOPOROSIS: DOES IT INFLUENCE BONE DEFORMITY IN DISTAL-RADIUS FRACTURES?

Abstract

Osteoporosis has been implicated as one of the causative factors for Colles’ fracture. The current study was designed to establish whether the degree of osteoporosis has any influence on the radiological severity of Colles’ fracture in active elderly peri-menopausal female patients.

Female peri-menopausal patients who sustained a Colles’ fracture were studied. The ultra distal Bone Mineral Density (uBMD) was determined using DXA in the contralateral non-fractured wrists, which were also x-rayed. Anthropometric measurements were recorded, the radiological severity of the fracture was assessed using a computerised image analysis system, which measured the radial angle, height and width on AP view and the dorsal tilt on lateral view. Measurements were carried out on the fractured and the normal wrist. Pearson’s correlations between age, height, weight, BMI, uBMD and fracture measurements were carried out. The Bone Deformity Index (BDI) was defined as the summation of all the differences of the previous parameters between the normal and fractured wrists on the AP view. ANOVA, with bonferroni correction, was used to compare the parameters and the radiological measurements between normal, osteopenic and osteoporotic patients.

Sixty-seven patients were recruited. Those with Barton fractures, previous fractures of the wrist or a previous history of chronic treatment with bone modifying drugs were excluded. Forty eight patients were analysed. The parameters measured had a tendency to be worse with increasing degree of osteoporosis, although the only significance was in the measurement of dorsal tilt on the lateral view (p = 0.05). The normal patients were significantly heavier (89.3 kg) than the other two groups (p =0.03). In the osteoporotic group the correlation between uBMD and the BDI was −0.6, between uBMD and radial height difference was –0.5 and between uBMD and the angle difference in AP was also –0.5. Similar correlations in normal patients were not statistically significant. Power estimates were performed. Because of the relatively large variability within the samples, a sample size of 550 cases will be necessary to reach a power of 80% to detect a pre-defined clinically significant difference of 3 units in the BDI between groups.

The evidence from this study suggests that the initial radiological deformity in osteoporotic patients was greater in those patients with severe degree of osteoporosis. The deformity in normal patients did not have a correlation with the uBMD but these patients were significantly heavier, indicating a different combination of causative factors in these two groups. The precision of the current method of x-ray measurements has enabled a precise definition of the variability within the different groups, resulting in the production of information that was not previously available.