A TEST OF STABILITY IN DISTAL RADIUS AND ULNA FRACTURES IN CHILDREN.

Abstract

Aims:

1. 1) To determine the predictive value of a simple stability test in children’s wrist fractures treated with simple manipulation and plaster of Paris (PoP) cast immobilisation.

2. 2) To determine the effect of cast quality as reflected in the skin cast distance (distance between the cast and the skin in the plane of major displacement or angulation) and the cast index (the inside diameter of the cast in the sagittal plane divided by the inside diameter in the coronal plane) on re-displacement rates in children’s wrist fractures treated with simple manipulation and plaster of Paris (PoP) cast immobilisation.

Methods: This is a prospective study of 57 children aged 4 to 15 with metaphyseal and Salter-Harris II wrist fractures treated with simple manipulation. Under fluoroscopic imaging, a simple stability test involving moving the hand at the wrist in the dorsopalmar, and radioulnar planes was performed following reduction, and x-ray images were saved. We recorded and compared the displacement and angulation on the initial x-rays, during the test, and at one-and 6-week follow-up. We also recorded the skin-cast distance (SCD), and the cast index (CI).

Results: 38 patients had isolated radius fractures and 19 had radius and ulna fractures. Four patients needed remanipulation with K-wire fixation. Multiple regression analysis revealed significant correlation between percentage loss of reduction on testing and subsequent re-displacement (relationship between the two sets of values r = 0.6167, (p< 0.001)). This indicates that instability on testing (seen as a significant percentage loss of reduction) is likely to be associated with some loss of reduction on follow-up. There was a significant relationship between the skin cast distance and the cast index, and loss of reduction on one week follow-up. (p=0.006). Isolated radius fractures had a higher risk of re-displacement than radius and ulna fractures (3.9% and 0.9% respectively; p< 0.05%)

Conclusion: Stable reduction on stability testing in wrist fractures in children immobilised in a good cast (reflected in a low SCD, and CI) is associated with a good outcome. Isolated radius and ulna fractures are more likely to re-displace than radius and ulna fractures. There is a relationship between instability and loss of position at the 1-week follow-up. Potentially unstable fractures can be prevented from slipping by a good cast. A stable fracture on our stability test rarely slips. We therefore feel that stability test is a useful adjunct in decision-making.