Abstract
Introduction
To investigate if the gap index measured in the follow-up X-rays predicts the reduction of swelling in the plaster cast thereby increasing the risk of re-displacement of fracture treated by manipulation alone.
Materials/Methods
We selected for this study a cohort of children who presented with a traumatic displaced fracture of distal radius at the junction of metaphysis and diaphysis who were treated with manipulation alone. This cohort was chosen because of the high risk of re-displacement following closed manipulation of this unstable fracture and to maintain uniformity of the fracture type. Cast index and Gap index was measured in the intra-operative radiograph and at two-weeks to note the change in these indices. Gap index which is measured by summing radial and ulnar translation/inner diameter of cast in the AP X-ray and similar translation on the lateral x-ray/inner diameter of cast, with a measure of <0.15 considered to be a satisfactory cast.
Results
Forty-one children with a mean age of 9 years (mode-8, range 4–15 yrs) admitted between Jan 2008 and Feb 2010 with the above described fracture and were treated with manipulation alone were included in this study. Serial radiographs show a gradual loss of reduction in 34 (83%) children and 17 (41%) of these children required re-manipulation. As the plaster cast was not changed the cast index remained same while the gap index increased in the follow-up x-rays as the swelling subsided. In those children whose reduction remained satisfactory, the initial gap index was 0.14 which changed to 0.18 (n=7, p>0.05) while in children in whom the fracture lost reduction, the initial gap index was 0.18 and changed to 0.25 (n=34, p=0.0092) at two weeks.
Conclusion
Gap index can easily be calculated on follow-up radiographs and can be used to assess the adequacy of plaster cast. From this study we can conclude that it is effective in assessing the adequacy of plaster cast as the swelling subsides.
