An assessment of the accuracy of the Three Point Index in predicting the redisplacement of distal radial fractures in children

Purpose

Distal metaphyseal radial fractures are common in the paediatric population and the management of these fractures is controversial. The incidence of re-displacement in the closed management of these fractures is as much as 30% in some studies. Various methods have been described with the view to predict fracture displacement of distal radial fractures in children. One of these indices is the three point index (TPI). This index seeks to assess the adequacy of 3 point moulding and thus predict fracture displacement. It is a calculated ratio that if above 0.8 states that there is an increased risk of fracture re-displacement. The purpose of this study is to assess the accuracy of this index in predicting displacement of distal radial fractures in children.

Methods

This retrospective study included 65 patients of both sexes under the age of 13 for a period of one year from January 2011 to January 2012. All patients with a dorsally displaced fracture of the distal radius were included. 22 patients were excluded because of loss to follow-up or absence of a complete series of x-rays. All patients were taken to theatre for a general anaesthetic and manipulation of their fractures using an image intensifier to confirm reduction. X-rays of initial fracture displacement, post manipulation position and follow-up fracture position at 2 and 6 weeks were assessed. The sensitivity, specificity, negative and positive predictive values of the TPI in screening for fracture re-displacement were calculated.

Results

Of the 43 patients included in the study, 93% of patients had an anatomical reduction in theatre with an average TPI of 1. Nineteen patients suffered significant displacement from 2 to 6 weeks postoperatively. We found that the TPI in our study had a sensitivity of 84%, a specificity of 37%, a negative predictive value of 75% and a positive predictive value of 51%.

Conclusion

We found the TPI to be a useful screening tool of later displacement for the closed management of distal metaphyseal radius fractures.

NO DISCLOSURES