Intra- and inter-observer agreement in distal radius fracture dislocation measurement of casting position

Most displaced distal radius fractures (DRF) are treated nonoperatively, with reduction and immobilization in a cast. Studies assessing intra- or inter-observer agreement on radiologic measurements of casting position have not been published, which was the aim of our study.

Our study is based on the Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE) study. All detected DRFs during the OSTPRE follow-up were retrieved and based on sample size calculations 50 fractures were randomly selected for the study. 5 independent reviewers measured dislocation parameters and wrist position in a cast from the radiographs. A linear mixed model was used to estimate the concordance correlation coefficient (CCC) and total deviance index (TDI) that were used to evaluate intra- and inter-observer agreement. We used Kappa values to determine intra- and inter-rater agreement on radiographically acceptable reduction of the DRF. Limits of acceptable position were those defined by Finnish Current Care Guidelines.

For radial inclination, radial shortening, and dorsal/volar tilt, intra- and inter-observer correlations were high (CCC > 0.76). In addition, measurements of wrist angle in a splint had high correlations (CCC > 0.78), whereas measurement of intra-articular gap and step had poor correlations (CCC < 0.52). The Kappa value for overall agreement on the radiographically acceptable position of the DRF was modest (0.59).

Intra- and inter-observer repeatability of casting position of radial inclination, radial shortening, and dorsal/volar tilt were high whereas intra-articular gap and step had poor correlations.