Inter- and intraobserver agreement on the Load Sharing Classification of thoracolumbar spine fractures.

The Load Sharing Classification (LSC) allocates one to three points to each of three different radiological characteristics of traumatic thoracolumbar fractures: the vertebral body involved in the fracture, the displacement of the fracture parts and the kyphotic deformity. Added up, a minimal score of three and a maximal score of nine can be obtained. When the LSC score is three to six, a short segment pedicle screw fixation suffices. When the LSC score is seven to nine, a high rate of failure in patients with a short segment pedicle screw fixation exists. In these cases an anterior stabilising procedure of the spine is advised. The LSC has been examined by Dai and Jin, who claim an almost perfect inter- and intraobserver agreement, according to the Landis and Koch criteria. Dai and Jin only present results for the separate three items of the LSC and for the total LSC scores. Observer agreement for the two LSC score categories (three to six and seven to nine) have not been studied. The aim of this study is to study the inter- and intraobserver agreement of the LSC for the total score, the three separate items and also for the two LSC score categories. Three observers determine twice the LSC scores of forty traumatic thoracolumbar fractures. The average standard Cohen's kappa values for the separate LSC items range between 0.06 and 0.48. For the total LSC score the average standard Cohen's kappa and weighted kappa values are 0.22 and 0.67 respectively. For the two LSC score categories, there is unanimous agreement in 55% of the cases and a majority agreement in 40%. In the remaining 5% of the fractures there is a split decision. Standard Cohen's kappa value for the two LSC score categories is 0.53. The standard Cohen's kappa values can be rated as fair to moderate. From these data it can be concluded that the inter- and intraobserver reliability of the Load Sharing Classification of Spinal fractures can be rated as fair.