Proposed guidelines for increasing the reliability and validity of Letournel classification system.

The aim of this study was to improve the reliability of Letournel classification system using a guideline algorithm protocol. The study was conducted upon two groups of orthopaedic surgeons with different experience and was consisted of two observation sessions (A and B). In session A, every observer studied, with no instructions or guidelines, a particular set of acetabular fractures on AP and Judet oblique views. In session B the observers had to examine the same set of radiographs by taking into account a guideline algorithm protocol. The unweighted kappa coefficient was utilised to estimate the observers' agreement arising from the examination of the given X-rays. Finally, the agreement of the observers, related to the intraoperative diagnosis was estimated. The main finding of the herein study lies on the improvement of the agreement rate experienced within both groups, in session B over session A. It is reasonable to assume that the main reason behind this result is the provision of the guideline algorithm protocol in the second session. The total agreement rate was increased from 59.9% in session A to 72.1% in session B, (p value=0.0267). Our findings confirm the reliability of Letournel classification system and the proposed guideline algorithm protocol further improve the ability to classify the most complex acetabular fractures types.