RESUMEN
PURPOSE OF THE STUDY Pauwels classification system is widely used to classify the femoral neck fractures. Even its widely usage there are severals debates about its reliability. After the femoral neck fracture occured the lower extremity rotates externally and this external rotation deformity could lead to misevaluation of Pauwels angle at the initial radiographs. The purpose of our study is to investigate whether the reliability of Pauwels classification increases after reduction of femoral neck fractures. MATERIAL AND METHODS Two power point presentation was prepared with 117 slides that include antero-posterior radiographs of each femoral neck fracture. The first one included preoperatively taken radiographs and the second one included early postoperatively taken radiographs. Eight observers evaluated these radiographs and they classified the fractures according to Pauwels classification system. After 3 months, the order of the slides were changed for each presentation and the observers were asked to evaluate the radiographs again. Intraclass correlation coefficient values were calculated for evaluation of inter- and intra-observer reliability. RESULTS The mean intra-observer agreement of preoperative evaluation was 0.406 (0.071-0.626) and the interobserver agreements were 0.263 (0.197-0.342) and 0.359 (0.287-0.447), respectively. The intra-observer agreement of postoperative evaluation was 0.508 (0.393-0.757), inter-observer agreements were 0.427 (0.353-0.509) and 0.431 (0.356-0.513), respectively. According to preoperative and postoperative evaluations, 6 of 8 observers' intra-observer agreements were found to be increased and the remaining 2 decreased. Interobserver reliability was improved from poor to fair-good values after evaluating the reducted fracture radiographs. DISCUSSION Femoral neck fractures(FNF) are common and anatomical reduction and internal fixation are preferred as a treatment option in young people and patients have good bone quality. Pauwels classification system is used for classify the FNF based on the shearing angle of the fracture line. As this angle increases, the fracture becomes unstable and nowadays stronger fixation devices are preferred for unstable fractures. Therefore, misevaluation of the fracture can lead to wrong treatment method selection. Non-optimal X-rays taken in the emergency rooms may cause misinterpretation of femoral neck fractures according to Pauwels classification system. We hypothized that the reliability of this classification system could be improved after reduction of the fracture. CONCLUSIONS Our study showed that classifying the femoral neck fracture according to Pauwels classification system is more confidential after the reduction, however we can not state that it's reliability is adequate. Key words: femoral neck fracture, Pauwels classification, reliability, inter-observer, intra-observer.