Observer assessment of femoral neck radiographs after reduction and dynamic hip screw fixation

Introduction It is not known how the described methods of reduction and dynamic hip screw (DHS) fixation of displaced intracapsular femoral neck fractures translate into proper assessment of the postoperative radiographs. At teaching or evaluation sessions in daily practice, frequent discussion arises about postoperative technical assessment. The assessment of correct reduction and DHS fixation using the described methods in the literature may be subject to differences between observers. The aim of this study was to assess the extent of inter- and intraobserver agreement on technique, based on the methods in the literature, in a simulated daily practice setting. Materials and methods The postoperative anteroposterior (AP) and lateral radiographs of 35 randomly selected patients aged 60-90 years were rated twice, 2 months apart, by six surgical observers from three institutions with similar views on reduction and DHS fixation for this fracture type. The radiographs were of sufficient quality for proper assessment. Criteria for reduction and fixation could be rated as either adequate or inadequate. An adequate rating was assigned if in the observers opinion, regardless of likely outcome, technical perfection according to the described methods had been achieved. The kappa statistic was calculated as a measure of agreement. Results Fracture reduction on the AP view approached a good kappa value (0.54). Poor to moderate interobserver agreement was found for fracture reduction on the lateral view and aspects of DHS fixation (kappa 0.10-0.36). Intraobserver agreement was good for five out of six observers for reduction and DHS fixation aspects (kappa 0.51-0.81). Conclusion During routine practice six surgical observers can nearly agree on adequate fracture reduction on the AP view, but do not agree on adequate reduction on the lateral view and adequate DHS fixation on the postoperative radiographs of displaced intracapsular femoral neck fractures.