Validation of two methods to measure posterior tilt in femoral neck fractures

Abstract

Introduction: Posterior tilt of the femoral head in femoral neck fractures (FNF) may influence stability of the fracture and may therefore affect the treatment outcome. Posterior tilt can be measured with different methods. The Lateral Garden Angle (LGA) has been used for this purpose for decades and more recently the Posterior Tilt Measurement (PTM) was introduced. Despite the fact that both methods (LGA and PTM) are used in multiple studies, they have never been compared for reliability in a direct study. The aim of this study is to analyze the intra and inter observer reliability of the LGA described by Garden and the PTM according to Palm.

Methods: Four observers measured the posterior tilt on the radiographs of 50 FNF two times with both methods. Intra and inter observer reliability were determined for the LGA and the PTM.

Results: The intra observer reliability for both methods is substantial with an intra class coefficient of 0.75. The inter observer reliability of the PTM is also substantial with an intra class coefficient of 0.75 compared to a moderate reliability of the LGA with an intraclass coefficient of 0.60.

Conclusion: Based on our results we believe the LGA and the PTM are both reliable methods to measure posterior tilt. Yet the Posterior Tilt Measurement seems to have a better inter observer reliability and therefore has a slight preference over the Lateral Garden Angle.