The purpose of this study was to define a more accurate way of assessing guide wire navigation performance, which is a crucial first step in fixing an intertrochanteric femoral fracture. This study introduces a new measurement technique called the trajectory accuracy metric (TAM) to quantify the placement of a guide wire with respect to an ideal trajectory. A total of seventy-two cases were collected in which a Post Graduate Year 1 (PGY1) resident was instructed to place a guide wire through the neck and head of a synthetic femur as close to a center-center position as possible. Each resident was guided by the use of fluoroscopic anteroposterior (AP) and lateral images. A simple geometrical model of a femur was used to define an ideal wire trajectory in which the wire was inserted at a neck-shaft angle (NSA) of 130° and placed centrally through the femoral neck. 3D models of the femur and wire were created for each case, and the wire trajectory was compared with respect to ideal by calculating TAM, which is the average distance between the two wires. The average TAM across all cases was 8.62mm, with a minimum value of 3.35mm and a maximum value of 24.17mm. Since this is a novel measurement, further studies should be done to evaluate its reliability and validity. Additionally, more wire trajectories should be incorporated into this measurement because successful placement of a guide wire is not restricted to one correct trajectory.

Another application of assessing guide wire navigation performance can be applied to a surgical simulation study, in particular, if skills obtained during surgical simulation carry over to a setting that closely resembled the OR. A cross-over experimental design was used for two groups, and metrics used to determine improvement included tip-apex distance (TAD), procedural time, number of fluoroscopic shots requested, additional breaches of the lateral cortex, and number of entries into the joint space. Twenty-four PGY1 residents participated in this study and were told to minimize all metrics, especially TAD. Significant improvements were seen in procedural time and the number of fluoroscopic images requested. In the future, including additional participants may demonstrate a more prominent transfer of skill.

Furthermore, the variability of TAD was explored. This is an important metric as a TAD of over 25mm is widely viewed as being a predictor of screw cut-out. Since TAD is very subjective, a new technique of TAD measurement was introduced to incorporate a 3D apex location on the femoral head. This measurement was found to significantly decrease the amount of both interobserver and intraobserver variability. Further work needs to be done to determine the most accurate way of assessing TAD as a reliable predictor of screw cut-out.