Intraoperative Evaluation of the Anatomic Lateral Distal Femoral Angle and Its Variation due to Positioning.

Academic Article


  • BACKGROUND/PURPOSE: Preoperative evaluation of the contralateral anatomic lateral distal femoral angle (aLDFA) at our institution is used to judge coronal plane alignment. In our study, we investigated 4 different techniques for obtaining an anteroposterior intraoperative fluoroscopic image of the distal femur to determine which technique provides (1) the greatest interobserver reliability; (2) the lowest variability from the previously published population mean; and (3) the lowest side-to-side variability. METHODS: Inclusion criteria included lower extremity injuries needing fixation that required intraoperative fluoroscopy with an intact femur and an intact extensor mechanism (N = 100). Fluoroscopic images were obtained of the distal femur in 4 positions differentiated by the position of the limb and the orientation of the C-arm beam to the femoral shaft. RESULTS: All measurement techniques resulted in mean measurements within one degree of 81 degrees. Variance between measurements was small among patients with all views, but images that involved a true anteroposterior with the beam perpendicular to the femur had the lowest rate of measurements that were <78 or >84 degrees. CONCLUSION: Side-to-side differences in patients were <2 degrees on average with every image used. With the best-performing images, 20% of patients had an aLDFA > 3 degrees different from the population mean of 81 degrees and 3% of patients were >5 degrees different. Although restoring aLDFA to 81 degrees will be within 3 degrees of the contralateral side the vast majority of the time, matching the aLDFA to the injured side will be the most accurate reconstruction.
  • Authors

    Published In


  • Adult, Female, Femoral Fractures, Femur, Fluoroscopy, Follow-Up Studies, Fracture Fixation, Humans, Intraoperative Period, Male, Patient Positioning, Prospective Studies, ROC Curve, Reproducibility of Results
  • Digital Object Identifier (doi)

    Author List

  • Bergin PF; Miles DT; Mathis TP; Graves ML; Spitler CA; Replogle WH; Jones LC; Stronach B
  • Start Page

  • 414
  • End Page

  • 418
  • Volume

  • 32
  • Issue

  • 8