Influence of lower limb rotation on hindfoot alignment using a conventional two-dimensional radiographic technique

• DOI: 10.1016/j.fas.2016.02.003
• Publication Date: 2016-03-31T05:45:16Z
• Authors: L. Baverel; J. Brilhault; G. Odri; M. Boissard; François Lintz
• Keywords: Reproducibility of Results; Models, Theoretical; Radiography; 03 medical and health sciences; 0302 clinical medicine; Lower Extremity; Predictive Value of Tests; Cadaver; Humans; Female; Range of Motion, Articular; Ankle Joint; Aged

Rotation is one of the variables explaining lack of reproducibility in assessing hindfoot alignment. The hypothesis for this study was that a mathematical model predicts how this modifies radiographic hindfoot alignment measurements.A cadaveric lower limb, disjointed at knee level, was used. Sagittal and coronal planes were fixed using a custom clamp. Standard AP views were shot every five degrees and measured hindfoot alignments were compared to theoretical values obtained from a mathematical simulation.Hindfoot angle was 7.04° at 0° rotation and 2.11° at -90°. Intra-class and inter-investigator correlation was 0.863. The t-test showed no significant difference (p=0.73). Intra-investigator correlation was 0.957. The R2 correlation index was 0.852.The mathematical model accurately predicted the variations of the hindfoot angle which was maximum when the foot was aligned with the X-rays source. It then decreased when the foot rotated away, following a parabolic curve.