Validity and reliability of different techniques of neck–shaft angle measurement

Aren Joe Bizdikian (1) , Ayman Assi (2, 3, 4) , Ziad Bakouny (5, 6, 3) , Elie Saghbini (2) , G. E. Bakhos (2) , S. Esber (2, 7) , Nour Khalil (2) , Joeffroy Otayek (2, 8) , Joe Ghanimeh (2) , Christophe Sauret (2, 4) , Wafa Skalli (4) , Ismat Ghanem (4)

1 LBMA - Laboratoire de Biotechnologie et Microbiologie Appliquée
2 LBM - Laboratoire de biomécanique
3 USJ - Université Saint-Joseph de Beyrouth
4 Institut de Biomecanique Humaine Georges Charpak
5 LBMC UMR T9406 - Laboratoire de Biomécanique et Mécanique des Chocs
6 LBM-E4 - Microorganismes, Molécules Bioactives et Physiopathologie Intestinale
7 LBM UMR 7203 - Laboratoire des biomolécules
8 LBM-E1 - Peptides, glycoconjugués et métaux en biologie

AIM: To determine a valid and reliable neck-shaft angle (NSA) measurement method while rotating the pelvises in increments of 5° in order to simulate patient malpositioning. MATERIALS AND METHODS: CT images of 17 patients were used to produce digitally reconstructed radiographs in frontal and lateral views and three-dimensional (3D)-reconstructions of the femurs, considered to be the reference standard. Malpositioning was simulated by axially rotating the frontal radiographs from 0° to 20°. Three operators measured in two-dimensions the NSA using four different methods, three times each, at each axial rotation (AR) position. Method 1 (femoral neck axis drawn by joining the centre of the femoral head (CFH) to the median of the femoral neck base; femoral diaphysis axis drawn by joining the median of two lines passing through the medial and lateral edges of the femoral axis below the lesser trochanter) and method 2 (femoral axis taken as the median of a triangle passing through base of femoral neck and medial and lateral head-neck junction; femoral diaphysis as previous) were described for the first time; method 3 was based on a previous study; method 4 was a free-hand technique. Reliability, validity, and global uncertainty were assessed. RESULTS: Method 1 showed the best reliability and validity. The global uncertainty also showed minimal values for method 1, ranging from 7.4° to 14.3° across AR positions. CONCLUSION: Method 1, based on locating the CFH, was the most reliable and valid method and should be considered as a standardised two-dimensional NSA measurement method for clinical application.

Domaines: Biomécanique [physics.med-ph]

Aren Joe Bizdikian, Ayman Assi, Ziad Bakouny, Elie Saghbini, G. E. Bakhos, et al.. Validity and reliability of different techniques of neck–shaft angle measurement. Clinical Radiology, 2018, 73 (11), pp.984.e1-984.e9. ⟨10.1016/j.crad.2018.06.006⟩. ⟨hal-02197360⟩