Radiographic quantification of dynamic hip screw migration.

Authors :: Audigé L
Cagienard F
Sprecher CM
Suhm N
Müller MA
Source :: International orthopaedics [Int Orthop] 2014 Apr; Vol. 38 (4), pp. 839-45. Date of Electronic Publication: 2013 Oct 22.
Publication Year :: 2014
Abstract: Purpose: This study aimed to propose a technique to quantify dynamic hip screw (DHS®) migration on serial anteroposterior (AP) radiographs by accounting for femoral rotation and flexion.<br />Methods: Femoral rotation and flexion were estimated using radiographic projections of the DHS® plate thickness and length, respectively. The method accuracy was evaluated using a synthetic femur fixed with a DHS® and positioned at pre-defined rotation and flexion settings. Standardised measurements of DHS® migration were trigonometrically adjusted for femoral rotation and flexion, and compared with unadjusted estimates in 34 patients.<br />Results: The mean difference between the estimated and true femoral rotation and flexion values was 1.3° (95% CI 0.9-1.7°) and -3.0° (95% CI - 4.2° to -1.9°), respectively. Adjusted measurements of DHS® migration were significantly larger than unadjusted measurements (p = 0.045).<br />Conclusion: The presented method allows quantification of DHS® migration with adequate bias correction due to femoral rotation and flexion.