The EOS imaging system for understanding a patellofemoral disorder following THR

An aspect of patellofemoral syndrome secondary to total hip replacement (THR) is mainly suggestive of a problem of femoral implant torsion. We here present the first reported case of patellofemoral syndrome secondary to THR relating to limb-length discrepancy, with no abnormality of femoral torsion. The pelvis adapted to the length inequality by axial rotation rather than frontal tilt, and this went undetected on standard X-ray and CT-scan. 3D imaging in upright posture on the EOS system enabled the situation to be clearly described and analyzed, and adapted surgical correction to be indicated. (C) 2011 Published by Elsevier Masson SAS.