Detection of the hip center in computer-assisted surgery: An in vitro assessment study

Abstract

The HKA i.e. the angle between the hip, knee and ankle centers is a clinical parameter widely used in orthopedic surgery. It can be intraoperatively assessed with computer-assisted surgery navigation systems by computing the 3D location of these joint centers. The hip center is computed using functional methods but is defined by the experts as the anatomical center of the femoral head. The aim of this in vitro study is therefore to assess, first, the accuracy of these functional methods for the determination of the HKA and, second, their reproducibility. We have analyzed on six cadaveric lower limbs the accuracy and the reproducibility of functional methods and their impact on the HKA values. The anatomical hip center has been used as the reference value. The reproducibility is 5.2mm for the determination of the functional hip centers. The average impact on the HKA is 1.2° (4° max). Despite a lack of reproducibility of the functional methods, the impact on the HKA is limited. The accuracy of the functional methods on the HKA can therefore be enough for some clinical applications.