Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning

Christopher Fleischmann,Irina Leher,Stefan Sesselmann,Jörg Miehling,David Scherb,Alexander Wolf,Sandro Wartzack

doi:10.1515/cdbme-2020-3125

Abstract

Abstract Biomechanical functionality of artificial hips strongly correlates with quality of life of patients after total hip arthroplasty. As the numbers of total hip arthroplasty are growing due to increasing life expectancy, biomechanical research is of utmost importance to improve the implants used and the operative procedures applied. Multibody simulation is used to predict forces and moments inside the human body. Generic scaling is usually performed to adapt the human models used in multibody simulation to individual patients. However, since the shape and size of the bones can vary considerably, this type of scaling often is not sufficient. In this work various CT datasets were used to quantify differences of individual femoral shapes, especially with regard to important biomechanical hip parameters, such as the CCD angle or the femoral offset. Our results prove that multibody simulations should be modeled more patientspecific to be able to calculate articular forces and moments more precisely, and thus, to improve surgical planning.

Highlights

total hip arthroplasty (THA) was designated as one of the most successful operations of the 20th century, with a life rate of up to 95% after 10 years in patients older than 75 years, an increasing number of revision surgeries is expected in nearer future [3, 4]
Important geometrical parameters with influence on the biomechanical function such as the CCD angle or the femoral offset were determined in 2D anatomical planes (Fig 1a)
Four different landmarks were set to the 3D femur model on the femoral center of rotation (COR), the proximal posterior greater trochanter point (PPTP), posterior femoral head point (PFHP) and the anterior femoral head point (AFHP)

Summary

Introduction

Revision THA is characterized by the fact that it does not improve pain and function as well as primary THA [5, 6]. Meticulous planning of hip surgery parameters, such as the femoral centrum-collum-diaphyseal (CCD) angle or the acetabular anteversion is of utmost importance to ensure functionality in case of revision THA. Joint forces and moments as well as other important biomechanical factors are not considered in THA planning at all. Multibody simulation (MBS) is essential to correctly estimate these parameters and to improve surgical planning. MBS allow to simulate forces, moments and muscle activities in order to gain important information about human biomechanics [7, 8]

Objectives

Methods

Results