Diagnostic Tool for Initial Fixation of Acetabular Implant

<div>Initial fixation of cementless components of Total Hip arthroplasty (THA) plays a crucial role for long term survival of implant and the overall success of the surgical procedure. Every year a million of THA is performed and objective intra – operative assessment of initial fixation has not been available for clinical use yet. Currently, surgeons have to rely on their clinical experience, however they have a sophisticated screening method, but not suitable for intra operative assessment of initial fixation. They can use RSA, EBRA or the radiographic analysis for checking the healing process of implant, evaluating implant migration or bone resorption and osteolysis around the bone – implant interface. These methods are suitable for follow - up studies, but do not assist the surgeon during implantation process. Vibrational analysis has been recognized as a promising tool in biomechanics to identify mechanical properties of bone structure, to assess the primary and secondary stability of dental implants and to evaluate fracture healing of bone. In literature some studies dealing with intra – operative initial fixation assessment during THA can be found. Most of them are focused on femoral stem fixation, although acetabular component (AC) fails with the same rate as femoral stem or even frequently. The main objective of proposed work is to investigate the ability of vibrational methods reflect the initial fixation of acetabular implant in some measurable quantity. The bone - implant interface is recognized as one of the potential candidates that would explain the changes in dynamic response of bone - implant system undergoes an ambient excitation. The bone - implant interface is investigated trough numerical modeling. In the experimental part of thesis, different pres fitting forces are compared with the dynamic response of bone - implant system. From numerical analysis it follows that there is a different level of relation between shared contact area and modal parameters of system. Experimental part shows also the relation between evaluation of fixation of implant and its response parameters.