Screw Placement Influence on Implant Stability and Osseointegration Potential in Revision Hip Arthroplasty Involving...

Achieving acetabular cup stability following revision total hip arthroplasty (rTHA) involving acetabular defects is challenging. Current computational modeling approaches to investigate implant stability under physiological loading are time consuming to implement and, to date, have been based on low sample sizes across limited defect classifications. This study had two aims. First, to develop an automated rTHA simulation framework to estimate postoperative implant response to physiological loading across the range of Paprosky acetabular defects; and second, to use this framework to estimate regional implant stability and osseointegration potential of rTHA implants augmented with four different screw configurations: (i) superior fixation only (ii) superior and infero-posterior fixation (iii) superior and infero-anterior fixation, and (iv) superior, infero-posterior, and infero-anterior fixation. A modeling pipeline employing artificial neural networks and statistical shape modeling was developed to convert patient computed tomography (CT) images to finite element models for automated surgical planning and simulation of rTHA involving acetabular defects. Computed tomography images from sixty subjects were used as input to the framework resulting in 214 completed simulations. An infero-posterior screw when used with a superior screw was associated with a significant reduction in posterior acetabular micromotion compared to using a superior screw alone (mean reduction: 129 μm, p < 0.001). Use of an infero-posterior screw improved overall implant stability more than that of an infero-anterior screw. The results suggest that screw holes allowing inferior fixation ought to be made standard in revision acetabular components. The findings of this study may be useful in surgical planning for rTHA.