Surgical anatomy of the ischial and pubic bone for screw fixation during total hip arthroplasty revision surgery

Total hip arthroplasties (THA) are nowadays an extremely common orthopaedic surgery. The demographic changes in our ageing population combined with the decreasing age at primary implantation significantly challenges the longevity of the joint replacements. Even in an immortal population, all hip replacements would eventually fail due to normal tribological and biological processes (Evans et al. 2019). This situation evokes the need for successful revision surgeries once the inevitable deterioration of the primary prosthesis has occurred. The main challenge of revision surgeries is the deficient bone stock most patients present with. This baseline situation challenges the success of the surgery. The main aims of the revision are to restore the centre of rotation, repair bony defects and achieve sufficient primary stability of the new acetabular cup. Various methods have been introduced to attain these goals. However, they all suffer from shortcomings and are only indicated in certain situations. This study aimed to investigate the usage of supporting transacetabular screws as an adjunct treatment option. Screws are commonly inserted into the superior ilium, however, the potential of inferior fixation within the ischium or anterior fixation within the pubis has not been well documented. The main aims of this study were to examine these additional fixation areas and retrospectively using CT imaging to calculate the appropriate angle of screw insertion and maximal screw length. The ultimate goal was to develop a simple system that would allow orthopaedic surgeons to confidently place further supporting screws. This study included 43 patients (22 men and 21 women) who had previously received a total hip arthroplasty from the orthopaedic department in the Waldkliniken Eisenberg. Their CT imaging of the pelvis was imported into the DICOM viewer HOROS.