Aims

Instability is a common indication for revision total hip arthroplasty (THA). However, even after the initial revision, some patients continue to have recurrent dislocation. The aim of this study was to assess the risk for recurrent dislocation after revision THA for instability.

The inability to consistently position components is associated with the major complications of hip replacement including instability, wear, liner breakage, limb length discrepancy, and limited function. This was a major catalyst for the demise of hard-on-hard bearings. The greatest challenge is accurate, reproducible positioning of acetabular component which is obtained in a surprisingly low percentage of cases. Other major issues include consistently obtaining proper limb length, offset, component sizing, and complete seating without fracture of either the acetabulum or the femur. There are two approaches to this issue; to either use virtual reality which applies technology that provides surrogates to direct visualization of components. The major issues with computer assisted techniques include questions of accuracy and increased time and cost. The other approach is to utilise intraoperative imaging which has been the gold standard traditionally, however, previously it has been a challenge to utilise intraoperative imaging without adding substantial time and cost. Historically intraoperative imaging has not been adopted because it disrupts work flow, the quality of images has been inadequate, and it has added too much additional time to allow for a series of repeat radiographs to be obtained. Modifications of existing portable imaging that utilise direct radiography (DR plate technology) allow for intraoperative images that display within seconds. Imbedded software allows measurement of all parameters of interest. Three or 4 systems are currently in use, and this is not virtual reality but it is the gold standard. Advantages include higher quality images, faster service speed, minimal impact on OR work flow, eventual reduction in operating costs, elimination of processing of chemicals and film room/storage room, and most importantly the elimination of outliers and return to the operating room due to unexpected findings on recovery room radiographs. Intraoperative imaging has been utilised at a number of centers in recent years and has led to numerous intraoperative changes to optimise component implantation in a surprisingly high percentage of cases. Advances in technology have made intraoperative digital imaging a practical feasible strategy to avoid outliers that increase complications and compromise results. The rapidly evolving technology makes this a very attractive option for optimising total hip component placement. In addition it is an excellent teaching tool that is rapidly embraced by residents and fellows and is an extremely effective in eliminating outliers