Work-in-progress #1. The lithotriptor and its potential use in the revision of total hip arthroplasty.

Revision total hip arthroplasty, particularly femoral component replacement, has proved extremely difficult and has met with frequent complications. Despite a variety of devices and techniques that have been developed to facilitate removal of the femoral stem, the procedure remains difficult. Extracorporeal shock wave lithotripsy (ESWL) is a new technique initially created to pulverize renal stones by means of repetitive shock waves delivered to a discrete area. It was felt that perhaps this technique might also be utilized to facilitate the removal of the femoral component and cement from the femoral canal in revision total hip arthroplasty. Using bone cement, cadaveric canine femora were implanted with stainless steel rods placed within the medullary canal. The implanted femora were treated with ESWL, sectioned, and examined, using scanning electron microscopy. Microfracturing of the cement and a disruption of the cement/bone interface were seen in the treated specimens. ESWL has the potential to be used prior to revision total hip arthroplasty to facilitate cement and component removal, although there are several questions that need to be answered prior to considering its clinical use.