Percutaneous interface tissue removal for hip refixation: The first step in instrument design

In the Netherlands about 36.000 total hip prostheses are implanted every year. Survival of these prostheses at 10 year follow-up is 90% in patients older than 70 years at the index operation. In younger patients these results decrease to about 80–85% at 10 years follow-up. The main cause of failure in total hip replacement is aseptic (mechanical) loosening which is caused by a biological response to wear products of the articulation of the joint. This foreign body reaction is associated with periprosthetic bone resorption and subsequent formation of periprosthetic fibrous (interface) tissue. As a result the implant is becoming increasingly loosened, causing debilitating pain on ambulation. At present, patients with loosened prostheses can only undergo revision surgery. This procedure is often extensive (3–5 hr surgery and over 1 liter of blood loss), due to the necessity of removing the prosthesis and all interface tissue; thereafter a new prosthesis is implanted. This revision surgery has a high complication rate in elderly patients with comorbidities (e.g. cardiovascular disease, diabetes etc), which can even result into death in a small percentage. Because of this high complication rate, this demanding procedure cannot be performed in patients with a poor general health, thus these patients remain with this debilitating pain. Therefore, we investigated the possibilities of an alternative minimally invasive refixation procedure that leaves the prosthesis in place, but relies on removing the periprosthetic interface membrane and replacing it with bone cement. Before the refixation procedure can be executed this way, an instrument to remove the interface tissue needs to be developed.