THE NEED FOR NAVIGATION IN HIP RESURFACING

Abstract

Hip resurfacing is a challenging task. Not only because of the historic failure of the early resurfacings, like the Wagner cup, that mainly failed due to deficits in technology. But two other issues make resurfacing such a difficult undertaking: the femoral head and neck are not removed, which makes access to the acetabulum more difficult.

There are two critical steps during hip resurfacing that call for utmost precision: the placement of the central guiding rod in the femoral head and neck and the orientation of the cup. The central head/neck rod is crucial for the success of the surgery: it decides upon the alignment of the femoral component and whether any impingement with the femoral neck occurs or not. Initially this rod was introduced in a retrograde fashion from the lateral side, using a jig similar to those used during arthroscopic k-wire placement. This worked well and safely, yet required a large extension of the incision, which seems unacceptable in these minimal invasive days. The new jig allows for smaller incisions and seems to be working well, but still requires a lot of talent and/or training on behalf of the surgeon, and certainly is not fail safe. It is rather based on trial and error. Simple computer navigated placement of the central rod is feasible, cheap and fast, and it will guarantee precision in every case.

The same goes for cup placement. As the method requires a rather big cup, there is not much room for correction once the acetabulum is reamed. The very enlightening publications from Tony DiGioia and Branko Jaramaz have shown the susceptibility for error during cup reaming and placement. Adaptation of the existing navigation systems for the purposes of hip resurfacing is simple and fast. One should not hesitate to incorporate this extra quantum of security for the sake of the patients, for the sake of the method and, last but not least, for the sake of the surgeons.