My husband is going to have a total hip replacement. The surgeon showed us the different types of implants. I noticed one that looked like a clothespin on the end. What does that feature offer that the regular implant doesn’t have?

Implant designers are looking for ways to get a good solid implantation without problems such as implant loosening, fracture, or bone loss. Research tells us that the stiffer the implant, the greater the amount of bone loss.

In an effort to reduce this bone loss, companies are designing and doctors are trying different implant designs. The first wave of studies compared implants made of different materials such as chromium or titanium.

The second series of studies looked at the coating painted onto the implants. The thought was that bone responded differently to various kinds of coatings. This research is ongoing but so far has not been conclusive.

Geometric angles, width of implants, and now slots or flutes in the bottom have all been examined. The clothes-pin design you saw splits the bottom part of the stem in an effort to reduce implant ridigity. So far studies have not shown a significant difference with this feature.

Now researchers have reason to believe the shape, size, and design at the top of the implant may be more important than the bottom tip. More studies are needed before the perfect implant design is invented. Until then, a wide variety of sizes, shapes, and materials will be tried.