DEAR DOCTOR K: You recently discussed hip replacement in your column. Shouldn’t the option of hip resurfacing have been part of the discussion?

DEAR READER: In the column you’re referring to, a reader in his 50s asked how to time his hip replacement. I advised him to find a balance: “Operate too soon, and you’ll increase your chance of revision surgery; wait too long, and you’ll subject yourself to additional months and years of pain.” What I told him was correct. I didn’t mention an additional option, hip resurfacing, because in my opinion, its long-term success is untested.

The hip is a ball-and-socket joint. The ball – the top of the femur – fits into the socket, the cup-shaped area in the pelvis called the acetabulum. In a total hip replacement, the surgeon removes the damaged surface of the socket, and also removes the femoral head and the neck of the femur. Then the surgeon replaces the surface of the socket and the top of the femur bone with artificial components.

In a hip resurfacing, the surgeon replaces the socket, as in a hip replacement. However, the surgeon keeps the femur in place, reshapes the ball on top of the femur and places an artificial cap (a new “surface”) on top of the ball.

So far, so good. But now the problems start. First of all, not everyone who needs hip surgery can have hip resurfacing. That includes small women with poor bone quality and people with certain femoral head anatomies that make femur fractures more likely.

And here’s the bigger problem: Traditional total hip replacement surgery has been practiced for nearly 50 years; we know a lot about the long-term results. The artificial parts of the new hip tend to last between 15 and 20 years. Hip resurfacing surgery is new enough that we really don’t know how long it will last.

Finally, there’s an increased risk of a particular fracture in hip resurfacing patients. And it requires a second operation – a hip replacement.