In hip resurfacing, a metal cap is glued on the arthritic ball instead of replacing the ball itself. Some implant companies and surgeons have promoted hip resurfacing in recent years, but hip resurfacing has been around for many decades.
Hip resurfacing and hip replacement are similar. Both replace all arthritic surfaces in the arthritic hip. On the socket side, both operations entail removing a layer of arthritic bone and cartilage from the pelvis, and replacing it with a metal cup.
The main difference between hip replacement and hip resurfacing is what is done to the femoral bone (thighbone).
In hip resurfacing, the arthritic ball is prepared such that a metal cap is glued onto your bone. The diameter of the metal cap matches that of the artificial socket.
In hip replacement, the arthritic femoral ball is cut and replaced with a new ball. The inside of the femur bone is prepared to implant a metal stem 3 to 5 inches in length. On this stem, a mechanism allows attachment of a metal or ceramic ball that matches the size of the socket. Once the ball is placed into the socket, the hip replacement is complete.
A hip resurfacing is more expensive because surgical time is longer and the implants are more costly. At present, the parts for hip resurfacing cost about twice as much as hip replacement parts.
The advantage of hip resurfacing is preservation of 1 to 2 inches of bone, on top of the thighbone. In theory, if you need repeat surgery in the future, this bone is available to the surgeon to work with.
This made sense in previous decades, when the lifespan of hip replacements was limited by material quality; the older synthetic ball-socket would wear out in 10 to 15 years. The wear particles would result in inflammation and bone loss around the implants. As a result, the implants would loosen, requiring repeat surgery.
Modern hip replacement bearings and implants are much improved though, and should outlast the lifespan of most patients. This assumes of course that the prosthetic parts are properly implanted and accurately aligned during surgery.
Also, today, if repeat surgery is needed on a prosthetic hip, modern metal technologies allow us to rebuild and reconstitute missing skeletal bone.
Therefore, the only advantage of hip resurfacing (preservation of an insignificant amount of femoral bone) when compared to hip replacement, has little practical value.
Hip resurfacing and replacement feel the same to patients, and are equally effective in relieving pain, restoring function, and restoring the ability to participate in any activity.
One, the metal cap must be glued to the arthritic femoral head. This glue can loosen up over time, causing the resurfacing to fail. There is no cement-less version of the metal cap in hip resurfacing.
Two, the bone directly underneath the metal cap, called the femoral neck, can break, especially if it is weakened during implantation of the metal cap. If this happens, urgent surgery is needed to convert the hip resurfacing to a hip replacement.
Three, hip resurfacing is more invasive than hip replacement. Since the femoral head is preserved in hip resurfacing, the surgeon has less room to work; therefore, the incision is longer and the surgical exposure is more extensive with hip resurfacing. Some surgical methods, such as the anterior surgical approach, allow hip resurfacing through a less invasive approach, but the operation is still more extensive than a hip replacement.
Four, the only kind of bearing in hip resurfacing is metal-on-metal. In hip resurfacing, the inside of the socket is a polished metal, and so is the metal cap that covers the femoral head. Actual hip movement in hip resurfacing is from metal-metal contact; this bearing is the only one possible in all modern hip resurfacings. Recent studies have raised a worry that metal-metal hip bearings can cause a reaction in some patients, requiring more surgery.
A key advantage is its longevity and track record. The technology used in modern hip replacements is safe and well-proven in millions of patients. The nuances, complications, surgical techniques, and outcomes of this operation have been thoroughly investigated. A properly performed hip replacement should outlast the patient; this is significant since no one wants repeat surgery.
Of note, different bearing surfaces can be used in hip replacement. This is because there is more latitude in the engineering design of hip replacement components. In hip replacement, once the metal shell and the femoral stem are implanted, the surgeon and patient have a choice of bearing, including metal-metal, metal-plastic, metal-ceramic, ceramic-plastic, and ceramic-ceramic.
Also, hip replacement bearings can be changed out several years after the surgery; the bearings are removable independent of the implants. In contrast, hip resurfacing bearings cannot be changed; the entire component must be removed, along with some bone, if a change of bearing is desired for any reason in the future.
The disadvantage, when compared to hip resurfacing, is that an additional 1 to 2 inches of bone at the top of the femur must be sacrificed. However, removal of this bone is of little, if any, practical consequence. If a hip replacement should ever fail, repeat surgery is relatively straightforward and predictable in the hands of an experienced surgeon. Also, we have many ways of making up for lost bone today; saving an inch or two of bone is of no clinical consequence over the long-term.
If a hip resurfacing is your choice, then that is the operation we will perform for you. In our practice, there is no preference or bias, nor any financial inducement toward one procedure or the other. The above comments are presented to share information known to professionals in our field, and may differ from claims made by hospitals and surgeons promoting hip resurfacing.