In the last year, there has been increased interest in surface replacement surgery. This is a procedure that replaces the socket side of a hip with a metal shell and the ball side with a metal cap with a very short stem which is cemented over the ball of the hip joint. This is different from a traditional total hip replacement in that a hip replacement involves a stem which goes down the inside of the thighbone for approximately 5 inches and has a metal ball attached to it. In the past, surface replacements have not yielded as good a result when compared to total hip replacement. Therefore, it use was generally abandoned in the United States.
There has been renewed interest in surface replacement, particularly in Europe and Australia, and there are several implant companies awaiting approval for surface replacement surgery in the United States. The perceived benefit of surface replacement is the use of a large ball which will improve range of motion and decrease the dislocation rate. This advantage has seemed to outweigh the disadvantage of decreased longevity with surface replacement. In the last two years, there has been an introduction of large head total hip replacements. We now have extremely large head sizes available for standard total hip replacements making range of motion and stability a reality for hip replacement as well. These improvements in total hip replacements have perhaps rendered some of the potential benefits of surface replacement less compelling.
The advantage of a large head total hip replacement includes better motion and better stability to avoid dislocation. These large-head total hip replacements are metal-on-metal bearings. With this type of bearing, the larger size favors less wear and better lubrication. Ask your orthopedic surgeon about advancements in head size to total hip replacement.