W hen Engh Jr. and colleagues began studying metal-on-metal (MoM) versus ceramic-on-metal (CoM) bearings, determining the articulation of choice was an important question—at the time (between August 2005 and October 2006) MoM bearings were gaining in popularity. Therefore, a study that compares two different hard surfaces articulating with the same design of metal acetabular components promised to shed light on the relative performance of metal versus ceramic heads in this articulation. Nearly a decade later, MoM components have suffered a number of failures, as well as the recall of one design followed by lawsuits. All of this has dramatically reduced the interest in, and use of, hard bearings with a metal acetabular components. Today, the comparison might considered less relevant than it otherwise would have been. While there is decreased enthusiasm for these devices in the marketplace, it is important that we continue to follow and report on as many of the patients with hard-on-hard bearings as possible. The paper by Engh Jr. and colleagues provides short-term results of a well-designed and closely studied group of patients, which suggests that, against metal acetabula, ceramic heads may do somewhat better than metal heads in terms of survivorship. An important question still remains: Why do articulations with a ceramic head result in fewer revisions?