Figure 1From: A comparison of polyethylene wear between cobalt-chrome ball heads and alumina ball heads after total hip arthroplasty: a 10-year follow-upSchematic diagram of the measurement techniques for acetabular cup wear. A circle was drawn to determine the size of the head. A line was then drawn connecting the lateral opening of the cup, and the distances between the head and the cup (a and c) were measured.Back to article page