Fig. 3From: Reliability and validity test of a novel three-dimensional acetabular bone defect classification system aided with additive manufacturingIllustration of the three-point fixation spanning over 180 degrees. A the cup rotates when only fixed by two points; B the cup inclines to the unsupported side when fixed by three points spanning within 180 degrees; C three points spanning over 180 degrees hold the hemisphere cup firmlyBack to article page