Method of CT-osteoabsorptiometry on 3D reconstructions to determine density distribution within the subchondral bone plate. (a) Distal femur in posterior view with fabella arranged in anterior view (subchondral bone plate of articular surface shown). (b) Subchondral bone plates shown with colour-coded density distribution (black, red, yellow, green, and blue = Hounsfield units in descending order in 200 unit steps). (c) Fabella in original position on density distribution pattern. (d) Density distribution with marked region of fabella contact on the posterolateral femoral condyle.