Table 1.

Reference points (RP) and lines (RL) used for dividing the ovine tibial plateau into subregions based on 2-D micro-CT images.

Reference point/line	Description	Comment
RP1	Posterior edge of the medial tibial plateau.	First image of the data set showing the bony tibial plateau. Definition: 0% of the tibial plateau length.
RP2	Posterior beginning of the medial tibial spine as position where the medial tibial spine starts to emerge as seen from posterior.	Although the lateral tibial spine starts more posterior, this beginning of the medial tibial spine can be better identified.
RP3	Position of the point (saddle) where the medial tibial spine fuses with the lateral tibial spine as seen from posterior.	The point where both tibial spines fuse is easily recognizable because of its flat U-form, comparable to a saddle.
RP4	Position where the bony prominence of the area intercondylaris anterior starts to emerge above the height of the anterior end of both tibial spines.	This point is located similar to the anterior beginning of the medial tibial spine.
RP5	Anterior edge of the lateral tibial plateau. Anterior beginning of the bony part of the lateral tibial plateau, similar to the bony groove of the extensor digitorum longus tendon.	Definition: 100% of the tibial plateau length. This is not the last image of the data set, as the prominent tibial tuberosity (where the patellar tendon attaches) follows more anteriorly, outside of both tibial plateaus.
RL1	Line parallel to the coronal section of the tibial plateau, crossing RP1.
RL2	Line parallel to the coronal section of the tibial plateau, crossing RP2.	RL2 is not needed for determining the regions.
RL3	Line parallel to the coronal section of the tibial plateau, crossing RP3.
RL4	Line parallel to the coronal section of the tibial plateau, crossing RP4.
RL5	Line parallel to the coronal section of the tibial plateau, crossing RP5.
RL6	Line connecting the halving point of RL3 between the lateral tibial spine and external edge of the lateral tibial plateau, with the halving point of RL4 between the lateral tibial spine and the external edge of the lateral tibial plateau.	RL6 or RL7 lines can be made visible in the micro-CT analysing programs (e.g. CTan from Bruker Micro-CT) as defining small regions of interests (ROIs) on the fixed points of the RLs described here, and performing inter- and extrapolation through the whole image set.
RL7	Line connecting the halving point of RL3 between the medial tibial spine and the external edge of the medial tibial plateau, with the point where RL5 meets with the edge of the medial tibial plateau.
RL8	Peripheral margin, lateral tibial plateau.
RL9	Peripheral margin, medial tibial plateau.
RL10	Line spanning along the lateral tibial spine, representing the central margin of the lateral tibial plateau.	RL10 or RL11 lines can be made visible in the micro-CT analysing program as defining small ROIs on the lateral or medial tibial spines and performing inter- and extrapolation through the whole image set.
RL11	Line spanning along the medial tibial spine, representing the central margin of the medial tibial plateau.