Fig. 8.

The labrum zones of circulation: a Zone II—inner or articular side and c Zone I—outer or capsular side. Each of these is then divided into the peripheral part, IA and IIA, and the part closest to the acetabular rim, IB and IIB. The main vascular source is from the bony rim that primarily supplies Zone IB, the capsular side of the labrum closest to the rim (green arrow and open arrow). From there, the circulation extends to the periphery, to the peripheral capsular Zone IA (red arrow and white arrow). Through this peripheral capsular side, Zone IA, the peripheral articular side, Zone IIA is supplied. The inner articular side, merging with the articular cartilage, Zone IIB is relatively avascular (black arrow) (modified with permission from Kelly et al. [11]: (a) p. 9, Fig. 6; (b) p. 6, Fig. 3A; (c) p. 10, Fig. 7)