Normal and healing ligament vascularity: a quantitative histological assessment in the adult rabbit medial collateral ligament.

Normal and healing adult rabbit medial collateral ligaments (MCL) have been assessed for microvascular anatomy using a quantitative image analysis methodology. MCL preparation by ink-gelatin perfusion enabled acceptable visualisation of microvascular channels within the tissue. Fifteen adult rabbits were studied; 3 normal rabbits formed an external time-zero control group; 12 animals received a standardised gap injury to the right MCL. The ligament injury was permitted to heal for 3, 6, 17 or 40 wk (3 animals in each healing group). Results confirmed that the normal MCL is hypovascular (about 1.46% vascularity by area) and that microvascular channels are highly organised and oriented longitudinally deep within the tissue. Healing MCL scar becomes twice as vascular as normal ligament early on, but returns to near normal values by 40 wk. Microvascular channels appear less organised in scar than in contralateral controls, but remodel with time. The directional scatter and spatial extent of ligament microvascular channels is quantifiable in normal and healing tissues.