COLLAGEN FIBRIL DIAMETERS IN THE RABBIT MEDIAL COLLATERAL LIGAMENT SCAR - A LONGER TERM ASSESSMENT

Previous transmission electron microscopic investigations of collagen fibril diameters in rabbit medial collateral ligament (MCL) scars have indicated a homogeneous population of small fibrils for the first 40 weeks of healing, In this stud; four 8 mm MCL gap scars were studied a t 78 weeks of healing and another three at 104 weeks, Results showed i ncreased heterogeneity in the distribution of fibril diameters in all scars, with the appearance of progressively slightly larger fibrils in 78 and 104 week specimens, All longer term scars still contained roug hly 90% small fibrils plus some ''patches'' of larger fibrils, but the re was considerable variation between animals in these proportions, No scar contained the fibril populations typical of uninjured adult rabb it MCLs, These results suggest slow but on-going collagen fibril turno ver and remodeling in this gap healing rabbit MCL model via currently unidentified mechanisms.