Variation of collagen fiber alignment in a joint surface: A scanning electron microscope study of the tibial plateau in dog, rabbit, and man

TLDR

The study examined whether collagen fiber organization in articular cartilage varies by location on the tibial plateau across dogs, humans, and rabbits using scanning electron microscopy. Specimens were fixed, dehydrated, and radially fractured to compare peripheral and central regions on the same joint surface. Fibers were more tightly packed on the lateral side and periphery, with the center exhibiting thicker cartilage dominated by a radial zone of straight vertical fibers; the periphery’s tangential and transitional zones comprised up to 50 % of cartilage depth compared to only 5 % centrally, explaining the center’s soft, dull appearance due to the absence of a true surface layer of tangential fibers.

Abstract

Abstract To determine if articular cartilage collagen fiber organization differs with location on the tibial plateau, specimens from dogs, humans, and rabbits were studied by scanning electron microscopy. Joint surfaces were fixed, dehydrated, and fractured radially so that the periphery could be compared with the center on single specimens. Generally, fibers were more tightly packed in the lateral side than in the medial and in the periphery as compared with the center, where the cartilage was consistently thicker and the radial zone was dominant and composed of straight vertical fibers. In the periphery, the tangential and transitional zones were better developed and contributed up to 50% of the cartilage depth in comparison to only 5% centrally. The soft, dull, malacic appearance of the center results from lack of a true surface layer of tangential collagen fibers.