Figure 1.
Continuum of knee joint connective tissues.
Based on their structural compositions, the major connective tissues of the knee joint can be conceptualized along a continuum from hyaline (condylar and patellar cartilage), to fibrocartilaginous (meniscus), to fibrous (ligament).
Figure 2.
Histology of representative joint tissues.
Picrosirius red staining for collagen showed that hyaline cartilage, meniscus, and ligament all had significant collagen content. The meniscus and ligament samples stained more intensely for collagen than hyaline cartilage. Safranin O/fast green staining for GAG showed that hyaline cartilage had significant GAG content; meniscus and ligament did not exhibit GAG staining.
Figure 3.
Collagen and pyridinoline content of joint tissues.
(A) Collagen normalized to wet weight was significantly higher for the menisci, collateral ligaments, and patellar ligament. (B) Collagen normalized to dry weight was highest in the menisci and lowest in the hyaline cartilages. (C) Pyridinoline normalized to wet weight was highest for menisci, patellar ligament, and the caudal cruciate ligament. Crosslink content was lowest for patellar cartilage. (D) Pyridinoline normalized to collagen was highest for the hyaline cartilages and cruciate ligaments. Groups denoted by different letters are significantly different (p<0.05).
Figure 4.
Tensile properties of joint tissues.
(a) Young's modulus was highest for the menisci and patellar ligament and lowest for the cranial cruciate ligament. (b) Ultimate tensile strength was also higher for the patellar ligament and the menisci. Groups denoted by different letters are significantly different (p<0.05).