Abstract
The correlation between the thickness and the macroscopic changes of the articular cartilage of the tibial plateau was studied in order to reveal the meaning of the thickness of articular cartilage to the development of degenerative arthritis. Previously 52 cadaver knees from persons aged 49 to 85 years old had been examined to study macroscopic changes of the tibial plateau. The surface morphology and topographical distribution of the lesions were described for the submeniscal region of the tibial plateau and its uncovered region. The degenerative changes of the articular surface were examined by the naked eye for the following four grades of lesion; normal, fibrillation of the superficial layer, fragmentation and fissuring, and ulceration and/or eburnation. The 20 specimens with minimal change of the articular surface among those 52 cadaver knees were chosen, then dehydrated by alcohol and perfused in polyester resins. Each specimen was cut consecutively with a vertical milling machine in the frontal plane. The thickness of the articular cartilage in each cut was assessed.
Degenerative changes of the tibial plateau were more encountered at the uncovered region than the submeniscal region except at its lateral posterior segment. Gross degenerative change such as erosion, ulceration and eburnation was almost extirely localized at the posterior segment of the submeniscal region of the lateral tibial plateau, and at the intercondylar eminence region of a few knees. The distributed pattern of the cartilage thickness was classified into 3 types on each side of the tibial plateau. The thicker cartilage was distributed from the area of the uncovered region to the posterior segment of the submeniscal region. It was shown to be the same as the distribution of the degenerative changes of the tibial plateau. These areas that frequently encountered degenerative changes and had thicker cartilage were nearly equal to the so-called contact area of tibio-femoral articulation. According to these findings it is probable that the articular cartilage tends to be thickened at the weight-bearing area, and then degenerates due to the heavy loads and its own thickness.
